TimeCheck: Update code to support a callback (5c6d68ad) · Commits · e / os / android_frameworks_av

media/utils/TimeCheck.cpp

+43 −16

Original line number	Diff line number	Diff line
		@@ -24,7 +24,7 @@
		#include <utils/Log.h>
		#include "debuggerd/handler.h"

		namespace android {
		namespace android::mediautils {

		namespace {

		@@ -48,7 +48,7 @@ std::string formatTime(std::chrono::system_clock::time_point t) {
		void TimeCheck::accessAudioHalPids(std::vector<pid_t>* pids, bool update) {
		static constexpr int kNumAudioHalPidsVectors = 3;
		static std::vector<pid_t> audioHalPids[kNumAudioHalPidsVectors];
		static std::atomic<int> curAudioHalPids = 0;
		static std::atomic<unsigned> curAudioHalPids = 0;

		if (update) {
		audioHalPids[(curAudioHalPids++ + 1) % kNumAudioHalPidsVectors] = *pids;
		@@ -70,27 +70,54 @@ std::vector<pid_t> TimeCheck::getAudioHalPids() {
		}

		/* static */
		TimerThread* TimeCheck::getTimeCheckThread() {
		static TimerThread* sTimeCheckThread = new TimerThread();
		TimerThread& TimeCheck::getTimeCheckThread() {
		static TimerThread sTimeCheckThread{};
		return sTimeCheckThread;
		}

		TimeCheck::TimeCheck(const char* tag, uint32_t timeoutMs)
		: mTimerHandle(getTimeCheckThread()->scheduleTask(
		[tag, startTime = std::chrono::system_clock::now()] { crash(tag, startTime); },
		TimeCheck::TimeCheck(std::string tag, OnTimerFunc&& onTimer, uint32_t timeoutMs,
		bool crashOnTimeout)
		: mTimeCheckHandler(new TimeCheckHandler{
		std::move(tag), std::move(onTimer), crashOnTimeout,
		std::chrono::system_clock::now(), gettid()})
		, mTimerHandle(getTimeCheckThread().scheduleTask(
		// Pass in all the arguments by value to this task for safety.
		// The thread could call the callback before the constructor is finished.
		// The destructor will be blocked on the callback, but that is implementation
		// dependent.
		[ timeCheckHandler = mTimeCheckHandler ] {
		timeCheckHandler->onTimeout();
		},
		std::chrono::milliseconds(timeoutMs))) {}

		TimeCheck::~TimeCheck() {
		getTimeCheckThread()->cancelTask(mTimerHandle);
		mTimeCheckHandler->onCancel(mTimerHandle);
		}

		/* static */
		void TimeCheck::crash(const char* tag, std::chrono::system_clock::time_point startTime) {
		std::chrono::system_clock::time_point endTime = std::chrono::system_clock::now();
		void TimeCheck::TimeCheckHandler::onCancel(TimerThread::Handle timerHandle) const
		{
		if (TimeCheck::getTimeCheckThread().cancelTask(timerHandle) && onTimer) {
		const std::chrono::system_clock::time_point endTime = std::chrono::system_clock::now();
		onTimer(false /* timeout */,
		std::chrono::duration_cast<std::chrono::duration<float, std::milli>>(
		endTime - startTime).count());
		}
		}

		void TimeCheck::TimeCheckHandler::onTimeout() const
		{
		const std::chrono::system_clock::time_point endTime = std::chrono::system_clock::now();
		if (onTimer) {
		onTimer(true /* timeout */,
		std::chrono::duration_cast<std::chrono::duration<float, std::milli>>(
		endTime - startTime).count());
		}

		if (!crashOnTimeout) return;

		// Generate audio HAL processes tombstones and allow time to complete
		// before forcing restart
		std::vector<pid_t> pids = getAudioHalPids();
		std::vector<pid_t> pids = TimeCheck::getAudioHalPids();
		if (pids.size() != 0) {
		for (const auto& pid : pids) {
		ALOGI("requesting tombstone for pid: %d", pid);
		@@ -100,9 +127,9 @@ void TimeCheck::crash(const char* tag, std::chrono::system_clock::time_point sta
		} else {
		ALOGI("No HAL process pid available, skipping tombstones");
		}
		LOG_EVENT_STRING(LOGTAG_AUDIO_BINDER_TIMEOUT, tag);
		LOG_ALWAYS_FATAL("TimeCheck timeout for %s (start=%s, end=%s)", tag,
		formatTime(startTime).c_str(), formatTime(endTime).c_str());
		LOG_EVENT_STRING(LOGTAG_AUDIO_BINDER_TIMEOUT, tag.c_str());
		LOG_ALWAYS_FATAL("TimeCheck timeout for %s on thread %d (start=%s, end=%s)",
		tag.c_str(), tid, formatTime(startTime).c_str(), formatTime(endTime).c_str());
		}

