From bd589e324898ed77dff9cd3516d88ce4aca68352 Mon Sep 17 00:00:00 2001 From: Mathias Agopian Date: Mon, 20 Aug 2012 20:07:34 -0700 Subject: [PATCH] fix various issues in SF's EventThread - one issues caused most timestamps to be reported as 0 - on rare occasions an uninitialized variable could be used - vsync counts per connection were accessed unthreadsafely we now have 2 lists of connections in the main loop, one just keeps a list of strong refs to the connections because once we have a strong ref we're not allowed to release it while holding the lock. the 2nd list holds the connections that have a vsync event to be reported. all the calculations are made with the lock held. Change-Id: Iacfad3745b05df79d9ece3719bd4c34ddbfd5b83 --- services/surfaceflinger/EventThread.cpp | 101 ++++++++++++------------ services/surfaceflinger/EventThread.h | 1 - 2 files changed, 51 insertions(+), 51 deletions(-) diff --git a/services/surfaceflinger/EventThread.cpp b/services/surfaceflinger/EventThread.cpp index 3833f4839..59390c0ce 100644 --- a/services/surfaceflinger/EventThread.cpp +++ b/services/surfaceflinger/EventThread.cpp @@ -19,6 +19,8 @@ #include #include +#include + #include #include #include @@ -123,35 +125,53 @@ bool EventThread::threadLoop() { nsecs_t timestamp; size_t vsyncCount; - size_t activeEvents; DisplayEventReceiver::Event vsync; Vector< sp > activeConnections; + Vector< sp > 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; - // check if we should be waiting for VSYNC events - activeEvents = 0; - bool waitForNextVsync = false; + // find out connections waiting for VSYNC events size_t count = mDisplayEventConnections.size(); for (size_t i=0 ; i connection(mDisplayEventConnections[i].promote()); if (connection != NULL) { activeConnections.add(connection); if (connection->count >= 0) { - // at least one continuous mode or active one-shot event - waitForNextVsync = true; - activeEvents++; - break; + // 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) { - if (!waitForNextVsync) { + // 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(); @@ -164,14 +184,14 @@ bool EventThread::threadLoop() { // we'll wait to receive the event and we'll // reevaluate whether we need to dispatch it and/or // disable VSYNC events then. - if (waitForNextVsync) { + if (waitForVSync) { // enable enableVSyncLocked(); } } // wait for something to happen - if (mUseSoftwareVSync && waitForNextVsync) { + 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 @@ -180,54 +200,35 @@ bool EventThread::threadLoop() { mVSyncCount++; } } else { - mCondition.wait(mLock); + if (!timestamp || signalConnections.isEmpty()) { + // This is where we spend most of our time, waiting + // for a vsync events and registered clients + mCondition.wait(mLock); + } } - vsyncCount = mVSyncCount; - } while (!activeConnections.size()); - - if (!activeEvents) { - // no events to return. start over. - // (here we make sure to exit the scope of this function - // so that we release our Connection references) - return true; - } + } while (!timestamp || signalConnections.isEmpty()); // dispatch vsync events to listeners... vsync.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC; vsync.header.timestamp = timestamp; vsync.vsync.count = vsyncCount; - const size_t count = activeConnections.size(); + const size_t count = signalConnections.size(); for (size_t i=0 ; i& conn(activeConnections[i]); + const sp& conn(signalConnections[i]); // now see if we still need to report this VSYNC event - const int32_t vcount = conn->count; - if (vcount >= 0) { - bool reportVsync = false; - if (vcount == 0) { - // fired this time around - conn->count = -1; - reportVsync = true; - } else if (vcount == 1 || (vsyncCount % vcount) == 0) { - // continuous event, and time to report it - reportVsync = true; - } - - if (reportVsync) { - status_t err = conn->postEvent(vsync); - 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. - // 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, but it doesn't matter for VSYNC. - } 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. - removeDisplayEventConnection(activeConnections[i]); - } - } + status_t err = conn->postEvent(vsync); + 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. + // 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, but it doesn't matter for VSYNC. + } 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. + removeDisplayEventConnection(signalConnections[i]); } } diff --git a/services/surfaceflinger/EventThread.h b/services/surfaceflinger/EventThread.h index d23b9fad9..aa0ea7f3c 100644 --- a/services/surfaceflinger/EventThread.h +++ b/services/surfaceflinger/EventThread.h @@ -47,7 +47,6 @@ class EventThread : public Thread { // count >= 1 : continuous event. count is the vsync rate // count == 0 : one-shot event that has not fired // count ==-1 : one-shot event that fired this round / disabled - // count ==-2 : one-shot event that fired the round before int32_t count; private: