simplify further vsync handling
- we now clean-up "dead" connection in the main loop,
this entirely avoid the problem with the side effects of
releasing strong references. We now only hold on to strong
reference for the connection we will signal.
- also simplify how we build the list of "ready" connections, by
only adding them to the list when we did receive a vsync event
Change-Id: I2a84da431320a2af8e8a93e07622a1d258236f43
diff --git a/services/surfaceflinger/EventThread.cpp b/services/surfaceflinger/EventThread.cpp
index 59390c0..a39b7d8 100644
--- a/services/surfaceflinger/EventThread.cpp
+++ b/services/surfaceflinger/EventThread.cpp
@@ -60,14 +60,6 @@
return NO_ERROR;
}
-status_t EventThread::unregisterDisplayEventConnection(
- const wp<EventThread::Connection>& connection) {
- Mutex::Autolock _l(mLock);
- mDisplayEventConnections.remove(connection);
- mCondition.broadcast();
- return NO_ERROR;
-}
-
void EventThread::removeDisplayEventConnection(
const wp<EventThread::Connection>& connection) {
Mutex::Autolock _l(mLock);
@@ -122,97 +114,11 @@
}
bool EventThread::threadLoop() {
-
- nsecs_t timestamp;
- size_t vsyncCount;
DisplayEventReceiver::Event vsync;
- Vector< sp<EventThread::Connection> > activeConnections;
Vector< sp<EventThread::Connection> > signalConnections;
-
- do {
- // release our references
- signalConnections.clear();
- activeConnections.clear();
-
- Mutex::Autolock _l(mLock);
-
- // latch VSYNC event if any
- bool waitForVSync = false;
- vsyncCount = mVSyncCount;
- timestamp = mVSyncTimestamp;
- mVSyncTimestamp = 0;
-
- // find out connections waiting for VSYNC events
- size_t count = mDisplayEventConnections.size();
- for (size_t i=0 ; i<count ; i++) {
- sp<Connection> connection(mDisplayEventConnections[i].promote());
- if (connection != NULL) {
- activeConnections.add(connection);
- if (connection->count >= 0) {
- // we need vsync events because at least
- // one connection is waiting for it
- waitForVSync = true;
- if (connection->count == 0) {
- // fired this time around
- if (timestamp) {
- // only "consume" this event if we're going to
- // report it
- connection->count = -1;
- }
- signalConnections.add(connection);
- } else if (connection->count == 1 ||
- (vsyncCount % connection->count) == 0) {
- // continuous event, and time to report it
- signalConnections.add(connection);
- }
- }
- }
- }
-
- if (timestamp) {
- // we have a vsync event we can dispatch
- if (!waitForVSync) {
- // we received a VSYNC but we have no clients
- // don't report it, and disable VSYNC events
- disableVSyncLocked();
- } else {
- // report VSYNC event
- break;
- }
- } else {
- // never disable VSYNC events immediately, instead
- // we'll wait to receive the event and we'll
- // reevaluate whether we need to dispatch it and/or
- // disable VSYNC events then.
- if (waitForVSync) {
- // enable
- enableVSyncLocked();
- }
- }
-
- // wait for something to happen
- if (CC_UNLIKELY(mUseSoftwareVSync && waitForVSync)) {
- // h/w vsync cannot be used (screen is off), so we use
- // a timeout instead. it doesn't matter how imprecise this
- // is, we just need to make sure to serve the clients
- if (mCondition.waitRelative(mLock, ms2ns(16)) == TIMED_OUT) {
- mVSyncTimestamp = systemTime(SYSTEM_TIME_MONOTONIC);
- mVSyncCount++;
- }
- } else {
- if (!timestamp || signalConnections.isEmpty()) {
- // This is where we spend most of our time, waiting
- // for a vsync events and registered clients
- mCondition.wait(mLock);
- }
- }
- } while (!timestamp || signalConnections.isEmpty());
+ signalConnections = waitForEvent(&vsync);
// dispatch vsync events to listeners...
- vsync.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
- vsync.header.timestamp = timestamp;
- vsync.vsync.count = vsyncCount;
-
const size_t count = signalConnections.size();
for (size_t i=0 ; i<count ; i++) {
const sp<Connection>& conn(signalConnections[i]);
@@ -231,10 +137,94 @@
removeDisplayEventConnection(signalConnections[i]);
}
}
-
return true;
}
+Vector< sp<EventThread::Connection> > EventThread::waitForEvent(
+ DisplayEventReceiver::Event* event)
+{
+ Mutex::Autolock _l(mLock);
+
+ size_t vsyncCount;
+ nsecs_t timestamp;
+ Vector< sp<EventThread::Connection> > signalConnections;
+
+ do {
+ // latch VSYNC event if any
+ bool waitForVSync = false;
+ vsyncCount = mVSyncCount;
+ timestamp = mVSyncTimestamp;
+ mVSyncTimestamp = 0;
+
+ // find out connections waiting for events
+ size_t count = mDisplayEventConnections.size();
+ for (size_t i=0 ; i<count ; i++) {
+ sp<Connection> connection(mDisplayEventConnections[i].promote());
+ if (connection != NULL) {
+ 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);
+ } else if (connection->count == 1 ||
+ (vsyncCount % connection->count) == 0) {
+ // continuous event, and time to report it
+ signalConnections.add(connection);
+ }
+ }
+ }
+ } else {
+ // we couldn't promote this reference, the connection has
+ // died, so clean-up!
+ mDisplayEventConnections.removeAt(i);
+ --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) {
+ enableVSyncLocked();
+ }
+
+ // note: !timestamp implies signalConnections.isEmpty()
+ if (!timestamp) {
+ // wait for something to happen
+ if (CC_UNLIKELY(mUseSoftwareVSync && waitForVSync)) {
+ // h/w vsync cannot be used (screen is off), so we use
+ // a timeout instead. it doesn't matter how imprecise this
+ // is, we just need to make sure to serve the clients
+ if (mCondition.waitRelative(mLock, ms2ns(16)) == TIMED_OUT) {
+ mVSyncTimestamp = systemTime(SYSTEM_TIME_MONOTONIC);
+ mVSyncCount++;
+ }
+ } else {
+ // This is where we spend most of our time, waiting
+ // for a vsync events and registered clients
+ mCondition.wait(mLock);
+ }
+ }
+ } while (signalConnections.isEmpty());
+
+ // here we're guaranteed to have a timestamp and some connections to signal
+
+ // dispatch vsync events to listeners...
+ event->header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
+ event->header.timestamp = timestamp;
+ event->vsync.count = vsyncCount;
+
+ return signalConnections;
+}
+
void EventThread::enableVSyncLocked() {
if (!mUseSoftwareVSync) {
// never enable h/w VSYNC when screen is off
@@ -280,7 +270,8 @@
}
EventThread::Connection::~Connection() {
- mEventThread->unregisterDisplayEventConnection(this);
+ // do nothing here -- clean-up will happen automatically
+ // when the main thread wakes up
}
void EventThread::Connection::onFirstRef() {