res_sorcery_memory_cache.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2015, Digium, Inc.
 *
 * Joshua Colp <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*!
 * \file
 *
 * \brief Sorcery Memory Cache Object Wizard
 *
 * \author Joshua Colp <[email protected]>
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/module.h"
#include "asterisk/sorcery.h"
#include "asterisk/astobj2.h"
#include "asterisk/sched.h"
#include "asterisk/test.h"
#include "asterisk/heap.h"
#include "asterisk/cli.h"
#include "asterisk/manager.h"

/*** DOCUMENTATION
   <manager name="SorceryMemoryCacheExpireObject" language="en_US">
      <synopsis>
         Expire (remove) an object from a sorcery memory cache.
      </synopsis>
      <syntax>
         <xi:include xpointer="xpointer(/docs/manager[@name='Login']/syntax/parameter[@name='ActionID'])" />
         <parameter name="Cache" required="true">
            <para>The name of the cache to expire the object from.</para>
         </parameter>
         <parameter name="Object" required="true">
            <para>The name of the object to expire.</para>
         </parameter>
      </syntax>
      <description>
         <para>Expires (removes) an object from a sorcery memory cache. If full backend caching is enabled
         this action is not available and will fail. In this case the SorceryMemoryCachePopulate or
         SorceryMemoryCacheExpire AMI actions must be used instead.</para>
      </description>
   </manager>
   <manager name="SorceryMemoryCacheExpire" language="en_US">
      <synopsis>
         Expire (remove) ALL objects from a sorcery memory cache.
      </synopsis>
      <syntax>
         <xi:include xpointer="xpointer(/docs/manager[@name='Login']/syntax/parameter[@name='ActionID'])" />
         <parameter name="Cache" required="true">
            <para>The name of the cache to expire all objects from.</para>
         </parameter>
      </syntax>
      <description>
         <para>Expires (removes) ALL objects from a sorcery memory cache.</para>
      </description>
   </manager>
   <manager name="SorceryMemoryCacheStaleObject" language="en_US">
      <synopsis>
         Mark an object in a sorcery memory cache as stale.
      </synopsis>
      <syntax>
         <xi:include xpointer="xpointer(/docs/manager[@name='Login']/syntax/parameter[@name='ActionID'])" />
         <parameter name="Cache" required="true">
            <para>The name of the cache to mark the object as stale in.</para>
         </parameter>
         <parameter name="Object" required="true">
            <para>The name of the object to mark as stale.</para>
         </parameter>
         <parameter name="Reload" required="false">
            <para>If true, then immediately reload the object from the backend cache instead of waiting for the next retrieval</para>
         </parameter>
      </syntax>
      <description>
         <para>Marks an object as stale within a sorcery memory cache.</para>
      </description>
   </manager>
   <manager name="SorceryMemoryCacheStale" language="en_US">
      <synopsis>
         Marks ALL objects in a sorcery memory cache as stale.
      </synopsis>
      <syntax>
         <xi:include xpointer="xpointer(/docs/manager[@name='Login']/syntax/parameter[@name='ActionID'])" />
         <parameter name="Cache" required="true">
            <para>The name of the cache to mark all object as stale in.</para>
         </parameter>
      </syntax>
      <description>
         <para>Marks ALL objects in a sorcery memory cache as stale.</para>
      </description>
   </manager>
   <manager name="SorceryMemoryCachePopulate" language="en_US">
      <synopsis>
         Expire all objects from a memory cache and populate it with all objects from the backend.
      </synopsis>
      <syntax>
         <xi:include xpointer="xpointer(/docs/manager[@name='Login']/syntax/parameter[@name='ActionID'])" />
         <parameter name="Cache" required="true">
            <para>The name of the cache to populate.</para>
         </parameter>
      </syntax>
      <description>
         <para>Expires all objects from a memory cache and populate it with all objects from the backend.</para>
      </description>
   </manager>
 ***/

/*! \brief Structure for storing a memory cache */
struct sorcery_memory_cache {
   /*! \brief The name of the memory cache */
   char *name;
   /*! \brief Objects in the cache */
   struct ao2_container *objects;
   /*! \brief The maximum number of objects permitted in the cache, 0 if no limit */
   unsigned int maximum_objects;
   /*! \brief The maximum time (in seconds) an object will stay in the cache, 0 if no limit */
   unsigned int object_lifetime_maximum;
   /*! \brief The amount of time (in seconds) before an object is marked as stale, 0 if disabled */
   unsigned int object_lifetime_stale;
   /*! \brief Whether all objects are expired when the object type is reloaded, 0 if disabled */
   unsigned int expire_on_reload;
   /*! \brief Whether this is a cache of the entire backend, 0 if disabled */
   unsigned int full_backend_cache;
   /*! \brief Heap of cached objects. Oldest object is at the top. */
   struct ast_heap *object_heap;
   /*! \brief Scheduler item for expiring oldest object. */
   int expire_id;
   /*! \brief scheduler id of stale update task */
   int stale_update_sched_id;
   /*! \brief An unreffed pointer to the sorcery instance, accessible only with lock held */
   const struct ast_sorcery *sorcery;
   /*! \brief The type of object we are caching */
   char *object_type;
   /*! TRUE if trying to stop the oldest object expiration scheduler item. */
   unsigned int del_expire:1;
#ifdef TEST_FRAMEWORK
   /*! \brief Variable used to indicate we should notify a test when we reach empty */
   unsigned int cache_notify;
   /*! \brief Mutex lock used for signaling when the cache has reached empty */
   ast_mutex_t lock;
   /*! \brief Condition used for signaling when the cache has reached empty */
   ast_cond_t cond;
   /*! \brief Variable that is set when the cache has reached empty */
   unsigned int cache_completed;
#endif
};

/*! \brief Structure for stored a cached object */
struct sorcery_memory_cached_object {
   /*! \brief The cached object */
   void *object;
   /*! \brief The time at which the object was created */
   struct timeval created;
   /*! \brief index required by heap */
   ssize_t __heap_index;
   /*! \brief scheduler id of stale update task */
   int stale_update_sched_id;
   /*! \brief Cached objectset for field and regex retrieval */
   struct ast_variable *objectset;
};

/*! \brief Structure used for fields comparison */
struct sorcery_memory_cache_fields_cmp_params {
   /*! \brief Pointer to the sorcery structure */
   const struct ast_sorcery *sorcery;
   /*! \brief The sorcery memory cache */
   struct sorcery_memory_cache *cache;
   /*! \brief Pointer to the fields to check */
   const struct ast_variable *fields;
   /*! \brief Regular expression for checking object id */
   regex_t *regex;
   /*! \brief Prefix for matching object id */
   const char *prefix;
   /*! \brief Prefix length in bytes for matching object id */
   const size_t prefix_len;
   /*! \brief Optional container to put object into */
   struct ao2_container *container;
};

static void *sorcery_memory_cache_open(const char *data);
static int sorcery_memory_cache_create(const struct ast_sorcery *sorcery, void *data, void *object);
static void sorcery_memory_cache_load(void *data, const struct ast_sorcery *sorcery, const char *type);
static void sorcery_memory_cache_reload(void *data, const struct ast_sorcery *sorcery, const char *type);
static void *sorcery_memory_cache_retrieve_id(const struct ast_sorcery *sorcery, void *data, const char *type,
   const char *id);
static void *sorcery_memory_cache_retrieve_fields(const struct ast_sorcery *sorcery, void *data, const char *type,
   const struct ast_variable *fields);
static void sorcery_memory_cache_retrieve_multiple(const struct ast_sorcery *sorcery, void *data, const char *type,
   struct ao2_container *objects, const struct ast_variable *fields);
static void sorcery_memory_cache_retrieve_regex(const struct ast_sorcery *sorcery, void *data, const char *type,
   struct ao2_container *objects, const char *regex);
static void sorcery_memory_cache_retrieve_prefix(const struct ast_sorcery *sorcery, void *data, const char *type,
   struct ao2_container *objects, const char *prefix, const size_t prefix_len);
static int sorcery_memory_cache_delete(const struct ast_sorcery *sorcery, void *data, void *object);
static void sorcery_memory_cache_close(void *data);

static struct ast_sorcery_wizard memory_cache_object_wizard = {
   .name = "memory_cache",
   .open = sorcery_memory_cache_open,
   .create = sorcery_memory_cache_create,
   .update = sorcery_memory_cache_create,
   .delete = sorcery_memory_cache_delete,
   .load = sorcery_memory_cache_load,
   .reload = sorcery_memory_cache_reload,
   .retrieve_id = sorcery_memory_cache_retrieve_id,
   .retrieve_fields = sorcery_memory_cache_retrieve_fields,
   .retrieve_multiple = sorcery_memory_cache_retrieve_multiple,
   .retrieve_regex = sorcery_memory_cache_retrieve_regex,
   .retrieve_prefix = sorcery_memory_cache_retrieve_prefix,
   .close = sorcery_memory_cache_close,
};

/*! \brief The bucket size for the container of caches */
#define CACHES_CONTAINER_BUCKET_SIZE 53

/*! \brief The default bucket size for the container of objects in the cache */
#define CACHE_CONTAINER_BUCKET_SIZE 53

/*! \brief Height of heap for cache object heap. Allows 31 initial objects */
#define CACHE_HEAP_INIT_HEIGHT 5

/*! \brief Container of created caches */
static struct ao2_container *caches;

/*! \brief Scheduler for cache management */
static struct ast_sched_context *sched;

#define PASSTHRU_UPDATE_THREAD_ID 0x5EED1E55
AST_THREADSTORAGE(passthru_update_id_storage);

static int is_passthru_update(void)
{
   uint32_t *passthru_update_thread_id;

   passthru_update_thread_id = ast_threadstorage_get(&passthru_update_id_storage,
      sizeof(*passthru_update_thread_id));
   if (!passthru_update_thread_id) {
      return 0;
   }

   return *passthru_update_thread_id == PASSTHRU_UPDATE_THREAD_ID;
}

static void set_passthru_update(uint32_t value)
{
   uint32_t *passthru_update_thread_id;

   passthru_update_thread_id = ast_threadstorage_get(&passthru_update_id_storage,
      sizeof(*passthru_update_thread_id));
   if (!passthru_update_thread_id) {
      ast_log(LOG_ERROR, "Could not set passthru update ID for sorcery memory cache thread\n");
      return;
   }

   *passthru_update_thread_id = value;
}

static void start_passthru_update(void)
{
   set_passthru_update(PASSTHRU_UPDATE_THREAD_ID);
}

static void end_passthru_update(void)
{
   set_passthru_update(0);
}

/*!
 * \internal
 * \brief Hashing function for the container holding caches
 *
 * \param obj A sorcery memory cache or name of one
 * \param flags Hashing flags
 *
 * \return The hash of the memory cache name
 */
static int sorcery_memory_cache_hash(const void *obj, int flags)
{
   const struct sorcery_memory_cache *cache = obj;
   const char *name = obj;
   int hash;

   switch (flags & OBJ_SEARCH_MASK) {
   default:
   case OBJ_SEARCH_OBJECT:
      name = cache->name;
      /* Fall through */
   case OBJ_SEARCH_KEY:
      hash = ast_str_hash(name);
      break;
   case OBJ_SEARCH_PARTIAL_KEY:
      /* Should never happen in hash callback. */
      ast_assert(0);
      hash = 0;
      break;
   }
   return hash;
}

/*!
 * \internal
 * \brief Comparison function for the container holding caches
 *
 * \param obj A sorcery memory cache
 * \param arg A sorcery memory cache, or name of one
 * \param flags Comparison flags
 *
 * \retval CMP_MATCH if the name is the same
 * \retval 0 if the name does not match
 */
static int sorcery_memory_cache_cmp(void *obj, void *arg, int flags)
{
   const struct sorcery_memory_cache *left = obj;
   const struct sorcery_memory_cache *right = arg;
   const char *right_name = arg;
   int cmp;

   switch (flags & OBJ_SEARCH_MASK) {
   default:
   case OBJ_SEARCH_OBJECT:
      right_name = right->name;
      /* Fall through */
   case OBJ_SEARCH_KEY:
      cmp = strcmp(left->name, right_name);
      break;
   case OBJ_SEARCH_PARTIAL_KEY:
      cmp = strncmp(left->name, right_name, strlen(right_name));
      break;
   }
   return cmp ? 0 : CMP_MATCH;
}

/*!
 * \internal
 * \brief Hashing function for the container holding cached objects
 *
 * \param obj A cached object or id of one
 * \param flags Hashing flags
 *
 * \return The hash of the cached object id
 */
static int sorcery_memory_cached_object_hash(const void *obj, int flags)
{
   const struct sorcery_memory_cached_object *cached = obj;
   const char *name = obj;
   int hash;

   switch (flags & OBJ_SEARCH_MASK) {
   default:
   case OBJ_SEARCH_OBJECT:
      name = ast_sorcery_object_get_id(cached->object);
      /* Fall through */
   case OBJ_SEARCH_KEY:
      hash = ast_str_hash(name);
      break;
   case OBJ_SEARCH_PARTIAL_KEY:
      /* Should never happen in hash callback. */
      ast_assert(0);
      hash = 0;
      break;
   }
   return hash;
}

/*!
 * \internal
 * \brief Comparison function for the container holding cached objects
 *
 * \param obj A cached object
 * \param arg A cached object, or id of one
 * \param flags Comparison flags
 *
 * \retval CMP_MATCH if the id is the same
 * \retval 0 if the id does not match
 */
static int sorcery_memory_cached_object_cmp(void *obj, void *arg, int flags)
{
   struct sorcery_memory_cached_object *left = obj;
   struct sorcery_memory_cached_object *right = arg;
   const char *right_name = arg;
   int cmp;

   switch (flags & OBJ_SEARCH_MASK) {
   default:
   case OBJ_SEARCH_OBJECT:
      right_name = ast_sorcery_object_get_id(right->object);
      /* Fall through */
   case OBJ_SEARCH_KEY:
      cmp = strcmp(ast_sorcery_object_get_id(left->object), right_name);
      break;
   case OBJ_SEARCH_PARTIAL_KEY:
      cmp = strncmp(ast_sorcery_object_get_id(left->object), right_name, strlen(right_name));
      break;
   }
   return cmp ? 0 : CMP_MATCH;
}

/*!
 * \internal
 * \brief Destructor function for a sorcery memory cache
 *
 * \param obj A sorcery memory cache
 */
static void sorcery_memory_cache_destructor(void *obj)
{
   struct sorcery_memory_cache *cache = obj;

   ast_free(cache->name);
   if (cache->object_heap) {
      ast_heap_destroy(cache->object_heap);
   }
   ao2_cleanup(cache->objects);
   ast_free(cache->object_type);
}

/*!
 * \internal
 * \brief Destructor function for sorcery memory cached objects
 *
 * \param obj A sorcery memory cached object
 */
static void sorcery_memory_cached_object_destructor(void *obj)
{
   struct sorcery_memory_cached_object *cached = obj;

   ao2_cleanup(cached->object);
   ast_variables_destroy(cached->objectset);
}

static int schedule_cache_expiration(struct sorcery_memory_cache *cache);

