[FFmpeg-devel] [PATCH 2/5] lavc: replace and deprecate the lock manager
wm4
nfxjfg at googlemail.com
Fri Dec 22 00:22:21 EET 2017
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 ++-
4 files changed, 26 insertions(+), 99 deletions(-)
diff --git a/doc/APIchanges b/doc/APIchanges
index da444ffb7c..df1391d83a 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-xx-xx - xxxxxxx - lavc 58.8.100 - avcodec.h
The MediaCodec decoders now support AVCodecContext.hw_device_ctx.
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index ce089b7c4a..a9182a9e3d 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 873f39f9bd..c7f8cdf08f 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 pthread_mutex_t codec_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t avformat_mutex = PTHREAD_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 (pthread_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 (pthread_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 pthread_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 pthread_mutex_unlock(&avformat_mutex) ? -1 : 0;
}
unsigned int avpriv_toupper4(unsigned int x)
diff --git a/libavcodec/version.h b/libavcodec/version.h
index d55de89797..47a15d52b8 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 */
--
2.15.1
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