services/surfaceflinger/Scheduler/EventThread.cpp - SHIFTPHONES/android_frameworks_native - Gitiles

 /*
  * Copyright (C) 2011 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define ATRACE_TAG ATRACE_TAG_GRAPHICS

 #include <pthread.h>
 #include <sched.h>
 #include <sys/types.h>

 #include <chrono>
 #include <cstdint>
 #include <optional>
 #include <type_traits>

 #include <android-base/stringprintf.h>

 #include <cutils/compiler.h>
 #include <cutils/sched_policy.h>

 #include <gui/DisplayEventReceiver.h>

 #include <utils/Errors.h>
 #include <utils/Trace.h>

 #include "EventThread.h"

 using namespace std::chrono_literals;

 namespace android {

 using base::StringAppendF;
 using base::StringPrintf;

 namespace {

 auto vsyncPeriod(VSyncRequest request) {
     return static_cast<std::underlying_type_t<VSyncRequest>>(request);
 }

 std::string toString(VSyncRequest request) {
     switch (request) {
         case VSyncRequest::None:
             return "VSyncRequest::None";
         case VSyncRequest::Single:
             return "VSyncRequest::Single";
         default:
             return StringPrintf("VSyncRequest::Periodic{period=%d}", vsyncPeriod(request));
     }
 }

 std::string toString(const EventThreadConnection& connection) {
     return StringPrintf("Connection{%p, %s}", &connection,
                         toString(connection.vsyncRequest).c_str());
 }

 std::string toString(const DisplayEventReceiver::Event& event) {
     switch (event.header.type) {
         case DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG:
             return StringPrintf("Hotplug{displayId=%" ANDROID_PHYSICAL_DISPLAY_ID_FORMAT ", %s}",
                                 event.header.displayId,
                                 event.hotplug.connected ? "connected" : "disconnected");
         case DisplayEventReceiver::DISPLAY_EVENT_VSYNC:
             return StringPrintf("VSync{displayId=%" ANDROID_PHYSICAL_DISPLAY_ID_FORMAT
                                 ", count=%u}",
                                 event.header.displayId, event.vsync.count);
         default:
             return "Event{}";
     }
 }

 DisplayEventReceiver::Event makeHotplug(PhysicalDisplayId displayId, nsecs_t timestamp,
                                         bool connected) {
     DisplayEventReceiver::Event event;
     event.header = {DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG, displayId, timestamp};
     event.hotplug.connected = connected;
     return event;
 }

 DisplayEventReceiver::Event makeVSync(PhysicalDisplayId displayId, nsecs_t timestamp,
                                       uint32_t count) {
     DisplayEventReceiver::Event event;
     event.header = {DisplayEventReceiver::DISPLAY_EVENT_VSYNC, displayId, timestamp};
     event.vsync.count = count;
     return event;
 }

 } // namespace

 EventThreadConnection::EventThreadConnection(EventThread* eventThread,
                                              ResyncCallback resyncCallback,
                                              ResetIdleTimerCallback resetIdleTimerCallback)
       : resyncCallback(std::move(resyncCallback)),
         resetIdleTimerCallback(std::move(resetIdleTimerCallback)),
         mEventThread(eventThread),
         mChannel(gui::BitTube::DefaultSize) {}

 EventThreadConnection::~EventThreadConnection() {
     // do nothing here -- clean-up will happen automatically
     // when the main thread wakes up
 }

 void EventThreadConnection::onFirstRef() {
     // NOTE: mEventThread doesn't hold a strong reference on us
     mEventThread->registerDisplayEventConnection(this);
 }

 status_t EventThreadConnection::stealReceiveChannel(gui::BitTube* outChannel) {
     outChannel->setReceiveFd(mChannel.moveReceiveFd());
     return NO_ERROR;
 }

 status_t EventThreadConnection::setVsyncRate(uint32_t rate) {
     mEventThread->setVsyncRate(rate, this);
     return NO_ERROR;
 }

 void EventThreadConnection::requestNextVsync() {
     ATRACE_NAME("requestNextVsync");
     mEventThread->requestNextVsync(this, true);
 }

 void EventThreadConnection::requestNextVsyncForHWC() {
     ATRACE_NAME("requestNextVsyncForHWC");
     mEventThread->requestNextVsync(this, false);
 }

 status_t EventThreadConnection::postEvent(const DisplayEventReceiver::Event& event) {
     ssize_t size = DisplayEventReceiver::sendEvents(&mChannel, &event, 1);
     return size < 0 ? status_t(size) : status_t(NO_ERROR);
 }

