lock.h

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2010, Digium, Inc.
 *
 * Mark Spencer <[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 Asterisk locking-related definitions:
 * - ast_mutex_t, ast_rwlock_t and related functions;
 * - atomic arithmetic instructions;
 * - wrappers for channel locking.
 *
 * - See \ref LockDef
 */

/*! \page LockDef Asterisk thread locking models
 *
 * This file provides different implementation of the functions,
 * depending on the platform, the use of DEBUG_THREADS, and the way
 * module-level mutexes are initialized.
 *
 *  - \b static: the mutex is assigned the value AST_MUTEX_INIT_VALUE
 *        this is done at compile time, and is the way used on Linux.
 *        This method is not applicable to all platforms e.g. when the
 *        initialization needs that some code is run.
 *
 *  - \b through constructors: for each mutex, a constructor function is
 *        defined, which then runs when the program (or the module)
 *        starts. The problem with this approach is that there is a
 *        lot of code duplication (a new block of code is created for
 *        each mutex). Also, it does not prevent a user from declaring
 *        a global mutex without going through the wrapper macros,
 *        so sane programming practices are still required.
 */

#ifndef _ASTERISK_LOCK_H
#define _ASTERISK_LOCK_H

#include <pthread.h>
#include <time.h>
#include <sys/param.h>
#ifdef HAVE_BKTR
#include <execinfo.h>
#endif

#ifndef HAVE_PTHREAD_RWLOCK_TIMEDWRLOCK
#include "asterisk/time.h"
#endif

#include "asterisk/backtrace.h"
#include "asterisk/logger.h"
#include "asterisk/compiler.h"

#define AST_PTHREADT_NULL (pthread_t) -1
#define AST_PTHREADT_STOP (pthread_t) -2

#if (defined(SOLARIS) || defined(BSD))
#define AST_MUTEX_INIT_W_CONSTRUCTORS
#endif /* SOLARIS || BSD */

/* Asterisk REQUIRES recursive (not error checking) mutexes
   and will not run without them. */
#if defined(HAVE_PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP) && defined(HAVE_PTHREAD_MUTEX_RECURSIVE_NP)
#define PTHREAD_MUTEX_INIT_VALUE PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
#define AST_MUTEX_KIND        PTHREAD_MUTEX_RECURSIVE_NP
#else
#define PTHREAD_MUTEX_INIT_VALUE PTHREAD_MUTEX_INITIALIZER
#define AST_MUTEX_KIND        PTHREAD_MUTEX_RECURSIVE
#endif /* PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP */

#ifdef HAVE_PTHREAD_RWLOCK_INITIALIZER
#define __AST_RWLOCK_INIT_VALUE     PTHREAD_RWLOCK_INITIALIZER
#else  /* HAVE_PTHREAD_RWLOCK_INITIALIZER */
#define __AST_RWLOCK_INIT_VALUE     {0}
#endif /* HAVE_PTHREAD_RWLOCK_INITIALIZER */

#ifdef HAVE_BKTR
#define AST_LOCK_TRACK_INIT_VALUE { { NULL }, { 0 }, 0, { NULL }, { 0 }, {{{ 0 }}}, PTHREAD_MUTEX_INIT_VALUE }
#else
#define AST_LOCK_TRACK_INIT_VALUE { { NULL }, { 0 }, 0, { NULL }, { 0 }, PTHREAD_MUTEX_INIT_VALUE }
#endif

#define AST_MUTEX_INIT_VALUE { PTHREAD_MUTEX_INIT_VALUE, NULL, {1, 0} }
#define AST_MUTEX_INIT_VALUE_NOTRACKING { PTHREAD_MUTEX_INIT_VALUE, NULL, {0, 0} }

#define AST_RWLOCK_INIT_VALUE { __AST_RWLOCK_INIT_VALUE, NULL, {1, 0} }
#define AST_RWLOCK_INIT_VALUE_NOTRACKING { __AST_RWLOCK_INIT_VALUE, NULL, {0, 0} }

#define AST_MAX_REENTRANCY 10

struct ast_channel;

/*!
 * \brief Lock tracking information.
 *
 * \note Any changes to this struct MUST be reflected in the
 * lock.c:restore_lock_tracking() function.
 */
struct ast_lock_track {
   const char *file[AST_MAX_REENTRANCY];
   int lineno[AST_MAX_REENTRANCY];
   int reentrancy;
   const char *func[AST_MAX_REENTRANCY];
   pthread_t thread_id[AST_MAX_REENTRANCY];
#ifdef HAVE_BKTR
   struct ast_bt backtrace[AST_MAX_REENTRANCY];
#endif
   pthread_mutex_t reentr_mutex;
};

struct ast_lock_track_flags {
   /*! non-zero if lock tracking is enabled */
   unsigned int tracking:1;
   /*! non-zero if track is setup */
   volatile unsigned int setup:1;
};