/*!
 * \internal
 * \brief Remove an object from the cache.
 *
 * This removes the item from both the hashtable and the heap.
 *
 * \pre cache->objects is write-locked
 *
 * \param cache The cache from which the object is being removed.
 * \param id The sorcery object id of the object to remove.
 * \param reschedule Reschedule cache expiration if this was the oldest object.
 *
 * \retval 0 Success
 * \retval non-zero Failure
 */
static int remove_from_cache(struct sorcery_memory_cache *cache, const char *id, int reschedule)
{
   struct sorcery_memory_cached_object *hash_object;
   struct sorcery_memory_cached_object *oldest_object;
   struct sorcery_memory_cached_object *heap_object;

   hash_object = ao2_find(cache->objects, id, OBJ_SEARCH_KEY | OBJ_UNLINK | OBJ_NOLOCK);
   if (!hash_object) {
      return -1;
   }

   ast_assert(!strcmp(ast_sorcery_object_get_id(hash_object->object), id));

   oldest_object = ast_heap_peek(cache->object_heap, 1);
   heap_object = ast_heap_remove(cache->object_heap, hash_object);

   ast_assert(heap_object == hash_object);

   ao2_ref(hash_object, -1);

   if (reschedule && (oldest_object == heap_object)) {
      schedule_cache_expiration(cache);
   }

   return 0;
}

/*!
 * \internal
 * \brief Scheduler callback invoked to expire old objects
 *
 * \param data The opaque callback data (in our case, the memory cache)
 */
static int expire_objects_from_cache(const void *data)
{
   struct sorcery_memory_cache *cache = (struct sorcery_memory_cache *)data;
   struct sorcery_memory_cached_object *cached;

   /*
    * We need to do deadlock avoidance between a non-scheduler thread
    * blocking when trying to delete the scheduled entry for this
    * callback because the scheduler thread is running this callback
    * and this callback waiting for the cache->objects container lock
    * that the blocked non-scheduler thread already holds.
    */
   while (ao2_trywrlock(cache->objects)) {
      if (cache->del_expire) {
         cache->expire_id = -1;
         ao2_ref(cache, -1);
         return 0;
      }
      sched_yield();
   }

   cache->expire_id = -1;

   /* This is an optimization for objects which have been cached close to each other */
   while ((cached = ast_heap_peek(cache->object_heap, 1))) {
      int expiration;

      expiration = ast_tvdiff_ms(ast_tvadd(cached->created, ast_samp2tv(cache->object_lifetime_maximum, 1)), ast_tvnow());

      /* If the current oldest object has not yet expired stop and reschedule for it */
      if (expiration > 0) {
         break;
      }

      remove_from_cache(cache, ast_sorcery_object_get_id(cached->object), 0);
   }

   schedule_cache_expiration(cache);

   ao2_unlock(cache->objects);

   ao2_ref(cache, -1);

   return 0;
}

/*!
 * \internal
 * \brief Remove all objects from the cache.
 *
 * This removes ALL objects from both the hash table and heap.
 *
 * \pre cache->objects is write-locked
 *
 * \param cache The cache to empty.
 */
static void remove_all_from_cache(struct sorcery_memory_cache *cache)
{
   while (ast_heap_pop(cache->object_heap)) {
   }

   ao2_callback(cache->objects, OBJ_UNLINK | OBJ_NOLOCK | OBJ_NODATA | OBJ_MULTIPLE,
      NULL, NULL);

   cache->del_expire = 1;
   AST_SCHED_DEL_UNREF(sched, cache->expire_id, ao2_ref(cache, -1));
   cache->del_expire = 0;
}

/*!
 * \internal
 * \brief AO2 callback function for making an object stale immediately
 *
 * This changes the creation time of an object so it appears as though it is stale immediately.
 *
 * \param obj The cached object
 * \param arg The cache itself
 * \param flags Unused flags
 */
static int object_stale_callback(void *obj, void *arg, int flags)
{
   struct sorcery_memory_cached_object *cached = obj;
   struct sorcery_memory_cache *cache = arg;

   /* Since our granularity is seconds it's possible for something to retrieve us within a window
    * where we wouldn't be treated as stale. To ensure that doesn't happen we use the configured stale
    * time plus a second.
    */
   cached->created = ast_tvsub(cached->created, ast_samp2tv(cache->object_lifetime_stale + 1, 1));

   return CMP_MATCH;
}

/*!
 * \internal
 * \brief Mark an object as stale explicitly.
 *
 * This changes the creation time of an object so it appears as though it is stale immediately.
 *
 * \pre cache->objects is read-locked
 *
 * \param cache The cache the object is in
 * \param id The unique identifier of the object
 *
 * \retval 0 success
 * \retval -1 failure
 */
static int mark_object_as_stale_in_cache(struct sorcery_memory_cache *cache, const char *id)
{
   struct sorcery_memory_cached_object *cached;

   cached = ao2_find(cache->objects, id, OBJ_SEARCH_KEY | OBJ_NOLOCK);
   if (!cached) {
      return -1;
   }

   ast_assert(!strcmp(ast_sorcery_object_get_id(cached->object), id));

   object_stale_callback(cached, cache, 0);
   ao2_ref(cached, -1);

   return 0;
}

/*!
 * \internal
 * \brief Mark all objects as stale within a cache.
 *
 * This changes the creation time of ALL objects so they appear as though they are stale.
 *
 * \pre cache->objects is read-locked
 *
 * \param cache
 */
static void mark_all_as_stale_in_cache(struct sorcery_memory_cache *cache)
{
   ao2_callback(cache->objects, OBJ_NOLOCK | OBJ_NODATA | OBJ_MULTIPLE, object_stale_callback, cache);
}

/*!
 * \internal
 * \brief Schedule a callback for cached object expiration.
 *
 * \pre cache->objects is write-locked
 *
 * \param cache The cache that is having its callback scheduled.
 *
 * \retval 0 success
 * \retval -1 failure
 */
static int schedule_cache_expiration(struct sorcery_memory_cache *cache)
{
   struct sorcery_memory_cached_object *cached;
   int expiration = 0;

   if (!cache->object_lifetime_maximum) {
      return 0;
   }

   cache->del_expire = 1;
   AST_SCHED_DEL_UNREF(sched, cache->expire_id, ao2_ref(cache, -1));
   cache->del_expire = 0;

   cached = ast_heap_peek(cache->object_heap, 1);
   if (!cached) {
#ifdef TEST_FRAMEWORK
      ast_mutex_lock(&cache->lock);
      cache->cache_completed = 1;
      ast_cond_signal(&cache->cond);
      ast_mutex_unlock(&cache->lock);
#endif
      return 0;
   }

   expiration = MAX(ast_tvdiff_ms(ast_tvadd(cached->created, ast_samp2tv(cache->object_lifetime_maximum, 1)), ast_tvnow()),
      1);

   cache->expire_id = ast_sched_add(sched, expiration, expire_objects_from_cache, ao2_bump(cache));
   if (cache->expire_id < 0) {
      ao2_ref(cache, -1);
      return -1;
   }

   return 0;
}

/*!
 * \internal
 * \brief Remove the oldest item from the cache.
 *
 * \pre cache->objects is write-locked
 *
 * \param cache The cache from which to remove the oldest object
 *
 * \retval 0 Success
 * \retval non-zero Failure
 */
static int remove_oldest_from_cache(struct sorcery_memory_cache *cache)
{
   struct sorcery_memory_cached_object *heap_old_object;
   struct sorcery_memory_cached_object *hash_old_object;

   heap_old_object = ast_heap_pop(cache->object_heap);
   if (!heap_old_object) {
      return -1;
   }
   hash_old_object = ao2_find(cache->objects, heap_old_object,
      OBJ_SEARCH_OBJECT | OBJ_UNLINK | OBJ_NOLOCK);

   ast_assert(heap_old_object == hash_old_object);

   ao2_ref(hash_old_object, -1);

   schedule_cache_expiration(cache);

   return 0;
}

/*!
 * \internal
 * \brief Add a new object to the cache.
 *
 * \pre cache->objects is write-locked
 *
 * \param cache The cache in which to add the new object
 * \param cached_object The object to add to the cache
 *
 * \retval 0 Success
 * \retval non-zero Failure
 */
static int add_to_cache(struct sorcery_memory_cache *cache,
      struct sorcery_memory_cached_object *cached_object)
{
   struct sorcery_memory_cached_object *front;

   if (!ao2_link_flags(cache->objects, cached_object, OBJ_NOLOCK)) {
      return -1;
   }

   if (cache->full_backend_cache && (front = ast_heap_peek(cache->object_heap, 1))) {
      /* For a full backend cache all objects share the same lifetime */
      cached_object->created = front->created;
   }

   if (ast_heap_push(cache->object_heap, cached_object)) {
      ao2_find(cache->objects, cached_object,
         OBJ_SEARCH_OBJECT | OBJ_UNLINK | OBJ_NODATA | OBJ_NOLOCK);
      return -1;
   }

   if (cache->expire_id == -1) {
      schedule_cache_expiration(cache);
   }

   return 0;
}

/*!
 * \internal
 * \brief Allocate a cached object for caching an object
 *
 * \param sorcery The sorcery instance
 * \param cache The sorcery memory cache
 * \param object The object to cache
 *
 * \retval non-NULL success
 * \retval NULL failure
 */
static struct sorcery_memory_cached_object *sorcery_memory_cached_object_alloc(const struct ast_sorcery *sorcery,
   const struct sorcery_memory_cache *cache, void *object)
{
   struct sorcery_memory_cached_object *cached;

   cached = ao2_alloc(sizeof(*cached), sorcery_memory_cached_object_destructor);
   if (!cached) {
      return NULL;
   }

   cached->object = ao2_bump(object);
   cached->created = ast_tvnow();
   cached->stale_update_sched_id = -1;

   if (cache->full_backend_cache) {
      /* A cached objectset allows us to easily perform all retrieval operations in a
       * minimal of time.
       */
      cached->objectset = ast_sorcery_objectset_create(sorcery, object);
      if (!cached->objectset) {
         ao2_ref(cached, -1);
         return NULL;
      }
   }

   return cached;
}

/*!
 * \internal
 * \brief Callback function to cache an object in a memory cache
 *
 * \param sorcery The sorcery instance
 * \param data The sorcery memory cache
 * \param object The object to cache
 *
 * \retval 0 success
 * \retval -1 failure
 */
static int sorcery_memory_cache_create(const struct ast_sorcery *sorcery, void *data, void *object)
{
   struct sorcery_memory_cache *cache = data;
   struct sorcery_memory_cached_object *cached;

   cached = sorcery_memory_cached_object_alloc(sorcery, cache, object);
   if (!cached) {
      return -1;
   }

   /* As there is no guarantee that this won't be called by multiple threads wanting to cache
    * the same object we remove any old ones, which turns this into a create/update function
    * in reality. As well since there's no guarantee that the object in the cache is the same
    * one here we remove any old objects using the object identifier.
    */

   ao2_wrlock(cache->objects);
   remove_from_cache(cache, ast_sorcery_object_get_id(object), 1);
   if (cache->maximum_objects && ao2_container_count(cache->objects) >= cache->maximum_objects) {
      if (remove_oldest_from_cache(cache)) {
         ast_log(LOG_ERROR, "Unable to make room in cache for sorcery object '%s'.\n",
            ast_sorcery_object_get_id(object));
         ao2_unlock(cache->objects);
         ao2_ref(cached, -1);
         return -1;
      }
      ast_assert(ao2_container_count(cache->objects) != cache->maximum_objects);
   }
   if (add_to_cache(cache, cached)) {
      ast_log(LOG_ERROR, "Unable to add object '%s' to the cache\n",
         ast_sorcery_object_get_id(object));
      ao2_unlock(cache->objects);
      ao2_ref(cached, -1);
      return -1;
   }
   ao2_unlock(cache->objects);

   ao2_ref(cached, -1);
   return 0;
}

/*!
 * \internal
 * \brief AO2 callback function for adding an object to a memory cache
 *
 * \param obj The cached object
 * \param arg The sorcery instance
 * \param data The cache itself
 * \param flags Unused flags
 */
static int object_add_to_cache_callback(void *obj, void *arg, void *data, int flags)
{
   struct sorcery_memory_cache *cache = data;
   struct sorcery_memory_cached_object *cached;

   cached = sorcery_memory_cached_object_alloc(arg, cache, obj);
   if (!cached) {
      return CMP_STOP;
   }

   add_to_cache(cache, cached);
   ao2_ref(cached, -1);

   return 0;
}

struct stale_cache_update_task_data {
   struct ast_sorcery *sorcery;
   struct sorcery_memory_cache *cache;
   char *type;
};

static void stale_cache_update_task_data_destructor(void *obj)
{
   struct stale_cache_update_task_data *task_data = obj;

   ao2_cleanup(task_data->cache);
   ast_sorcery_unref(task_data->sorcery);
   ast_free(task_data->type);
}

static struct stale_cache_update_task_data *stale_cache_update_task_data_alloc(struct ast_sorcery *sorcery,
      struct sorcery_memory_cache *cache, const char *type)
{
   struct stale_cache_update_task_data *task_data;

   task_data = ao2_alloc_options(sizeof(*task_data), stale_cache_update_task_data_destructor,
      AO2_ALLOC_OPT_LOCK_NOLOCK);
   if (!task_data) {
      return NULL;
   }

   task_data->sorcery = ao2_bump(sorcery);
   task_data->cache = ao2_bump(cache);
   task_data->type = ast_strdup(type);
   if (!task_data->type) {
      ao2_ref(task_data, -1);
      return NULL;
   }

   return task_data;
}

static int stale_cache_update(const void *data)
{
   struct stale_cache_update_task_data *task_data = (struct stale_cache_update_task_data *) data;
   struct ao2_container *backend_objects;

   start_passthru_update();
   backend_objects = ast_sorcery_retrieve_by_fields(task_data->sorcery, task_data->type,
      AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL);
   end_passthru_update();

   if (!backend_objects) {
      task_data->cache->stale_update_sched_id = -1;
      ao2_ref(task_data, -1);
      return 0;
   }

   if (task_data->cache->maximum_objects && ao2_container_count(backend_objects) >= task_data->cache->maximum_objects) {
      ast_log(LOG_ERROR, "The backend contains %d objects while the sorcery memory cache '%s' is explicitly configured to only allow %d\n",
         ao2_container_count(backend_objects), task_data->cache->name, task_data->cache->maximum_objects);
      task_data->cache->stale_update_sched_id = -1;
      ao2_ref(task_data, -1);
      return 0;
   }

   ao2_wrlock(task_data->cache->objects);
   remove_all_from_cache(task_data->cache);
   ao2_callback_data(backend_objects, OBJ_NOLOCK | OBJ_NODATA | OBJ_MULTIPLE, object_add_to_cache_callback,
      task_data->sorcery, task_data->cache);

