fix an issue with vsync event delivery

vsync events were sometimes delivered to connected
client who didn't request them. this happened if
another client requested the delivery and that client
was first in the client list.

also fix the vsync test which didn't request any events as
well as DisplayEventReveiver documentation which was misleading
about the necessity to request vsync events.

Change-Id: Ie990fda3f337f8f0042745c4b2cde67936c45686

2 files changed, 5 insertions, 7 deletions

diff --git a/services/surfaceflinger/EventThread.cpp b/services/surfaceflinger/EventThread.cpp
index 92d4266..af0da0b 100644
--- a/services/surfaceflinger/EventThread.cpp
+++ b/services/surfaceflinger/EventThread.cpp
@@ -151,9 +151,9 @@ bool EventThread::threadLoop() {
             mLastVSyncTimestamp = timestamp;
 
             // now see if we still need to report this VSYNC event
-            bool reportVsync = false;
-            size_t count = mDisplayEventConnections.size();
+            const size_t count = mDisplayEventConnections.size();
             for (size_t i=0 ; i<count ; i++) {
+                bool reportVsync = false;
                 const ConnectionInfo& info(
                         mDisplayEventConnections.valueAt(i));
                 if (info.count >= 1) {
@@ -174,11 +174,7 @@ bool EventThread::threadLoop() {
                     displayEventConnections.add(mDisplayEventConnections.keyAt(i));
                 }
             }
-
-            if (reportVsync) {
-                break;
-            }
-        } while (true);
+        } while (!displayEventConnections.size());
 
         // dispatch vsync events to listeners...
         vsync.header.type = DisplayEventReceiver::DISPLAY_EVENT_VSYNC;
diff --git a/services/surfaceflinger/tests/vsync/vsync.cpp b/services/surfaceflinger/tests/vsync/vsync.cpp
index 4f79080..b0d54c4 100644
--- a/services/surfaceflinger/tests/vsync/vsync.cpp
+++ b/services/surfaceflinger/tests/vsync/vsync.cpp
@@ -55,6 +55,8 @@ int main(int argc, char** argv)
     loop->addFd(myDisplayEvent.getFd(), 0, ALOOPER_EVENT_INPUT, receiver,
             &myDisplayEvent);
 
+    myDisplayEvent.setVsyncRate(1);
+
     do {
         //printf("about to poll...\n");
         int32_t ret = loop->pollOnce(-1);