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/*
* 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 <cutils/compiler.h>
#include <cutils/sched_policy.h>
#include <gui/DisplayEventReceiver.h>
#include <utils/Errors.h>
#include <utils/String8.h>
#include <utils/Trace.h>
#include "EventThread.h"
using namespace std::chrono_literals;
// ---------------------------------------------------------------------------
namespace android {
// ---------------------------------------------------------------------------
EventThread::~EventThread() = default;
namespace impl {
EventThread::EventThread(VSyncSource* src, ResyncWithRateLimitCallback resyncWithRateLimitCallback,
InterceptVSyncsCallback interceptVSyncsCallback, const char* threadName)
: mVSyncSource(src),
mResyncWithRateLimitCallback(resyncWithRateLimitCallback),
mInterceptVSyncsCallback(interceptVSyncsCallback) {
for (auto& event : mVSyncEvent) {
event.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
event.header.id = 0;
event.header.timestamp = 0;
event.vsync.count = 0;
}
mThread = std::thread(&EventThread::threadMain, this);
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() {
{
std::lock_guard<std::mutex> lock(mMutex);
mKeepRunning = false;
mCondition.notify_all();
}
mThread.join();
}
void EventThread::setPhaseOffset(nsecs_t phaseOffset) {
std::lock_guard<std::mutex> lock(mMutex);
mVSyncSource->setPhaseOffset(phaseOffset);
}
sp<BnDisplayEventConnection> EventThread::createEventConnection() const {
return new Connection(const_cast<EventThread*>(this));
}
status_t EventThread::registerDisplayEventConnection(
const sp<EventThread::Connection>& connection) {
std::lock_guard<std::mutex> lock(mMutex);
mDisplayEventConnections.add(connection);
mCondition.notify_all();
return NO_ERROR;
}
void EventThread::removeDisplayEventConnectionLocked(const wp<EventThread::Connection>& connection) {
mDisplayEventConnections.remove(connection);
}
void EventThread::setVsyncRate(uint32_t count, const sp<EventThread::Connection>& connection) {
if (int32_t(count) >= 0) { // server must protect against bad params
std::lock_guard<std::mutex> lock(mMutex);
const int32_t new_count = (count == 0) ? -1 : count;
if (connection->count != new_count) {
connection->count = new_count;
mCondition.notify_all();
}
}
}
void EventThread::requestNextVsync(const sp<EventThread::Connection>& connection) {
std::lock_guard<std::mutex> lock(mMutex);
if (mResyncWithRateLimitCallback) {
mResyncWithRateLimitCallback();
}
if (connection->count < 0) {
connection->count = 0;
mCondition.notify_all();
}
}
void EventThread::onScreenReleased() {
std::lock_guard<std::mutex> lock(mMutex);
if (!mUseSoftwareVSync) {
// disable reliance on h/w vsync
mUseSoftwareVSync = true;
mCondition.notify_all();
}
}
void EventThread::onScreenAcquired() {
std::lock_guard<std::mutex> lock(mMutex);
if (mUseSoftwareVSync) {
// resume use of h/w vsync
mUseSoftwareVSync = false;
mCondition.notify_all();
}
}
void EventThread::onVSyncEvent(nsecs_t timestamp) {
std::lock_guard<std::mutex> lock(mMutex);
mVSyncEvent[0].header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
mVSyncEvent[0].header.id = 0;
mVSyncEvent[0].header.timestamp = timestamp;
mVSyncEvent[0].vsync.count++;
mCondition.notify_all();
}
void EventThread::onHotplugReceived(int type, bool connected) {
ALOGE_IF(type >= DisplayDevice::NUM_BUILTIN_DISPLAY_TYPES,
"received hotplug event for an invalid display (id=%d)", type);
std::lock_guard<std::mutex> lock(mMutex);
if (type < DisplayDevice::NUM_BUILTIN_DISPLAY_TYPES) {
DisplayEventReceiver::Event event;
event.header.type = DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG;
event.header.id = type;
event.header.timestamp = systemTime();
event.hotplug.connected = connected;
mPendingEvents.add(event);
mCondition.notify_all();
}
}
void EventThread::threadMain() NO_THREAD_SAFETY_ANALYSIS {
std::unique_lock<std::mutex> lock(mMutex);
while (mKeepRunning) {
DisplayEventReceiver::Event event;
Vector<sp<EventThread::Connection> > signalConnections;
signalConnections = waitForEventLocked(&lock, &event);
// dispatch events to listeners...