/*! \brief Structure for mutex and tracking information.
 *
 * We have tracking information in this structure regardless of DEBUG_THREADS being enabled.
 * The information will just be ignored in the core if a module does not request it..
 */
struct ast_mutex_info {
   pthread_mutex_t mutex;
#if !defined(DEBUG_THREADS) && !defined(DEBUG_THREADS_LOOSE_ABI)
   /*!
    * These fields are renamed to ensure they are never used when
    * DEBUG_THREADS is not defined.
    */
   struct ast_lock_track *_track;
   struct ast_lock_track_flags _flags;
#elif defined(DEBUG_THREADS)
   /*! Track which thread holds this mutex. */
   struct ast_lock_track *track;
   struct ast_lock_track_flags flags;
#endif
};

/*! \brief Structure for rwlock and tracking information.
 *
 * We have tracking information in this structure regardless of DEBUG_THREADS being enabled.
 * The information will just be ignored in the core if a module does not request it..
 */
struct ast_rwlock_info {
   pthread_rwlock_t lock;
#if !defined(DEBUG_THREADS) && !defined(DEBUG_THREADS_LOOSE_ABI)
   /*!
    * These fields are renamed to ensure they are never used when
    * DEBUG_THREADS is not defined.
    */
   struct ast_lock_track *_track;
   struct ast_lock_track_flags _flags;
#elif defined(DEBUG_THREADS)
   /*! Track which thread holds this lock */
   struct ast_lock_track *track;
   struct ast_lock_track_flags flags;
#endif
};

typedef struct ast_mutex_info ast_mutex_t;

typedef struct ast_rwlock_info ast_rwlock_t;

typedef pthread_cond_t ast_cond_t;

int __ast_pthread_mutex_init(int tracking, const char *filename, int lineno, const char *func, const char *mutex_name, ast_mutex_t *t);
int __ast_pthread_mutex_destroy(const char *filename, int lineno, const char *func, const char *mutex_name, ast_mutex_t *t);
int __ast_pthread_mutex_lock(const char *filename, int lineno, const char *func, const char* mutex_name, ast_mutex_t *t);
int __ast_pthread_mutex_trylock(const char *filename, int lineno, const char *func, const char* mutex_name, ast_mutex_t *t);
int __ast_pthread_mutex_unlock(const char *filename, int lineno, const char *func, const char *mutex_name, ast_mutex_t *t);

#define ast_mutex_init(pmutex)            __ast_pthread_mutex_init(1, __FILE__, __LINE__, __PRETTY_FUNCTION__, #pmutex, pmutex)
#define ast_mutex_init_notracking(pmutex) __ast_pthread_mutex_init(0, __FILE__, __LINE__, __PRETTY_FUNCTION__, #pmutex, pmutex)
#define ast_mutex_destroy(a)              __ast_pthread_mutex_destroy(__FILE__, __LINE__, __PRETTY_FUNCTION__, #a, a)
#define ast_mutex_lock(a)                 __ast_pthread_mutex_lock(__FILE__, __LINE__, __PRETTY_FUNCTION__, #a, a)
#define ast_mutex_unlock(a)               __ast_pthread_mutex_unlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, #a, a)
#define ast_mutex_trylock(a)              __ast_pthread_mutex_trylock(__FILE__, __LINE__, __PRETTY_FUNCTION__, #a, a)


int __ast_cond_init(const char *filename, int lineno, const char *func, const char *cond_name, ast_cond_t *cond, pthread_condattr_t *cond_attr);
int __ast_cond_signal(const char *filename, int lineno, const char *func, const char *cond_name, ast_cond_t *cond);
int __ast_cond_broadcast(const char *filename, int lineno, const char *func, const char *cond_name, ast_cond_t *cond);
int __ast_cond_destroy(const char *filename, int lineno, const char *func, const char *cond_name, ast_cond_t *cond);
int __ast_cond_wait(const char *filename, int lineno, const char *func, const char *cond_name, const char *mutex_name, ast_cond_t *cond, ast_mutex_t *t);
int __ast_cond_timedwait(const char *filename, int lineno, const char *func, const char *cond_name, const char *mutex_name, ast_cond_t *cond, ast_mutex_t *t, const struct timespec *abstime);