 // ---------------------------------------------------------------------------

 EventThread::~EventThread() = default;

 namespace impl {

 EventThread::EventThread(std::unique_ptr<VSyncSource> src,
                          InterceptVSyncsCallback interceptVSyncsCallback, const char* threadName)
       : EventThread(nullptr, std::move(src), std::move(interceptVSyncsCallback), threadName) {}

 EventThread::EventThread(VSyncSource* src, InterceptVSyncsCallback interceptVSyncsCallback,
                          const char* threadName)
       : EventThread(src, nullptr, std::move(interceptVSyncsCallback), threadName) {}

 EventThread::EventThread(VSyncSource* src, std::unique_ptr<VSyncSource> uniqueSrc,
                          InterceptVSyncsCallback interceptVSyncsCallback, const char* threadName)
       : mVSyncSource(src),
         mVSyncSourceUnique(std::move(uniqueSrc)),
         mInterceptVSyncsCallback(std::move(interceptVSyncsCallback)),
         mThreadName(threadName) {
     if (src == nullptr) {
         mVSyncSource = mVSyncSourceUnique.get();
     }
     mVSyncSource->setCallback(this);

     mThread = std::thread([this]() NO_THREAD_SAFETY_ANALYSIS {
         std::unique_lock<std::mutex> lock(mMutex);
         threadMain(lock);
     });

     pthread_setname_np(mThread.native_handle(), threadName);

     pid_t tid = pthread_gettid_np(mThread.native_handle());

     // Use SCHED_FIFO to minimize jitter
     constexpr int EVENT_THREAD_PRIORITY = 2;
     struct sched_param param = {0};
     param.sched_priority = EVENT_THREAD_PRIORITY;
     if (pthread_setschedparam(mThread.native_handle(), SCHED_FIFO, &param) != 0) {
         ALOGE("Couldn't set SCHED_FIFO for EventThread");
     }

     set_sched_policy(tid, SP_FOREGROUND);
 }

 EventThread::~EventThread() {
     mVSyncSource->setCallback(nullptr);

     {
         std::lock_guard<std::mutex> lock(mMutex);
         mState = State::Quit;
         mCondition.notify_all();
     }
     mThread.join();
 }

 void EventThread::setPhaseOffset(nsecs_t phaseOffset) {
     std::lock_guard<std::mutex> lock(mMutex);
     mVSyncSource->setPhaseOffset(phaseOffset);
 }

 void EventThread::pauseVsyncCallback(bool pause) {
     std::lock_guard<std::mutex> lock(mMutex);
     ATRACE_INT("vsyncPaused", pause);
     mVSyncSource->pauseVsyncCallback(pause);
 }

 sp<EventThreadConnection> EventThread::createEventConnection(
         ResyncCallback resyncCallback, ResetIdleTimerCallback resetIdleTimerCallback) const {
     return new EventThreadConnection(const_cast<EventThread*>(this), std::move(resyncCallback),
                                      std::move(resetIdleTimerCallback));
 }

 status_t EventThread::registerDisplayEventConnection(const sp<EventThreadConnection>& connection) {
     std::lock_guard<std::mutex> lock(mMutex);

