sorcery.h

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2012 - 2013, 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 Data Access Layer API
 * \author Joshua Colp <[email protected]>
 * \ref AstSorcery
 */

/*!
 * \page AstSorcery Data Access Layer API
 *
 * Sorcery is a unifying data access layer which utilizes the configuration framework,
 * realtime, and astdb to allow object creation, retrieval, updating, and deletion.
 *
 * \par Initialization
 *
 * Usage of sorcery is accomplished by first opening a sorcery structure. This structure holds
 * all information about the object types, object fields, and object mappings. All API functions
 * require the sorcery structure to operate. When sorcery is no longer needed the structure can
 * be unreferenced using \ref ast_sorcery_unref
 *
 * Once opened the sorcery structure must have object mappings applied to it. This maps the
 * object types to their respective wizards (object storage modules). If the developer would like
 * to allow the user to configure this using the sorcery.conf configuration file the
 * \ref ast_sorcery_apply_config API call can be used to read in the configuration file and apply the
 * mappings. \ref ast_sorcery_open will automatically call \ref ast_sorcery_apply_config to allow
 * for configuration of objects using the same category name as the module that is opening the
 * sorcery instance. Direct calls to \ref ast_sorcery_apply_config should only be performed if a
 * module wishes to allow for additional configuration sections in sorcery.conf to be used.
 * If the storage of the object types are such that a default wizard can be used this can
 * be applied using the \ref ast_sorcery_apply_default API call. Note that the default mappings will not
 * override configured mappings. They are only used in the case where no configured mapping exists.
 *
 * Configuring object mappings implicitly creates a basic version of an object type. The object type
 * must be fully registered, however, using the \ref ast_sorcery_object_register API call before any
 * objects of the type can be allocated, created, or retrieved.
 *
 * Once the object type itself has been fully registered the individual fields within the object must
 * be registered using the \ref ast_sorcery_object_field_register API call. Note that not all fields *need*
 * be registered. Only fields that should be accessible using the sorcery API have to be registered.
 *
 * \par Creating Objects
 *
 * Before an object can be created within the sorcery API it must first be allocated using the
 * \ref ast_sorcery_alloc API call. This allocates a new instance of the object, sets sorcery specific
 * details, and applies default values to the object. A unique identifier can optionally be specified
 * when allocating an object. If it is not provided one will be automatically generated. Allocating
 * an object does not create it within any object storage mechanisms that are configured for the
 * object type. Creation must explicitly be done using the \ref ast_sorcery_create API call. This API call
 * passes the object to each configured object storage mechanism for the object type until one
 * successfully persists the object.
 *
 * \par Retrieving Objects
 *
 * To retrieve a single object using its unique identifier the \ref ast_sorcery_retrieve_by_id API call
 * can be used.
 *
 * To retrieve potentially multiple objects using specific fields the \ref ast_sorcery_retrieve_by_fields
 * API call can be used. The behavior of this API call is controlled using different flags. If the
 * AST_RETRIEVE_FLAG_MULTIPLE flag is used a container will be returned which contains all matching objects.
 * To retrieve all objects the AST_RETRIEVE_FLAG_ALL flag can be specified. Note that when specifying this flag
 * you do not need to pass any fields.
 *
 * Both API calls return shared objects. Modification of the object can not occur until it has been copied.
 *
 * \par Updating Objects
 *
 * As retrieved objects may be shared the first step to updating the object with new details is creating a
 * copy using the \ref ast_sorcery_copy API call. This will return a new object which is specific to the caller.
 * Any field within the object may be modified as needed. Once changes are done the changes can be committed
 * using the \ref ast_sorcery_update API call. Note that as the copied object is specific to the caller it must
 * be unreferenced after use.
 *
 * \par Deleting Objects
 *
 * To delete an object simply call the \ref ast_sorcery_delete API call with an object retrieved using the
 * ast_sorcery_retrieve_by_* API calls or a copy returned from \ref ast_sorcery_copy.
 */

#ifndef _ASTERISK_SORCERY_H
#define _ASTERISK_SORCERY_H

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

#include "asterisk/config_options.h"
#include "asterisk/uuid.h"

/*! \brief Maximum size of an object type */
#define MAX_OBJECT_TYPE 64

/*! \brief Maximum length of an object field name */
#define MAX_OBJECT_FIELD 128

/*!
 * \brief Retrieval flags
 */
enum ast_sorcery_retrieve_flags {
   /*! \brief Default retrieval flags */
   AST_RETRIEVE_FLAG_DEFAULT = 0,

   /*! \brief Return all matching objects */
   AST_RETRIEVE_FLAG_MULTIPLE = (1 << 0),

   /*! \brief Perform no matching, return all objects */
   AST_RETRIEVE_FLAG_ALL = (1 << 1),
};

/*!
 * \brief Field handler flags
 */
enum ast_sorcery_field_handler_flags {
   /*! \brief Try both handlers, string first */
   AST_HANDLER_PREFER_STRING,

   /*! \brief Try both handlers, list first */
   AST_HANDLER_PREFER_LIST,

   /*! \brief Use string handler only */
   AST_HANDLER_ONLY_STRING,

   /*! \brief Use list handler only */
   AST_HANDLER_ONLY_LIST,
};


/*! \brief Forward declaration for the sorcery main structure and wizard structure */
struct ast_sorcery;
struct ast_sorcery_wizard;

/*!
 * \brief A callback function for translating a value into a string
 *
 * \param obj Object to get value from
 * \param args Where the field is
 * \param buf Pointer to the buffer that the handler has created which contains the field value
 *
 * \retval 0 success
 * \retval -1 failure
 */
typedef int (*sorcery_field_handler)(const void *obj, const intptr_t *args, char **buf);

/*!
 * \brief A callback function for translating multiple values into an ast_variable list
 *
 * \param obj Object to get values from
 * \param fields Pointer to store the list of fields
 *
 * \retval 0 success
 * \retval -1 failure
 */
typedef int (*sorcery_fields_handler)(const void *obj, struct ast_variable **fields);

/*!
 * \brief A callback function for performing a transformation on an object set
 *
 * \param set The existing object set
 *
 * \retval non-NULL new object set if changed
 * \retval NULL if no changes present
 *
 * \note The returned ast_variable list must be *new*. You can not return the input set.
 */
typedef struct ast_variable *(*sorcery_transform_handler)(struct ast_variable *set);

/*!
 * \brief A callback function for when an object set is successfully applied to an object
 *
 * \note On a failure return, the state of the object is left undefined. It is a bad
 * idea to try to use this object.
 *
 * \param sorcery Sorcery structure in use
 * \param obj The object itself
 * \retval 0 Success
 * \retval non-zero Failure
 */
typedef int (*sorcery_apply_handler)(const struct ast_sorcery *sorcery, void *obj);