#define ast_cond_init(cond, attr)             __ast_cond_init(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, cond, attr)
#define ast_cond_destroy(cond)                __ast_cond_destroy(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, cond)
#define ast_cond_signal(cond)                 __ast_cond_signal(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, cond)
#define ast_cond_broadcast(cond)              __ast_cond_broadcast(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, cond)
#define ast_cond_wait(cond, mutex)            __ast_cond_wait(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, #mutex, cond, mutex)
#define ast_cond_timedwait(cond, mutex, time) __ast_cond_timedwait(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, #mutex, cond, mutex, time)


int __ast_rwlock_init(int tracking, const char *filename, int lineno, const char *func, const char *rwlock_name, ast_rwlock_t *t);
int __ast_rwlock_destroy(const char *filename, int lineno, const char *func, const char *rwlock_name, ast_rwlock_t *t);
int __ast_rwlock_unlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name);
int __ast_rwlock_rdlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name);
int __ast_rwlock_wrlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name);
int __ast_rwlock_timedrdlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name, const struct timespec *abs_timeout);
int __ast_rwlock_timedwrlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name, const struct timespec *abs_timeout);
int __ast_rwlock_tryrdlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name);
int __ast_rwlock_trywrlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name);

/*!
 * \brief wrapper for rwlock with tracking enabled
 * \return 0 on success, non zero for error
 * \since 1.6.1
 */
#define ast_rwlock_init(rwlock)            __ast_rwlock_init(1, __FILE__, __LINE__, __PRETTY_FUNCTION__, #rwlock, rwlock)

/*!
 * \brief wrapper for ast_rwlock_init with tracking disabled
 * \return 0 on success, non zero for error
 * \since 1.6.1
 */
#define ast_rwlock_init_notracking(rwlock) __ast_rwlock_init(0, __FILE__, __LINE__, __PRETTY_FUNCTION__, #rwlock, rwlock)

#define ast_rwlock_destroy(rwlock)         __ast_rwlock_destroy(__FILE__, __LINE__, __PRETTY_FUNCTION__, #rwlock, rwlock)
#define ast_rwlock_unlock(a)               __ast_rwlock_unlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a)
#define ast_rwlock_rdlock(a)               __ast_rwlock_rdlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a)
#define ast_rwlock_wrlock(a)               __ast_rwlock_wrlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a)
#define ast_rwlock_tryrdlock(a)            __ast_rwlock_tryrdlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a)
#define ast_rwlock_trywrlock(a)            __ast_rwlock_trywrlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a)
#define ast_rwlock_timedrdlock(a, b)       __ast_rwlock_timedrdlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a, b)
#define ast_rwlock_timedwrlock(a, b)       __ast_rwlock_timedwrlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a, b)

#define  ROFFSET  ((lt->reentrancy > 0) ? (lt->reentrancy-1) : 0)

#ifdef DEBUG_THREADS

#ifdef THREAD_CRASH
#define DO_THREAD_CRASH do { *((int *)(0)) = 1; } while(0)
#else
#define DO_THREAD_CRASH do { } while (0)
#endif

#include <errno.h>

enum ast_lock_type {
   AST_MUTEX,
   AST_RDLOCK,
   AST_WRLOCK,
};

/*!
 * \brief Store lock info for the current thread
 *
 * This function gets called in ast_mutex_lock() and ast_mutex_trylock() so
 * that information about this lock can be stored in this thread's
 * lock info struct.  The lock is marked as pending as the thread is waiting
 * on the lock.  ast_mark_lock_acquired() will mark it as held by this thread.
 */
void ast_store_lock_info(enum ast_lock_type type, const char *filename,
   int line_num, const char *func, const char *lock_name, void *lock_addr, struct ast_bt *bt);

/*!
 * \brief Mark the last lock as acquired
 */
void ast_mark_lock_acquired(void *lock_addr);

/*!
 * \brief Mark the last lock as failed (trylock)
 */
void ast_mark_lock_failed(void *lock_addr);

/*!
 * \brief remove lock info for the current thread
 *
 * this gets called by ast_mutex_unlock so that information on the lock can
 * be removed from the current thread's lock info struct.
 */
void ast_remove_lock_info(void *lock_addr, struct ast_bt *bt);
void ast_suspend_lock_info(void *lock_addr);
void ast_restore_lock_info(void *lock_addr);