   /* If the number of cached objects does not match the number of backend objects we encountered a memory allocation
    * failure and the cache is incomplete, so drop everything and fall back to querying the backend directly
    * as it may be able to provide what is wanted.
    */
   if (ao2_container_count(task_data->cache->objects) != ao2_container_count(backend_objects)) {
      ast_log(LOG_WARNING, "The backend contains %d objects while only %d could be added to sorcery memory cache '%s'\n",
         ao2_container_count(backend_objects), ao2_container_count(task_data->cache->objects), task_data->cache->name);
      remove_all_from_cache(task_data->cache);
   }

   ao2_unlock(task_data->cache->objects);
   ao2_ref(backend_objects, -1);

   task_data->cache->stale_update_sched_id = -1;
   ao2_ref(task_data, -1);

   return 0;
}

struct stale_update_task_data {
   struct ast_sorcery *sorcery;
   struct sorcery_memory_cache *cache;
   void *object;
};

static void stale_update_task_data_destructor(void *obj)
{
   struct stale_update_task_data *task_data = obj;

   ao2_cleanup(task_data->cache);
   ao2_cleanup(task_data->object);
   ast_sorcery_unref(task_data->sorcery);
}

static struct stale_update_task_data *stale_update_task_data_alloc(struct ast_sorcery *sorcery,
      struct sorcery_memory_cache *cache, const char *type, void *object)
{
   struct stale_update_task_data *task_data;

   task_data = ao2_alloc_options(sizeof(*task_data), stale_update_task_data_destructor,
      AO2_ALLOC_OPT_LOCK_NOLOCK);
   if (!task_data) {
      return NULL;
   }

   task_data->sorcery = ao2_bump(sorcery);
   task_data->cache = ao2_bump(cache);
   task_data->object = ao2_bump(object);

   return task_data;
}

static int stale_item_update(const void *data)
{
   struct stale_update_task_data *task_data = (struct stale_update_task_data *) data;
   void *object;

   start_passthru_update();

   object = ast_sorcery_retrieve_by_id(task_data->sorcery,
      ast_sorcery_object_get_type(task_data->object),
      ast_sorcery_object_get_id(task_data->object));
   if (!object) {
      ast_debug(1, "Backend no longer has object type '%s' ID '%s'. Removing from cache\n",
         ast_sorcery_object_get_type(task_data->object),
         ast_sorcery_object_get_id(task_data->object));
      sorcery_memory_cache_delete(task_data->sorcery, task_data->cache,
         task_data->object);
   } else {
      ast_debug(1, "Refreshing stale cache object type '%s' ID '%s'\n",
         ast_sorcery_object_get_type(task_data->object),
         ast_sorcery_object_get_id(task_data->object));
      sorcery_memory_cache_create(task_data->sorcery, task_data->cache,
         object);
      ao2_ref(object, -1);
   }

   ast_test_suite_event_notify("SORCERY_MEMORY_CACHE_REFRESHED", "Cache: %s\r\nType: %s\r\nName: %s\r\n",
      task_data->cache->name, ast_sorcery_object_get_type(task_data->object),
      ast_sorcery_object_get_id(task_data->object));

   ao2_ref(task_data, -1);
   end_passthru_update();

   return 0;
}

/*!
 * \internal
 * \brief Populate the cache with all objects from the backend
 *
 * \pre cache->objects is write-locked
 *
 * \param sorcery The sorcery instance
 * \param type The type of object
 * \param cache The sorcery memory cache
 */
static void memory_cache_populate(const struct ast_sorcery *sorcery, const char *type, struct sorcery_memory_cache *cache)
{
   struct ao2_container *backend_objects;

   start_passthru_update();
   backend_objects = ast_sorcery_retrieve_by_fields(sorcery, type, AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL);
   end_passthru_update();

   if (!backend_objects) {
      /* This will occur in off-nominal memory allocation failure scenarios */
      return;
   }

   if (cache->maximum_objects && ao2_container_count(backend_objects) >= cache->maximum_objects) {
      ast_log(LOG_ERROR, "The backend contains %d objects while the sorcery memory cache '%s' is explicitly configured to only allow %d\n",
         ao2_container_count(backend_objects), cache->name, cache->maximum_objects);
      return;
   }

   ao2_callback_data(backend_objects, OBJ_NOLOCK | OBJ_NODATA | OBJ_MULTIPLE, object_add_to_cache_callback,
      (struct ast_sorcery*)sorcery, cache);

   /* If the number of cached objects does not match the number of backend objects we encountered a memory allocation
    * failure and the cache is incomplete, so drop everything and fall back to querying the backend directly
    * as it may be able to provide what is wanted.
    */
   if (ao2_container_count(cache->objects) != ao2_container_count(backend_objects)) {
      ast_log(LOG_WARNING, "The backend contains %d objects while only %d could be added to sorcery memory cache '%s'\n",
         ao2_container_count(backend_objects), ao2_container_count(cache->objects), cache->name);
      remove_all_from_cache(cache);
   }

   ao2_ref(backend_objects, -1);
}

/*!
 * \internal
 * \brief Determine if a full backend cache update is needed and do it
 *
 * \param sorcery The sorcery instance
 * \param type The type of object
 * \param cache The sorcery memory cache
 */
static void memory_cache_full_update(const struct ast_sorcery *sorcery, const char *type, struct sorcery_memory_cache *cache)
{
   if (!cache->full_backend_cache) {
      return;
   }

   ao2_wrlock(cache->objects);
   if (!ao2_container_count(cache->objects)) {
      memory_cache_populate(sorcery, type, cache);
   }
   ao2_unlock(cache->objects);
}

/*!
 * \internal
 * \brief Queue a full cache update
 *
 * \param sorcery The sorcery instance
 * \param cache The sorcery memory cache
 * \param type The type of object
 */
static void memory_cache_stale_update_full(const struct ast_sorcery *sorcery, struct sorcery_memory_cache *cache,
   const char *type)
{
   ao2_wrlock(cache->objects);
   if (cache->stale_update_sched_id == -1) {
      struct stale_cache_update_task_data *task_data;

      task_data = stale_cache_update_task_data_alloc((struct ast_sorcery *) sorcery,
         cache, type);
      if (task_data) {
         cache->stale_update_sched_id = ast_sched_add(sched, 1,
            stale_cache_update, task_data);
      }
      if (cache->stale_update_sched_id < 0) {
         ao2_cleanup(task_data);
      }
   }
   ao2_unlock(cache->objects);
}

/*!
 * \internal
 * \brief Queue a stale object update
 *
 * \param sorcery The sorcery instance
 * \param cache The sorcery memory cache
 * \param cached The cached object
 */
static void memory_cache_stale_update_object(const struct ast_sorcery *sorcery, struct sorcery_memory_cache *cache,
   struct sorcery_memory_cached_object *cached)
{
   ao2_lock(cached);
   if (cached->stale_update_sched_id == -1) {
      struct stale_update_task_data *task_data;

      task_data = stale_update_task_data_alloc((struct ast_sorcery *) sorcery,
         cache, ast_sorcery_object_get_type(cached->object), cached->object);
      if (task_data) {
         ast_debug(1, "Cached sorcery object type '%s' ID '%s' is stale. Refreshing\n",
            ast_sorcery_object_get_type(cached->object), ast_sorcery_object_get_id(cached->object));
         cached->stale_update_sched_id = ast_sched_add(sched, 1,
            stale_item_update, task_data);
      }
      if (cached->stale_update_sched_id < 0) {
         ao2_cleanup(task_data);
         ast_log(LOG_ERROR, "Unable to update stale cached object type '%s', ID '%s'.\n",
            ast_sorcery_object_get_type(cached->object), ast_sorcery_object_get_id(cached->object));
      }
   }
   ao2_unlock(cached);
}

/*!
 * \internal
 * \brief Check whether an object (or cache) is stale and queue an update
 *
 * \param sorcery The sorcery instance
 * \param cache The sorcery memory cache
 * \param cached The cached object
 */
static void memory_cache_stale_check_object(const struct ast_sorcery *sorcery, struct sorcery_memory_cache *cache,
   struct sorcery_memory_cached_object *cached)
{
   struct timeval elapsed;

   if (!cache->object_lifetime_stale) {
      return;
   }

   /* For a full cache as every object has the same expiration/staleness we can do the same check */
   elapsed = ast_tvsub(ast_tvnow(), cached->created);

   if (elapsed.tv_sec < cache->object_lifetime_stale) {
      return;
   }

   if (cache->full_backend_cache) {
      memory_cache_stale_update_full(sorcery, cache, ast_sorcery_object_get_type(cached->object));
   } else {
      memory_cache_stale_update_object(sorcery, cache, cached);
   }

}

/*!
 * \internal
 * \brief Check whether the entire cache is stale or not and queue an update
 *
 * \param sorcery The sorcery instance
 * \param cache The sorcery memory cache
 *
 * \note Unlike \ref memory_cache_stale_check this does not require  an explicit object
 */
static void memory_cache_stale_check(const struct ast_sorcery *sorcery, struct sorcery_memory_cache *cache)
{
   struct sorcery_memory_cached_object *cached;

   ao2_rdlock(cache->objects);
   cached = ao2_bump(ast_heap_peek(cache->object_heap, 1));
   ao2_unlock(cache->objects);

   if (!cached) {
      return;
   }

   memory_cache_stale_check_object(sorcery, cache, cached);
   ao2_ref(cached, -1);
}

/*!
 * \internal
 * \brief Callback function to retrieve an object from a memory cache
 *
 * \param sorcery The sorcery instance
 * \param data The sorcery memory cache
 * \param type The type of the object to retrieve
 * \param id The id of the object to retrieve
 *
 * \retval non-NULL success
 * \retval NULL failure
 */
static void *sorcery_memory_cache_retrieve_id(const struct ast_sorcery *sorcery, void *data, const char *type, const char *id)
{
   struct sorcery_memory_cache *cache = data;
   struct sorcery_memory_cached_object *cached;
   void *object;

   if (is_passthru_update()) {
      return NULL;
   }

   memory_cache_full_update(sorcery, type, cache);

   cached = ao2_find(cache->objects, id, OBJ_SEARCH_KEY);
   if (!cached) {
      return NULL;
   }

   ast_assert(!strcmp(ast_sorcery_object_get_id(cached->object), id));

   memory_cache_stale_check_object(sorcery, cache, cached);

   object = ao2_bump(cached->object);
   ao2_ref(cached, -1);

   return object;
}

/*!
 * \internal
 * \brief AO2 callback function for comparing a retrieval request and finding applicable objects
 *
 * \param obj The cached object
 * \param arg The comparison parameters
 * \param flags Unused flags
 */
static int sorcery_memory_cache_fields_cmp(void *obj, void *arg, int flags)
{
   struct sorcery_memory_cached_object *cached = obj;
   const struct sorcery_memory_cache_fields_cmp_params *params = arg;
   RAII_VAR(struct ast_variable *, diff, NULL, ast_variables_destroy);

   if (params->regex) {
      /* If a regular expression has been provided see if it matches, otherwise move on */
      if (!regexec(params->regex, ast_sorcery_object_get_id(cached->object), 0, NULL, 0)) {
         ao2_link(params->container, cached->object);
      }
      return 0;
   } else if (params->prefix) {
      if (!strncmp(params->prefix, ast_sorcery_object_get_id(cached->object), params->prefix_len)) {
         ao2_link(params->container, cached->object);
      }
      return 0;
   } else if (params->fields &&
        (!ast_variable_lists_match(cached->objectset, params->fields, 0))) {
      /* If we can't turn the object into an object set OR if differences exist between the fields
       * passed in and what are present on the object they are not a match.
       */
      return 0;
   }

   if (params->container) {
      ao2_link(params->container, cached->object);

      /* As multiple objects are being returned keep going */
      return 0;
   } else {
      /* Immediately stop and return, we only want a single object */
      return CMP_MATCH | CMP_STOP;
   }
}

/*!
 * \internal
 * \brief Callback function to retrieve a single object based on fields
 *
 * \param sorcery The sorcery instance
 * \param data The sorcery memory cache
 * \param type The type of the object to retrieve
 * \param fields Any explicit fields to search for
 */
static void *sorcery_memory_cache_retrieve_fields(const struct ast_sorcery *sorcery, void *data, const char *type,
   const struct ast_variable *fields)
{
   struct sorcery_memory_cache *cache = data;
   struct sorcery_memory_cache_fields_cmp_params params = {
      .sorcery = sorcery,
      .cache = cache,
      .fields = fields,
   };
   struct sorcery_memory_cached_object *cached;
   void *object = NULL;

   if (is_passthru_update() || !cache->full_backend_cache || !fields) {
      return NULL;
   }

   cached = ao2_callback(cache->objects, 0, sorcery_memory_cache_fields_cmp, &params);

   if (cached) {
      memory_cache_stale_check_object(sorcery, cache, cached);
      object = ao2_bump(cached->object);
      ao2_ref(cached, -1);
   }

   return object;
}

/*!
 * \internal
 * \brief Callback function to retrieve multiple objects from a memory cache
 *
 * \param sorcery The sorcery instance
 * \param data The sorcery memory cache
 * \param type The type of the object to retrieve
 * \param objects Container to place the objects into
 * \param fields Any explicit fields to search for
 */
static void sorcery_memory_cache_retrieve_multiple(const struct ast_sorcery *sorcery, void *data, const char *type,
   struct ao2_container *objects, const struct ast_variable *fields)
{
   struct sorcery_memory_cache *cache = data;
   struct sorcery_memory_cache_fields_cmp_params params = {
      .sorcery = sorcery,
      .cache = cache,
      .fields = fields,
      .container = objects,
   };

   if (is_passthru_update() || !cache->full_backend_cache) {
      return;
   }

   memory_cache_full_update(sorcery, type, cache);
   ao2_callback(cache->objects, 0, sorcery_memory_cache_fields_cmp, &params);

   if (ao2_container_count(objects)) {
      memory_cache_stale_check(sorcery, cache);
   }
}

/*!
 * \internal
 * \brief Callback function to retrieve multiple objects using a regex on the object id
 *
 * \param sorcery The sorcery instance
 * \param data The sorcery memory cache
 * \param type The type of the object to retrieve
 * \param objects Container to place the objects into
 * \param regex Regular expression to apply to the object id
 */
static void sorcery_memory_cache_retrieve_regex(const struct ast_sorcery *sorcery, void *data, const char *type,
   struct ao2_container *objects, const char *regex)
{
   struct sorcery_memory_cache *cache = data;
   regex_t expression;
   struct sorcery_memory_cache_fields_cmp_params params = {
      .sorcery = sorcery,
      .cache = cache,
      .container = objects,
      .regex = &expression,
   };

   if (is_passthru_update() || !cache->full_backend_cache || regcomp(&expression, regex, REG_EXTENDED | REG_NOSUB)) {
      return;
   }

   memory_cache_full_update(sorcery, type, cache);
   ao2_callback(cache->objects, 0, sorcery_memory_cache_fields_cmp, &params);
   regfree(&expression);

   if (ao2_container_count(objects)) {
      memory_cache_stale_check(sorcery, cache);
   }
}