/*!
 * \brief A callback function for copying the contents of one object to another
 *
 * \param src The source object
 * \param dst The destination object
 *
 * \retval 0 success
 * \retval -1 failure
 */
typedef int (*sorcery_copy_handler)(const void *src, void *dst);

/*!
 * \brief A callback function for generating a changeset between two objects
 *
 * \param original The original object
 * \param modified The modified object
 * \param changes The changeset
 *
 * \param 0 success
 * \param -1 failure
 */
typedef int (*sorcery_diff_handler)(const void *original, const void *modified, struct ast_variable **changes);

/*! \brief Interface for the global sorcery observer */
struct ast_sorcery_global_observer {
   /*! \brief Callback after an instance is created */
   void (*instance_created)(const char *name, struct ast_sorcery *sorcery);

   /*! \brief Callback after an wizard is registered */
   void (*wizard_registered)(const char *name,
      const struct ast_sorcery_wizard *wizard);

   /*! \brief Callback before an instance is destroyed */
   void (*instance_destroying)(const char *name, struct ast_sorcery *sorcery);

   /*! \brief Callback before a wizard is unregistered */
   void (*wizard_unregistering)(const char *name,
      const struct ast_sorcery_wizard *wizard);
};

/*! \brief Interface for the sorcery instance observer */
struct ast_sorcery_instance_observer {
   /*! \brief Callback before instance is loaded/reloaded */
   void (*instance_loading)(const char *name, const struct ast_sorcery *sorcery,
      int reloaded);

   /*! \brief Callback after instance is loaded/reloaded */
   void (*instance_loaded)(const char *name, const struct ast_sorcery *sorcery,
      int reloaded);

   /*! \brief Callback after a wizard is mapped to an object_type */
   void (*wizard_mapped)(const char *name, struct ast_sorcery *sorcery,
      const char *object_type, struct ast_sorcery_wizard *wizard,
      const char *wizard_args, void *wizard_data);

   /*! \brief Callback after any object_type is registered */
   void (*object_type_registered)(const char *name, struct ast_sorcery *sorcery,
      const char *object_type);

   /*! \brief Callback before any object_type is loaded/reloaded */
   void (*object_type_loading)(const char *name, const struct ast_sorcery *sorcery,
      const char *object_type, int reloaded);

   /*! \brief Callback after any object_type is loaded/reloaded */
   void (*object_type_loaded)(const char *name, const struct ast_sorcery *sorcery,
      const char *object_type, int reloaded);
};

/*! \brief Interface for the sorcery wizard observer */
struct ast_sorcery_wizard_observer {
   /*! \brief Callback before a wizard is loaded/reloaded for any type */
   void (*wizard_loading)(const char *name, const struct ast_sorcery_wizard *wizard,
      const char *object_type, int reloaded);

   /*! \brief Callback after a wizard is loaded/reloaded for any type */
   void (*wizard_loaded)(const char *name, const struct ast_sorcery_wizard *wizard,
      const char *object_type, int reloaded);
};

/*! \brief Interface for a sorcery wizard */
struct ast_sorcery_wizard {
   /*! \brief Name of the wizard */
   const char *name;

   /*! \brief Pointer to the Asterisk module this wizard is implemented by */
   struct ast_module *module;

   /*! \brief Callback for opening a wizard */
   void *(*open)(const char *data);

   /*! \brief Optional callback for loading persistent objects */
   void (*load)(void *data, const struct ast_sorcery *sorcery, const char *type);

   /*! \brief Optional callback for reloading persistent objects */
   void (*reload)(void *data, const struct ast_sorcery *sorcery, const char *type);

   /*! \brief Callback for creating an object */
   int (*create)(const struct ast_sorcery *sorcery, void *data, void *object);

   /*! \brief Callback for retrieving an object using an id */
   void *(*retrieve_id)(const struct ast_sorcery *sorcery, void *data, const char *type, const char *id);

   /*! \brief Callback for retrieving multiple objects using a regex on their id */
   void (*retrieve_regex)(const struct ast_sorcery *sorcery, void *data, const char *type, struct ao2_container *objects, const char *regex);

   /*! \brief Optional callback for retrieving multiple objects by matching their id with a prefix */
   void (*retrieve_prefix)(const struct ast_sorcery *sorcery,
         void *data,
         const char *type,
         struct ao2_container *objects,
         const char *prefix,
         const size_t prefix_len);

   /*! \brief Optional callback for retrieving an object using fields */
   void *(*retrieve_fields)(const struct ast_sorcery *sorcery, void *data, const char *type, const struct ast_variable *fields);

   /*! \brief Optional callback for retrieving multiple objects using some optional field criteria */
   void (*retrieve_multiple)(const struct ast_sorcery *sorcery, void *data, const char *type, struct ao2_container *objects, const struct ast_variable *fields);

   /*! \brief Callback for updating an object */
   int (*update)(const struct ast_sorcery *sorcery, void *data, void *object);

   /*! \brief Callback for deleting an object */
   int (*delete)(const struct ast_sorcery *sorcery, void *data, void *object);

   /*! \brief Callback for closing a wizard */
   void (*close)(void *data);

   /* \brief Callback for whether or not the wizard believes the object is stale */
   int (*is_stale)(const struct ast_sorcery *sorcery, void *data, void *object);

   /*! \brief Optional callback for forcing a reload to occur, even if wizard has determined no changes */
   void (*force_reload)(void *data, const struct ast_sorcery *sorcery, const char *type);
};

/*! \brief Interface for a sorcery object type observer */
struct ast_sorcery_observer {
   /*! \brief Callback for when an object is created */
   void (*created)(const void *object);

   /*! \brief Callback for when an object is updated */
   void (*updated)(const void *object);

   /*! \brief Callback for when an object is deleted */
   void (*deleted)(const void *object);

   /*! \brief Callback for when an object type is loaded/reloaded */
   void (*loaded)(const char *object_type);
};

/*! \brief Opaque structure for internal sorcery object */
struct ast_sorcery_object;

/*! \brief Structure which contains details about a sorcery object */
struct ast_sorcery_object_details {
   /*! \brief Pointer to internal sorcery object information */
   struct ast_sorcery_object *object;
};

/*! \brief Macro which must be used at the beginning of each sorcery capable object */
#define SORCERY_OBJECT(details)                    \
struct {                                           \
   struct ast_sorcery_object_details details; \
}                                                  \

/*!
 * \brief Initialize the sorcery API
 *
 * \retval 0 success
 * \retval -1 failure
 */
int ast_sorcery_init(void);

/*!
 * \brief Register a sorcery wizard
 *
 * \param interface Pointer to a wizard interface
 * \param module Pointer to the module implementing the interface
 *
 * \retval 0 success
 * \retval -1 failure
 */
int __ast_sorcery_wizard_register(const struct ast_sorcery_wizard *interface, struct ast_module *module);