/*!
 * \brief log info for the current lock with ast_log().
 *
 * this function would be mostly for debug. If you come across a lock
 * that is unexpectedly but momentarily locked, and you wonder who
 * are fighting with for the lock, this routine could be called, IF
 * you have the thread debugging stuff turned on.
 * \param this_lock_addr lock address to return lock information
 * \since 1.6.1
 */
void ast_log_show_lock(void *this_lock_addr);

/*!
 * \brief Generate a lock dump equivalent to "core show locks".
 *
 * The lock dump generated is generally too large to be output by a
 * single ast_verbose/log/debug/etc. call. Only ast_cli() handles it
 * properly without changing BUFSIZ in logger.c.
 *
 * Note: This must be ast_free()d when you're done with it.
 *
 * \retval An ast_str containing the lock dump
 * \retval NULL on error
 * \since 12
 */
struct ast_str *ast_dump_locks(void);

/*!
 * \brief retrieve lock info for the specified mutex
 *
 * this gets called during deadlock avoidance, so that the information may
 * be preserved as to what location originally acquired the lock.
 */
int ast_find_lock_info(void *lock_addr, char *filename, size_t filename_size, int *lineno, char *func, size_t func_size, char *mutex_name, size_t mutex_name_size);

/*!
 * \brief Unlock a lock briefly
 *
 * used during deadlock avoidance, to preserve the original location where
 * a lock was originally acquired.
 */
#define AO2_DEADLOCK_AVOIDANCE(obj) \
   do { \
      char __filename[80], __func[80], __mutex_name[80]; \
      int __lineno; \
      int __res = ast_find_lock_info(ao2_object_get_lockaddr(obj), __filename, sizeof(__filename), &__lineno, __func, sizeof(__func), __mutex_name, sizeof(__mutex_name)); \
      int __res2 = ao2_unlock(obj); \
      usleep(1); \
      if (__res < 0) { /* Could happen if the ao2 object does not have a mutex. */ \
         if (__res2) { \
            ast_log(LOG_WARNING, "Could not unlock ao2 object '%s': %s and no lock info found!  I will NOT try to relock.\n", #obj, strerror(__res2)); \
         } else { \
            ao2_lock(obj); \
         } \
      } else { \
         if (__res2) { \
            ast_log(LOG_WARNING, "Could not unlock ao2 object '%s': %s.  {{{Originally locked at %s line %d: (%s) '%s'}}}  I will NOT try to relock.\n", #obj, strerror(__res2), __filename, __lineno, __func, __mutex_name); \
         } else { \
            __ao2_lock(obj, AO2_LOCK_REQ_MUTEX, __filename, __func, __lineno, __mutex_name); \
         } \
      } \
   } while (0)

#define CHANNEL_DEADLOCK_AVOIDANCE(chan) \
   do { \
      char __filename[80], __func[80], __mutex_name[80]; \
      int __lineno; \
      int __res = ast_find_lock_info(ao2_object_get_lockaddr(chan), __filename, sizeof(__filename), &__lineno, __func, sizeof(__func), __mutex_name, sizeof(__mutex_name)); \
      int __res2 = ast_channel_unlock(chan); \
      usleep(1); \
      if (__res < 0) { /* Shouldn't ever happen, but just in case... */ \
         if (__res2) { \
            ast_log(LOG_WARNING, "Could not unlock channel '%s': %s and no lock info found!  I will NOT try to relock.\n", #chan, strerror(__res2)); \
         } else { \
            ast_channel_lock(chan); \
         } \
      } else { \
         if (__res2) { \
            ast_log(LOG_WARNING, "Could not unlock channel '%s': %s.  {{{Originally locked at %s line %d: (%s) '%s'}}}  I will NOT try to relock.\n", #chan, strerror(__res2), __filename, __lineno, __func, __mutex_name); \
         } else { \
            __ao2_lock(chan, AO2_LOCK_REQ_MUTEX, __filename, __func, __lineno, __mutex_name); \
         } \
      } \
   } while (0)

#define DEADLOCK_AVOIDANCE(lock) \
   do { \
      char __filename[80], __func[80], __mutex_name[80]; \
      int __lineno; \
      int __res = ast_find_lock_info(lock, __filename, sizeof(__filename), &__lineno, __func, sizeof(__func), __mutex_name, sizeof(__mutex_name)); \
      int __res2 = ast_mutex_unlock(lock); \
      usleep(1); \
      if (__res < 0) { /* Shouldn't ever happen, but just in case... */ \
         if (__res2 == 0) { \
            ast_mutex_lock(lock); \
         } else { \
            ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s and no lock info found!  I will NOT try to relock.\n", #lock, strerror(__res2)); \
         } \
      } else { \
         if (__res2 == 0) { \
            __ast_pthread_mutex_lock(__filename, __lineno, __func, __mutex_name, lock); \
         } else { \
            ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s.  {{{Originally locked at %s line %d: (%s) '%s'}}}  I will NOT try to relock.\n", #lock, strerror(__res2), __filename, __lineno, __func, __mutex_name); \
         } \
      } \
   } while (0)

