This is needed in preparation for a fix to be applied to
pcm_ioplug which will be in a following commit.
Signed-off-by: Ben Russell <thematrixeatsyou@xxxxxxxxx>
---
src/pcm/pcm_local.h | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/src/pcm/pcm_local.h b/src/pcm/pcm_local.h
index 05ed935f..649d84f2 100644
--- a/src/pcm/pcm_local.h
+++ b/src/pcm/pcm_local.h
@@ -1171,9 +1171,41 @@ static inline void snd_pcm_unlock(snd_pcm_t *pcm)
if (pcm->lock_enabled && pcm->need_lock)
pthread_mutex_unlock(&pcm->lock);
}
+
+/*
+ * snd_pcm_is_locked() is used to determine if the lock is currently held.
+ * It is mostly provided as a workaround for pcm_ioplug, which otherwise would
+ * for some functions assume that the plugin is locked even when it isn't.
+ *
+ * If $LIBASOUND_THREAD_SAFE=0 is set then this always returns 0 as there
+ * is no mutex in that case.
+ */
+static inline int snd_pcm_is_locked(snd_pcm_t *pcm)
+{
+ int trylock_result;
+ int unlock_result;
+
+ if (pcm->lock_enabled) {
+ trylock_result = pthread_mutex_trylock(&pcm->lock);
+ assert(trylock_result == 0 || trylock_result == EBUSY);
+ if (trylock_result == 0) {
+ /* we managed to grab the lock; therefore, it wasn't locked */
+ unlock_result = pthread_mutex_unlock(&pcm->lock);
+ assert(unlock_result == 0);
+ return 0;
+ } else {
+ /* we failed to grab the lock; therefore, it was locked */
+ return 1;
+ }
+ } else {
+ return 0;
+ }
+}
+
#else /* THREAD_SAFE_API */
#define __snd_pcm_lock(pcm) do {} while (0)
#define __snd_pcm_unlock(pcm) do {} while (0)
#define snd_pcm_lock(pcm) do {} while (0)
#define snd_pcm_unlock(pcm) do {} while (0)
+#define snd_pcm_is_locked(pcm) 0
#endif /* THREAD_SAFE_API */
--
2.23.0
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