/*!
 * \brief See \ref __ast_sorcery_wizard_register()
 */
#define ast_sorcery_wizard_register(interface) __ast_sorcery_wizard_register(interface, AST_MODULE_SELF)

/*!
 * \brief Unregister a sorcery wizard
 *
 * \param interface Pointer to the wizard interface
 *
 * \retval 0 success
 * \retval -1 failure
 */
int ast_sorcery_wizard_unregister(const struct ast_sorcery_wizard *interface);

/*!
 * \brief Open a new sorcery structure
 *
 * \param module The module name (AST_MODULE)
 *
 * When called, this will automatically also call __ast_sorcery_apply_config()
 * with the module name as the configuration section.
 *
 * \retval non-NULL success
 * \retval NULL if allocation failed
 */
struct ast_sorcery *__ast_sorcery_open(const char *module, const char *file, int line, const char *func);

#define ast_sorcery_open() __ast_sorcery_open(AST_MODULE, __FILE__, __LINE__, __PRETTY_FUNCTION__)

/*!
 * \brief Retrieves an existing sorcery instance by module name
 *
 * \param module The module name
 *
 * \retval non-NULL success
 * \retval NULL if no instance was found
 *
 * \note The returned instance has its reference count incremented.  The caller
 * must decrement the count when they're finished with it.
 *
 */
struct ast_sorcery *ast_sorcery_retrieve_by_module_name(const char *module);

enum ast_sorcery_apply_result {
   /*! Sorcery wizard failed to apply. */
   AST_SORCERY_APPLY_FAIL = -1,
   /*! Sorcery wizard applied successfully. */
   AST_SORCERY_APPLY_SUCCESS = 0,
   /*! Sorcery wizard has already been applied to the object type. */
   AST_SORCERY_APPLY_DUPLICATE = 1,
   /*! Default sorcery wizard is unnecessary since a wizard has already been applied to the object type. */
   AST_SORCERY_APPLY_DEFAULT_UNNECESSARY = 2,
   /*! No sorcery.conf configuration file was found to apply. */
   AST_SORCERY_APPLY_NO_CONFIGURATION = 3,
};

/*!
 * \brief Apply configured wizard mappings
 *
 * \param sorcery Pointer to a sorcery structure
 * \param name Name of the category to use within the configuration file, normally the module name
 * \param module The module name (AST_MODULE)
 *
 * This function is called automatically by __ast_sorcery_open() using the module name as the
 * configuration category. The only reason you should call this function is if your module
 * wishes to apply configuration from additional sections of sorcery.conf.
 *
 * If a configuration section attempts to apply the same sorcery wizard to an object type
 * more than once, the wizard will only be applied one time.
 *
 * \return What happened when attempting to apply the config.
 */
enum ast_sorcery_apply_result __ast_sorcery_apply_config(struct ast_sorcery *sorcery,
      const char *name, const char *module);

#define ast_sorcery_apply_config(sorcery, name) \
   __ast_sorcery_apply_config((sorcery), (name), AST_MODULE)

/*!
 * \brief Apply default object wizard mappings
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to apply to
 * \param module The name of the module, typically AST_MODULE
 * \param name Name of the wizard to use
 * \param data Data to be passed to wizard
 *
 * \return What occurred when applying the default
 *
 * \note This should be called *after* applying configuration sourced mappings
 *
 * \note Only a single default can exist per object type
 */
enum ast_sorcery_apply_result __ast_sorcery_apply_default(struct ast_sorcery *sorcery,
      const char *type, const char *module, const char *name, const char *data);

#define ast_sorcery_apply_default(sorcery, type, name, data) \
   __ast_sorcery_apply_default((sorcery), (type), AST_MODULE, (name), (data))


/*!
 * \brief Apply additional object wizard mappings
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to apply to
 * \param module The name of the module, typically AST_MODULE
 * \param name Name of the wizard to use
 * \param data Data to be passed to wizard
 * \param caching Wizard should cache
 *
 * \return What occurred when applying the mapping
 *
 * \note This should be called *after* applying default mappings
 */
enum ast_sorcery_apply_result __ast_sorcery_apply_wizard_mapping(struct ast_sorcery *sorcery,
      const char *type, const char *module, const char *name, const char *data, unsigned int caching);

/*!
 * \brief Apply additional object wizard mappings
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to apply to
 * \param module The name of the module, typically AST_MODULE
 * \param name Name of the wizard to use
 * \param data Data to be passed to wizard
 *
 * \return What occurred when applying the mapping
 *
 * \note This should be called *after* applying default mappings
 */
#define ast_sorcery_apply_wizard_mapping(sorcery, type, name, data, caching) \
   __ast_sorcery_apply_wizard_mapping((sorcery), (type), AST_MODULE, (name), (data), (caching));


/*!
 * \brief Pre-defined locations to insert at
 */
enum ast_sorcery_wizard_position {
   AST_SORCERY_WIZARD_POSITION_LAST = -1,
   AST_SORCERY_WIZARD_POSITION_FIRST = 0,
};

/*!
 * \brief Insert an additional object wizard mapping at a specific position
 * in the wizard list
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to apply to
 * \param module The name of the module, typically AST_MODULE
 * \param name Name of the wizard to use
 * \param data Data to be passed to wizard
 * \param caching Wizard should cache
 * \param position An index to insert to or one of ast_sorcery_wizard_position
 *
 * \return What occurred when applying the mapping
 *
 * \note This should be called *after* applying default mappings
 * \note Wizards can be retrieved by using ast_sorcery_get_wizard_mapping_count
 * and iterating over them using ast_sorcery_get_wizard_mapping.
 *
 * \since 13.4.0
 */
enum ast_sorcery_apply_result __ast_sorcery_insert_wizard_mapping(struct ast_sorcery *sorcery,
   const char *type, const char *module, const char *name, const char *data,
   unsigned int caching, int position);

/*!
 * \brief Insert an additional object wizard mapping at a specific position
 * in the wizard list
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to apply to
 * \param module The name of the module, typically AST_MODULE
 * \param name Name of the wizard to use
 * \param data Data to be passed to wizard
 * \param position One of ast_sorcery_wizard_position
 *
 * \return What occurred when applying the mapping
 *
 * \note This should be called *after* applying default mappings
 * \since 13.4.0
 */
#define ast_sorcery_insert_wizard_mapping(sorcery, type, name, data, caching, position) \
   __ast_sorcery_insert_wizard_mapping((sorcery), (type), AST_MODULE, (name), (data), \
      (caching), (position))