		}; // namespace android
		} // namespace android::mediautils

media/utils/TimerThread.cpp

+5 −2

Original line number	Diff line number	Diff line
		@@ -50,9 +50,12 @@ TimerThread::Handle TimerThread::scheduleTaskAtDeadline(std::function<void()>&&
		return deadline;
		}

		void TimerThread::cancelTask(Handle handle) {
		// Returns true if cancelled, false if handle doesn't exist.
		// Beware of lock inversion with cancelTask() as the callback
		// is called while holding mMutex.
		bool TimerThread::cancelTask(Handle handle) {
		std::lock_guard _l(mMutex);
		mMonitorRequests.erase(handle);
		return mMonitorRequests.erase(handle) != 0;
		}

		void TimerThread::threadFunc() {

media/utils/fuzzers/TimeCheckFuzz.cpp

+2 −2

Original line number	Diff line number	Diff line
		@@ -44,11 +44,11 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {

		// 2. We also have setAudioHalPids, which is populated with the pids set
		// above.
		android::TimeCheck::setAudioHalPids(pids);
		android::mediautils::TimeCheck::setAudioHalPids(pids);
		std::string name = data_provider.ConsumeRandomLengthString(kMaxStringLen);

		// 3. The constructor, which is fuzzed here:
		android::TimeCheck timeCheck(name.c_str(), timeoutMs);
		android::mediautils::TimeCheck timeCheck(name.c_str(), {} /* onTimer */, timeoutMs);
		// We will leave some buffer to avoid sleeping too long
		uint8_t sleep_amount_ms = data_provider.ConsumeIntegralInRange<uint8_t>(0, timeoutMs / 2);

media/utils/include/mediautils/TimeCheck.h

+54 −5

Original line number	Diff line number	Diff line
		@@ -20,27 +20,76 @@

		#include <mediautils/TimerThread.h>

		namespace android {
		namespace android::mediautils {

		// A class monitoring execution time for a code block (scoped variable) and causing an assert
		// if it exceeds a certain time

		class TimeCheck {
		public:
		using OnTimerFunc = std::function<void(bool /* timeout /, float / elapsedMs */ )>;

		// The default timeout is chosen to be less than system server watchdog timeout
		static constexpr uint32_t kDefaultTimeOutMs = 5000;

		TimeCheck(const char* tag, uint32_t timeoutMs = kDefaultTimeOutMs);
		/**
		* TimeCheck is a RAII object which will notify a callback
		* on timer expiration or when the object is deallocated.
		*
		* TimeCheck is used as a watchdog and aborts by default on timer expiration.
		* When it aborts, it will also send a debugger signal to pids passed in through
		* setAudioHalPids().
		*
		* If the callback function returns for timeout it will not be called again for
		* the deallocation.
		*
		* \param tag string associated with the TimeCheck object.
		* \param onTimer callback function with 2 parameters
		* bool timeout (which is true when the TimeCheck object
		* times out, false when the TimeCheck object is
		* destroyed or leaves scope before the timer expires.)
		* float elapsedMs (the elapsed time to this event).
		* The callback when timeout is true will be called on a different thread.
		* Currently this is guaranteed to block the destructor
		* (potential lock inversion warning here) nevertheless
		* it would be safer not to depend on stack contents.
		* \param timeoutMs timeout in milliseconds.
		* \param crashOnTimeout true if the object issues an abort on timeout.
		*/
		explicit TimeCheck(std::string tag, OnTimerFunc&& onTimer = {},
		uint32_t timeoutMs = kDefaultTimeOutMs, bool crashOnTimeout = true);
		// Remove copy constructors as there should only be one call to the destructor.
		// Move is kept implicitly disabled, but would be logically consistent if enabled.
		TimeCheck(const TimeCheck& other) = delete;
		TimeCheck& operator=(const TimeCheck&) = delete;

		~TimeCheck();
		static void setAudioHalPids(const std::vector<pid_t>& pids);
		static std::vector<pid_t> getAudioHalPids();

		private:
		static TimerThread* getTimeCheckThread();
		static TimerThread& getTimeCheckThread();
		static void accessAudioHalPids(std::vector<pid_t>* pids, bool update);
		static void crash(const char* tag, std::chrono::system_clock::time_point startTime);

		// Helper class for handling events.
		// The usage here is const safe.
		class TimeCheckHandler {
		public:
		const std::string tag;
		const OnTimerFunc onTimer;
		const bool crashOnTimeout;
		const std::chrono::system_clock::time_point startTime;
		const pid_t tid;

		void onCancel(TimerThread::Handle handle) const;
		void onTimeout() const;
		};

		// mTimeCheckHandler is immutable, prefer to be first initialized, last destroyed.
		// Technically speaking, we do not need a shared_ptr here because TimerThread::cancelTask()
		// is mutually exclusive of the callback, but the price paid for lifetime safety is minimal.
		const std::shared_ptr<const TimeCheckHandler> mTimeCheckHandler;
		const TimerThread::Handle mTimerHandle;
		};

		}; // namespace android
		} // namespace android::mediautils

media/utils/include/mediautils/TimerThread.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -48,9 +48,9 @@ class TimerThread {

		/**
		* Cancel a task, previously scheduled with scheduleTask().
		* If the task has already executed, this is a no-op.
		* If the task has already executed, this is a no-op and returns false.
		*/
		void cancelTask(Handle handle);
		bool cancelTask(Handle handle);

		private:
		using TimePoint = std::chrono::steady_clock::time_point;