/*!
 * \internal
 * \brief Callback function to retrieve multiple objects whose id matches a prefix
 *
 * \param sorcery The sorcery instance
 * \param data The sorcery memory cache
 * \param type The type of the object to retrieve
 * \param objects Container to place the objects into
 * \param prefix Prefix to match against the object id
 */
static void sorcery_memory_cache_retrieve_prefix(const struct ast_sorcery *sorcery, void *data, const char *type,
   struct ao2_container *objects, const char *prefix, const size_t prefix_len)
{
   struct sorcery_memory_cache *cache = data;
   struct sorcery_memory_cache_fields_cmp_params params = {
      .sorcery = sorcery,
      .cache = cache,
      .container = objects,
      .prefix = prefix,
      .prefix_len = prefix_len,
   };

   if (is_passthru_update() || !cache->full_backend_cache) {
      return;
   }

   memory_cache_full_update(sorcery, type, cache);
   ao2_callback(cache->objects, 0, sorcery_memory_cache_fields_cmp, &params);

   if (ao2_container_count(objects)) {
      memory_cache_stale_check(sorcery, cache);
   }
}

/*!
 * \internal
 * \brief Callback function to finish configuring the memory cache
 *
 * \param data The sorcery memory cache
 * \param sorcery The sorcery instance
 * \param type The type of object being loaded
 */
static void sorcery_memory_cache_load(void *data, const struct ast_sorcery *sorcery, const char *type)
{
   struct sorcery_memory_cache *cache = data;

   /* If no name was explicitly specified generate one given the sorcery instance and object type */
   if (ast_strlen_zero(cache->name)) {
      ast_asprintf(&cache->name, "%s/%s", ast_sorcery_get_module(sorcery), type);
   }

   ao2_link(caches, cache);
   ast_debug(1, "Memory cache '%s' associated with sorcery instance '%p' of module '%s' with object type '%s'\n",
      cache->name, sorcery, ast_sorcery_get_module(sorcery), type);

   cache->sorcery = sorcery;
   cache->object_type = ast_strdup(type);
}

/*!
 * \internal
 * \brief Callback function to expire objects from the memory cache on reload (if configured)
 *
 * \param data The sorcery memory cache
 * \param sorcery The sorcery instance
 * \param type The type of object being reloaded
 */
static void sorcery_memory_cache_reload(void *data, const struct ast_sorcery *sorcery, const char *type)
{
   struct sorcery_memory_cache *cache = data;

   if (!cache->expire_on_reload) {
      return;
   }

   ao2_wrlock(cache->objects);
   remove_all_from_cache(cache);
   ao2_unlock(cache->objects);
}

/*!
 * \internal
 * \brief Function used to take an unsigned integer based configuration option and parse it
 *
 * \param value The string value of the configuration option
 * \param result The unsigned integer to place the result in
 *
 * \retval 0 failure
 * \retval 1 success
 */
static int configuration_parse_unsigned_integer(const char *value, unsigned int *result)
{
   if (ast_strlen_zero(value) || !strncmp(value, "-", 1)) {
      return 0;
   }

   return sscanf(value, "%30u", result);
}

static int age_cmp(void *a, void *b)
{
   return ast_tvcmp(((struct sorcery_memory_cached_object *) b)->created,
         ((struct sorcery_memory_cached_object *) a)->created);
}

/*!
 * \internal
 * \brief Callback function to create a new sorcery memory cache using provided configuration
 *
 * \param data A stringified configuration for the memory cache
 *
 * \retval non-NULL success
 * \retval NULL failure
 */
static void *sorcery_memory_cache_open(const char *data)
{
   char *options = ast_strdup(data), *option;
   RAII_VAR(struct sorcery_memory_cache *, cache, NULL, ao2_cleanup);

   cache = ao2_alloc_options(sizeof(*cache), sorcery_memory_cache_destructor, AO2_ALLOC_OPT_LOCK_NOLOCK);
   if (!cache) {
      return NULL;
   }

   cache->expire_id = -1;
   cache->stale_update_sched_id = -1;

   /* If no configuration options have been provided this memory cache will operate in a default
    * configuration.
    */
   while (!ast_strlen_zero(options) && (option = strsep(&options, ","))) {
      char *name = strsep(&option, "="), *value = option;

      if (!strcasecmp(name, "name")) {
         if (ast_strlen_zero(value)) {
            ast_log(LOG_ERROR, "A name must be specified for the memory cache\n");
            return NULL;
         }
         ast_free(cache->name);
         cache->name = ast_strdup(value);
      } else if (!strcasecmp(name, "maximum_objects")) {
         if (configuration_parse_unsigned_integer(value, &cache->maximum_objects) != 1) {
            ast_log(LOG_ERROR, "Unsupported maximum objects value of '%s' used for memory cache\n",
               value);
            return NULL;
         }
      } else if (!strcasecmp(name, "object_lifetime_maximum")) {
         if (configuration_parse_unsigned_integer(value, &cache->object_lifetime_maximum) != 1) {
            ast_log(LOG_ERROR, "Unsupported object maximum lifetime value of '%s' used for memory cache\n",
               value);
            return NULL;
         }
      } else if (!strcasecmp(name, "object_lifetime_stale")) {
         if (configuration_parse_unsigned_integer(value, &cache->object_lifetime_stale) != 1) {
            ast_log(LOG_ERROR, "Unsupported object stale lifetime value of '%s' used for memory cache\n",
               value);
            return NULL;
         }
      } else if (!strcasecmp(name, "expire_on_reload")) {
         cache->expire_on_reload = ast_true(value);
      } else if (!strcasecmp(name, "full_backend_cache")) {
         cache->full_backend_cache = ast_true(value);
      } else {
         ast_log(LOG_ERROR, "Unsupported option '%s' used for memory cache\n", name);
         return NULL;
      }
   }

   cache->objects = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_RWLOCK, 0,
      cache->maximum_objects ? cache->maximum_objects : CACHE_CONTAINER_BUCKET_SIZE,
      sorcery_memory_cached_object_hash, NULL, sorcery_memory_cached_object_cmp);
   if (!cache->objects) {
      ast_log(LOG_ERROR, "Could not create a container to hold cached objects for memory cache\n");
      return NULL;
   }

   cache->object_heap = ast_heap_create(CACHE_HEAP_INIT_HEIGHT, age_cmp,
      offsetof(struct sorcery_memory_cached_object, __heap_index));
   if (!cache->object_heap) {
      ast_log(LOG_ERROR, "Could not create heap to hold cached objects\n");
      return NULL;
   }

   /* The memory cache is not linked to the caches container until the load callback is invoked.
    * Linking occurs there so an intelligent cache name can be constructed using the module of
    * the sorcery instance and the specific object type if no cache name was specified as part
    * of the configuration.
    */

   /* This is done as RAII_VAR will drop the reference */
   return ao2_bump(cache);
}

/*!
 * \internal
 * \brief Callback function to delete an object from a memory cache
 *
 * \param sorcery The sorcery instance
 * \param data The sorcery memory cache
 * \param object The object to cache
 *
 * \retval 0 success
 * \retval -1 failure
 */
static int sorcery_memory_cache_delete(const struct ast_sorcery *sorcery, void *data, void *object)
{
   struct sorcery_memory_cache *cache = data;
   int res;

   ao2_wrlock(cache->objects);
   res = remove_from_cache(cache, ast_sorcery_object_get_id(object), 1);
   ao2_unlock(cache->objects);

   if (res) {
      ast_debug(1, "Unable to delete object '%s' from sorcery cache\n", ast_sorcery_object_get_id(object));
   }

   return res;
}

/*!
 * \internal
 * \brief Callback function to terminate a memory cache
 *
 * \param data The sorcery memory cache
 */
static void sorcery_memory_cache_close(void *data)
{
   struct sorcery_memory_cache *cache = data;

   /* This can occur if a cache is created but never loaded */
   if (!ast_strlen_zero(cache->name)) {
      ao2_unlink(caches, cache);
   }

   if (cache->object_lifetime_maximum) {
      /* If object lifetime support is enabled we need to explicitly drop all cached objects here
       * and stop the scheduled task. Failure to do so could potentially keep the cache around for
       * a prolonged period of time.
       */
      ao2_wrlock(cache->objects);
      remove_all_from_cache(cache);
      ao2_unlock(cache->objects);
   }

   if (cache->full_backend_cache) {
      ao2_wrlock(cache->objects);
      cache->sorcery = NULL;
      ao2_unlock(cache->objects);
   }

   ao2_ref(cache, -1);
}

/*!
 * \internal
 * \brief CLI tab completion for cache names
 */
static char *sorcery_memory_cache_complete_name(const char *word, int state)
{
   struct sorcery_memory_cache *cache;
   struct ao2_iterator it_caches;
   int wordlen = strlen(word);
   int which = 0;
   char *result = NULL;

   it_caches = ao2_iterator_init(caches, 0);
   while ((cache = ao2_iterator_next(&it_caches))) {
      if (!strncasecmp(word, cache->name, wordlen)
         && ++which > state) {
         result = ast_strdup(cache->name);
      }
      ao2_ref(cache, -1);
      if (result) {
         break;
      }
   }
   ao2_iterator_destroy(&it_caches);
   return result;
}

/*!
 * \internal
 * \brief CLI command implementation for 'sorcery memory cache show'
 */
static char *sorcery_memory_cache_show(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   struct sorcery_memory_cache *cache;

   switch (cmd) {
   case CLI_INIT:
      e->command = "sorcery memory cache show";
      e->usage =
          "Usage: sorcery memory cache show <name>\n"
          "       Show sorcery memory cache configuration and statistics.\n";
      return NULL;
   case CLI_GENERATE:
      if (a->pos == 4) {
         return sorcery_memory_cache_complete_name(a->word, a->n);
      } else {
         return NULL;
      }
   }

   if (a->argc != 5) {
      return CLI_SHOWUSAGE;
   }

   cache = ao2_find(caches, a->argv[4], OBJ_SEARCH_KEY);
   if (!cache) {
      ast_cli(a->fd, "Specified sorcery memory cache '%s' does not exist\n", a->argv[4]);
      return CLI_FAILURE;
   }

   ast_cli(a->fd, "Sorcery memory cache: %s\n", cache->name);
   ast_cli(a->fd, "Number of objects within cache: %d\n", ao2_container_count(cache->objects));
   if (cache->maximum_objects) {
      ast_cli(a->fd, "Maximum allowed objects: %d\n", cache->maximum_objects);
   } else {
      ast_cli(a->fd, "There is no limit on the maximum number of objects in the cache\n");
   }
   if (cache->object_lifetime_maximum) {
      ast_cli(a->fd, "Number of seconds before object expires: %d\n", cache->object_lifetime_maximum);
   } else {
      ast_cli(a->fd, "Object expiration is not enabled - cached objects will not expire\n");
   }
   if (cache->object_lifetime_stale) {
      ast_cli(a->fd, "Number of seconds before object becomes stale: %d\n", cache->object_lifetime_stale);
   } else {
      ast_cli(a->fd, "Object staleness is not enabled - cached objects will not go stale\n");
   }
   ast_cli(a->fd, "Expire all objects on reload: %s\n", AST_CLI_ONOFF(cache->expire_on_reload));

   ao2_ref(cache, -1);

   return CLI_SUCCESS;
}

/*! \brief Structure used to pass data for printing cached object information */
struct print_object_details {
   /*! \brief The sorcery memory cache */
   struct sorcery_memory_cache *cache;
   /*! \brief The CLI arguments */
   struct ast_cli_args *a;
};

/*!
 * \internal
 * \brief Callback function for displaying object within the cache
 */
static int sorcery_memory_cache_print_object(void *obj, void *arg, int flags)
{
#define FORMAT "%-25.25s %-15u %-15u \n"
   struct sorcery_memory_cached_object *cached = obj;
   struct print_object_details *details = arg;
   int seconds_until_expire = 0, seconds_until_stale = 0;

   if (details->cache->object_lifetime_maximum) {
      seconds_until_expire = ast_tvdiff_ms(ast_tvadd(cached->created, ast_samp2tv(details->cache->object_lifetime_maximum, 1)), ast_tvnow()) / 1000;
   }
   if (details->cache->object_lifetime_stale) {
      seconds_until_stale = ast_tvdiff_ms(ast_tvadd(cached->created, ast_samp2tv(details->cache->object_lifetime_stale, 1)), ast_tvnow()) / 1000;
   }

   ast_cli(details->a->fd, FORMAT, ast_sorcery_object_get_id(cached->object), MAX(seconds_until_stale, 0), MAX(seconds_until_expire, 0));

   return CMP_MATCH;
#undef FORMAT
}

/*!
 * \internal
 * \brief CLI command implementation for 'sorcery memory cache dump'
 */
static char *sorcery_memory_cache_dump(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
#define FORMAT "%-25.25s %-15.15s %-15.15s \n"
   struct sorcery_memory_cache *cache;
   struct print_object_details details;

   switch (cmd) {
   case CLI_INIT:
      e->command = "sorcery memory cache dump";
      e->usage =
          "Usage: sorcery memory cache dump <name>\n"
          "       Dump a list of the objects within the cache, listed by object identifier.\n";
      return NULL;
   case CLI_GENERATE:
      if (a->pos == 4) {
         return sorcery_memory_cache_complete_name(a->word, a->n);
      } else {
         return NULL;
      }
   }

   if (a->argc != 5) {
      return CLI_SHOWUSAGE;
   }

   cache = ao2_find(caches, a->argv[4], OBJ_SEARCH_KEY);
   if (!cache) {
      ast_cli(a->fd, "Specified sorcery memory cache '%s' does not exist\n", a->argv[4]);
      return CLI_FAILURE;
   }

   details.cache = cache;
   details.a = a;

   ast_cli(a->fd, "Dumping sorcery memory cache '%s':\n", cache->name);
   if (!cache->object_lifetime_stale) {
      ast_cli(a->fd, " * Staleness is not enabled - objects will not go stale\n");
   }
   if (!cache->object_lifetime_maximum) {
      ast_cli(a->fd, " * Object lifetime is not enabled - objects will not expire\n");
   }
   ast_cli(a->fd, FORMAT, "Object Name", "Stale In", "Expires In");
   ast_cli(a->fd, FORMAT, "-------------------------", "---------------", "---------------");
   ao2_callback(cache->objects, OBJ_NODATA | OBJ_MULTIPLE, sorcery_memory_cache_print_object, &details);
   ast_cli(a->fd, FORMAT, "-------------------------", "---------------", "---------------");
   ast_cli(a->fd, "Total number of objects cached: %d\n", ao2_container_count(cache->objects));

   ao2_ref(cache, -1);

   return CLI_SUCCESS;
#undef FORMAT
}

/*!
 * \internal
 * \brief CLI tab completion for cached object names
 */
static char *sorcery_memory_cache_complete_object_name(const char *cache_name, const char *word, int state)
{
   struct sorcery_memory_cache *cache;
   struct sorcery_memory_cached_object *cached;
   struct ao2_iterator it_cached;
   int wordlen = strlen(word);
   int which = 0;
   char *result = NULL;