/*!
 * \brief Wizard Apply Flags
 *
 * These flags apply only to a wizard/object-type combination.
 * The same wizard may be applied to a different object-type with
 * different flags and behavior.  If ALLOW_DUPLICATE is set
 * the wizard could even be applied to the same object-type
 * with different flags.
 */
enum ast_sorcery_wizard_apply_flags {
   /*! Apply no special behavior */
   AST_SORCERY_WIZARD_APPLY_NONE = (0 << 0),
   /*! This wizard will cache this object type's entries */
   AST_SORCERY_WIZARD_APPLY_CACHING = (1 << 0),
   /*! This wizard won't allow Create, Update or Delete operations on this object type */
   AST_SORCERY_WIZARD_APPLY_READONLY = (1 << 1),
   /*! This wizard will allow other instances of itself on the same object type */
   AST_SORCERY_WIZARD_APPLY_ALLOW_DUPLICATE = (1 << 2)
};

/*!
 * \brief Insert an additional object wizard mapping at a specific position
 * in the wizard list returning wizard information
 * \since 13.26.0
 * \since 16.3.0
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object_type_name Name of the object type to apply to
 * \param module The name of the module, typically AST_MODULE
 * \param wizard_type_name Name of the wizard type to use
 * \param wizard_args Opaque string to be passed to the wizard
 *             May be NULL but see note below
 * \param flags One or more of enum ast_sorcery_wizard_apply_flags
 * \param position An index to insert to or one of ast_sorcery_wizard_position
 * \param[out] wizard A variable to receive a pointer to the ast_sorcery_wizard structure.
 *             May be NULL if not needed.
 * \param[out] wizard_data A variable to receive a pointer to the wizard's internal data.
 *             May be NULL if not needed.
 *
 * \return What occurred when applying the mapping
 *
 * \note This should be called *after* applying default mappings
 *
 * \note Although \ref wizard_args is an optional parameter it is highly
 * recommended to supply one.  If you use the AST_SORCERY_WIZARD_APPLY_ALLOW_DUPLICATE
 * flag, and you intend to ever remove a wizard mapping, you'll need wizard_args
 * to remove specific instances of a wizard type.
 */
enum ast_sorcery_apply_result __ast_sorcery_object_type_insert_wizard(struct ast_sorcery *sorcery,
   const char *object_type_name, const char *module, const char *wizard_type_name,
   const char *wizard_args, enum ast_sorcery_wizard_apply_flags flags, int position,
   struct ast_sorcery_wizard **wizard, void **wizard_data);

/*!
 * \brief Insert an additional object wizard mapping at a specific position
 * in the wizard list returning wizard information
 * \since 13.26.0
 * \since 16.3.0
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object_type_name Name of the object type to apply to
 * \param wizard_type_name Name of the wizard type to use
 * \param wizard_args Opaque string to be passed to the wizard
 *             May be NULL but see note below
 * \param flags One or more of enum ast_sorcery_wizard_apply_flags
 * \param position An index to insert to or one of ast_sorcery_wizard_position
 * \param[out] wizard A variable to receive a pointer to the ast_sorcery_wizard structure.
 *             May be NULL if not needed.
 * \param[out] wizard_data A variable to receive a pointer to the wizard's internal data.
 *             May be NULL if not needed.
 *
 * \return What occurred when applying the mapping
 *
 * \note This should be called *after* applying default mappings
 *
 * \note Although \ref wizard_args is an optional parameter it is highly
 * recommended to supply one.  If you use the AST_SORCERY_WIZARD_APPLY_ALLOW_DUPLICATE
 * flag, and you intend to ever remove a wizard mapping, you'll need wizard_args
 * to remove specific instances.
 */
#define ast_sorcery_object_type_insert_wizard(sorcery, \
   object_type_name, wizard_type_name, wizard_args, flags, \
   position, wizard, wizard_data) \
   __ast_sorcery_object_type_insert_wizard((sorcery), \
      (object_type_name), AST_MODULE, (wizard_type_name), (wizard_args), (flags), \
      position, (wizard), (wizard_data))

/*!
 * \brief Apply additional object wizard mappings returning wizard information
 * \since 13.26.0
 * \since 16.3.0
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object_type_name Name of the object type to apply to
 * \param wizard_type_name Name of the wizard type to use
 * \param wizard_args Opaque string to be passed to the wizard
 *             May be NULL but see note below
 * \param flags One or more of enum ast_sorcery_wizard_apply_flags
 * \param[out] wizard A variable to receive a pointer to the ast_sorcery_wizard structure.
 *             May be NULL if not needed.
 * \param[out] wizard_data A variable to receive a pointer to the wizard's internal data.
 *             May be NULL if not needed.
 *
 * \return What occurred when applying the mapping
 *
 * \note This should be called *after* applying default mappings
 *
 * \note Although \ref wizard_args is an optional parameter it is highly
 * recommended to supply one.  If you use the AST_SORCERY_WIZARD_APPLY_ALLOW_DUPLICATE
 * flag, and you intend to ever remove a wizard mapping, you'll need wizard_args
 * to remove specific instances.
 */
#define ast_sorcery_object_type_apply_wizard(sorcery, \
   object_type_name, wizard_type_name, wizard_args, flags, \
   wizard, wizard_data) \
   __ast_sorcery_object_type_insert_wizard((sorcery), \
      (object_type_name), AST_MODULE, (wizard_type_name), (wizard_args), (flags), \
      AST_SORCERY_WIZARD_POSITION_LAST, (wizard), (wizard_data))

/*!
 * \brief Remove an object wizard mapping
 * \since 13.26.0
 * \since 16.3.0
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object_type_name Name of the object type to remove from
 * \param module The name of the module, typically AST_MODULE
 * \param wizard_type_name The name of the of the wizard type to remove
 * \param wizard_args Opaque string originally passed to the wizard
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \note If there were multiple instances of the same wizard type
 * added to this object type without using \ref wizard_args, then
 * only the first wizard matching wizard_type will be removed.
 */
int __ast_sorcery_object_type_remove_wizard(struct ast_sorcery *sorcery,
   const char *object_type_name, const char *module, const char *wizard_type_name,
   const char *wizard_args);

/*!
 * \brief Remove an object wizard mapping
 * \since 13.26.0
 * \since 16.3.0
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object_type_name Name of the object type to remove from
 * \param wizard_type_name The name of the of the wizard type to remove
 * \param wizard_args Opaque string originally passed to the wizard
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \note If there were multiple instances of the same wizard type
 * added to this object type without using \ref wizard_args, then
 * only the first wizard matching wizard_type will be removed.
 */
#define ast_sorcery_object_type_remove_wizard(sorcery, object_type_name, \
   wizard_type_name, wizard_args) \
   __ast_sorcery_object_type_remove_wizard((sorcery), (object_type_name), \
      AST_MODULE, (wizard_type_name), (wizard_args))

