Merge "Reduce rollovers of unique ID generator" into nyc-dev (88bd61e3) · Commits · e / os / android_frameworks_av

services/audioflinger/AudioFlinger.cpp

+22 −6

Original line number	Original line	Diff line number	Diff line
	@@ -176,7 +176,7 @@ AudioFlinger::AudioFlinger()
	mHardwareStatus(AUDIO_HW_IDLE),		mHardwareStatus(AUDIO_HW_IDLE),
	mMasterVolume(1.0f),		mMasterVolume(1.0f),
	mMasterMute(false),		mMasterMute(false),
	mNextUniqueId(AUDIO_UNIQUE_ID_USE_MAX), // zero has a special meaning, so unavailable		// mNextUniqueId(AUDIO_UNIQUE_ID_USE_MAX),
	mMode(AUDIO_MODE_INVALID),		mMode(AUDIO_MODE_INVALID),
	mBtNrecIsOff(false),		mBtNrecIsOff(false),
	mIsLowRamDevice(true),		mIsLowRamDevice(true),
	@@ -184,6 +184,12 @@ AudioFlinger::AudioFlinger()
	mGlobalEffectEnableTime(0),		mGlobalEffectEnableTime(0),
	mSystemReady(false)		mSystemReady(false)
	{		{
			// unsigned instead of audio_unique_id_use_t, because ++ operator is unavailable for enum
			for (unsigned use = AUDIO_UNIQUE_ID_USE_UNSPECIFIED; use < AUDIO_UNIQUE_ID_USE_MAX; use++) {
			// zero ID has a special meaning, so unavailable
			mNextUniqueIds[use] = AUDIO_UNIQUE_ID_USE_MAX;
			}

	getpid_cached = getpid();		getpid_cached = getpid();
	const bool doLog = property_get_bool("ro.test_harness", false);		const bool doLog = property_get_bool("ro.test_harness", false);
	if (doLog) {		if (doLog) {
	@@ -2440,14 +2446,24 @@ AudioFlinger::RecordThread *AudioFlinger::checkRecordThread_l(audio_io_handle_t

	audio_unique_id_t AudioFlinger::nextUniqueId(audio_unique_id_use_t use)		audio_unique_id_t AudioFlinger::nextUniqueId(audio_unique_id_use_t use)
	{		{
	int32_t base = android_atomic_add(AUDIO_UNIQUE_ID_USE_MAX, &mNextUniqueId);
	// We have no way of recovering from wraparound
	LOG_ALWAYS_FATAL_IF(base == 0, "unique ID overflow");
	// This is the internal API, so it is OK to assert on bad parameter.		// This is the internal API, so it is OK to assert on bad parameter.
	LOG_ALWAYS_FATAL_IF((unsigned) use >= (unsigned) AUDIO_UNIQUE_ID_USE_MAX);		LOG_ALWAYS_FATAL_IF((unsigned) use >= (unsigned) AUDIO_UNIQUE_ID_USE_MAX);
			const int maxRetries = use == AUDIO_UNIQUE_ID_USE_SESSION ? 3 : 1;
			for (int retry = 0; retry < maxRetries; retry++) {
			// The cast allows wraparound from max positive to min negative instead of abort
			uint32_t base = (uint32_t) atomic_fetch_add_explicit(&mNextUniqueIds[use],
			(uint_fast32_t) AUDIO_UNIQUE_ID_USE_MAX, memory_order_acq_rel);
	ALOG_ASSERT(audio_unique_id_get_use(base) == AUDIO_UNIQUE_ID_USE_UNSPECIFIED);		ALOG_ASSERT(audio_unique_id_get_use(base) == AUDIO_UNIQUE_ID_USE_UNSPECIFIED);
			// allow wrap by skipping 0 and -1 for session ids
			if (!(base == 0 \|\| base == (~0u & ~AUDIO_UNIQUE_ID_USE_MASK))) {
			ALOGW_IF(retry != 0, "unique ID overflow for use %d", use);
	return (audio_unique_id_t) (base \| use);		return (audio_unique_id_t) (base \| use);
	}		}
			}
			// We have no way of recovering from wraparound
			LOG_ALWAYS_FATAL("unique ID overflow for use %d", use);
			// TODO Use a floor after wraparound. This may need a mutex.
			}

	AudioFlinger::PlaybackThread *AudioFlinger::primaryPlaybackThread_l() const		AudioFlinger::PlaybackThread *AudioFlinger::primaryPlaybackThread_l() const
	{		{

services/audioflinger/AudioFlinger.h

+2 −3

Original line number	Original line	Diff line number	Diff line
	@@ -679,9 +679,8 @@ private:
	// protected by mClientLock		// protected by mClientLock
	DefaultKeyedVector< pid_t, sp<NotificationClient> > mNotificationClients;		DefaultKeyedVector< pid_t, sp<NotificationClient> > mNotificationClients;

	volatile int32_t mNextUniqueId; // updated by android_atomic_inc		// updated by atomic_fetch_add_explicit
	// nextUniqueId() returns uint32_t, but this is declared int32_t		volatile atomic_uint_fast32_t mNextUniqueIds[AUDIO_UNIQUE_ID_USE_MAX];
	// because the atomic operations require an int32_t

	audio_mode_t mMode;		audio_mode_t mMode;
	bool mBtNrecIsOff;		bool mBtNrecIsOff;