Merge "Call applyPendingTransactions when frame didn't draw"

core/java/android/view/ViewRootImpl.java

@@ -4031,6 +4031,10 @@ public final class ViewRootImpl implements ViewParent,
                 mBlastBufferQueue.setNextTransaction(null);
                 mBlastBufferQueue.setTransactionCompleteCallback(mRtLastAttemptedDrawFrameNum,
                         null);
+                // Apply the transactions that were sent to mergeWithNextTransaction since the
+                // frame didn't draw on this vsync. It's possible the frame will draw later, but
+                // it's better to not be sync than to block on a frame that may never come.
+                mBlastBufferQueue.applyPendingTransactions(mRtLastAttemptedDrawFrameNum);
             }
 
             mHandler.postAtFrontOfQueue(() -> {

core/jni/android_graphics_BLASTBufferQueue.cpp

@@ -139,6 +139,11 @@ static jlong nativeGetLastAcquiredFrameNum(JNIEnv* env, jclass clazz, jlong ptr)
     return queue->getLastAcquiredFrameNum();
 }
 
+static void nativeApplyPendingTransactions(JNIEnv* env, jclass clazz, jlong ptr, jlong frameNum) {
+    sp<BLASTBufferQueue> queue = reinterpret_cast<BLASTBufferQueue*>(ptr);
+    queue->applyPendingTransactions(frameNum);
+}
+
 static const JNINativeMethod gMethods[] = {
         /* name, signature, funcPtr */
         // clang-format off
@@ -152,6 +157,7 @@ static const JNINativeMethod gMethods[] = {
                 "(JJLandroid/graphics/BLASTBufferQueue$TransactionCompleteCallback;)V",
                 (void*)nativeSetTransactionCompleteCallback},
         {"nativeGetLastAcquiredFrameNum", "(J)J", (void*)nativeGetLastAcquiredFrameNum},
+        {"nativeApplyPendingTransactions", "(JJ)V", (void*)nativeApplyPendingTransactions},
         // clang-format on
 };
 

graphics/java/android/graphics/BLASTBufferQueue.java

@@ -39,6 +39,7 @@ public final class BLASTBufferQueue {
     private static native void nativeSetTransactionCompleteCallback(long ptr, long frameNumber,
             TransactionCompleteCallback callback);
     private static native long nativeGetLastAcquiredFrameNum(long ptr);
+    private static native void nativeApplyPendingTransactions(long ptr, long frameNumber);
 
     /**
      * Callback sent to {@link #setTransactionCompleteCallback(long, TransactionCompleteCallback)}
@@ -141,6 +142,17 @@ public final class BLASTBufferQueue {
         nativeMergeWithNextTransaction(mNativeObject, nativeTransaction, frameNumber);
     }
 
+    /**
+     * Apply any transactions that were passed to {@link #mergeWithNextTransaction} with the
+     * specified frameNumber. This is intended to ensure transactions don't get stuck as pending
+     * if the specified frameNumber is never drawn.
+     *
+     * @param frameNumber The frameNumber used to determine which transactions to apply.
+     */
+    public void applyPendingTransactions(long frameNumber) {
+        nativeApplyPendingTransactions(mNativeObject, frameNumber);
+    }
+
     public long getLastAcquiredFrameNum() {
         return nativeGetLastAcquiredFrameNum(mNativeObject);
     }