/*!
 * \brief Remove an object wizard mapping
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to remove from
 * \param module The name of the module, typically AST_MODULE
 * \param name The name of the wizard to remove
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \since 13.4.0
 */
int __ast_sorcery_remove_wizard_mapping(struct ast_sorcery *sorcery,
   const char *type, const char *module, const char *name);

/*!
 * \brief Remove an object wizard mapping
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to remove from
 * \param name The name of the wizard to remove
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \since 13.4.0
 */
#define ast_sorcery_remove_wizard_mapping(sorcery, type, name) \
   __ast_sorcery_remove_wizard_mapping((sorcery), (type), AST_MODULE, (name))

/*!
 * \brief Return the number of wizards mapped to an object type
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 *
 * \return Number of wizards or -1 for error
 * \since 13.4.0
 */
int ast_sorcery_get_wizard_mapping_count(struct ast_sorcery *sorcery,
   const char *type);

/*!
 * \brief By index, return a wizard mapped to an object type
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param index Index of the wizard
 * \param wizard A pointer to receive the wizard pointer
 * \param data A pointer to receive the data pointer
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \warning The wizard will have its reference count bumped so you must
 * call ao2_cleanup when you're done with it.
 *
 * \note The wizard and data returned are valid only for this object type
 * and only while the wizard is applied to the object type.
 *
 * \since 13.4.0
 */
int ast_sorcery_get_wizard_mapping(struct ast_sorcery *sorcery,
   const char *type, int index, struct ast_sorcery_wizard **wizard, void **data);

/*!
 * \brief Unregister an object type
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 *
 * \retval 0 success
 * \retval -1 failure
 */
int ast_sorcery_object_unregister(struct ast_sorcery *sorcery, const char *type);

/*!
 * \brief Register an object type
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param hidden All objects of this type are internal and should not be manipulated by users
 * \param reloadable All objects of this type are reloadable
 * \param alloc Required object allocation callback
 * \param transform Optional transformation callback
 * \param apply Optional object set apply callback
 *
 * \note In general, this function should not be used directly. One of the various
 * macro'd versions should be used instead.
 *
 * \retval 0 success
 * \retval -1 failure
 */
int __ast_sorcery_object_register(struct ast_sorcery *sorcery, const char *type, unsigned int hidden, unsigned int reloadable, aco_type_item_alloc alloc, sorcery_transform_handler transform, sorcery_apply_handler apply);

/*!
 * \brief Register an object type
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param alloc Required object allocation callback
 * \param transform Optional transformation callback
 * \param apply Optional object set apply callback
 *
 * \retval 0 success
 * \retval -1 failure
 */
#define ast_sorcery_object_register(sorcery, type, alloc, transform, apply) \
   __ast_sorcery_object_register((sorcery), (type), 0, 1, (alloc), (transform), (apply))

/*!
 * \brief Register an object type that is not reloadable
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param alloc Required object allocation callback
 * \param transform Optional transformation callback
 * \param apply Optional object set apply callback
 *
 * \retval 0 success
 * \retval -1 failure
 */
#define ast_sorcery_object_register_no_reload(sorcery, type, alloc, transform, apply) \
   __ast_sorcery_object_register((sorcery), (type), 0, 0, (alloc), (transform), (apply))

/*!
 * \brief Register an internal, hidden object type
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param alloc Required object allocation callback
 * \param transform Optional transformation callback
 * \param apply Optional object set apply callback
 *
 * \retval 0 success
 * \retval -1 failure
 */
#define ast_sorcery_internal_object_register(sorcery, type, alloc, transform, apply) \
   __ast_sorcery_object_register((sorcery), (type), 1, 1, (alloc), (transform), (apply))

/*!
 * \brief Set the high and low alert water marks of the sorcery object type.
 * \since 13.10.0
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param low_water New queue low water mark. (-1 to set as 90% of high_water)
 * \param high_water New queue high water mark.
 *
 * \retval 0 on success.
 * \retval -1 on error (water marks not changed).
 */
int ast_sorcery_object_set_congestion_levels(struct ast_sorcery *sorcery, const char *type, long low_water, long high_water);

/*!
 * \brief Set the copy handler for an object type
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param copy Copy handler
 */
void ast_sorcery_object_set_copy_handler(struct ast_sorcery *sorcery, const char *type, sorcery_copy_handler copy);

/*!
 * \brief Set the diff handler for an object type
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param diff Diff handler
 */
void ast_sorcery_object_set_diff_handler(struct ast_sorcery *sorcery, const char *type, sorcery_diff_handler diff);

/*!
 * \brief Register a regex for multiple fields within an object
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param regex A regular expression pattern for the fields
 * \param config_handler A custom handler for translating the string representation of the fields
 * \param sorcery_handler A custom handler for translating the native representation of the fields
 *
 * \retval 0 success
 * \retval -1 failure
 */
int ast_sorcery_object_fields_register(struct ast_sorcery *sorcery, const char *type, const char *regex, aco_option_handler config_handler,
                              sorcery_fields_handler sorcery_handler);

/*!
 * \brief Register a field within an object
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param name Name of the field
 * \param default_val Default value of the field
 * \param config_handler A custom handler for translating the string representation of the fields
 * \param sorcery_handler A custom handler for translating the native representation of the fields
 * \param multiple_handler A custom handler for translating the native representation of the fields
 * \param opt_type Option type
 * \param flags Option type specific flags
 * \param no_doc Field should not be documented
 * \param alias Interpret and apply field value only
 *
 * \retval 0 success
 * \retval -1 failure
 */
int __ast_sorcery_object_field_register(struct ast_sorcery *sorcery, const char *type,
   const char *name, const char *default_val, enum aco_option_type opt_type,
   aco_option_handler config_handler, sorcery_field_handler sorcery_handler,
   sorcery_fields_handler multiple_handler, unsigned int flags, unsigned int no_doc,
   unsigned int alias, size_t argc, ...);

/*!
 * \brief Register a field within an object
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param name Name of the field
 * \param default_val Default value of the field
 * \param opt_type Option type
 * \param flags Option type specific flags
 *
 * \retval 0 success
 * \retval -1 failure
 */
#define ast_sorcery_object_field_register(sorcery, type, name, default_val, opt_type, flags, ...) \
    __ast_sorcery_object_field_register(sorcery, type, name, default_val, opt_type, NULL, NULL, NULL, flags, 0, 0, VA_NARGS(__VA_ARGS__), __VA_ARGS__)

/*!
 * \brief Register a field within an object as an alias
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param name Name of the field
 * \param default_val Default value of the field
 * \param opt_type Option type
 * \param flags Option type specific flags
 *
 * \retval 0 success
 * \retval -1 failure
 */
#define ast_sorcery_object_field_register_alias(sorcery, type, name, default_val, opt_type, flags, ...) \
    __ast_sorcery_object_field_register(sorcery, type, name, default_val, opt_type, NULL, NULL, NULL, flags, 1, 1, VA_NARGS(__VA_ARGS__), __VA_ARGS__)