     // this should never happen
     auto it = std::find(mDisplayEventConnections.cbegin(),
             mDisplayEventConnections.cend(), connection);
     if (it != mDisplayEventConnections.cend()) {
         ALOGW("DisplayEventConnection %p already exists", connection.get());
         mCondition.notify_all();
         return ALREADY_EXISTS;
     }

     mDisplayEventConnections.push_back(connection);
     mCondition.notify_all();
     return NO_ERROR;
 }

 void EventThread::removeDisplayEventConnectionLocked(const wp<EventThreadConnection>& connection) {
     auto it = std::find(mDisplayEventConnections.cbegin(),
             mDisplayEventConnections.cend(), connection);
     if (it != mDisplayEventConnections.cend()) {
         mDisplayEventConnections.erase(it);
     }
 }

 void EventThread::setVsyncRate(uint32_t rate, const sp<EventThreadConnection>& connection) {
     if (static_cast<std::underlying_type_t<VSyncRequest>>(rate) < 0) {
         return;
     }

     std::lock_guard<std::mutex> lock(mMutex);

     const auto request = rate == 0 ? VSyncRequest::None : static_cast<VSyncRequest>(rate);
     if (connection->vsyncRequest != request) {
         connection->vsyncRequest = request;
         mCondition.notify_all();
     }
 }

 void EventThread::requestNextVsync(const sp<EventThreadConnection>& connection, bool reset) {
     if (connection->resetIdleTimerCallback && reset) {
         ATRACE_NAME("resetIdleTimer");
         connection->resetIdleTimerCallback();
     }

     if (connection->resyncCallback) {
         connection->resyncCallback();
     }

     std::lock_guard<std::mutex> lock(mMutex);

     if (connection->vsyncRequest == VSyncRequest::None) {
         connection->vsyncRequest = VSyncRequest::Single;
         mCondition.notify_all();
     }
 }

 void EventThread::onScreenReleased() {
     std::lock_guard<std::mutex> lock(mMutex);
     if (!mVSyncState || mVSyncState->synthetic) {
         return;
     }

     mVSyncState->synthetic = true;
     mCondition.notify_all();
 }

 void EventThread::onScreenAcquired() {
     std::lock_guard<std::mutex> lock(mMutex);
     if (!mVSyncState || !mVSyncState->synthetic) {
         return;
     }

     mVSyncState->synthetic = false;
     mCondition.notify_all();
 }

 void EventThread::onVSyncEvent(nsecs_t timestamp) {
     std::lock_guard<std::mutex> lock(mMutex);

     LOG_FATAL_IF(!mVSyncState);
     mPendingEvents.push_back(makeVSync(mVSyncState->displayId, timestamp, ++mVSyncState->count));
     mCondition.notify_all();
 }

 void EventThread::onHotplugReceived(PhysicalDisplayId displayId, bool connected) {
     std::lock_guard<std::mutex> lock(mMutex);

     mPendingEvents.push_back(makeHotplug(displayId, systemTime(), connected));
     mCondition.notify_all();
 }

 void EventThread::threadMain(std::unique_lock<std::mutex>& lock) {
     DisplayEventConsumers consumers;

     while (mState != State::Quit) {
         std::optional<DisplayEventReceiver::Event> event;

         // Determine next event to dispatch.
         if (!mPendingEvents.empty()) {
             event = mPendingEvents.front();
             mPendingEvents.pop_front();

             switch (event->header.type) {
                 case DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG:
                     if (event->hotplug.connected && !mVSyncState) {
                         mVSyncState.emplace(event->header.displayId);
                     } else if (!event->hotplug.connected && mVSyncState &&
                                mVSyncState->displayId == event->header.displayId) {
                         mVSyncState.reset();
                     }
                     break;

                 case DisplayEventReceiver::DISPLAY_EVENT_VSYNC:
                     if (mInterceptVSyncsCallback) {
                         mInterceptVSyncsCallback(event->header.timestamp);
                     }
                     break;
             }
         }

         bool vsyncRequested = false;

         // Find connections that should consume this event.
         auto it = mDisplayEventConnections.begin();
         while (it != mDisplayEventConnections.end()) {
             if (const auto connection = it->promote()) {
                 vsyncRequested |= connection->vsyncRequest != VSyncRequest::None;

                 if (event && shouldConsumeEvent(*event, connection)) {
                     consumers.push_back(connection);
                 }

                 ++it;
             } else {
                 it = mDisplayEventConnections.erase(it);
             }
         }

         if (!consumers.empty()) {
             dispatchEvent(*event, consumers);
             consumers.clear();
         }