/*!
 * \brief Deadlock avoidance unlock
 *
 * In certain deadlock avoidance scenarios, there is more than one lock to be
 * unlocked and relocked.  Therefore, this pair of macros is provided for that
 * purpose.  Note that every DLA_UNLOCK _MUST_ be paired with a matching
 * DLA_LOCK.  The intent of this pair of macros is to be used around another
 * set of deadlock avoidance code, mainly CHANNEL_DEADLOCK_AVOIDANCE, as the
 * locking order specifies that we may safely lock a channel, followed by its
 * pvt, with no worries about a deadlock.  In any other scenario, this macro
 * may not be safe to use.
 */
#define DLA_UNLOCK(lock) \
   do { \
      char __filename[80], __func[80], __mutex_name[80]; \
      int __lineno; \
      int __res = ast_find_lock_info(lock, __filename, sizeof(__filename), &__lineno, __func, sizeof(__func), __mutex_name, sizeof(__mutex_name)); \
      int __res2 = ast_mutex_unlock(lock);

/*!
 * \brief Deadlock avoidance lock
 *
 * In certain deadlock avoidance scenarios, there is more than one lock to be
 * unlocked and relocked.  Therefore, this pair of macros is provided for that
 * purpose.  Note that every DLA_UNLOCK _MUST_ be paired with a matching
 * DLA_LOCK.  The intent of this pair of macros is to be used around another
 * set of deadlock avoidance code, mainly CHANNEL_DEADLOCK_AVOIDANCE, as the
 * locking order specifies that we may safely lock a channel, followed by its
 * pvt, with no worries about a deadlock.  In any other scenario, this macro
 * may not be safe to use.
 */
#define DLA_LOCK(lock) \
      if (__res < 0) { /* Shouldn't ever happen, but just in case... */ \
         if (__res2) { \
            ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s and no lock info found!  I will NOT try to relock.\n", #lock, strerror(__res2)); \
         } else { \
            ast_mutex_lock(lock); \
         } \
      } else { \
         if (__res2) { \
            ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s.  {{{Originally locked at %s line %d: (%s) '%s'}}}  I will NOT try to relock.\n", #lock, strerror(__res2), __filename, __lineno, __func, __mutex_name); \
         } else { \
            __ast_pthread_mutex_lock(__filename, __lineno, __func, __mutex_name, lock); \
         } \
      } \
   } while (0)

static inline void ast_reentrancy_lock(struct ast_lock_track *lt)
{
   int res;
   if ((res = pthread_mutex_lock(&lt->reentr_mutex))) {
      fprintf(stderr, "ast_reentrancy_lock failed: '%s' (%d)\n", strerror(res), res);
#if defined(DO_CRASH) || defined(THREAD_CRASH)
      abort();
#endif
   }
}

static inline void ast_reentrancy_unlock(struct ast_lock_track *lt)
{
   int res;
   if ((res = pthread_mutex_unlock(&lt->reentr_mutex))) {
      fprintf(stderr, "ast_reentrancy_unlock failed: '%s' (%d)\n", strerror(res), res);
#if defined(DO_CRASH) || defined(THREAD_CRASH)
      abort();
#endif
   }
}

#else /* !DEBUG_THREADS */

#define AO2_DEADLOCK_AVOIDANCE(obj) \
   ao2_unlock(obj); \
   usleep(1); \
   ao2_lock(obj);

#define CHANNEL_DEADLOCK_AVOIDANCE(chan) \
   ast_channel_unlock(chan); \
   usleep(1); \
   ast_channel_lock(chan);

#define DEADLOCK_AVOIDANCE(lock) \
   do { \
      int __res; \
      if (!(__res = ast_mutex_unlock(lock))) { \
         usleep(1); \
         ast_mutex_lock(lock); \
      } else { \
         ast_log(LOG_WARNING, "Failed to unlock mutex '%s' (%s).  I will NOT try to relock. {{{ THIS IS A BUG. }}}\n", #lock, strerror(__res)); \
      } \
   } while (0)

#define DLA_UNLOCK(lock) ast_mutex_unlock(lock)