/*!
 * \brief Register a field within an object without documentation
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param name Name of the field
 * \param default_val Default value of the field
 * \param opt_type Option type
 * \param flags Option type specific flags
 *
 * \retval 0 success
 * \retval -1 failure
 */
#define ast_sorcery_object_field_register_nodoc(sorcery, type, name, default_val, opt_type, flags, ...) \
    __ast_sorcery_object_field_register(sorcery, type, name, default_val, opt_type, NULL, NULL, NULL, flags, 1, 0, VA_NARGS(__VA_ARGS__), __VA_ARGS__)

/*!
 * \brief Register a field within an object with custom handlers
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param name Name of the field
 * \param default_val Default value of the field
 * \param config_handler Custom configuration handler
 * \param sorcery_handler Custom sorcery handler
 * \param multiple_handler Custom multiple handler
 * \param flags Option type specific flags
 *
 * \retval 0 success
 * \retval -1 failure
 */
#define ast_sorcery_object_field_register_custom(sorcery, type, name, default_val, config_handler, sorcery_handler, multiple_handler, flags, ...) \
    __ast_sorcery_object_field_register(sorcery, type, name, default_val, OPT_CUSTOM_T, config_handler, sorcery_handler, multiple_handler, flags, 0, 0, VA_NARGS(__VA_ARGS__), __VA_ARGS__);

/*!
 * \brief Register a field within an object with custom handlers as an alias
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param name Name of the field
 * \param default_val Default value of the field
 * \param config_handler Custom configuration handler
 * \param sorcery_handler Custom sorcery handler
 * \param flags Option type specific flags
 *
 * \retval 0 success
 * \retval -1 failure
 */
#define ast_sorcery_object_field_register_custom_alias(sorcery, type, name, default_val, config_handler, sorcery_handler, multiple_handler, flags, ...) \
    __ast_sorcery_object_field_register(sorcery, type, name, default_val, OPT_CUSTOM_T, config_handler, sorcery_handler, multiple_handler, flags, 1, 1, VA_NARGS(__VA_ARGS__), __VA_ARGS__);

/*!
 * \brief Register a field within an object with custom handlers without documentation
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object
 * \param name Name of the field
 * \param default_val Default value of the field
 * \param config_handler Custom configuration handler
 * \param sorcery_handler Custom sorcery handler
 * \param multiple_handler Custom multiple handler
 * \param flags Option type specific flags
 *
 * \retval 0 success
 * \retval -1 failure
 */
#define ast_sorcery_object_field_register_custom_nodoc(sorcery, type, name, default_val, config_handler, sorcery_handler, multiple_handler, flags, ...) \
    __ast_sorcery_object_field_register(sorcery, type, name, default_val, OPT_CUSTOM_T, config_handler, sorcery_handler, multiple_handler, flags, 1, 0, VA_NARGS(__VA_ARGS__), __VA_ARGS__);

/*!
 * \brief Inform any wizards to load persistent objects
 *
 * \param sorcery Pointer to a sorcery structure
 */
void ast_sorcery_load(const struct ast_sorcery *sorcery);

/*!
 * \brief Inform any wizards of a specific object type to load persistent objects
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Name of the object type to load
 */
void ast_sorcery_load_object(const struct ast_sorcery *sorcery, const char *type);

/*!
 * \brief Inform any wizards to reload persistent objects
 *
 * \param sorcery Pointer to a sorcery structure
 */
void ast_sorcery_reload(const struct ast_sorcery *sorcery);

/*!
 * \brief Inform any wizards to reload persistent objects, even if no changes determined
 *
 * \param sorcery Pointer to a sorcery structure
 *
 * \since 13.32.0
 * \since 16.9.0
 * \since 17.3.0
 */
void ast_sorcery_force_reload(const struct ast_sorcery *sorcery);

/*!
 * \brief Inform any wizards of a specific object type to reload persistent objects
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Name of the object type to reload
 */
void ast_sorcery_reload_object(const struct ast_sorcery *sorcery, const char *type);

/*!
 * \brief Inform any wizards of a specific object type to reload persistent objects
 *        even if no changes determined
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Name of the object type to reload
 *
 * \since 13.32.0
 * \since 16.9.0
 * \since 17.3.0
 */
void ast_sorcery_force_reload_object(const struct ast_sorcery *sorcery, const char *type);

/*!
 * \brief Increase the reference count of a sorcery structure
 *
 * \param sorcery Pointer to a sorcery structure
 */
void ast_sorcery_ref(struct ast_sorcery *sorcery);


/*!
 * \brief Create an object set (KVP list) for an object
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object Pointer to a sorcery object
 * \param flags Flags indicating which handler to use and in what order.
 *
 * \retval non-NULL success
 * \retval NULL if error occurred
 *
 * \note The returned ast_variable list must be destroyed using ast_variables_destroy
 */
struct ast_variable *ast_sorcery_objectset_create2(const struct ast_sorcery *sorcery,
   const void *object, enum ast_sorcery_field_handler_flags flags);

/*!
 * \brief Create an object set (KVP list) for an object
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object Pointer to a sorcery object
 *
 * \retval non-NULL success
 * \retval NULL if error occurred
 *
 * \note The returned ast_variable list must be destroyed using ast_variables_destroy
 *
 * \note This function attempts to use a field's sorcery_fields_handler first and if that
 * doesn't exist or fails, a field's sorcery_field_handler is used.  The difference is
 * that the former may return multiple list entries for the same field and the latter will only
 * return 1.  It's up to the field itself to determine what the appropriate content is.
 */
#define ast_sorcery_objectset_create(sorcery, object) \
   ast_sorcery_objectset_create2(sorcery, object, AST_HANDLER_PREFER_LIST)

/*!
 * \brief Create an object set in JSON format for an object
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object Pointer to a sorcery object
 *
 * \retval non-NULL success
 * \retval NULL if error occurred
 *
 * \note The returned ast_json object must be unreferenced using ast_json_unref
 */
struct ast_json *ast_sorcery_objectset_json_create(const struct ast_sorcery *sorcery, const void *object);

/*!
 * \brief Apply an object set (KVP list) to an object
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object Pointer to a sorcery object
 * \param objectset Object set itself
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \note This operation is *not* atomic. If this fails it is possible for the object to be left with a partially
 *       applied object set.
 */
int ast_sorcery_objectset_apply(const struct ast_sorcery *sorcery, void *object, struct ast_variable *objectset);