         State nextState;
         if (mVSyncState && vsyncRequested) {
             nextState = mVSyncState->synthetic ? State::SyntheticVSync : State::VSync;
         } else {
             ALOGW_IF(!mVSyncState, "Ignoring VSYNC request while display is disconnected");
             nextState = State::Idle;
         }

         if (mState != nextState) {
             if (mState == State::VSync) {
                 mVSyncSource->setVSyncEnabled(false);
             } else if (nextState == State::VSync) {
                 mVSyncSource->setVSyncEnabled(true);
             }

             mState = nextState;
         }

         if (event) {
             continue;
         }

         // Wait for event or client registration/request.
         if (mState == State::Idle) {
             mCondition.wait(lock);
         } else {
             // Generate a fake VSYNC after a long timeout in case the driver stalls. When the
             // display is off, keep feeding clients at 60 Hz.
             const auto timeout = mState == State::SyntheticVSync ? 16ms : 1000ms;
             if (mCondition.wait_for(lock, timeout) == std::cv_status::timeout) {
                 ALOGW_IF(mState == State::VSync, "Faking VSYNC due to driver stall");

                 LOG_FATAL_IF(!mVSyncState);
                 mPendingEvents.push_back(makeVSync(mVSyncState->displayId,
                                                    systemTime(SYSTEM_TIME_MONOTONIC),
                                                    ++mVSyncState->count));
             }
         }
     }
 }

 bool EventThread::shouldConsumeEvent(const DisplayEventReceiver::Event& event,
                                      const sp<EventThreadConnection>& connection) const {
     switch (event.header.type) {
         case DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG:
             return true;

         case DisplayEventReceiver::DISPLAY_EVENT_VSYNC:
             switch (connection->vsyncRequest) {
                 case VSyncRequest::None:
                     return false;
                 case VSyncRequest::Single:
                     connection->vsyncRequest = VSyncRequest::None;
                     return true;
                 case VSyncRequest::Periodic:
                     return true;
                 default:
                     return event.vsync.count % vsyncPeriod(connection->vsyncRequest) == 0;
             }

         default:
             return false;
     }
 }

 void EventThread::dispatchEvent(const DisplayEventReceiver::Event& event,
                                 const DisplayEventConsumers& consumers) {
     for (const auto& consumer : consumers) {
         switch (consumer->postEvent(event)) {
             case NO_ERROR:
                 break;

             case -EAGAIN:
                 // TODO: Try again if pipe is full.
                 ALOGW("Failed dispatching %s for %s", toString(event).c_str(),
                       toString(*consumer).c_str());
                 break;

             default:
                 // Treat EPIPE and other errors as fatal.
                 removeDisplayEventConnectionLocked(consumer);
         }
     }
 }

 void EventThread::dump(std::string& result) const {
     std::lock_guard<std::mutex> lock(mMutex);

     StringAppendF(&result, "%s: state=%s VSyncState=", mThreadName, toCString(mState));
     if (mVSyncState) {
         StringAppendF(&result, "{displayId=%" ANDROID_PHYSICAL_DISPLAY_ID_FORMAT ", count=%u%s}\n",
                       mVSyncState->displayId, mVSyncState->count,
                       mVSyncState->synthetic ? ", synthetic" : "");
     } else {
         StringAppendF(&result, "none\n");
     }

     StringAppendF(&result, "  pending events (count=%zu):\n", mPendingEvents.size());
     for (const auto& event : mPendingEvents) {
         StringAppendF(&result, "    %s\n", toString(event).c_str());
     }

     StringAppendF(&result, "  connections (count=%zu):\n", mDisplayEventConnections.size());
     for (const auto& ptr : mDisplayEventConnections) {
         if (const auto connection = ptr.promote()) {
             StringAppendF(&result, "    %s\n", toString(*connection).c_str());
         }
     }
 }

 const char* EventThread::toCString(State state) {
     switch (state) {
         case State::Idle:
             return "Idle";
         case State::Quit:
             return "Quit";
         case State::SyntheticVSync:
             return "SyntheticVSync";
         case State::VSync:
             return "VSync";
     }
 }