   cache = ao2_find(caches, cache_name, OBJ_SEARCH_KEY);
   if (!cache) {
      return NULL;
   }

   it_cached = ao2_iterator_init(cache->objects, 0);
   while ((cached = ao2_iterator_next(&it_cached))) {
      if (!strncasecmp(word, ast_sorcery_object_get_id(cached->object), wordlen)
         && ++which > state) {
         result = ast_strdup(ast_sorcery_object_get_id(cached->object));
      }
      ao2_ref(cached, -1);
      if (result) {
         break;
      }
   }
   ao2_iterator_destroy(&it_cached);

   ao2_ref(cache, -1);

   return result;
}

/*!
 * \internal
 * \brief CLI command implementation for 'sorcery memory cache expire'
 */
static char *sorcery_memory_cache_expire(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   struct sorcery_memory_cache *cache;

   switch (cmd) {
   case CLI_INIT:
      e->command = "sorcery memory cache expire";
      e->usage =
          "Usage: sorcery memory cache expire <cache name> [object name]\n"
          "       Expire a specific object or ALL objects within a sorcery memory cache.\n";
      return NULL;
   case CLI_GENERATE:
      if (a->pos == 4) {
         return sorcery_memory_cache_complete_name(a->word, a->n);
      } else if (a->pos == 5) {
         return sorcery_memory_cache_complete_object_name(a->argv[4], a->word, a->n);
      } else {
         return NULL;
      }
   }

   if (a->argc < 5 || a->argc > 6) {
      return CLI_SHOWUSAGE;
   }

   cache = ao2_find(caches, a->argv[4], OBJ_SEARCH_KEY);
   if (!cache) {
      ast_cli(a->fd, "Specified sorcery memory cache '%s' does not exist\n", a->argv[4]);
      return CLI_FAILURE;
   }

   ao2_wrlock(cache->objects);
   if (a->argc == 5) {
      remove_all_from_cache(cache);
      ast_cli(a->fd, "All objects have been removed from cache '%s'\n", a->argv[4]);
   } else {
      if (cache->full_backend_cache) {
         ast_cli(a->fd, "Due to full backend caching per-object expiration is not available on cache '%s'\n", a->argv[4]);
      } else if (!remove_from_cache(cache, a->argv[5], 1)) {
         ast_cli(a->fd, "Successfully expired object '%s' from cache '%s'\n", a->argv[5], a->argv[4]);
      } else {
         ast_cli(a->fd, "Object '%s' was not expired from cache '%s' as it was not found\n", a->argv[5],
            a->argv[4]);
      }
   }
   ao2_unlock(cache->objects);

   ao2_ref(cache, -1);

   return CLI_SUCCESS;
}

/*!
 * \internal
 * \brief CLI command implementation for 'sorcery memory cache stale'
 */
static char *sorcery_memory_cache_stale(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   struct sorcery_memory_cache *cache;
   int reload = 0;

   switch (cmd) {
   case CLI_INIT:
      e->command = "sorcery memory cache stale";
      e->usage =
          "Usage: sorcery memory cache stale <cache name> [object name [reload]]\n"
          "       Mark a specific object or ALL objects as stale in a sorcery memory cache.\n"
          "       If \"reload\" is specified, then the object is marked stale and immediately\n"
          "       retrieved from backend storage to repopulate the cache\n";
      return NULL;
   case CLI_GENERATE:
      if (a->pos == 4) {
         return sorcery_memory_cache_complete_name(a->word, a->n);
      } else if (a->pos == 5) {
         return sorcery_memory_cache_complete_object_name(a->argv[4], a->word, a->n);
      } else if (a->pos == 6) {
         static const char * const completions[] = { "reload", NULL };
         return ast_cli_complete(a->word, completions, a->n);
      } else {
         return NULL;
      }
   }

   if (a->argc < 5 || a->argc > 7) {
      return CLI_SHOWUSAGE;
   }

   if (a->argc == 7) {
      if (!strcasecmp(a->argv[6], "reload")) {
         reload = 1;
      } else {
         return CLI_SHOWUSAGE;
      }
   }

   cache = ao2_find(caches, a->argv[4], OBJ_SEARCH_KEY);
   if (!cache) {
      ast_cli(a->fd, "Specified sorcery memory cache '%s' does not exist\n", a->argv[4]);
      return CLI_FAILURE;
   }

   if (!cache->object_lifetime_stale) {
      ast_cli(a->fd, "Specified sorcery memory cache '%s' does not have staleness enabled\n", a->argv[4]);
      ao2_ref(cache, -1);
      return CLI_FAILURE;
   }

   ao2_rdlock(cache->objects);
   if (a->argc == 5) {
      mark_all_as_stale_in_cache(cache);
      ast_cli(a->fd, "Marked all objects in sorcery memory cache '%s' as stale\n", a->argv[4]);
   } else {
      if (!mark_object_as_stale_in_cache(cache, a->argv[5])) {
         ast_cli(a->fd, "Successfully marked object '%s' in memory cache '%s' as stale\n",
            a->argv[5], a->argv[4]);
         if (reload) {
            struct sorcery_memory_cached_object *cached;

            cached = ao2_find(cache->objects, a->argv[5], OBJ_SEARCH_KEY | OBJ_NOLOCK);
            if (cached) {
               memory_cache_stale_update_object(cache->sorcery, cache, cached);
               ao2_ref(cached, -1);
            }
         }
      } else {
         ast_cli(a->fd, "Object '%s' in sorcery memory cache '%s' could not be marked as stale as it was not found\n",
            a->argv[5], a->argv[4]);
      }
   }
   ao2_unlock(cache->objects);

   ao2_ref(cache, -1);

   return CLI_SUCCESS;
}

/*!
 * \internal
 * \brief CLI command implementation for 'sorcery memory cache populate'
 */
static char *sorcery_memory_cache_populate(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   struct sorcery_memory_cache *cache;

   switch (cmd) {
   case CLI_INIT:
      e->command = "sorcery memory cache populate";
      e->usage =
          "Usage: sorcery memory cache populate <cache name>\n"
          "       Expire all objects in the cache and populate it with ALL objects from backend.\n";
      return NULL;
   case CLI_GENERATE:
      if (a->pos == 4) {
         return sorcery_memory_cache_complete_name(a->word, a->n);
      } else {
         return NULL;
      }
   }

   if (a->argc != 5) {
      return CLI_SHOWUSAGE;
   }

   cache = ao2_find(caches, a->argv[4], OBJ_SEARCH_KEY);
   if (!cache) {
      ast_cli(a->fd, "Specified sorcery memory cache '%s' does not exist\n", a->argv[4]);
      return CLI_FAILURE;
   }

   if (!cache->full_backend_cache) {
      ast_cli(a->fd, "Specified sorcery memory cache '%s' does not have full backend caching enabled\n", a->argv[4]);
      ao2_ref(cache, -1);
      return CLI_FAILURE;
   }

   ao2_wrlock(cache->objects);
   if (!cache->sorcery) {
      ast_cli(a->fd, "Specified sorcery memory cache '%s' is no longer active\n", a->argv[4]);
      ao2_unlock(cache->objects);
      ao2_ref(cache, -1);
      return CLI_FAILURE;
   }

   remove_all_from_cache(cache);
   memory_cache_populate(cache->sorcery, cache->object_type, cache);

   ast_cli(a->fd, "Specified sorcery memory cache '%s' has been populated with '%d' objects from the backend\n",
      a->argv[4], ao2_container_count(cache->objects));

   ao2_unlock(cache->objects);

   ao2_ref(cache, -1);

   return CLI_SUCCESS;
}

static struct ast_cli_entry cli_memory_cache[] = {
   AST_CLI_DEFINE(sorcery_memory_cache_show, "Show sorcery memory cache information"),
   AST_CLI_DEFINE(sorcery_memory_cache_dump, "Dump all objects within a sorcery memory cache"),
   AST_CLI_DEFINE(sorcery_memory_cache_expire, "Expire a specific object or ALL objects within a sorcery memory cache"),
   AST_CLI_DEFINE(sorcery_memory_cache_stale, "Mark a specific object or ALL objects as stale within a sorcery memory cache"),
   AST_CLI_DEFINE(sorcery_memory_cache_populate, "Clear and populate the sorcery memory cache with objects from the backend"),
};

/*!
 * \internal
 * \brief AMI command implementation for 'SorceryMemoryCacheExpireObject'
 */
static int sorcery_memory_cache_ami_expire_object(struct mansession *s, const struct message *m)
{
   const char *cache_name = astman_get_header(m, "Cache");
   const char *object_name = astman_get_header(m, "Object");
   struct sorcery_memory_cache *cache;
   int res;

   if (ast_strlen_zero(cache_name)) {
      astman_send_error(s, m, "SorceryMemoryCacheExpireObject requires that a cache name be provided.\n");
      return 0;
   } else if (ast_strlen_zero(object_name)) {
      astman_send_error(s, m, "SorceryMemoryCacheExpireObject requires that an object name be provided\n");
      return 0;
   }

   cache = ao2_find(caches, cache_name, OBJ_SEARCH_KEY);
   if (!cache) {
      astman_send_error(s, m, "The provided cache does not exist\n");
      return 0;
   }

   ao2_wrlock(cache->objects);
   if (cache->full_backend_cache) {
      res = 1;
   } else {
      res = remove_from_cache(cache, object_name, 1);
   }
   ao2_unlock(cache->objects);

   ao2_ref(cache, -1);

   if (res == 1) {
      astman_send_error(s, m, "Due to full backend caching per-object expiration is not available, consider using SorceryMemoryCachePopulate or SorceryMemoryCacheExpire instead\n");
   } else if (!res) {
      astman_send_ack(s, m, "The provided object was expired from the cache\n");
   } else {
      astman_send_error(s, m, "The provided object could not be expired from the cache\n");
   }

   return 0;
}

/*!
 * \internal
 * \brief AMI command implementation for 'SorceryMemoryCacheExpire'
 */
static int sorcery_memory_cache_ami_expire(struct mansession *s, const struct message *m)
{
   const char *cache_name = astman_get_header(m, "Cache");
   struct sorcery_memory_cache *cache;

   if (ast_strlen_zero(cache_name)) {
      astman_send_error(s, m, "SorceryMemoryCacheExpire requires that a cache name be provided.\n");
      return 0;
   }

   cache = ao2_find(caches, cache_name, OBJ_SEARCH_KEY);
   if (!cache) {
      astman_send_error(s, m, "The provided cache does not exist\n");
      return 0;
   }

   ao2_wrlock(cache->objects);
   remove_all_from_cache(cache);
   ao2_unlock(cache->objects);

   ao2_ref(cache, -1);

   astman_send_ack(s, m, "All objects were expired from the cache\n");

   return 0;
}

/*!
 * \internal
 * \brief AMI command implementation for 'SorceryMemoryCacheStaleObject'
 */
static int sorcery_memory_cache_ami_stale_object(struct mansession *s, const struct message *m)
{
   const char *cache_name = astman_get_header(m, "Cache");
   const char *object_name = astman_get_header(m, "Object");
   const char *reload = astman_get_header(m, "Reload");
   struct sorcery_memory_cache *cache;
   int res;

   if (ast_strlen_zero(cache_name)) {
      astman_send_error(s, m, "SorceryMemoryCacheStaleObject requires that a cache name be provided.\n");
      return 0;
   } else if (ast_strlen_zero(object_name)) {
      astman_send_error(s, m, "SorceryMemoryCacheStaleObject requires that an object name be provided\n");
      return 0;
   }

   cache = ao2_find(caches, cache_name, OBJ_SEARCH_KEY);
   if (!cache) {
      astman_send_error(s, m, "The provided cache does not exist\n");
      return 0;
   }

   ao2_rdlock(cache->objects);

   res = mark_object_as_stale_in_cache(cache, object_name);

   if (ast_true(reload)) {
      struct sorcery_memory_cached_object *cached;

      cached = ao2_find(cache->objects, object_name, OBJ_SEARCH_KEY | OBJ_NOLOCK);
      if (cached) {
         memory_cache_stale_update_object(cache->sorcery, cache, cached);
         ao2_ref(cached, -1);
      }
   }

   ao2_unlock(cache->objects);

   ao2_ref(cache, -1);

   if (!res) {
      astman_send_ack(s, m, "The provided object was marked as stale in the cache\n");
   } else {
      astman_send_error(s, m, "The provided object could not be marked as stale in the cache\n");
   }

   return 0;
}

/*!
 * \internal
 * \brief AMI command implementation for 'SorceryMemoryCacheStale'
 */
static int sorcery_memory_cache_ami_stale(struct mansession *s, const struct message *m)
{
   const char *cache_name = astman_get_header(m, "Cache");
   struct sorcery_memory_cache *cache;

   if (ast_strlen_zero(cache_name)) {
      astman_send_error(s, m, "SorceryMemoryCacheStale requires that a cache name be provided.\n");
      return 0;
   }

   cache = ao2_find(caches, cache_name, OBJ_SEARCH_KEY);
   if (!cache) {
      astman_send_error(s, m, "The provided cache does not exist\n");
      return 0;
   }

   ao2_rdlock(cache->objects);
   mark_all_as_stale_in_cache(cache);
   ao2_unlock(cache->objects);

   ao2_ref(cache, -1);

   astman_send_ack(s, m, "All objects were marked as stale in the cache\n");

   return 0;
}

/*!
 * \internal
 * \brief AMI command implementation for 'SorceryMemoryCachePopulate'
 */
static int sorcery_memory_cache_ami_populate(struct mansession *s, const struct message *m)
{
   const char *cache_name = astman_get_header(m, "Cache");
   struct sorcery_memory_cache *cache;

   if (ast_strlen_zero(cache_name)) {
      astman_send_error(s, m, "SorceryMemoryCachePopulate requires that a cache name be provided.\n");
      return 0;
   }

   cache = ao2_find(caches, cache_name, OBJ_SEARCH_KEY);
   if (!cache) {
      astman_send_error(s, m, "The provided cache does not exist\n");
      return 0;
   }

   if (!cache->full_backend_cache) {
      astman_send_error(s, m, "The provided cache does not have full backend caching enabled\n");
      ao2_ref(cache, -1);
      return 0;
   }

   ao2_wrlock(cache->objects);
   if (!cache->sorcery) {
      astman_send_error(s, m, "The provided cache is no longer active\n");
      ao2_unlock(cache->objects);
      ao2_ref(cache, -1);
      return 0;
   }

   remove_all_from_cache(cache);
   memory_cache_populate(cache->sorcery, cache->object_type, cache);

   ao2_unlock(cache->objects);

   ao2_ref(cache, -1);

   astman_send_ack(s, m, "Cache has been expired and populated\n");

   return 0;
}

#ifdef TEST_FRAMEWORK

/*! \brief Dummy sorcery object */
struct test_sorcery_object {
   SORCERY_OBJECT(details);
};