#define DLA_LOCK(lock) ast_mutex_lock(lock)

#endif /* !DEBUG_THREADS */

#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS)
/*
 * If AST_MUTEX_INIT_W_CONSTRUCTORS is defined, use file scope constructors
 * and destructors to create/destroy global mutexes.
 */
#define __AST_MUTEX_DEFINE(scope, mutex, init_val, track)   \
   scope ast_mutex_t mutex = init_val;       \
static void  __attribute__((constructor)) init_##mutex(void)   \
{                       \
   if (track)                 \
      ast_mutex_init(&mutex);          \
   else                    \
      ast_mutex_init_notracking(&mutex);     \
}                       \
                        \
static void  __attribute__((destructor)) fini_##mutex(void) \
{                       \
   ast_mutex_destroy(&mutex);          \
}
#else /* !AST_MUTEX_INIT_W_CONSTRUCTORS */
/* By default, use static initialization of mutexes. */
#define __AST_MUTEX_DEFINE(scope, mutex, init_val, track) scope ast_mutex_t mutex = init_val
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */

#define AST_MUTEX_DEFINE_STATIC(mutex) __AST_MUTEX_DEFINE(static, mutex, AST_MUTEX_INIT_VALUE, 1)
#define AST_MUTEX_DEFINE_STATIC_NOTRACKING(mutex) __AST_MUTEX_DEFINE(static, mutex, AST_MUTEX_INIT_VALUE_NOTRACKING, 0)


/* Statically declared read/write locks */
#ifdef AST_MUTEX_INIT_W_CONSTRUCTORS
#define __AST_RWLOCK_DEFINE(scope, rwlock, init_val, track) \
        scope ast_rwlock_t rwlock = init_val; \
static void  __attribute__((constructor)) init_##rwlock(void) \
{ \
   if (track) \
         ast_rwlock_init(&rwlock); \
   else \
      ast_rwlock_init_notracking(&rwlock); \
} \
static void  __attribute__((destructor)) fini_##rwlock(void) \
{ \
        ast_rwlock_destroy(&rwlock); \
}
#else
#define __AST_RWLOCK_DEFINE(scope, rwlock, init_val, track) scope ast_rwlock_t rwlock = init_val
#endif

#define AST_RWLOCK_DEFINE_STATIC(rwlock) __AST_RWLOCK_DEFINE(static, rwlock, AST_RWLOCK_INIT_VALUE, 1)
#define AST_RWLOCK_DEFINE_STATIC_NOTRACKING(rwlock) __AST_RWLOCK_DEFINE(static, rwlock, AST_RWLOCK_INIT_VALUE_NOTRACKING, 0)

/*!
 * \brief Scoped Locks
 *
 * Scoped locks provide a way to use RAII locks. In other words,
 * declaration of a scoped lock will automatically define and lock
 * the lock. When the lock goes out of scope, it will automatically
 * be unlocked.
 *
 * \code
 * int some_function(struct ast_channel *chan)
 * {
 *     SCOPED_LOCK(lock, chan, ast_channel_lock, ast_channel_unlock);
 *
 *     if (!strcmp(ast_channel_name(chan, "foo")) {
 *         return 0;
 *     }
 *
 *     return -1;
 * }
 * \endcode
 *
 * In the above example, neither return path requires explicit unlocking
 * of the channel.
 *
 * \note
 * Care should be taken when using SCOPED_LOCKS in conjunction with ao2 objects.
 * ao2 objects should be unlocked before they are unreffed. Since SCOPED_LOCK runs
 * once the variable goes out of scope, this can easily lead to situations where the
 * variable gets unlocked after it is unreffed.
 *
 * \param varname The unique name to give to the scoped lock. You are not likely to reference
 * this outside of the SCOPED_LOCK invocation.
 * \param lock The variable to lock. This can be anything that can be passed to a locking
 * or unlocking function.
 * \param lockfunc The function to call to lock the lock
 * \param unlockfunc The function to call to unlock the lock
 */
#define SCOPED_LOCK(varname, lock, lockfunc, unlockfunc) \
   RAII_VAR(typeof((lock)), varname, ({lockfunc((lock)); (lock); }), unlockfunc)

/*!
 * \brief scoped lock specialization for mutexes
 */
#define SCOPED_MUTEX(varname, lock) SCOPED_LOCK(varname, (lock), ast_mutex_lock, ast_mutex_unlock)

/*!
 * \brief scoped lock specialization for read locks
 */
#define SCOPED_RDLOCK(varname, lock) SCOPED_LOCK(varname, (lock), ast_rwlock_rdlock, ast_rwlock_unlock)

