5 files changed, 27 insertions, 43 deletions

diff --git a/core/jni/android/graphics/SurfaceTexture.cpp b/core/jni/android/graphics/SurfaceTexture.cpp
index dd8b378..2de0932 100644
--- a/core/jni/android/graphics/SurfaceTexture.cpp
+++ b/core/jni/android/graphics/SurfaceTexture.cpp
@@ -233,12 +233,6 @@ static jlong SurfaceTexture_getTimestamp(JNIEnv* env, jobject thiz)
     return surfaceTexture->getTimestamp();
 }
 
-static jint SurfaceTexture_getQueuedCount(JNIEnv* env, jobject thiz)
-{
-    sp<SurfaceTexture> surfaceTexture(SurfaceTexture_getSurfaceTexture(env, thiz));
-    return surfaceTexture->getQueuedCount();
-}
-
 // ----------------------------------------------------------------------------
 
 static JNINativeMethod gSurfaceTextureMethods[] = {
@@ -249,7 +243,6 @@ static JNINativeMethod gSurfaceTextureMethods[] = {
     {"nativeUpdateTexImage",     "()V",   (void*)SurfaceTexture_updateTexImage },
     {"nativeGetTransformMatrix", "([F)V", (void*)SurfaceTexture_getTransformMatrix },
     {"nativeGetTimestamp",       "()J",   (void*)SurfaceTexture_getTimestamp },
-    {"nativeGetQueuedCount",     "()I",   (void*)SurfaceTexture_getQueuedCount }
 };
 
 int register_android_graphics_SurfaceTexture(JNIEnv* env)
diff --git a/graphics/java/android/graphics/SurfaceTexture.java b/graphics/java/android/graphics/SurfaceTexture.java
index adb6eac..90a7ac2 100644
--- a/graphics/java/android/graphics/SurfaceTexture.java
+++ b/graphics/java/android/graphics/SurfaceTexture.java
@@ -144,10 +144,6 @@ public class SurfaceTexture {
      */
     public void updateTexImage() {
         nativeUpdateTexImage();
-        if (nativeGetQueuedCount() > 0) {
-            Message m = mEventHandler.obtainMessage();
-            mEventHandler.sendMessage(m);
-        }
     }
 
     /**
diff --git a/include/gui/SurfaceTexture.h b/include/gui/SurfaceTexture.h
index e558dfd..c82fb9b 100644
--- a/include/gui/SurfaceTexture.h
+++ b/include/gui/SurfaceTexture.h
@@ -46,11 +46,14 @@ public:
     enum { NUM_BUFFER_SLOTS = 32 };
 
     struct FrameAvailableListener : public virtual RefBase {
-        // onFrameAvailable() is called from queueBuffer() is the FIFO is
-        // empty. You can use SurfaceTexture::getQueuedCount() to
-        // figure out if there are more frames waiting.
-        // This is called without any lock held can be called concurrently by
-        // multiple threads.
+        // onFrameAvailable() is called from queueBuffer() each time an
+        // additional frame becomes available for consumption. This means that
+        // frames that are queued while in asynchronous mode only trigger the
+        // callback if no previous frames are pending. Frames queued while in
+        // synchronous mode always trigger the callback.
+        //
+        // This is called without any lock held and can be called concurrently
+        // by multiple threads.
         virtual void onFrameAvailable() = 0;
     };
 
@@ -101,11 +104,6 @@ public:
     // target texture belongs is bound to the calling thread.
     status_t updateTexImage();
 
-    // getqueuedCount returns the number of queued frames waiting in the
-    // FIFO. In asynchronous mode, this always returns 0 or 1 since
-    // frames are not accumulating in the FIFO.
-    size_t getQueuedCount() const;
-
     // setBufferCountServer set the buffer count. If the client has requested
     // a buffer count using setBufferCount, the server-buffer count will
     // take effect once the client sets the count back to zero.
diff --git a/libs/gui/SurfaceTexture.cpp b/libs/gui/SurfaceTexture.cpp
index 37e6d11..96ab284 100644
--- a/libs/gui/SurfaceTexture.cpp
+++ b/libs/gui/SurfaceTexture.cpp
@@ -417,17 +417,22 @@ status_t SurfaceTexture::queueBuffer(int buf, int64_t timestamp) {
             return -EINVAL;
         }
 
-        if (mQueue.empty()) {
-            listener = mFrameAvailableListener;
-        }
-
         if (mSynchronousMode) {
-            // in synchronous mode we queue all buffers in a FIFO
+            // In synchronous mode we queue all buffers in a FIFO.
             mQueue.push_back(buf);
+
+            // Synchronous mode always signals that an additional frame should
+            // be consumed.
+            listener = mFrameAvailableListener;
         } else {
-            // in asynchronous mode we only keep the most recent buffer
+            // In asynchronous mode we only keep the most recent buffer.
             if (mQueue.empty()) {
                 mQueue.push_back(buf);
+
+                // Asynchronous mode only signals that a frame should be
+                // consumed if no previous frame was pending. If a frame were
+                // pending then the consumer would have already been notified.
+                listener = mFrameAvailableListener;
             } else {
                 Fifo::iterator front(mQueue.begin());
                 // buffer currently queued is freed
@@ -561,11 +566,6 @@ status_t SurfaceTexture::updateTexImage() {
     return OK;
 }
 
-size_t SurfaceTexture::getQueuedCount() const {
-    Mutex::Autolock lock(mMutex);
-    return mQueue.size();
-}
-
 bool SurfaceTexture::isExternalFormat(uint32_t format)
 {
     switch (format) {
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 2bab6a8..35e29a6 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -101,9 +101,8 @@ Layer::~Layer()
 }
 
 void Layer::onFrameQueued() {
-    if (android_atomic_or(1, &mQueuedFrames) == 0) {
-        mFlinger->signalEvent();
-    }
+    android_atomic_inc(&mQueuedFrames);
+    mFlinger->signalEvent();
 }
 
 // called with SurfaceFlinger::mStateLock as soon as the layer is entered
@@ -406,20 +405,18 @@ bool Layer::isCropped() const {
 
 void Layer::lockPageFlip(bool& recomputeVisibleRegions)
 {
-    if (android_atomic_and(0, &mQueuedFrames)) {
+    if (mQueuedFrames > 0) {
+        // signal another event if we have more frames pending
+        if (android_atomic_dec(&mQueuedFrames) > 1) {
+            mFlinger->signalEvent();
+        }
+
         if (mSurfaceTexture->updateTexImage() < NO_ERROR) {
             // something happened!
             recomputeVisibleRegions = true;
             return;
         }
 
-        // signal another event if we have more frames waiting
-        if (mSurfaceTexture->getQueuedCount()) {
-            if (android_atomic_or(1, &mQueuedFrames) == 0) {
-                mFlinger->signalEvent();
-            }
-        }
-
         mActiveBuffer = mSurfaceTexture->getCurrentBuffer();
         mSurfaceTexture->getTransformMatrix(mTextureMatrix);