/*!
 * \internal
 * \brief Allocator for test object
 *
 * \param id The identifier for the object
 *
 * \retval non-NULL success
 * \retval NULL failure
 */
static void *test_sorcery_object_alloc(const char *id)
{
   return ast_sorcery_generic_alloc(sizeof(struct test_sorcery_object), NULL);
}

/*!
 * \internal
 * \brief Allocator for test sorcery instance
 *
 * \retval non-NULL success
 * \retval NULL failure
 */
static struct ast_sorcery *alloc_and_initialize_sorcery(void)
{
   struct ast_sorcery *sorcery;

   if (!(sorcery = ast_sorcery_open())) {
      return NULL;
   }

   if ((ast_sorcery_apply_default(sorcery, "test", "memory", NULL) != AST_SORCERY_APPLY_SUCCESS) ||
      ast_sorcery_internal_object_register(sorcery, "test", test_sorcery_object_alloc, NULL, NULL)) {
      ast_sorcery_unref(sorcery);
      return NULL;
   }

   return sorcery;
}

AST_TEST_DEFINE(open_with_valid_options)
{
   int res = AST_TEST_PASS;
   struct sorcery_memory_cache *cache;

   switch (cmd) {
   case TEST_INIT:
      info->name = "open_with_valid_options";
      info->category = "/res/res_sorcery_memory_cache/";
      info->summary = "Attempt to create sorcery memory caches using valid options";
      info->description = "This test performs the following:\n"
         "\t* Creates a memory cache with default configuration\n"
         "\t* Creates a memory cache with a maximum object count of 10 and verifies it\n"
         "\t* Creates a memory cache with a maximum object lifetime of 60 and verifies it\n"
         "\t* Creates a memory cache with a stale object lifetime of 90 and verifies it";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   cache = sorcery_memory_cache_open("");
   if (!cache) {
      ast_test_status_update(test, "Failed to create a sorcery memory cache using default configuration\n");
      res = AST_TEST_FAIL;
   } else {
      sorcery_memory_cache_close(cache);
   }

   cache = sorcery_memory_cache_open("maximum_objects=10");
   if (!cache) {
      ast_test_status_update(test, "Failed to create a sorcery memory cache with a maximum object count of 10\n");
      res = AST_TEST_FAIL;
   } else {
      if (cache->maximum_objects != 10) {
         ast_test_status_update(test, "Created a sorcery memory cache with a maximum object count of 10 but it has '%u'\n",
            cache->maximum_objects);
      }
      sorcery_memory_cache_close(cache);
   }

   cache = sorcery_memory_cache_open("object_lifetime_maximum=60");
   if (!cache) {
      ast_test_status_update(test, "Failed to create a sorcery memory cache with a maximum object lifetime of 60\n");
      res = AST_TEST_FAIL;
   } else {
      if (cache->object_lifetime_maximum != 60) {
         ast_test_status_update(test, "Created a sorcery memory cache with a maximum object lifetime of 60 but it has '%u'\n",
            cache->object_lifetime_maximum);
      }
      sorcery_memory_cache_close(cache);
   }

   cache = sorcery_memory_cache_open("object_lifetime_stale=90");
   if (!cache) {
      ast_test_status_update(test, "Failed to create a sorcery memory cache with a stale object lifetime of 90\n");
      res = AST_TEST_FAIL;
   } else {
      if (cache->object_lifetime_stale != 90) {
         ast_test_status_update(test, "Created a sorcery memory cache with a stale object lifetime of 90 but it has '%u'\n",
            cache->object_lifetime_stale);
      }
      sorcery_memory_cache_close(cache);
   }


   return res;
}

AST_TEST_DEFINE(open_with_invalid_options)
{
   int res = AST_TEST_PASS;
   struct sorcery_memory_cache *cache;

   switch (cmd) {
   case TEST_INIT:
      info->name = "open_with_invalid_options";
      info->category = "/res/res_sorcery_memory_cache/";
      info->summary = "Attempt to create sorcery memory caches using invalid options";
      info->description = "This test attempts to perform the following:\n"
         "\t* Create a memory cache with an empty name\n"
         "\t* Create a memory cache with a maximum object count of -1\n"
         "\t* Create a memory cache with a maximum object count of toast\n"
         "\t* Create a memory cache with a maximum object lifetime of -1\n"
         "\t* Create a memory cache with a maximum object lifetime of toast\n"
         "\t* Create a memory cache with a stale object lifetime of -1\n"
         "\t* Create a memory cache with a stale object lifetime of toast";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   cache = sorcery_memory_cache_open("name=");
   if (cache) {
      ast_test_status_update(test, "Created a sorcery memory cache with an empty name\n");
      sorcery_memory_cache_close(cache);
      res = AST_TEST_FAIL;
   }

   cache = sorcery_memory_cache_open("maximum_objects=-1");
   if (cache) {
      ast_test_status_update(test, "Created a sorcery memory cache with a maximum object count of -1\n");
      sorcery_memory_cache_close(cache);
      res = AST_TEST_FAIL;
   }

   cache = sorcery_memory_cache_open("maximum_objects=toast");
   if (cache) {
      ast_test_status_update(test, "Created a sorcery memory cache with a maximum object count of toast\n");
      sorcery_memory_cache_close(cache);
      res = AST_TEST_FAIL;
   }

   cache = sorcery_memory_cache_open("object_lifetime_maximum=-1");
   if (cache) {
      ast_test_status_update(test, "Created a sorcery memory cache with an object lifetime maximum of -1\n");
      sorcery_memory_cache_close(cache);
      res = AST_TEST_FAIL;
   }

   cache = sorcery_memory_cache_open("object_lifetime_maximum=toast");
   if (cache) {
      ast_test_status_update(test, "Created a sorcery memory cache with an object lifetime maximum of toast\n");
      sorcery_memory_cache_close(cache);
      res = AST_TEST_FAIL;
   }

   cache = sorcery_memory_cache_open("object_lifetime_stale=-1");
   if (cache) {
      ast_test_status_update(test, "Created a sorcery memory cache with a stale object lifetime of -1\n");
      sorcery_memory_cache_close(cache);
      res = AST_TEST_FAIL;
   }

   cache = sorcery_memory_cache_open("object_lifetime_stale=toast");
   if (cache) {
      ast_test_status_update(test, "Created a sorcery memory cache with a stale object lifetime of toast\n");
      sorcery_memory_cache_close(cache);
      res = AST_TEST_FAIL;
   }

   cache = sorcery_memory_cache_open("tacos");
   if (cache) {
      ast_test_status_update(test, "Created a sorcery memory cache with an invalid configuration option 'tacos'\n");
      sorcery_memory_cache_close(cache);
      res = AST_TEST_FAIL;
   }

   return res;
}

AST_TEST_DEFINE(create_and_retrieve)
{
   int res = AST_TEST_FAIL;
   struct ast_sorcery *sorcery = NULL;
   struct sorcery_memory_cache *cache = NULL;
   RAII_VAR(void *, object, NULL, ao2_cleanup);
   RAII_VAR(void *, cached_object, NULL, ao2_cleanup);

   switch (cmd) {
   case TEST_INIT:
      info->name = "create";
      info->category = "/res/res_sorcery_memory_cache/";
      info->summary = "Attempt to create an object in the cache";
      info->description = "This test performs the following:\n"
         "\t* Creates a memory cache with default options\n"
         "\t* Creates a sorcery instance with a test object\n"
         "\t* Creates a test object with an id of test\n"
         "\t* Pushes the test object into the memory cache\n"
         "\t* Confirms that the test object is in the cache";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   cache = sorcery_memory_cache_open("");
   if (!cache) {
      ast_test_status_update(test, "Failed to create a sorcery memory cache using default options\n");
      goto cleanup;
   }

   if (ao2_container_count(cache->objects)) {
      ast_test_status_update(test, "Memory cache contains cached objects before we added one\n");
      goto cleanup;
   }

   sorcery = alloc_and_initialize_sorcery();
   if (!sorcery) {
      ast_test_status_update(test, "Failed to create a test sorcery instance\n");
      goto cleanup;
   }

   object = ast_sorcery_alloc(sorcery, "test", "test");
   if (!object) {
      ast_test_status_update(test, "Failed to allocate a test object\n");
      goto cleanup;
   }

   sorcery_memory_cache_create(sorcery, cache, object);

   if (!ao2_container_count(cache->objects)) {
      ast_test_status_update(test, "Added test object to memory cache but cache remains empty\n");
      goto cleanup;
   }

   cached_object = sorcery_memory_cache_retrieve_id(sorcery, cache, "test", "test");
   if (!cached_object) {
      ast_test_status_update(test, "Object placed into memory cache could not be retrieved\n");
      goto cleanup;
   }

   if (cached_object != object) {
      ast_test_status_update(test, "Object retrieved from memory cached is not the one we cached\n");
      goto cleanup;
   }

   res = AST_TEST_PASS;

cleanup:
   if (cache) {
      sorcery_memory_cache_close(cache);
   }
   if (sorcery) {
      ast_sorcery_unref(sorcery);
   }

   return res;
}

AST_TEST_DEFINE(update)
{
   int res = AST_TEST_FAIL;
   struct ast_sorcery *sorcery = NULL;
   struct sorcery_memory_cache *cache = NULL;
   RAII_VAR(void *, original_object, NULL, ao2_cleanup);
   RAII_VAR(void *, updated_object, NULL, ao2_cleanup);
   RAII_VAR(void *, cached_object, NULL, ao2_cleanup);

   switch (cmd) {
   case TEST_INIT:
      info->name = "create";
      info->category = "/res/res_sorcery_memory_cache/";
      info->summary = "Attempt to create and then update an object in the cache";
      info->description = "This test performs the following:\n"
         "\t* Creates a memory cache with default options\n"
         "\t* Creates a sorcery instance with a test object\n"
         "\t* Creates a test object with an id of test\n"
         "\t* Pushes the test object into the memory cache\n"
         "\t* Confirms that the test object is in the cache\n"
         "\t* Creates a new test object with the same id of test\n"
         "\t* Pushes the new test object into the memory cache\n"
         "\t* Confirms that the new test object has replaced the old one";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   cache = sorcery_memory_cache_open("");
   if (!cache) {
      ast_test_status_update(test, "Failed to create a sorcery memory cache using default options\n");
      goto cleanup;
   }

   if (ao2_container_count(cache->objects)) {
      ast_test_status_update(test, "Memory cache contains cached objects before we added one\n");
      goto cleanup;
   }

   sorcery = alloc_and_initialize_sorcery();
   if (!sorcery) {
      ast_test_status_update(test, "Failed to create a test sorcery instance\n");
      goto cleanup;
   }

   original_object = ast_sorcery_alloc(sorcery, "test", "test");
   if (!original_object) {
      ast_test_status_update(test, "Failed to allocate a test object\n");
      goto cleanup;
   }

   sorcery_memory_cache_create(sorcery, cache, original_object);

   updated_object = ast_sorcery_alloc(sorcery, "test", "test");
   if (!updated_object) {
      ast_test_status_update(test, "Failed to allocate an updated test object\n");
      goto cleanup;
   }

   sorcery_memory_cache_create(sorcery, cache, updated_object);

   if (ao2_container_count(cache->objects) != 1) {
      ast_test_status_update(test, "Added updated test object to memory cache but cache now contains %d objects instead of 1\n",
         ao2_container_count(cache->objects));
      goto cleanup;
   }

   cached_object = sorcery_memory_cache_retrieve_id(sorcery, cache, "test", "test");
   if (!cached_object) {
      ast_test_status_update(test, "Updated object placed into memory cache could not be retrieved\n");
      goto cleanup;
   }

   if (cached_object == original_object) {
      ast_test_status_update(test, "Updated object placed into memory cache but old one is being retrieved\n");
      goto cleanup;
   } else if (cached_object != updated_object) {
      ast_test_status_update(test, "Updated object placed into memory cache but different one is being retrieved\n");
      goto cleanup;
   }

   res = AST_TEST_PASS;

cleanup:
   if (cache) {
      sorcery_memory_cache_close(cache);
   }
   if (sorcery) {
      ast_sorcery_unref(sorcery);
   }

   return res;
}

AST_TEST_DEFINE(delete)
{
   int res = AST_TEST_FAIL;
   struct ast_sorcery *sorcery = NULL;
   struct sorcery_memory_cache *cache = NULL;
   RAII_VAR(void *, object, NULL, ao2_cleanup);
   RAII_VAR(void *, cached_object, NULL, ao2_cleanup);

   switch (cmd) {
   case TEST_INIT:
      info->name = "delete";
      info->category = "/res/res_sorcery_memory_cache/";
      info->summary = "Attempt to create and then delete an object in the cache";
      info->description = "This test performs the following:\n"
         "\t* Creates a memory cache with default options\n"
         "\t* Creates a sorcery instance with a test object\n"
         "\t* Creates a test object with an id of test\n"
         "\t* Pushes the test object into the memory cache\n"
         "\t* Confirms that the test object is in the cache\n"
         "\t* Deletes the test object from the cache\n"
         "\t* Confirms that the test object is no longer in the cache";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   cache = sorcery_memory_cache_open("");
   if (!cache) {
      ast_test_status_update(test, "Failed to create a sorcery memory cache using default options\n");
      goto cleanup;
   }

   if (ao2_container_count(cache->objects)) {
      ast_test_status_update(test, "Memory cache contains cached objects before we added one\n");
      goto cleanup;
   }

   sorcery = alloc_and_initialize_sorcery();
   if (!sorcery) {
      ast_test_status_update(test, "Failed to create a test sorcery instance\n");
      goto cleanup;
   }

   object = ast_sorcery_alloc(sorcery, "test", "test");
   if (!object) {
      ast_test_status_update(test, "Failed to allocate a test object\n");
      goto cleanup;
   }

   sorcery_memory_cache_create(sorcery, cache, object);

   if (!ao2_container_count(cache->objects)) {
      ast_test_status_update(test, "Added test object to memory cache but cache contains no objects\n");
      goto cleanup;
   }

   cached_object = sorcery_memory_cache_retrieve_id(sorcery, cache, "test", "test");
   if (!cached_object) {
      ast_test_status_update(test, "Test object placed into memory cache could not be retrieved\n");
      goto cleanup;
   }

   ao2_ref(cached_object, -1);
   cached_object = NULL;

   sorcery_memory_cache_delete(sorcery, cache, object);

   cached_object = sorcery_memory_cache_retrieve_id(sorcery, cache, "test", "test");
   if (cached_object) {
      ast_test_status_update(test, "Test object deleted from memory cache can still be retrieved\n");
      goto cleanup;
   }

   res = AST_TEST_PASS;

cleanup:
   if (cache) {
      sorcery_memory_cache_close(cache);
   }
   if (sorcery) {
      ast_sorcery_unref(sorcery);
   }

   return res;
}

static int check_cache_content(struct ast_test *test, struct ast_sorcery *sorcery, struct sorcery_memory_cache *cache,
      const char **in_cache, size_t num_in_cache, const char **not_in_cache, size_t num_not_in_cache)
{
   int i;
   int res = 0;
   RAII_VAR(void *, cached_object, NULL, ao2_cleanup);

