Merge "Use mFutex as an event flag rather than semaphore" (269e91be) · Commits · e / os / android_frameworks_av

include/private/media/AudioTrackShared.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -94,8 +94,9 @@ struct audio_track_cblk_t
		// parameter
		// renamed to "_" to detect incorrect use

		volatile int32_t mFutex; // semaphore: down (P) by client,
		volatile int32_t mFutex; // event flag: down (P) by client,
		// up (V) by server or binderDied() or interrupt()
		#define CBLK_FUTEX_WAKE 1 // if event flag bit is set, then a deferred wake is pending

		private:

+5 −6

Original line number	Diff line number	Diff line
		@@ -207,15 +207,15 @@ status_t ClientProxy::obtainBuffer(Buffer* buffer, const struct timespec *reques
		ts = NULL;
		break;
		}
		int32_t old = android_atomic_dec(&cblk->mFutex);
		if (old <= 0) {
		int32_t old = android_atomic_and(~CBLK_FUTEX_WAKE, &cblk->mFutex);
		if (!(old & CBLK_FUTEX_WAKE)) {
		int rc;
		if (measure && !beforeIsValid) {
		clock_gettime(CLOCK_MONOTONIC, &before);
		beforeIsValid = true;
		}
		int ret = __futex_syscall4(&cblk->mFutex,
		mClientInServer ? FUTEX_WAIT_PRIVATE : FUTEX_WAIT, old - 1, ts);
		mClientInServer ? FUTEX_WAIT_PRIVATE : FUTEX_WAIT, old & ~CBLK_FUTEX_WAKE, ts);
		// update total elapsed time spent waiting
		if (measure) {
		struct timespec after;
		@@ -484,9 +484,8 @@ void ServerProxy::releaseBuffer(Buffer* buffer)
		}
		if (!mDeferWake && mAvailToClient + stepCount >= minimum) {
		ALOGV("mAvailToClient=%u stepCount=%u minimum=%u", mAvailToClient, stepCount, minimum);
		// could client be sleeping, or not need this increment and counter overflows?
		int32_t old = android_atomic_inc(&cblk->mFutex);
		if (old == -1) {
		int32_t old = android_atomic_or(CBLK_FUTEX_WAKE, &cblk->mFutex);
		if (!(old & CBLK_FUTEX_WAKE)) {
		(void) __futex_syscall3(&cblk->mFutex,
		mClientInServer ? FUTEX_WAKE_PRIVATE : FUTEX_WAKE, 1);
		}