/*!
 * \brief scoped lock specialization for write locks
 */
#define SCOPED_WRLOCK(varname, lock) SCOPED_LOCK(varname, (lock), ast_rwlock_wrlock, ast_rwlock_unlock)

/*!
 * \brief scoped lock specialization for ao2 mutexes.
 */
#define SCOPED_AO2LOCK(varname, obj) SCOPED_LOCK(varname, (obj), ao2_lock, ao2_unlock)

/*!
 * \brief scoped lock specialization for ao2 read locks.
 */
#define SCOPED_AO2RDLOCK(varname, obj) SCOPED_LOCK(varname, (obj), ao2_rdlock, ao2_unlock)

/*!
 * \brief scoped lock specialization for ao2 write locks.
 */
#define SCOPED_AO2WRLOCK(varname, obj) SCOPED_LOCK(varname, (obj), ao2_wrlock, ao2_unlock)

/*!
 * \brief scoped lock specialization for channels.
 */
#define SCOPED_CHANNELLOCK(varname, chan) SCOPED_LOCK(varname, (chan), ast_channel_lock, ast_channel_unlock)

#ifndef __CYGWIN__   /* temporary disabled for cygwin */
#define pthread_mutex_t    use_ast_mutex_t_instead_of_pthread_mutex_t
#define pthread_cond_t     use_ast_cond_t_instead_of_pthread_cond_t
#endif
#define pthread_mutex_lock use_ast_mutex_lock_instead_of_pthread_mutex_lock
#define pthread_mutex_unlock  use_ast_mutex_unlock_instead_of_pthread_mutex_unlock
#define pthread_mutex_trylock use_ast_mutex_trylock_instead_of_pthread_mutex_trylock
#define pthread_mutex_init use_ast_mutex_init_instead_of_pthread_mutex_init
#define pthread_mutex_destroy use_ast_mutex_destroy_instead_of_pthread_mutex_destroy
#define pthread_cond_init  use_ast_cond_init_instead_of_pthread_cond_init
#define pthread_cond_destroy  use_ast_cond_destroy_instead_of_pthread_cond_destroy
#define pthread_cond_signal   use_ast_cond_signal_instead_of_pthread_cond_signal
#define pthread_cond_broadcast   use_ast_cond_broadcast_instead_of_pthread_cond_broadcast
#define pthread_cond_wait  use_ast_cond_wait_instead_of_pthread_cond_wait
#define pthread_cond_timedwait   use_ast_cond_timedwait_instead_of_pthread_cond_timedwait

#define AST_MUTEX_INITIALIZER __use_AST_MUTEX_DEFINE_STATIC_rather_than_AST_MUTEX_INITIALIZER__

#define gethostbyname __gethostbyname__is__not__reentrant__use__ast_gethostbyname__instead__

#ifndef __linux__
#define pthread_create __use_ast_pthread_create_instead__
#endif

/*!
 * \brief Support for atomic instructions.
 *
 * These macros implement a uniform interface to use built-in atomic functionality.
 * If available __atomic built-ins are prefered.  Legacy __sync built-ins are used
 * as a fallback for older compilers.
 *
 * Detailed documentation can be found in the GCC manual, all API's are modeled after
 * the __atomic interfaces but using the namespace ast_atomic.
 *
 * The memorder argument is always ignored by legacy __sync functions.  Invalid
 * memorder arguments do not produce errors unless __atomic functions are supported
 * as the argument is erased by the preprocessor.
 *
 * \note ast_atomic_fetch_nand and ast_atomic_nand_fetch purposely do not exist.
 *       It's implementation was broken prior to gcc-4.4.
 *
 * @{
 */

#include "asterisk/inline_api.h"

#if defined(HAVE_C_ATOMICS)
/*! Atomic += */
#define ast_atomic_fetch_add(ptr, val, memorder)  __atomic_fetch_add((ptr), (val), (memorder))
#define ast_atomic_add_fetch(ptr, val, memorder)  __atomic_add_fetch((ptr), (val), (memorder))

/*! Atomic -= */
#define ast_atomic_fetch_sub(ptr, val, memorder)  __atomic_fetch_sub((ptr), (val), (memorder))
#define ast_atomic_sub_fetch(ptr, val, memorder)  __atomic_sub_fetch((ptr), (val), (memorder))

/*! Atomic &= */
#define ast_atomic_fetch_and(ptr, val, memorder)  __atomic_fetch_and((ptr), (val), (memorder))
#define ast_atomic_and_fetch(ptr, val, memorder)  __atomic_and_fetch((ptr), (val), (memorder))

