From a04c2c707de2ce850f79870e84ac9d7ec7aa9143 Mon Sep 17 00:00:00 2001 From: wm4 Date: Thu, 21 Dec 2017 22:39:24 +0100 Subject: [PATCH] lavc: replace and deprecate the lock manager Use static mutexes instead of requiring a lock manager. The behavior should be roughly the same before and after this change for API users which did not set the lock manager at all (except that a minor memory leak disappears). --- doc/APIchanges | 5 ++ libavcodec/avcodec.h | 8 +++- libavcodec/utils.c | 107 ++++--------------------------------------- libavcodec/version.h | 5 +- libavutil/thread.h | 2 + 5 files changed, 28 insertions(+), 99 deletions(-) diff --git a/doc/APIchanges b/doc/APIchanges index df79758e863..3c9f237596e 100644 --- a/doc/APIchanges +++ b/doc/APIchanges @@ -15,6 +15,11 @@ libavutil: 2017-10-21 API changes, most recent first: +2017-xx-xx - xxxxxxx - lavc 58.9.100 - avcodec.h + Deprecate av_lockmgr_register(). You need to build FFmpeg with threading + support enabled to get basic thread-safety (which is the default build + configuration). + 2017-12-xx - xxxxxxx - lavu 56.7.100 - cpu.h AVX-512 flags added. diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h index ce089b7c4ab..a9182a9e3da 100644 --- a/libavcodec/avcodec.h +++ b/libavcodec/avcodec.h @@ -5930,10 +5930,11 @@ attribute_deprecated AVHWAccel *av_hwaccel_next(const AVHWAccel *hwaccel); #endif - +#if FF_API_LOCKMGR /** * Lock operation used by lockmgr */ +attribute_deprecated enum AVLockOp { AV_LOCK_CREATE, ///< Create a mutex AV_LOCK_OBTAIN, ///< Lock the mutex @@ -5963,8 +5964,13 @@ enum AVLockOp { * mechanism (i.e. do not use a single static object to * implement your lock manager). If cb is set to NULL the * lockmgr will be unregistered. + * + * @deprecated This function does nothing, and always returns 0. Be sure to + * build with thread support to get basic thread safety. */ +attribute_deprecated int av_lockmgr_register(int (*cb)(void **mutex, enum AVLockOp op)); +#endif /** * Get the type of the given codec. diff --git a/libavcodec/utils.c b/libavcodec/utils.c index 873f39f9bda..eec44376935 100644 --- a/libavcodec/utils.c +++ b/libavcodec/utils.c @@ -67,58 +67,10 @@ #include "libavutil/ffversion.h" const char av_codec_ffversion[] = "FFmpeg version " FFMPEG_VERSION; -#if HAVE_PTHREADS || HAVE_W32THREADS || HAVE_OS2THREADS -static int default_lockmgr_cb(void **arg, enum AVLockOp op) -{ - void * volatile * mutex = arg; - int err; - - switch (op) { - case AV_LOCK_CREATE: - return 0; - case AV_LOCK_OBTAIN: - if (!*mutex) { - pthread_mutex_t *tmp = av_malloc(sizeof(pthread_mutex_t)); - if (!tmp) - return AVERROR(ENOMEM); - if ((err = pthread_mutex_init(tmp, NULL))) { - av_free(tmp); - return AVERROR(err); - } - if (avpriv_atomic_ptr_cas(mutex, NULL, tmp)) { - pthread_mutex_destroy(tmp); - av_free(tmp); - } - } - - if ((err = pthread_mutex_lock(*mutex))) - return AVERROR(err); - - return 0; - case AV_LOCK_RELEASE: - if ((err = pthread_mutex_unlock(*mutex))) - return AVERROR(err); - - return 0; - case AV_LOCK_DESTROY: - if (*mutex) - pthread_mutex_destroy(*mutex); - av_free(*mutex); - avpriv_atomic_ptr_cas(mutex, *mutex, NULL); - return 0; - } - return 1; -} -static int (*lockmgr_cb)(void **mutex, enum AVLockOp op) = default_lockmgr_cb; -#else -static int (*lockmgr_cb)(void **mutex, enum AVLockOp op) = NULL; -#endif - - volatile int ff_avcodec_locked; static atomic_int entangled_thread_counter = ATOMIC_VAR_INIT(0); -static void *codec_mutex; -static void *avformat_mutex; +static AVMutex codec_mutex = AV_MUTEX_INITIALIZER; +static AVMutex avformat_mutex = AV_MUTEX_INITIALIZER; void av_fast_padded_malloc(void *ptr, unsigned int *size, size_t min_size) { @@ -1909,55 +1861,26 @@ void av_register_hwaccel(AVHWAccel *hwaccel) } #endif +#if