   for (i = 0; i < num_in_cache; ++i) {
      cached_object = sorcery_memory_cache_retrieve_id(sorcery, cache, "test", in_cache[i]);
      if (!cached_object) {
         ast_test_status_update(test, "Failed to retrieve '%s' object from the cache\n",
               in_cache[i]);
         res = -1;
      }
      ao2_ref(cached_object, -1);
   }

   for (i = 0; i < num_not_in_cache; ++i) {
      cached_object = sorcery_memory_cache_retrieve_id(sorcery, cache, "test", not_in_cache[i]);
      if (cached_object) {
         ast_test_status_update(test, "Retrieved '%s' object from the cache unexpectedly\n",
               not_in_cache[i]);
         ao2_ref(cached_object, -1);
         res = -1;
      }
   }

   return res;
}

AST_TEST_DEFINE(maximum_objects)
{
   int res = AST_TEST_FAIL;
   struct ast_sorcery *sorcery = NULL;
   struct sorcery_memory_cache *cache = NULL;
   RAII_VAR(void *, alice, NULL, ao2_cleanup);
   RAII_VAR(void *, bob, NULL, ao2_cleanup);
   RAII_VAR(void *, charlie, NULL, ao2_cleanup);
   RAII_VAR(void *, cached_object, NULL, ao2_cleanup);
   const char *in_cache[2];
   const char *not_in_cache[2];

   switch (cmd) {
   case TEST_INIT:
      info->name = "maximum_objects";
      info->category = "/res/res_sorcery_memory_cache/";
      info->summary = "Ensure that the 'maximum_objects' option works as expected";
      info->description = "This test performs the following:\n"
         "\t* Creates a memory cache with maximum_objects=2\n"
         "\t* Creates a sorcery instance\n"
         "\t* Creates a three test objects: alice, bob, charlie, and david\n"
         "\t* Pushes alice and bob into the memory cache\n"
         "\t* Confirms that alice and bob are in the memory cache\n"
         "\t* Pushes charlie into the memory cache\n"
         "\t* Confirms that bob and charlie are in the memory cache\n"
         "\t* Deletes charlie from the memory cache\n"
         "\t* Confirms that only bob is in the memory cache\n"
         "\t* Pushes alice into the memory cache\n"
         "\t* Confirms that bob and alice are in the memory cache";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   cache = sorcery_memory_cache_open("maximum_objects=2");
   if (!cache) {
      ast_test_status_update(test, "Failed to create a sorcery memory cache with maximum_objects=2\n");
      goto cleanup;
   }

   if (ao2_container_count(cache->objects)) {
      ast_test_status_update(test, "Memory cache contains cached objects before we added one\n");
      goto cleanup;
   }

   sorcery = alloc_and_initialize_sorcery();
   if (!sorcery) {
      ast_test_status_update(test, "Failed to create a test sorcery instance\n");
      goto cleanup;
   }

   alice = ast_sorcery_alloc(sorcery, "test", "alice");
   bob = ast_sorcery_alloc(sorcery, "test", "bob");
   charlie = ast_sorcery_alloc(sorcery, "test", "charlie");

   if (!alice || !bob || !charlie) {
      ast_test_status_update(test, "Failed to allocate sorcery object(s)\n");
      goto cleanup;
   }

   sorcery_memory_cache_create(sorcery, cache, alice);
   in_cache[0] = "alice";
   in_cache[1] = NULL;
   not_in_cache[0] = "bob";
   not_in_cache[1] = "charlie";
   if (check_cache_content(test, sorcery, cache, in_cache, 1, not_in_cache, 2)) {
      goto cleanup;
   }

   /* Delays are added to ensure that we are not adding cache entries within the
    * same microsecond
    */
   usleep(1000);

   sorcery_memory_cache_create(sorcery, cache, bob);
   in_cache[0] = "alice";
   in_cache[1] = "bob";
   not_in_cache[0] = "charlie";
   not_in_cache[1] = NULL;
   if (check_cache_content(test, sorcery, cache, in_cache, 2, not_in_cache, 1)) {
      goto cleanup;
   }

   usleep(1000);

   sorcery_memory_cache_create(sorcery, cache, charlie);
   in_cache[0] = "bob";
   in_cache[1] = "charlie";
   not_in_cache[0] = "alice";
   not_in_cache[1] = NULL;
   if (check_cache_content(test, sorcery, cache, in_cache, 2, not_in_cache, 1)) {
      goto cleanup;
   }
   usleep(1000);

   sorcery_memory_cache_delete(sorcery, cache, charlie);
   in_cache[0] = "bob";
   in_cache[1] = NULL;
   not_in_cache[0] = "alice";
   not_in_cache[1] = "charlie";
   if (check_cache_content(test, sorcery, cache, in_cache, 1, not_in_cache, 2)) {
      goto cleanup;
   }
   usleep(1000);

   sorcery_memory_cache_create(sorcery, cache, alice);
   in_cache[0] = "bob";
   in_cache[1] = "alice";
   not_in_cache[0] = "charlie";
   not_in_cache[1] = NULL;
   if (check_cache_content(test, sorcery, cache, in_cache, 2, not_in_cache, 1)) {
      goto cleanup;
   }

   res = AST_TEST_PASS;

cleanup:
   if (cache) {
      sorcery_memory_cache_close(cache);
   }
   if (sorcery) {
      ast_sorcery_unref(sorcery);
   }

   return res;
}

AST_TEST_DEFINE(expiration)
{
   int res = AST_TEST_FAIL;
   struct ast_sorcery *sorcery = NULL;
   struct sorcery_memory_cache *cache = NULL;
   int i;

   switch (cmd) {
   case TEST_INIT:
      info->name = "expiration";
      info->category = "/res/res_sorcery_memory_cache/";
      info->summary = "Add objects to a cache configured with maximum lifetime, confirm they are removed";
      info->description = "This test performs the following:\n"
         "\t* Creates a memory cache with a maximum object lifetime of 5 seconds\n"
         "\t* Pushes 10 objects into the memory cache\n"
         "\t* Waits (up to) 10 seconds for expiration to occur\n"
         "\t* Confirms that the objects have been removed from the cache";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   cache = sorcery_memory_cache_open("object_lifetime_maximum=5");
   if (!cache) {
      ast_test_status_update(test, "Failed to create a sorcery memory cache using default options\n");
      goto cleanup;
   }

   sorcery = alloc_and_initialize_sorcery();
   if (!sorcery) {
      ast_test_status_update(test, "Failed to create a test sorcery instance\n");
      goto cleanup;
   }

   cache->cache_notify = 1;
   ast_mutex_init(&cache->lock);
   ast_cond_init(&cache->cond, NULL);

   for (i = 0; i < 5; ++i) {
      char uuid[AST_UUID_STR_LEN];
      void *object;

      object = ast_sorcery_alloc(sorcery, "test", ast_uuid_generate_str(uuid, sizeof(uuid)));
      if (!object) {
         ast_test_status_update(test, "Failed to allocate test object for expiration\n");
         goto cleanup;
      }

      sorcery_memory_cache_create(sorcery, cache, object);

      ao2_ref(object, -1);
   }

   ast_mutex_lock(&cache->lock);
   while (!cache->cache_completed) {
      struct timeval start = ast_tvnow();
      struct timespec end = {
         .tv_sec = start.tv_sec + 10,
         .tv_nsec = start.tv_usec * 1000,
      };

      if (ast_cond_timedwait(&cache->cond, &cache->lock, &end) == ETIMEDOUT) {
         break;
      }
   }
   ast_mutex_unlock(&cache->lock);

   if (ao2_container_count(cache->objects)) {
      ast_test_status_update(test, "Objects placed into the memory cache did not expire and get removed\n");
      goto cleanup;
   }

   res = AST_TEST_PASS;

cleanup:
   if (cache) {
      if (cache->cache_notify) {
         ast_cond_destroy(&cache->cond);
         ast_mutex_destroy(&cache->lock);
      }
      sorcery_memory_cache_close(cache);
   }
   if (sorcery) {
      ast_sorcery_unref(sorcery);
   }

   return res;
}

/*!
 * \brief Backend data that the mock sorcery wizard uses to create objects
 */
static struct backend_data {
   /*! An arbitrary data field */
   int salt;
   /*! Another arbitrary data field */
   int pepper;
   /*! Indicates whether the backend has data */
   int exists;
} *real_backend_data;

/*!
 * \brief Sorcery object created based on backend data
 */
struct test_data {
   SORCERY_OBJECT(details);
   /*! Mirrors the backend data's salt field */
   int salt;
   /*! Mirrors the backend data's pepper field */
   int pepper;
};

/*!
 * \brief Allocation callback for test_data sorcery object
 */
static void *test_data_alloc(const char *id) {
   return ast_sorcery_generic_alloc(sizeof(struct test_data), NULL);
}

/*!
 * \brief Callback for retrieving sorcery object by ID
 *
 * The mock wizard uses the \ref real_backend_data in order to construct
 * objects. If the backend data is "nonexisent" then no object is returned.
 * Otherwise, an object is created that has the backend data's salt and
 * pepper values copied.
 *
 * \param sorcery The sorcery instance
 * \param data Unused
 * \param type The object type. Will always be "test".
 * \param id The object id. Will always be "test".
 *
 * \retval NULL Backend data does not exist
 * \retval non-NULL An object representing the backend data
 */
static void *mock_retrieve_id(const struct ast_sorcery *sorcery, void *data,
      const char *type, const char *id)
{
   struct test_data *b_data;

   if (!real_backend_data->exists) {
      return NULL;
   }

   b_data = ast_sorcery_alloc(sorcery, type, id);
   if (!b_data) {
      return NULL;
   }

   b_data->salt = real_backend_data->salt;
   b_data->pepper = real_backend_data->pepper;
   return b_data;
}

/*!
 * \brief Callback for retrieving multiple sorcery objects
 *
 * The mock wizard uses the \ref real_backend_data in order to construct
 * objects. If the backend data is "nonexisent" then no object is returned.
 * Otherwise, the number of objects matching the exists value will be returned.
 *
 * \param sorcery The sorcery instance
 * \param data Unused
 * \param type The object type. Will always be "test".
 * \param objects Container to place objects into.
 * \param fields Fields to search for.
 */
static void mock_retrieve_multiple(const struct ast_sorcery *sorcery, void *data,
      const char *type, struct ao2_container *objects, const struct ast_variable *fields)
{
   int i;

   if (fields) {
      return;
   }

   for (i = 0; i < real_backend_data->exists; ++i) {
      char uuid[AST_UUID_STR_LEN];
      struct test_data *b_data;

      b_data = ast_sorcery_alloc(sorcery, type, ast_uuid_generate_str(uuid, sizeof(uuid)));
      if (!b_data) {
         continue;
      }

      b_data->salt = real_backend_data->salt;
      b_data->pepper = real_backend_data->pepper;

      ao2_link(objects, b_data);
      ao2_ref(b_data, -1);
   }
}

/*!
 * \brief A mock sorcery wizard used for the stale test
 */
static struct ast_sorcery_wizard mock_wizard = {
   .name = "mock",
   .retrieve_id = mock_retrieve_id,
   .retrieve_multiple = mock_retrieve_multiple,
};

/*!
 * \brief Wait for the cache to be updated after a stale object is retrieved.
 *
 * Since the cache does not know what type of objects it is dealing with, and
 * since we do not have the internals of the cache, the only way to make this
 * determination is to continuously retrieve an object from the cache until
 * we retrieve a different object than we had previously retrieved.
 *
 * \param sorcery The sorcery instance
 * \param previous_object The object we had previously retrieved from the cache
 * \param[out] new_object The new object we retrieve from the cache
 *
 * \retval 0 Successfully retrieved a new object from the cache
 * \retval non-zero Failed to retrieve a new object from the cache
 */
static int wait_for_cache_update(const struct ast_sorcery *sorcery,
      void *previous_object, struct test_data **new_object)
{
   struct timeval start = ast_tvnow();

   while (ast_remaining_ms(start, 5000) > 0) {
      void *object;

      object = ast_sorcery_retrieve_by_id(sorcery, "test", "test");
      if (object != previous_object) {
         *new_object = object;
         return 0;
      }
      ao2_cleanup(object);
   }

   return -1;
}

AST_TEST_DEFINE(stale)
{
   int res = AST_TEST_FAIL;
   struct ast_sorcery *sorcery = NULL;
   struct test_data *backend_object;
   struct backend_data iterations[] = {
      { .salt = 1,      .pepper = 2,       .exists = 1 },
      { .salt = 568729, .pepper = -234123, .exists = 1 },
      { .salt = 0,      .pepper = 0,       .exists = 0 },
   };
   struct backend_data initial = {
      .salt = 0,
      .pepper = 0,
      .exists = 1,
   };
   int i;

   switch (cmd) {
   case TEST_INIT:
      info->name = "stale";
      info->category = "/res/res_sorcery_memory_cache/";
      info->summary = "Ensure that stale objects are replaced with updated objects";
      info->description = "This test performs the following:\n"
         "\t* Create a sorcery instance with two wizards"
         "\t\t* The first is a memory cache that marks items stale after 3 seconds\n"
         "\t\t* The second is a mock of a back-end\n"
         "\t* Pre-populates the cache by retrieving some initial data from the backend.\n"
         "\t* Performs iterations of the following:\n"
         "\t\t* Update backend data with new values\n"
         "\t\t* Retrieve item from the cache\n"
         "\t\t* Ensure the retrieved item does not have the new backend values\n"
         "\t\t* Wait for cached object to become stale\n"
         "\t\t* Retrieve the stale cached object\n"
         "\t\t* Ensure that the stale object retrieved is the same as the fresh one from earlier\n"
         "\t\t* Wait for the cache to update with new data\n"
         "\t\t* Ensure that new data in the cache matches backend data";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   ast_sorcery_wizard_register(&mock_wizard);

   sorcery = ast_sorcery_open();
   if (!sorcery) {
      ast_test_status_update(test, "Failed to create sorcery instance\n");
      goto cleanup;
   }

   ast_sorcery_apply_wizard_mapping(sorcery, "test", "memory_cache",
         "object_lifetime_stale=3", 1);
   ast_sorcery_apply_wizard_mapping(sorcery, "test", "mock", NULL, 0);
   ast_sorcery_internal_object_register(sorcery, "test", test_data_alloc, NULL, NULL);