const size_t count = signalConnections.size();
for (size_t i = 0; i < count; i++) {
const sp<Connection>& conn(signalConnections[i]);
// now see if we still need to report this event
status_t err = conn->postEvent(event);
if (err == -EAGAIN || err == -EWOULDBLOCK) {
// The destination doesn't accept events anymore, it's probably
// full. For now, we just drop the events on the floor.
// FIXME: Note that some events cannot be dropped and would have
// to be re-sent later.
// Right-now we don't have the ability to do this.
ALOGW("EventThread: dropping event (%08x) for connection %p", event.header.type,
conn.get());
} else if (err < 0) {
// handle any other error on the pipe as fatal. the only
// reasonable thing to do is to clean-up this connection.
// The most common error we'll get here is -EPIPE.
removeDisplayEventConnectionLocked(signalConnections[i]);
}
}
}
}
// This will return when (1) a vsync event has been received, and (2) there was
// at least one connection interested in receiving it when we started waiting.
Vector<sp<EventThread::Connection> > EventThread::waitForEventLocked(
std::unique_lock<std::mutex>* lock, DisplayEventReceiver::Event* event) {
Vector<sp<EventThread::Connection> > signalConnections;
while (signalConnections.isEmpty() && mKeepRunning) {
bool eventPending = false;
bool waitForVSync = false;
size_t vsyncCount = 0;
nsecs_t timestamp = 0;
for (int32_t i = 0; i < DisplayDevice::NUM_BUILTIN_DISPLAY_TYPES; i++) {
timestamp = mVSyncEvent[i].header.timestamp;
if (timestamp) {
// we have a vsync event to dispatch
if (mInterceptVSyncsCallback) {
mInterceptVSyncsCallback(timestamp);
}
*event = mVSyncEvent[i];
mVSyncEvent[i].header.timestamp = 0;
vsyncCount = mVSyncEvent[i].vsync.count;
break;
}
}
if (!timestamp) {
// no vsync event, see if there are some other event
eventPending = !mPendingEvents.isEmpty();
if (eventPending) {
// we have some other event to dispatch
*event = mPendingEvents[0];
mPendingEvents.removeAt(0);
}
}
// find out connections waiting for events
size_t count = mDisplayEventConnections.size();
for (size_t i = 0; i < count;) {
sp<Connection> connection(mDisplayEventConnections[i].promote());
if (connection != nullptr) {
bool added = false;
if (connection->count >= 0) {
// we need vsync events because at least
// one connection is waiting for it
waitForVSync = true;
if (timestamp) {
// we consume the event only if it's time
// (ie: we received a vsync event)
if (connection->count == 0) {
// fired this time around
connection->count = -1;
signalConnections.add(connection);
added = true;
} else if (connection->count == 1 ||
(vsyncCount % connection->count) == 0) {
// continuous event, and time to report it
signalConnections.add(connection);
added = true;
}
}
}
if (eventPending && !timestamp && !added) {
// we don't have a vsync event to process
// (timestamp==0), but we have some pending
// messages.
signalConnections.add(connection);
}
++i;
} else {
// we couldn't promote this reference, the connection has
// died, so clean-up!
mDisplayEventConnections.removeAt(i);
--count;
}
}
// Here we figure out if we need to enable or disable vsyncs
if (timestamp && !waitForVSync) {
// we received a VSYNC but we have no clients
// don't report it, and disable VSYNC events
disableVSyncLocked();
} else if (!timestamp && waitForVSync) {
// we have at least one client, so we want vsync enabled
// (TODO: this function is called right after we finish
// notifying clients of a vsync, so this call will be made
// at the vsync rate, e.g. 60fps. If we can accurately
// track the current state we could avoid making this call
// so often.)
enableVSyncLocked();
}
// note: !timestamp implies signalConnections.isEmpty(), because we
// don't populate signalConnections if there's no vsync pending
if (!timestamp && !eventPending) {
// wait for something to happen
if (waitForVSync) {
// This is where we spend most of our time, waiting
// for vsync events and new client registrations.