/*!
 * \brief Create a changeset given two object sets
 *
 * \param original Original object set
 * \param modified Modified object set
 * \param changes Pointer to hold any changes between the object sets
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \note The returned ast_variable list must be destroyed using ast_variables_destroy
 */
int ast_sorcery_changeset_create(const struct ast_variable *original, const struct ast_variable *modified, struct ast_variable **changes);

/*!
 * \brief Allocate a generic sorcery capable object
 *
 * \param size Size of the object
 * \param destructor Optional destructor function
 *
 * \retval non-NULL success
 * \retval NULL failure
 *
 * \note The returned object does not support AO2 locking.
 */
void *ast_sorcery_generic_alloc(size_t size, ao2_destructor_fn destructor);

/*!
 * \since 14.1.0
 * \brief Allocate a generic sorcery capable object with locking.
 *
 * \details Sorcery objects may be replaced with new allocations during reloads.
 * If locking is required on sorcery objects it must be shared between the old
 * object and the new one.  lockobj can be any AO2 object with locking enabled,
 * but in most cases named locks should be used to provide stable locking.
 *
 * \param size Size of the object
 * \param destructor Optional destructor function
 * \param lockobj An AO2 object that will provide locking.
 *
 * \retval non-NULL success
 * \retval NULL failure
 */
void *ast_sorcery_lockable_alloc(size_t size, ao2_destructor_fn destructor, void *lockobj);

/*!
 * \brief Allocate an object
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to allocate
 * \param id Optional unique identifier, if none is provided one will be generated
 *
 * \retval non-NULL success
 * \retval NULL failure
 */
void *ast_sorcery_alloc(const struct ast_sorcery *sorcery, const char *type, const char *id);

/*!
 * \brief Create a copy of an object
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object Existing object
 *
 * \retval non-NULL success
 * \retval NULL failure
 */
void *ast_sorcery_copy(const struct ast_sorcery *sorcery, const void *object);

/*!
 * \brief Create a changeset of two objects
 *
 * \param sorcery Pointer to a sorcery structure
 * \param original Original object
 * \param modified Modified object
 * \param changes Pointer which will be populated with changes if any exist
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \note The returned ast_variable list must be destroyed using ast_variables_destroy
 *
 * \note While the objects must be of the same type they do not have to be the same object
 */
int ast_sorcery_diff(const struct ast_sorcery *sorcery, const void *original, const void *modified, struct ast_variable **changes);

/*!
 * \brief Add a global observer to sorcery
 *
 * \param callbacks Implementation of the global observer interface
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \note You must be ready to accept observer invocations before this function is called
 */
int ast_sorcery_global_observer_add(const struct ast_sorcery_global_observer *callbacks);

/*!
 * \brief Remove a global observer from sorcery.
 *
 * A global observer is notified...
 * After a new wizard is registered.
 * After a new sorcery instance is opened.
 * Before an instance is destroyed.
 * Before a wizard is unregistered.
 *
 * \param callbacks Implementation of the global observer interface
 */
void ast_sorcery_global_observer_remove(const struct ast_sorcery_global_observer *callbacks);

/*!
 * \brief Add an observer to a sorcery instance
 *
 * \param sorcery Pointer to a sorcery structure
 * \param callbacks Implementation of the instance observer interface
 *
 * An instance observer is notified...
 * Before an instance is loaded or reloaded.
 * After an instance is loaded or reloaded.
 * After a wizard is mapped to an object type.
 * After an object type is registered.
 * Before an object type is loaded or reloaded.
 * After an object type is loaded or reloaded.
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \note You must be ready to accept observer invocations before this function is called
 */
int ast_sorcery_instance_observer_add(struct ast_sorcery *sorcery,
   const struct ast_sorcery_instance_observer *callbacks);

/*!
 * \brief Remove an observer from a sorcery instance
 *
 * \param sorcery Pointer to a sorcery structure
 * \param callbacks Implementation of the instance observer interface
 */
void ast_sorcery_instance_observer_remove(struct ast_sorcery *sorcery,
   const struct ast_sorcery_instance_observer *callbacks);

/*!
 * \brief Add an observer to a sorcery wizard
 *
 * \param sorcery Pointer to a previously registered wizard structure
 * \param callbacks Implementation of the wizard observer interface
 *
 * A wizard observer is notified...
 * Before a wizard is loaded or reloaded.
 * After a wizard is loaded or reloaded.
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \note You must be ready to accept observer invocations before this function is called
 */
int ast_sorcery_wizard_observer_add(struct ast_sorcery_wizard *wizard,
   const struct ast_sorcery_wizard_observer *callbacks);

/*!
 * \brief Remove an observer from a sorcery wizard.
 *
 * \param sorcery Pointer to a sorcery structure
 * \param callbacks Implementation of the wizard observer interface
 */
void ast_sorcery_wizard_observer_remove(struct ast_sorcery_wizard *wizard,
   const struct ast_sorcery_wizard_observer *callbacks);

/*!
 * \brief Add an observer to a specific object type
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object that should be observed
 * \param callbacks Implementation of the observer interface
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \note You must be ready to accept observer invocations before this function is called
 */
int ast_sorcery_observer_add(const struct ast_sorcery *sorcery, const char *type, const struct ast_sorcery_observer *callbacks);

/*!
 * \brief Remove an observer from a specific object type
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object that should no longer be observed
 * \param callbacks Implementation of the observer interface
 *
 * \retval 0 success
 * \retval -1 failure
 */
void ast_sorcery_observer_remove(const struct ast_sorcery *sorcery, const char *type, const struct ast_sorcery_observer *callbacks);

/*!
 * \brief Create and potentially persist an object using an available wizard
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object Pointer to a sorcery object
 *
 * \retval 0 success
 * \retval -1 failure
 */
int ast_sorcery_create(const struct ast_sorcery *sorcery, void *object);

/*!
 * \brief Retrieve an object using its unique identifier
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to retrieve
 * \param id Unique object identifier
 *
 * \retval non-NULL if found
 * \retval NULL if not found
 */
void *ast_sorcery_retrieve_by_id(const struct ast_sorcery *sorcery, const char *type, const char *id);

/*!
 * \brief Retrieve an object or multiple objects using specific fields
 * \since 13.9.0
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to retrieve
 * \param flags Flags to control behavior
 * \param fields Optional object fields and values to match against
 *
 * \retval non-NULL if found
 * \retval NULL if not found
 *
 * \note If the AST_RETRIEVE_FLAG_MULTIPLE flag is specified the returned value will be an
 *       ao2_container that must be unreferenced after use.
 *
 * \note If the AST_RETRIEVE_FLAG_ALL flag is used you may omit fields to retrieve all objects
 *       of the given type.
 *
 * \note The fields parameter can contain realtime-style expressions in variable->name.
 *       All operators defined for ast_strings_match can be used except for regex as
 *       there's no common support for regex in the realtime backends at this time.
 *       If multiple variables are in the fields list, all must match for an object to
 *       be returned.  See ast_strings_match for more information.
 *
 * Example:
 *
 * The following code can be significantly faster when a realtime backend is in use
 * because the expression "qualify_frequency > 0" is passed to the database to limit
 * the number of rows returned.
 *
 *  struct ast_variable *var = ast_variable_new("qualify_frequency >", "0", "");
 *  struct ao2_container *aors;
 *
 *  if (!var) {
 *    return;
 *  }
 *
 *  aors = ast_sorcery_retrieve_by_fields(ast_sip_get_sorcery(),
 *      "aor", AST_RETRIEVE_FLAG_MULTIPLE, var);
 *
 */
void *ast_sorcery_retrieve_by_fields(const struct ast_sorcery *sorcery, const char *type, unsigned int flags, struct ast_variable *fields);