   /* Prepopulate the cache */
   real_backend_data = &initial;

   backend_object = ast_sorcery_retrieve_by_id(sorcery, "test", "test");
   if (!backend_object) {
      ast_test_status_update(test, "Unable to retrieve backend data and populate the cache\n");
      goto cleanup;
   }
   ao2_ref(backend_object, -1);

   for (i = 0; i < ARRAY_LEN(iterations); ++i) {
      RAII_VAR(struct test_data *, cache_fresh, NULL, ao2_cleanup);
      RAII_VAR(struct test_data *, cache_stale, NULL, ao2_cleanup);
      RAII_VAR(struct test_data *, cache_new, NULL, ao2_cleanup);

      real_backend_data = &iterations[i];

      ast_test_status_update(test, "Begininning iteration %d\n", i);

      cache_fresh = ast_sorcery_retrieve_by_id(sorcery, "test", "test");
      if (!cache_fresh) {
         ast_test_status_update(test, "Unable to retrieve fresh cached object\n");
         goto cleanup;
      }

      if (cache_fresh->salt == iterations[i].salt || cache_fresh->pepper == iterations[i].pepper) {
         ast_test_status_update(test, "Fresh cached object has unexpected values. Did we hit the backend?\n");
         goto cleanup;
      }

      sleep(5);

      cache_stale = ast_sorcery_retrieve_by_id(sorcery, "test", "test");
      if (!cache_stale) {
         ast_test_status_update(test, "Unable to retrieve stale cached object\n");
         goto cleanup;
      }

      if (cache_stale != cache_fresh) {
         ast_test_status_update(test, "Stale cache hit retrieved different object than fresh cache hit\n");
         goto cleanup;
      }

      if (wait_for_cache_update(sorcery, cache_stale, &cache_new)) {
         ast_test_status_update(test, "Cache was not updated\n");
         goto cleanup;
      }

      if (iterations[i].exists) {
         if (!cache_new) {
            ast_test_status_update(test, "Failed to retrieve item from cache when there should be one present\n");
            goto cleanup;
         } else if (cache_new->salt != iterations[i].salt ||
               cache_new->pepper != iterations[i].pepper) {
            ast_test_status_update(test, "New cached item has unexpected values\n");
            goto cleanup;
         }
      } else if (cache_new) {
         ast_test_status_update(test, "Retrieved a cached item when there should not have been one present\n");
         goto cleanup;
      }
   }

   res = AST_TEST_PASS;

cleanup:
   if (sorcery) {
      ast_sorcery_unref(sorcery);
   }
   ast_sorcery_wizard_unregister(&mock_wizard);
   return res;
}

AST_TEST_DEFINE(full_backend_cache_expiration)
{
   int res = AST_TEST_FAIL;
   struct ast_sorcery *sorcery = NULL;
   struct backend_data initial = {
      .salt = 0,
      .pepper = 0,
      .exists = 4,
   };
   struct ao2_container *objects;
   ast_mutex_t lock;
   ast_cond_t cond;
   struct timeval start;
   struct timespec end;

   switch (cmd) {
   case TEST_INIT:
      info->name = "full_backend_cache_expiration";
      info->category = "/res/res_sorcery_memory_cache/";
      info->summary = "Ensure that the full backend cache actually caches the backend";
      info->description = "This test performs the following:\n"
         "\t* Create a sorcery instance with two wizards"
         "\t\t* The first is a memory cache that expires objects after 3 seconds and does full backend caching\n"
         "\t\t* The second is a mock of a back-end\n"
         "\t* Populates the cache by requesting all objects which returns 4.\n"
         "\t* Updates the backend to contain a different number of objects, 8.\n"
         "\t* Requests all objects and confirms the number returned is only 4.\n"
         "\t* Wait for cached objects to expire.\n"
         "\t* Requests all objects and confirms the number returned is 8.";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   ast_sorcery_wizard_register(&mock_wizard);

   sorcery = ast_sorcery_open();
   if (!sorcery) {
      ast_test_status_update(test, "Failed to create sorcery instance\n");
      goto cleanup;
   }

   ast_sorcery_apply_wizard_mapping(sorcery, "test", "memory_cache",
         "object_lifetime_maximum=3,full_backend_cache=yes", 1);
   ast_sorcery_apply_wizard_mapping(sorcery, "test", "mock", NULL, 0);
   ast_sorcery_internal_object_register(sorcery, "test", test_data_alloc, NULL, NULL);
   ast_sorcery_object_field_register_nodoc(sorcery, "test", "salt", "0", OPT_UINT_T, 0, FLDSET(struct test_data, salt));
   ast_sorcery_object_field_register_nodoc(sorcery, "test", "pepper", "0", OPT_UINT_T, 0, FLDSET(struct test_data, pepper));

   /* Prepopulate the cache */
   real_backend_data = &initial;

   /* Get all current objects in the backend */
   objects = ast_sorcery_retrieve_by_fields(sorcery, "test", AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL);
   if (!objects) {
      ast_test_status_update(test, "Unable to retrieve all objects in backend and populate cache\n");
      goto cleanup;
   }
   ao2_ref(objects, -1);

   /* Update the backend to have a different number of objects */
   initial.exists = 8;

   /* Get all current objects in the backend */
   objects = ast_sorcery_retrieve_by_fields(sorcery, "test", AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL);
   if (!objects) {
      ast_test_status_update(test, "Unable to retrieve all objects in backend and populate cache\n");
      goto cleanup;
   }

   if (ao2_container_count(objects) == initial.exists) {
      ast_test_status_update(test, "Number of objects returned is of the current backend and not the cache\n");
      ao2_ref(objects, -1);
      goto cleanup;
   }

   ao2_ref(objects, -1);

   ast_mutex_init(&lock);
   ast_cond_init(&cond, NULL);

   start = ast_tvnow();
   end.tv_sec = start.tv_sec + 5;
   end.tv_nsec = start.tv_usec * 1000;

   ast_mutex_lock(&lock);
   while (ast_cond_timedwait(&cond, &lock, &end) != ETIMEDOUT) {
   }
   ast_mutex_unlock(&lock);

   ast_mutex_destroy(&lock);
   ast_cond_destroy(&cond);

   /* Get all current objects in the backend */
   objects = ast_sorcery_retrieve_by_fields(sorcery, "test", AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL);
   if (!objects) {
      ast_test_status_update(test, "Unable to retrieve all objects in backend and populate cache\n");
      goto cleanup;
   }

   if (ao2_container_count(objects) != initial.exists) {
      ast_test_status_update(test, "Number of objects returned is NOT of the current backend when it should be\n");
      ao2_ref(objects, -1);
      goto cleanup;
   }

   ao2_ref(objects, -1);

   res = AST_TEST_PASS;

cleanup:
   if (sorcery) {
      ast_sorcery_unref(sorcery);
   }
   ast_sorcery_wizard_unregister(&mock_wizard);
   return res;
}

AST_TEST_DEFINE(full_backend_cache_stale)
{
   int res = AST_TEST_FAIL;
   struct ast_sorcery *sorcery = NULL;
   struct backend_data initial = {
      .salt = 0,
      .pepper = 0,
      .exists = 4,
   };
   struct ao2_container *objects;
   ast_mutex_t lock;
   ast_cond_t cond;
   struct timeval start;
   struct timespec end;

   switch (cmd) {
   case TEST_INIT:
      info->name = "full_backend_cache_stale";
      info->category = "/res/res_sorcery_memory_cache/";
      info->summary = "Ensure that the full backend cache works with staleness";
      info->description = "This test performs the following:\n"
         "\t* Create a sorcery instance with two wizards"
         "\t\t* The first is a memory cache that stales objects after 1 second and does full backend caching\n"
         "\t\t* The second is a mock of a back-end\n"
         "\t* Populates the cache by requesting all objects which returns 4.\n"
         "\t* Wait for objects to go stale.\n"
         "\t* Updates the backend to contain a different number of objects, 8.\""
         "\t* Requests all objects and confirms the number returned is only 4.\n"
         "\t* Wait for objects to be refreshed from backend.\n"
         "\t* Requests all objects and confirms the number returned is 8.";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   ast_sorcery_wizard_register(&mock_wizard);

   ast_mutex_init(&lock);
   ast_cond_init(&cond, NULL);

   sorcery = ast_sorcery_open();
   if (!sorcery) {
      ast_test_status_update(test, "Failed to create sorcery instance\n");
      goto cleanup;
   }

   ast_sorcery_apply_wizard_mapping(sorcery, "test", "memory_cache",
         "object_lifetime_stale=1,full_backend_cache=yes", 1);
   ast_sorcery_apply_wizard_mapping(sorcery, "test", "mock", NULL, 0);
   ast_sorcery_internal_object_register(sorcery, "test", test_data_alloc, NULL, NULL);
   ast_sorcery_object_field_register_nodoc(sorcery, "test", "salt", "0", OPT_UINT_T, 0, FLDSET(struct test_data, salt));
   ast_sorcery_object_field_register_nodoc(sorcery, "test", "pepper", "0", OPT_UINT_T, 0, FLDSET(struct test_data, pepper));

   /* Prepopulate the cache */
   real_backend_data = &initial;

   /* Get all current objects in the backend */
   objects = ast_sorcery_retrieve_by_fields(sorcery, "test", AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL);
   if (!objects) {
      ast_test_status_update(test, "Unable to retrieve all objects in backend and populate cache\n");
      goto cleanup;
   }
   ao2_ref(objects, -1);

   start = ast_tvnow();
   end.tv_sec = start.tv_sec + 5;
   end.tv_nsec = start.tv_usec * 1000;

   ast_mutex_lock(&lock);
   while (ast_cond_timedwait(&cond, &lock, &end) != ETIMEDOUT) {
   }
   ast_mutex_unlock(&lock);

   initial.exists = 8;

   /* Get all current objects in the backend */
   objects = ast_sorcery_retrieve_by_fields(sorcery, "test", AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL);
   if (!objects) {
      ast_test_status_update(test, "Unable to retrieve all objects in backend and populate cache\n");
      goto cleanup;
   }

   if (ao2_container_count(objects) == initial.exists) {
      ast_test_status_update(test, "Number of objects returned is of the backend and not the cache\n");
      ao2_ref(objects, -1);
      goto cleanup;
   }

   ao2_ref(objects, -1);

   start = ast_tvnow();
   end.tv_sec = start.tv_sec + 5;
   end.tv_nsec = start.tv_usec * 1000;

   ast_mutex_lock(&lock);
   while (ast_cond_timedwait(&cond, &lock, &end) != ETIMEDOUT) {
   }
   ast_mutex_unlock(&lock);

   /* Get all current objects in the backend */
   objects = ast_sorcery_retrieve_by_fields(sorcery, "test", AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL);
   if (!objects) {
      ast_test_status_update(test, "Unable to retrieve all objects in backend and populate cache\n");
      goto cleanup;
   }

   if (ao2_container_count(objects) != initial.exists) {
      ast_test_status_update(test, "Number of objects returned is not of backend\n");
      ao2_ref(objects, -1);
      goto cleanup;
   }

   ao2_ref(objects, -1);

   start = ast_tvnow();
   end.tv_sec = start.tv_sec + 5;
   end.tv_nsec = start.tv_usec * 1000;

   ast_mutex_lock(&lock);
   while (ast_cond_timedwait(&cond, &lock, &end) != ETIMEDOUT) {
   }
   ast_mutex_unlock(&lock);

   res = AST_TEST_PASS;

cleanup:
   if (sorcery) {
      ast_sorcery_unref(sorcery);
   }
   ast_sorcery_wizard_unregister(&mock_wizard);
   ast_mutex_destroy(&lock);
   ast_cond_destroy(&cond);
   return res;
}

#endif

static int unload_module(void)
{
   AST_TEST_UNREGISTER(open_with_valid_options);
   AST_TEST_UNREGISTER(open_with_invalid_options);
   AST_TEST_UNREGISTER(create_and_retrieve);
   AST_TEST_UNREGISTER(update);
   AST_TEST_UNREGISTER(delete);
   AST_TEST_UNREGISTER(maximum_objects);
   AST_TEST_UNREGISTER(expiration);
   AST_TEST_UNREGISTER(stale);
   AST_TEST_UNREGISTER(full_backend_cache_expiration);
   AST_TEST_UNREGISTER(full_backend_cache_stale);

   ast_manager_unregister("SorceryMemoryCacheExpireObject");
   ast_manager_unregister("SorceryMemoryCacheExpire");
   ast_manager_unregister("SorceryMemoryCacheStaleObject");
   ast_manager_unregister("SorceryMemoryCacheStale");
   ast_manager_unregister("SorceryMemoryCachePopulate");

   ast_cli_unregister_multiple(cli_memory_cache, ARRAY_LEN(cli_memory_cache));

   ast_sorcery_wizard_unregister(&memory_cache_object_wizard);

   /*
    * XXX There is the potential to leak memory if there are pending
    * next-cache-expiration and stale-cache-update tasks in the scheduler.
    */
   if (sched) {
      ast_sched_context_destroy(sched);
      sched = NULL;
   }

   ao2_cleanup(caches);
   caches = NULL;

   return 0;
}

static int load_module(void)
{
   int res;

   caches = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0,
      CACHES_CONTAINER_BUCKET_SIZE, sorcery_memory_cache_hash, NULL,
      sorcery_memory_cache_cmp);
   if (!caches) {
      ast_log(LOG_ERROR, "Failed to create container for configured caches\n");
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   sched = ast_sched_context_create();
   if (!sched) {
      ast_log(LOG_ERROR, "Failed to create scheduler for cache management\n");
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   if (ast_sched_start_thread(sched)) {
      ast_log(LOG_ERROR, "Failed to create scheduler thread for cache management\n");
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   if (ast_sorcery_wizard_register(&memory_cache_object_wizard)) {
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   res = ast_cli_register_multiple(cli_memory_cache, ARRAY_LEN(cli_memory_cache));
   res |= ast_manager_register_xml("SorceryMemoryCacheExpireObject", EVENT_FLAG_SYSTEM, sorcery_memory_cache_ami_expire_object);
   res |= ast_manager_register_xml("SorceryMemoryCacheExpire", EVENT_FLAG_SYSTEM, sorcery_memory_cache_ami_expire);
   res |= ast_manager_register_xml("SorceryMemoryCacheStaleObject", EVENT_FLAG_SYSTEM, sorcery_memory_cache_ami_stale_object);
   res |= ast_manager_register_xml("SorceryMemoryCacheStale", EVENT_FLAG_SYSTEM, sorcery_memory_cache_ami_stale);
   res |= ast_manager_register_xml("SorceryMemoryCachePopulate", EVENT_FLAG_SYSTEM, sorcery_memory_cache_ami_populate);

   if (res) {
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   /* This causes the stale unit test to execute last, so if a sorcery instance persists
    * longer than expected subsequent unit tests don't fail when setting it up.
    */
   AST_TEST_REGISTER(stale);
   AST_TEST_REGISTER(open_with_valid_options);
   AST_TEST_REGISTER(open_with_invalid_options);
   AST_TEST_REGISTER(create_and_retrieve);
   AST_TEST_REGISTER(update);
   AST_TEST_REGISTER(delete);
   AST_TEST_REGISTER(maximum_objects);
   AST_TEST_REGISTER(expiration);
   AST_TEST_REGISTER(full_backend_cache_expiration);
   AST_TEST_REGISTER(full_backend_cache_stale);

   return AST_MODULE_LOAD_SUCCESS;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "Sorcery Memory Cache Object Wizard",
   .support_level = AST_MODULE_SUPPORT_CORE,
   .load = load_module,
   .unload = unload_module,
   .load_pri = AST_MODPRI_REALTIME_DRIVER,
);