FF_API_LOCKMGR int av_lockmgr_register(int (*cb)(void **mutex, enum AVLockOp op)) { - if (lockmgr_cb) { - // There is no good way to rollback a failure to destroy the - // mutex, so we ignore failures. - lockmgr_cb(&codec_mutex, AV_LOCK_DESTROY); - lockmgr_cb(&avformat_mutex, AV_LOCK_DESTROY); - lockmgr_cb = NULL; - codec_mutex = NULL; - avformat_mutex = NULL; - } - - if (cb) { - void *new_codec_mutex = NULL; - void *new_avformat_mutex = NULL; - int err; - if (err = cb(&new_codec_mutex, AV_LOCK_CREATE)) { - return err > 0 ? AVERROR_UNKNOWN : err; - } - if (err = cb(&new_avformat_mutex, AV_LOCK_CREATE)) { - // Ignore failures to destroy the newly created mutex. - cb(&new_codec_mutex, AV_LOCK_DESTROY); - return err > 0 ? AVERROR_UNKNOWN : err; - } - lockmgr_cb = cb; - codec_mutex = new_codec_mutex; - avformat_mutex = new_avformat_mutex; - } - return 0; } +#endif int ff_lock_avcodec(AVCodecContext *log_ctx, const AVCodec *codec) { if (codec->caps_internal & FF_CODEC_CAP_INIT_THREADSAFE || !codec->init) return 0; - if (lockmgr_cb) { - if ((*lockmgr_cb)(&codec_mutex, AV_LOCK_OBTAIN)) - return -1; - } + if (ff_mutex_lock(&codec_mutex)) + return -1; if (atomic_fetch_add(&entangled_thread_counter, 1)) { av_log(log_ctx, AV_LOG_ERROR, "Insufficient thread locking. At least %d threads are " "calling avcodec_open2() at the same time right now.\n", atomic_load(&entangled_thread_counter)); - if (!lockmgr_cb) - av_log(log_ctx, AV_LOG_ERROR, "No lock manager is set, please see av_lockmgr_register()\n"); ff_avcodec_locked = 1; ff_unlock_avcodec(codec); return AVERROR(EINVAL); @@ -1975,30 +1898,20 @@ int ff_unlock_avcodec(const AVCodec *codec) av_assert0(ff_avcodec_locked); ff_avcodec_locked = 0; atomic_fetch_add(&entangled_thread_counter, -1); - if (lockmgr_cb) { - if ((*lockmgr_cb)(&codec_mutex, AV_LOCK_RELEASE)) - return -1; - } + if (ff_mutex_unlock(&codec_mutex)) + return -1; return 0; } int avpriv_lock_avformat(void) { - if (lockmgr_cb) { - if ((*lockmgr_cb)(&avformat_mutex, AV_LOCK_OBTAIN)) - return -1; - } - return 0; + return ff_mutex_lock(&avformat_mutex) ? -1 : 0; } int avpriv_unlock_avformat(void) { - if (lockmgr_cb) { - if ((*lockmgr_cb)(&avformat_mutex, AV_LOCK_RELEASE)) - return -1; - } - return 0; + return ff_mutex_unlock(&avformat_mutex) ? -1 : 0; } unsigned int avpriv_toupper4(unsigned int x) diff --git a/libavcodec/version.h b/libavcodec/version.h index d55de897972..47a15d52b8f 100644 --- a/libavcodec/version.h +++ b/libavcodec/version.h @@ -28,7 +28,7 @@ #include "libavutil/version.h" #define LIBAVCODEC_VERSION_MAJOR 58 -#define LIBAVCODEC_VERSION_MINOR 8 +#define LIBAVCODEC_VERSION_MINOR 9 #define LIBAVCODEC_VERSION_MICRO 100 #define LIBAVCODEC_VERSION_INT AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \ @@ -126,6 +126,9 @@ #ifndef FF_API_USER_VISIBLE_AVHWACCEL #define FF_API_USER_VISIBLE_AVHWACCEL (LIBAVCODEC_VERSION_MAJOR < 59) #endif +#ifndef FF_API_LOCKMGR +#define FF_API_LOCKMGR (LIBAVCODEC_VERSION_MAJOR < 59) +#endif #endif /* AVCODEC_VERSION_H */ diff --git a/libavutil/thread.h b/libavutil/thread.h index 309414aa7dd..cc5272d3793 100644 --- a/libavutil/thread.h +++ b/libavutil/thread.h @@ -134,6 +134,7 @@ static inline int strict_pthread_once(pthread_once_t *once_control, void (*init_ #endif #define AVMutex pthread_mutex_t +#define AV_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER #define ff_mutex_init pthread_mutex_init #define ff_mutex_lock pthread_mutex_lock @@ -148,6 +149,7 @@ static inline int strict_pthread_once(pthread_once_t *once_control, void (*init_ #else #define AVMutex char +#define AV_MUTEX_INITIALIZER 0 static inline int ff_mutex_init(AVMutex *mutex, const void *attr){ return 0; } static inline int ff_mutex_lock(AVMutex *mutex){ return 0; } -- 2.39.2