/*!
 * \brief Retrieve multiple objects using a regular expression on their id
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to retrieve
 * \param regex Regular expression
 *
 * \retval non-NULL if error occurs
 * \retval NULL success
 *
 * \note The provided regex is treated as extended case sensitive.
 */
struct ao2_container *ast_sorcery_retrieve_by_regex(const struct ast_sorcery *sorcery, const char *type, const char *regex);

/*!
 * \brief Retrieve multiple objects whose id begins with the specified prefix
 * \since 13.19.0
 *
 * \param sorcery Pointer to a sorcery structure
 * \param type Type of object to retrieve
 * \param prefix Object id prefix
 * \param prefix_len The length of prefix in bytes
 *
 * \retval non-NULL if error occurs
 * \retval NULL success
 *
 * \note The prefix is matched in a case sensitive manner.
 */
struct ao2_container *ast_sorcery_retrieve_by_prefix(const struct ast_sorcery *sorcery, const char *type, const char *prefix, const size_t prefix_len);

/*!
 * \brief Update an object
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object Pointer to a sorcery object
 *
 * \retval 0 success
 * \retval -1 failure
 */
int ast_sorcery_update(const struct ast_sorcery *sorcery, void *object);

/*!
 * \brief Delete an object
 *
 * \param sorcery Pointer to a sorcery structure
 * \param object Pointer to a sorcery object
 *
 * \retval 0 success
 * \retval -1 failure
 */
int ast_sorcery_delete(const struct ast_sorcery *sorcery, void *object);

/*!
 * \brief Determine if a sorcery object is stale with respect to its backing datastore
 * \since 14.0.0
 *
 * This function will query the wizard(s) backing the particular sorcery object to
 * determine if the in-memory object is now stale. No action is taken to update
 * the object. Callers of this function may use one of the ast_sorcery_retrieve
 * functions to obtain a new instance of the object if desired.
 *
 * \retval 0 the object is not stale
 * \retval 1 the object is stale
 */
int ast_sorcery_is_stale(const struct ast_sorcery *sorcery, void *object);

/*!
 * \brief Decrease the reference count of a sorcery structure
 *
 * \param sorcery Pointer to a sorcery structure
 *
 * \note Prior to 16.0.0 this was a function which had to be used.
 *       Now you can use any variant of ao2_cleanup or ao2_ref to
 *       release a reference.
 */
#define ast_sorcery_unref(sorcery) \
   ao2_cleanup(sorcery)

/*!
 * \brief Get the unique identifier of a sorcery object
 *
 * \param object Pointer to a sorcery object
 *
 * \retval unique identifier
 */
const char *ast_sorcery_object_get_id(const void *object);

/*!
 * \since 14.0.0
 * \brief Get when the socery object was created
 *
 * \param object Pointer to a sorcery object
 *
 * \retval The time when the object was created
 */
const struct timeval ast_sorcery_object_get_created(const void *object);

/*!
 * \brief Get the type of a sorcery object
 *
 * \param object Pointer to a sorcery object
 *
 * \retval type of object
 */
const char *ast_sorcery_object_get_type(const void *object);

/*!
 * \brief Get an extended field value from a sorcery object
 *
 * \param object Pointer to a sorcery object
 * \param name Name of the extended field value
 *
 * \retval non-NULL if found
 * \retval NULL if not found
 *
 * \note The returned string does NOT need to be freed and is guaranteed to remain valid for the lifetime of the object
 */
const char *ast_sorcery_object_get_extended(const void *object, const char *name);

/*!
 * \brief Set an extended field value on a sorcery object
 *
 * \param object Pointer to a sorcery object
 * \param name Name of the extended field
 * \param value Value of the extended field
 *
 * \retval 0 success
 * \retval -1 failure
 *
 * \note The field name MUST begin with '@' to indicate it is an extended field.
 * \note If the extended field already exists it will be overwritten with the new value.
 */
int ast_sorcery_object_set_extended(const void *object, const char *name, const char *value);

/*!
 * \brief Get whether an object contains dynamic contents or not
 *
 * \param object Pointer to a sorcery object
 *
 * \since 19
 * \since 18.3.0
 * \since 16.17.0
 */
unsigned int ast_sorcery_object_has_dynamic_contents(const void *object);

/*!
 * \brief Set the dynamic contents flag on a sorcery object
 *
 * \param object Pointer to a sorcery object
 *
 * \since 19
 * \since 18.3.0
 * \since 16.17.0
 */
void ast_sorcery_object_set_has_dynamic_contents(const void *object);

/*!
 * \brief ao2 object comparator based on sorcery id.
 */
int ast_sorcery_object_id_compare(void *obj, void *arg, int flags);

/*!
 * \brief ao2 object sorter based on sorcery id.
 */
int ast_sorcery_object_id_sort(const void *obj, const void *arg, int flags);

/*!
 * \brief ao2 object hasher based on sorcery id.
 */
int ast_sorcery_object_id_hash(const void *obj, int flags);

/*!
 * \brief Get the sorcery object type given a type name.
 *
 * \param sorcery The sorcery from which to retrieve the object type
 * \param type The type name
 */
struct ast_sorcery_object_type *ast_sorcery_get_object_type(const struct ast_sorcery *sorcery,
      const char *type);

/*!
 * \brief Determine if a particular object field has been registered with sorcery
 *
 * \param object_type The object type to check against
 * \param field_name The name of the field to check
 *
 * \retval 0 The field is not registered for this sorcery type
 * \retval 1 The field is registered for this sorcery type
 */
int ast_sorcery_is_object_field_registered(const struct ast_sorcery_object_type *object_type,
      const char *field_name);

/*!
 * \brief Get the module that has opened the provided sorcery instance.
 *
 * \param sorcery The sorcery instance
 *
 * \return The module
 */
const char *ast_sorcery_get_module(const struct ast_sorcery *sorcery);

#if defined(__cplusplus) || defined(c_plusplus)
}
#endif

#endif /* _ASTERISK_SORCERY_H */