Fix an issue with VSYNC
one-shot VSYNC listeners could miss a VSYNC event if
scheduled while in waitForVsync().
Change-Id: I720485784aecfea6cc7a23c77081d7af3c9c71db
diff --git a/services/surfaceflinger/EventThread.cpp b/services/surfaceflinger/EventThread.cpp
index 9245781..035836e 100644
--- a/services/surfaceflinger/EventThread.cpp
+++ b/services/surfaceflinger/EventThread.cpp
@@ -107,27 +107,17 @@
{ // scope for the lock
Mutex::Autolock _l(mLock);
do {
- // wait for listeners
+ // see if we need to wait for the VSYNC at all
do {
bool waitForNextVsync = false;
size_t count = mDisplayEventConnections.size();
for (size_t i=0 ; i<count ; i++) {
const ConnectionInfo& info(
mDisplayEventConnections.valueAt(i));
- if (info.count >= 1) {
- // continuous mode
+ if (info.count >= 0) {
+ // at least one continuous mode or active one-shot event
waitForNextVsync = true;
- } else {
- // one-shot event
- if (info.count >= -1) {
- ConnectionInfo& info(
- mDisplayEventConnections.editValueAt(i));
- info.count--;
- if (info.count == -1) {
- // fired this time around
- waitForNextVsync = true;
- }
- }
+ break;
}
}
@@ -137,14 +127,38 @@
mCondition.wait(mLock);
} while(true);
- // wait for vsync
+ // at least one listener requested VSYNC
mLock.unlock();
timestamp = mHw.waitForVSync();
mLock.lock();
mDeliveredEvents++;
- // make sure we still have some listeners
- } while (!mDisplayEventConnections.size());
+ // now see if we still need to report this VSYNC event
+ bool reportVsync = false;
+ size_t count = mDisplayEventConnections.size();
+ for (size_t i=0 ; i<count ; i++) {
+ const ConnectionInfo& info(
+ mDisplayEventConnections.valueAt(i));
+ if (info.count >= 1) {
+ if (info.count==1 || (mDeliveredEvents % info.count) == 0) {
+ // continuous event, and time to report it
+ reportVsync = true;
+ }
+ } else if (info.count >= -1) {
+ ConnectionInfo& info(
+ mDisplayEventConnections.editValueAt(i));
+ if (info.count == 0) {
+ // fired this time around
+ reportVsync = true;
+ }
+ info.count--;
+ }
+ }
+
+ if (reportVsync) {
+ break;
+ }
+ } while (true);
// dispatch vsync events to listeners...
vsync.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
@@ -161,27 +175,6 @@
sp<DisplayEventConnection> conn(displayEventConnections.keyAt(i).promote());
// make sure the connection didn't die
if (conn != NULL) {
-
- const ConnectionInfo& info(
- displayEventConnections.valueAt(i));
-
- if ((info.count > 1) && (mDeliveredEvents % info.count)) {
- // continuous event, but not time to send this event yet
- continue;
- } else if (info.count < -1) {
- // disabled event
- continue;
- } else if (info.count == 0) {
- // impossible by construction. but we prefer to be safe.
- continue;
- }
-
- // here, either:
- // count = -1 : one-shot scheduled this time around
- // count = 1 : continuous not rate-limited
- // count > 1 : continuous, rate-limited
- // Note: count == 0 is not possible by construction
-
status_t err = conn->postEvent(vsync);
if (err == -EAGAIN || err == -EWOULDBLOCK) {
// The destination doesn't accept events anymore, it's probably