/*! Atomic |= */
#define ast_atomic_fetch_or(ptr, val, memorder)   __atomic_fetch_or((ptr), (val), (memorder))
#define ast_atomic_or_fetch(ptr, val, memorder)   __atomic_or_fetch((ptr), (val), (memorder))

/*! Atomic xor = */
#define ast_atomic_fetch_xor(ptr, val, memorder)  __atomic_fetch_xor((ptr), (val), (memorder))
#define ast_atomic_xor_fetch(ptr, val, memorder)  __atomic_xor_fetch((ptr), (val), (memorder))

#if 0
/* Atomic compare and swap
 *
 * See comments near the __atomic implementation for why this is disabled.
 */
#define ast_atomic_compare_exchange_n(ptr, expected, desired, success_memorder, failure_memorder) \
   __atomic_compare_exchange_n((ptr), (expected), (desired), 0, success_memorder, failure_memorder)

#define ast_atomic_compare_exchange(ptr, expected, desired, success_memorder, failure_memorder) \
   __atomic_compare_exchange((ptr), (expected), (desired), 0, success_memorder, failure_memorder)
#endif

#elif defined(HAVE_GCC_ATOMICS)
/*! Atomic += */
#define ast_atomic_fetch_add(ptr, val, memorder)  __sync_fetch_and_add((ptr), (val))
#define ast_atomic_add_fetch(ptr, val, memorder)  __sync_add_and_fetch((ptr), (val))

/*! Atomic -= */
#define ast_atomic_fetch_sub(ptr, val, memorder)  __sync_fetch_and_sub((ptr), (val))
#define ast_atomic_sub_fetch(ptr, val, memorder)  __sync_sub_and_fetch((ptr), (val))

/*! Atomic &= */
#define ast_atomic_fetch_and(ptr, val, memorder)  __sync_fetch_and_and((ptr), (val))
#define ast_atomic_and_fetch(ptr, val, memorder)  __sync_and_and_fetch((ptr), (val))

/*! Atomic |= */
#define ast_atomic_fetch_or(ptr, val, memorder)  __sync_fetch_and_or((ptr), (val))
#define ast_atomic_or_fetch(ptr, val, memorder)  __sync_or_and_fetch((ptr), (val))

/*! Atomic xor = */
#define ast_atomic_fetch_xor(ptr, val, memorder)  __sync_fetch_and_xor((ptr), (val))
#define ast_atomic_xor_fetch(ptr, val, memorder)  __sync_xor_and_fetch((ptr), (val))

#if 0
/* Atomic compare and swap
 *
 * The \a expected argument is a pointer, I'm guessing __atomic built-ins
 * perform all memory reads/writes in a single atomic operation.  I don't
 * believe this is possible to exactly replicate using __sync built-ins.
 * Will need to determine potential use cases of this feature and write a
 * wrapper which provides consistant behavior between __sync and __atomic
 * implementations.
 */
#define ast_atomic_compare_exchange_n(ptr, expected, desired, success_memorder, failure_memorder) \
   __sync_bool_compare_and_swap((ptr), *(expected), (desired))

#define ast_atomic_compare_exchange(ptr, expected, desired, success_memorder, failure_memorder) \
   __sync_bool_compare_and_swap((ptr), *(expected), *(desired))
#endif

#else
#error "Atomics not available."
#endif

/*! Atomic flag set */
#define ast_atomic_flag_set(ptr, val, memorder)   ast_atomic_fetch_or((ptr), (val), (memorder))

/*! Atomic flag clear */
#define ast_atomic_flag_clear(ptr, val, memorder) ast_atomic_fetch_and((ptr), ~(val), (memorder))

/*!
 * \brief Atomically add v to *p and return the previous value of *p.
 *
 * This can be used to handle reference counts, and the return value
 * can be used to generate unique identifiers.
 */
AST_INLINE_API(int ast_atomic_fetchadd_int(volatile int *p, int v),
{
   return ast_atomic_fetch_add(p, v, __ATOMIC_RELAXED);
})

/*!
 * \brief decrement *p by 1 and return true if the variable has reached 0.
 *
 * Useful e.g. to check if a refcount has reached 0.
 */
AST_INLINE_API(int ast_atomic_dec_and_test(volatile int *p),
{
   return ast_atomic_sub_fetch(p, 1, __ATOMIC_RELAXED) == 0;
})

/*! @} */

#endif /* _ASTERISK_LOCK_H */