 } // namespace impl
 } // namespace android
	/*
	* Copyright (C) 2011 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define ATRACE_TAG ATRACE_TAG_GRAPHICS

	#include <pthread.h>
	#include <sched.h>
	#include <sys/types.h>

	#include <chrono>
	#include <cstdint>
	#include <optional>
	#include <type_traits>

	#include <android-base/stringprintf.h>

	#include <cutils/compiler.h>
	#include <cutils/sched_policy.h>

	#include <gui/DisplayEventReceiver.h>

	#include <utils/Errors.h>
	#include <utils/Trace.h>

	#include "EventThread.h"

	using namespace std::chrono_literals;

	namespace android {

	using base::StringAppendF;
	using base::StringPrintf;

	namespace {

	auto vsyncPeriod(VSyncRequest request) {
	return static_cast<std::underlying_type_t<VSyncRequest>>(request);
	}

	std::string toString(VSyncRequest request) {
	switch (request) {
	case VSyncRequest::None:
	return "VSyncRequest::None";
	case VSyncRequest::Single:
	return "VSyncRequest::Single";
	default:
	return StringPrintf("VSyncRequest::Periodic{period=%d}", vsyncPeriod(request));
	}
	}

	std::string toString(const EventThreadConnection& connection) {
	return StringPrintf("Connection{%p, %s}", &connection,
	toString(connection.vsyncRequest).c_str());
	}

	std::string toString(const DisplayEventReceiver::Event& event) {
	switch (event.header.type) {
	case DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG:
	return StringPrintf("Hotplug{displayId=%" ANDROID_PHYSICAL_DISPLAY_ID_FORMAT ", %s}",
	event.header.displayId,
	event.hotplug.connected ? "connected" : "disconnected");
	case DisplayEventReceiver::DISPLAY_EVENT_VSYNC:
	return StringPrintf("VSync{displayId=%" ANDROID_PHYSICAL_DISPLAY_ID_FORMAT
	", count=%u}",
	event.header.displayId, event.vsync.count);
	default:
	return "Event{}";
	}
	}

	DisplayEventReceiver::Event makeHotplug(PhysicalDisplayId displayId, nsecs_t timestamp,
	bool connected) {
	DisplayEventReceiver::Event event;
	event.header = {DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG, displayId, timestamp};
	event.hotplug.connected = connected;
	return event;
	}

	DisplayEventReceiver::Event makeVSync(PhysicalDisplayId displayId, nsecs_t timestamp,
	uint32_t count) {
	DisplayEventReceiver::Event event;
	event.header = {DisplayEventReceiver::DISPLAY_EVENT_VSYNC, displayId, timestamp};
	event.vsync.count = count;
	return event;
	}

	} // namespace

	EventThreadConnection::EventThreadConnection(EventThread* eventThread,
	ResyncCallback resyncCallback,
	ResetIdleTimerCallback resetIdleTimerCallback)
	: resyncCallback(std::move(resyncCallback)),
	resetIdleTimerCallback(std::move(resetIdleTimerCallback)),
	mEventThread(eventThread),
	mChannel(gui::BitTube::DefaultSize) {}

	EventThreadConnection::~EventThreadConnection() {
	// do nothing here -- clean-up will happen automatically
	// when the main thread wakes up
	}

	void EventThreadConnection::onFirstRef() {
	// NOTE: mEventThread doesn't hold a strong reference on us
	mEventThread->registerDisplayEventConnection(this);
	}

	status_t EventThreadConnection::stealReceiveChannel(gui::BitTube* outChannel) {
	outChannel->setReceiveFd(mChannel.moveReceiveFd());
	return NO_ERROR;
	}

	status_t EventThreadConnection::setVsyncRate(uint32_t rate) {
	mEventThread->setVsyncRate(rate, this);
	return NO_ERROR;
	}

	void EventThreadConnection::requestNextVsync() {
	ATRACE_NAME("requestNextVsync");
	mEventThread->requestNextVsync(this, true);
	}

	void EventThreadConnection::requestNextVsyncForHWC() {
	ATRACE_NAME("requestNextVsyncForHWC");
	mEventThread->requestNextVsync(this, false);
	}

	status_t EventThreadConnection::postEvent(const DisplayEventReceiver::Event& event) {
	ssize_t size = DisplayEventReceiver::sendEvents(&mChannel, &event, 1);
	return size < 0 ? status_t(size) : status_t(NO_ERROR);
	}

