diff options
| -rw-r--r-- | libavcodec/avcodec.h | 28 | ||||
| -rw-r--r-- | libavcodec/utils.c | 36 | ||||
| -rw-r--r-- | libavcodec/version.h | 2 |
3 files changed, 44 insertions, 22 deletions
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h index dfbab9b60f..f0fa7a959f 100644 --- a/libavcodec/avcodec.h +++ b/libavcodec/avcodec.h @@ -4393,16 +4393,26 @@ enum AVLockOp { /** * Register a user provided lock manager supporting the operations - * specified by AVLockOp. mutex points to a (void *) where the - * lockmgr should store/get a pointer to a user allocated mutex. It's - * NULL upon AV_LOCK_CREATE and != NULL for all other ops. + * specified by AVLockOp. The "mutex" argument to the function points + * to a (void *) where the lockmgr should store/get a pointer to a user + * allocated mutex. It is NULL upon AV_LOCK_CREATE and equal to the + * value left by the last call for all other ops. If the lock manager is + * unable to perform the op then it should leave the mutex in the same + * state as when it was called and return a non-zero value. However, + * when called with AV_LOCK_DESTROY the mutex will always be assumed to + * have been successfully destroyed. If av_lockmgr_register succeeds + * it will return a non-negative value, if it fails it will return a + * negative value and destroy all mutex and unregister all callbacks. + * av_lockmgr_register is not thread-safe, it must be called from a + * single thread before any calls which make use of locking are used. * - * @param cb User defined callback. Note: Libav may invoke calls to this - * callback during the call to av_lockmgr_register(). - * Thus, the application must be prepared to handle that. - * If cb is set to NULL the lockmgr will be unregistered. - * Also note that during unregistration the previously registered - * lockmgr callback may also be invoked. + * @param cb User defined callback. av_lockmgr_register invokes calls + * to this callback and the previously registered callback. + * The callback will be used to create more than one mutex + * each of which must be backed by its own underlying locking + * 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. */ int av_lockmgr_register(int (*cb)(void **mutex, enum AVLockOp op)); diff --git a/libavcodec/utils.c b/libavcodec/utils.c index a47207610d..94eca9bd11 100644 --- a/libavcodec/utils.c +++ b/libavcodec/utils.c @@ -2318,20 +2318,32 @@ AVHWAccel *av_hwaccel_next(const AVHWAccel *hwaccel) int av_lockmgr_register(int (*cb)(void **mutex, enum AVLockOp op)) { if (lockmgr_cb) { - if (lockmgr_cb(&codec_mutex, AV_LOCK_DESTROY)) - return -1; - if (lockmgr_cb(&avformat_mutex, AV_LOCK_DESTROY)) - return -1; + // 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; } - lockmgr_cb = cb; - - if (lockmgr_cb) { - if (lockmgr_cb(&codec_mutex, AV_LOCK_CREATE)) - return -1; - if (lockmgr_cb(&avformat_mutex, AV_LOCK_CREATE)) - return -1; - } return 0; } diff --git a/libavcodec/version.h b/libavcodec/version.h index 849c4b2dad..773d21e355 100644 --- a/libavcodec/version.h +++ b/libavcodec/version.h @@ -30,7 +30,7 @@ #define LIBAVCODEC_VERSION_MAJOR 56 #define LIBAVCODEC_VERSION_MINOR 2 -#define LIBAVCODEC_VERSION_MICRO 0 +#define LIBAVCODEC_VERSION_MICRO 1 #define LIBAVCODEC_VERSION_INT AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \ LIBAVCODEC_VERSION_MINOR, \ |