//
// If the screen is off, we can't use h/w vsync, so we
// use a 16ms timeout instead. It doesn't need to be
// precise, we just need to keep feeding our clients.
//
// We don't want to stall if there's a driver bug, so we
// use a (long) timeout when waiting for h/w vsync, and
// generate fake events when necessary.
bool softwareSync = mUseSoftwareVSync;
auto timeout = softwareSync ? 16ms : 1000ms;
if (mCondition.wait_for(*lock, timeout) == std::cv_status::timeout) {
if (!softwareSync) {
ALOGW("Timed out waiting for hw vsync; faking it");
}
// FIXME: how do we decide which display id the fake
// vsync came from ?
mVSyncEvent[0].header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
mVSyncEvent[0].header.id = DisplayDevice::DISPLAY_PRIMARY;
mVSyncEvent[0].header.timestamp = systemTime(SYSTEM_TIME_MONOTONIC);
mVSyncEvent[0].vsync.count++;
}
} else {
// Nobody is interested in vsync, so we just want to sleep.
// h/w vsync should be disabled, so this will wait until we
// get a new connection, or an existing connection becomes
// interested in receiving vsync again.
mCondition.wait(*lock);
}
}
}
// here we're guaranteed to have a timestamp and some connections to signal
// (The connections might have dropped out of mDisplayEventConnections
// while we were asleep, but we'll still have strong references to them.)
return signalConnections;
}
void EventThread::enableVSyncLocked() {
if (!mUseSoftwareVSync) {
// never enable h/w VSYNC when screen is off
if (!mVsyncEnabled) {
mVsyncEnabled = true;
mVSyncSource->setCallback(this);
mVSyncSource->setVSyncEnabled(true);
}
}
mDebugVsyncEnabled = true;
}
void EventThread::disableVSyncLocked() {
if (mVsyncEnabled) {
mVsyncEnabled = false;
mVSyncSource->setVSyncEnabled(false);
mDebugVsyncEnabled = false;
}
}
void EventThread::dump(String8& result) const {
std::lock_guard<std::mutex> lock(mMutex);
result.appendFormat("VSYNC state: %s\n", mDebugVsyncEnabled ? "enabled" : "disabled");
result.appendFormat(" soft-vsync: %s\n", mUseSoftwareVSync ? "enabled" : "disabled");
result.appendFormat(" numListeners=%zu,\n events-delivered: %u\n",
mDisplayEventConnections.size(),
mVSyncEvent[DisplayDevice::DISPLAY_PRIMARY].vsync.count);
for (size_t i = 0; i < mDisplayEventConnections.size(); i++) {
sp<Connection> connection = mDisplayEventConnections.itemAt(i).promote();
result.appendFormat(" %p: count=%d\n", connection.get(),
connection != nullptr ? connection->count : 0);
}
}
// ---------------------------------------------------------------------------
EventThread::Connection::Connection(EventThread* eventThread)
: count(-1), mEventThread(eventThread), mChannel(gui::BitTube::DefaultSize) {}
EventThread::Connection::~Connection() {
// do nothing here -- clean-up will happen automatically
// when the main thread wakes up
}
void EventThread::Connection::onFirstRef() {
// NOTE: mEventThread doesn't hold a strong reference on us
mEventThread->registerDisplayEventConnection(this);
}
status_t EventThread::Connection::stealReceiveChannel(gui::BitTube* outChannel) {
outChannel->setReceiveFd(mChannel.moveReceiveFd());
return NO_ERROR;
}
status_t EventThread::Connection::setVsyncRate(uint32_t count) {
mEventThread->setVsyncRate(count, this);
return NO_ERROR;
}
void EventThread::Connection::requestNextVsync() {
mEventThread->requestNextVsync(this);
}
status_t EventThread::Connection::postEvent(const DisplayEventReceiver::Event& event) {
ssize_t size = DisplayEventReceiver::sendEvents(&mChannel, &event, 1);
return size < 0 ? status_t(size) : status_t(NO_ERROR);
}
// ---------------------------------------------------------------------------
} // namespace impl
} // namespace android