	// ---------------------------------------------------------------------------

	EventThread::~EventThread() = default;

	namespace impl {

	EventThread::EventThread(std::unique_ptr<VSyncSource> src,
	InterceptVSyncsCallback interceptVSyncsCallback, const char* threadName)
	: EventThread(nullptr, std::move(src), std::move(interceptVSyncsCallback), threadName) {}

	EventThread::EventThread(VSyncSource* src, InterceptVSyncsCallback interceptVSyncsCallback,
	const char* threadName)
	: EventThread(src, nullptr, std::move(interceptVSyncsCallback), threadName) {}

	EventThread::EventThread(VSyncSource* src, std::unique_ptr<VSyncSource> uniqueSrc,
	InterceptVSyncsCallback interceptVSyncsCallback, const char* threadName)
	: mVSyncSource(src),
	mVSyncSourceUnique(std::move(uniqueSrc)),
	mInterceptVSyncsCallback(std::move(interceptVSyncsCallback)),
	mThreadName(threadName) {
	if (src == nullptr) {
	mVSyncSource = mVSyncSourceUnique.get();
	}
	mVSyncSource->setCallback(this);

	mThread = std::thread([this]() NO_THREAD_SAFETY_ANALYSIS {
	std::unique_lock<std::mutex> lock(mMutex);
	threadMain(lock);
	});

	pthread_setname_np(mThread.native_handle(), threadName);

	pid_t tid = pthread_gettid_np(mThread.native_handle());

	// Use SCHED_FIFO to minimize jitter
	constexpr int EVENT_THREAD_PRIORITY = 2;
	struct sched_param param = {0};
	param.sched_priority = EVENT_THREAD_PRIORITY;
	if (pthread_setschedparam(mThread.native_handle(), SCHED_FIFO, &param) != 0) {
	ALOGE("Couldn't set SCHED_FIFO for EventThread");
	}

	set_sched_policy(tid, SP_FOREGROUND);
	}

	EventThread::~EventThread() {
	mVSyncSource->setCallback(nullptr);

	{
	std::lock_guard<std::mutex> lock(mMutex);
	mState = State::Quit;
	mCondition.notify_all();
	}
	mThread.join();
	}

	void EventThread::setPhaseOffset(nsecs_t phaseOffset) {
	std::lock_guard<std::mutex> lock(mMutex);
	mVSyncSource->setPhaseOffset(phaseOffset);
	}

	void EventThread::pauseVsyncCallback(bool pause) {
	std::lock_guard<std::mutex> lock(mMutex);
	ATRACE_INT("vsyncPaused", pause);
	mVSyncSource->pauseVsyncCallback(pause);
	}

	sp<EventThreadConnection> EventThread::createEventConnection(
	ResyncCallback resyncCallback, ResetIdleTimerCallback resetIdleTimerCallback) const {
	return new EventThreadConnection(const_cast<EventThread*>(this), std::move(resyncCallback),
	std::move(resetIdleTimerCallback));
	}

	status_t EventThread::registerDisplayEventConnection(const sp<EventThreadConnection>& connection) {
	std::lock_guard<std::mutex> lock(mMutex);

	// this should never happen
	auto it = std::find(mDisplayEventConnections.cbegin(),
	mDisplayEventConnections.cend(), connection);
	if (it != mDisplayEventConnections.cend()) {
	ALOGW("DisplayEventConnection %p already exists", connection.get());
	mCondition.notify_all();
	return ALREADY_EXISTS;
	}

	mDisplayEventConnections.push_back(connection);
	mCondition.notify_all();
	return NO_ERROR;
	}

	void EventThread::removeDisplayEventConnectionLocked(const wp<EventThreadConnection>& connection) {
	auto it = std::find(mDisplayEventConnections.cbegin(),
	mDisplayEventConnections.cend(), connection);
	if (it != mDisplayEventConnections.cend()) {
	mDisplayEventConnections.erase(it);
	}
	}

	void EventThread::setVsyncRate(uint32_t rate, const sp<EventThreadConnection>& connection) {
	if (static_cast<std::underlying_type_t<VSyncRequest>>(rate) < 0) {
	return;
	}

	std::lock_guard<std::mutex> lock(mMutex);

	const auto request = rate == 0 ? VSyncRequest::None : static_cast<VSyncRequest>(rate);
	if (connection->vsyncRequest != request) {
	connection->vsyncRequest = request;
	mCondition.notify_all();
	}
	}

	void EventThread::requestNextVsync(const sp<EventThreadConnection>& connection, bool reset) {
	if (connection->resetIdleTimerCallback && reset) {
	ATRACE_NAME("resetIdleTimer");
	connection->resetIdleTimerCallback();
	}

	if (connection->resyncCallback) {
	connection->resyncCallback();
	}

	std::lock_guard<std::mutex> lock(mMutex);

	if (connection->vsyncRequest == VSyncRequest::None) {
	connection->vsyncRequest = VSyncRequest::Single;
	mCondition.notify_all();
	}
	}

	void EventThread::onScreenReleased() {
	std::lock_guard<std::mutex> lock(mMutex);
	if (!mVSyncState \|\| mVSyncState->synthetic) {
	return;
	}

	mVSyncState->synthetic = true;
	mCondition.notify_all();
	}

	void EventThread::onScreenAcquired() {
	std::lock_guard<std::mutex> lock(mMutex);
	if (!mVSyncState \|\| !mVSyncState->synthetic) {
	return;
	}

	mVSyncState->synthetic = false;
	mCondition.notify_all();
	}

	void EventThread::onVSyncEvent(nsecs_t timestamp) {
	std::lock_guard<std::mutex> lock(mMutex);

	LOG_FATAL_IF(!mVSyncState);
	mPendingEvents.push_back(makeVSync(mVSyncState->displayId, timestamp, ++mVSyncState->count));
	mCondition.notify_all();
	}

	void EventThread::onHotplugReceived(PhysicalDisplayId displayId, bool connected) {
	std::lock_guard<std::mutex> lock(mMutex);

	mPendingEvents.push_back(makeHotplug(displayId, systemTime(), connected));
	mCondition.notify_all();
	}

	void EventThread::threadMain(std::unique_lock<std::mutex>& lock) {
	DisplayEventConsumers consumers;

	while (mState != State::Quit) {
	std::optional<DisplayEventReceiver::Event> event;

	// Determine next event to dispatch.
	if (!mPendingEvents.empty()) {
	event = mPendingEvents.front();
	mPendingEvents.pop_front();

	switch (event->header.type) {
	case DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG:
	if (event->hotplug.connected && !mVSyncState) {
	mVSyncState.emplace(event->header.displayId);
	} else if (!event->hotplug.connected && mVSyncState &&
	mVSyncState->displayId == event->header.displayId) {
	mVSyncState.reset();
	}
	break;

	case DisplayEventReceiver::DISPLAY_EVENT_VSYNC:
	if (mInterceptVSyncsCallback) {
	mInterceptVSyncsCallback(event->header.timestamp);
	}
	break;
	}
	}

	bool vsyncRequested = false;

	// Find connections that should consume this event.
	auto it = mDisplayEventConnections.begin();
	while (it != mDisplayEventConnections.end()) {
	if (const auto connection = it->promote()) {
	vsyncRequested \|= connection->vsyncRequest != VSyncRequest::None;

	if (event && shouldConsumeEvent(*event, connection)) {
	consumers.push_back(connection);
	}

	++it;
	} else {
	it = mDisplayEventConnections.erase(it);
	}
	}

	if (!consumers.empty()) {
	dispatchEvent(*event, consumers);
	consumers.clear();
	}

	State nextState;
	if (mVSyncState && vsyncRequested) {
	nextState = mVSyncState->synthetic ? State::SyntheticVSync : State::VSync;
	} else {
	ALOGW_IF(!mVSyncState, "Ignoring VSYNC request while display is disconnected");
	nextState = State::Idle;
	}

	if (mState != nextState) {
	if (mState == State::VSync) {
	mVSyncSource->setVSyncEnabled(false);
	} else if (nextState == State::VSync) {
	mVSyncSource->setVSyncEnabled(true);
	}

	mState = nextState;
	}

	if (event) {
	continue;
	}

	// Wait for event or client registration/request.
	if (mState == State::Idle) {
	mCondition.wait(lock);
	} else {
	// Generate a fake VSYNC after a long timeout in case the driver stalls. When the
	// display is off, keep feeding clients at 60 Hz.
	const auto timeout = mState == State::SyntheticVSync ? 16ms : 1000ms;
	if (mCondition.wait_for(lock, timeout) == std::cv_status::timeout) {
	ALOGW_IF(mState == State::VSync, "Faking VSYNC due to driver stall");

	LOG_FATAL_IF(!mVSyncState);
	mPendingEvents.push_back(makeVSync(mVSyncState->displayId,
	systemTime(SYSTEM_TIME_MONOTONIC),
	++mVSyncState->count));
	}
	}
	}
	}

	bool EventThread::shouldConsumeEvent(const DisplayEventReceiver::Event& event,
	const sp<EventThreadConnection>& connection) const {
	switch (event.header.type) {
	case DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG:
	return true;

	case DisplayEventReceiver::DISPLAY_EVENT_VSYNC:
	switch (connection->vsyncRequest) {
	case VSyncRequest::None:
	return false;
	case VSyncRequest::Single:
	connection->vsyncRequest = VSyncRequest::None;
	return true;
	case VSyncRequest::Periodic:
	return true;
	default:
	return event.vsync.count % vsyncPeriod(connection->vsyncRequest) == 0;
	}

	default:
	return false;
	}
	}

	void EventThread::dispatchEvent(const DisplayEventReceiver::Event& event,
	const DisplayEventConsumers& consumers) {
	for (const auto& consumer : consumers) {
	switch (consumer->postEvent(event)) {
	case NO_ERROR:
	break;

	case -EAGAIN:
	// TODO: Try again if pipe is full.
	ALOGW("Failed dispatching %s for %s", toString(event).c_str(),
	toString(*consumer).c_str());
	break;

	default:
	// Treat EPIPE and other errors as fatal.
	removeDisplayEventConnectionLocked(consumer);
	}
	}
	}

	void EventThread::dump(std::string& result) const {
	std::lock_guard<std::mutex> lock(mMutex);

	StringAppendF(&result, "%s: state=%s VSyncState=", mThreadName, toCString(mState));
	if (mVSyncState) {
	StringAppendF(&result, "{displayId=%" ANDROID_PHYSICAL_DISPLAY_ID_FORMAT ", count=%u%s}\n",
	mVSyncState->displayId, mVSyncState->count,
	mVSyncState->synthetic ? ", synthetic" : "");
	} else {
	StringAppendF(&result, "none\n");
	}

	StringAppendF(&result, " pending events (count=%zu):\n", mPendingEvents.size());
	for (const auto& event : mPendingEvents) {
	StringAppendF(&result, " %s\n", toString(event).c_str());
	}

	StringAppendF(&result, " connections (count=%zu):\n", mDisplayEventConnections.size());
	for (const auto& ptr : mDisplayEventConnections) {
	if (const auto connection = ptr.promote()) {
	StringAppendF(&result, " %s\n", toString(*connection).c_str());
	}
	}
	}

	const char* EventThread::toCString(State state) {
	switch (state) {
	case State::Idle:
	return "Idle";
	case State::Quit:
	return "Quit";
	case State::SyntheticVSync:
	return "SyntheticVSync";
	case State::VSync:
	return "VSync";
	}
	}

	} // namespace impl
	} // namespace android