RESTRICT AUTOMERGE BQ: retain buffer drop from BufferQueueProducer

Retain buffer drop from BufferQueueProducer::queueBuffer unless dequeue
timeout is set positive.

Bug: 122433957
Change-Id: I8432a7ad386836498e632c67953ad49c6be008bb
(cherry picked from commit fe8713cbb23b1a3f543ed18ce85ddfaecf513831)

4 files changed, 21 insertions, 5 deletions

diff --git a/libs/gui/BufferQueueCore.cpp b/libs/gui/BufferQueueCore.cpp
index bb703da3dd..7dddd8b2c4 100644
--- a/libs/gui/BufferQueueCore.cpp
+++ b/libs/gui/BufferQueueCore.cpp
@@ -73,6 +73,7 @@ BufferQueueCore::BufferQueueCore() :
     mActiveBuffers(),
     mDequeueCondition(),
     mDequeueBufferCannotBlock(false),
+    mQueueBufferCanDrop(false),
     mDefaultBufferFormat(PIXEL_FORMAT_RGBA_8888),
     mDefaultWidth(1),
     mDefaultHeight(1),
diff --git a/libs/gui/BufferQueueProducer.cpp b/libs/gui/BufferQueueProducer.cpp
index c96a2dd6a3..c01b2b6598 100644
--- a/libs/gui/BufferQueueProducer.cpp
+++ b/libs/gui/BufferQueueProducer.cpp
@@ -872,7 +872,7 @@ status_t BufferQueueProducer::queueBuffer(int slot,
         item.mFence = acquireFence;
         item.mFenceTime = acquireFenceTime;
         item.mIsDroppable = mCore->mAsyncMode ||
-                mCore->mDequeueBufferCannotBlock ||
+                mCore->mQueueBufferCanDrop ||
                 (mCore->mSharedBufferMode && mCore->mSharedBufferSlot == slot);
         item.mSurfaceDamage = surfaceDamage;
         item.mQueuedBuffer = true;
@@ -1213,9 +1213,10 @@ status_t BufferQueueProducer::connect(const sp<IProducerListener>& listener,
     mCore->mConnectedPid = IPCThreadState::self()->getCallingPid();
     mCore->mBufferHasBeenQueued = false;
     mCore->mDequeueBufferCannotBlock = false;
-    if (mDequeueTimeout < 0) {
-        mCore->mDequeueBufferCannotBlock =
-                mCore->mConsumerControlledByApp && producerControlledByApp;
+    mCore->mQueueBufferCanDrop = false;
+    if (mCore->mConsumerControlledByApp && producerControlledByApp) {
+        mCore->mDequeueBufferCannotBlock = mDequeueTimeout < 0;
+        mCore->mQueueBufferCanDrop = mDequeueTimeout <= 0;
     }
 
     mCore->mAllowAllocation = true;
@@ -1486,7 +1487,12 @@ status_t BufferQueueProducer::setDequeueTimeout(nsecs_t timeout) {
     }
 
     mDequeueTimeout = timeout;
-    mCore->mDequeueBufferCannotBlock = false;
+    if (timeout >= 0) {
+        mCore->mDequeueBufferCannotBlock = false;
+        if (timeout != 0) {
+            mCore->mQueueBufferCanDrop = false;
+        }
+    }
 
     VALIDATE_CONSISTENCY();
     return NO_ERROR;
diff --git a/libs/gui/include/gui/BufferQueueCore.h b/libs/gui/include/gui/BufferQueueCore.h
index 537c957746..f91babca11 100644
--- a/libs/gui/include/gui/BufferQueueCore.h
+++ b/libs/gui/include/gui/BufferQueueCore.h
@@ -225,6 +225,11 @@ private:
     // consumer are controlled by the application.
     bool mDequeueBufferCannotBlock;
 
+    // mQueueBufferCanDrop indicates whether queueBuffer is allowd to drop
+    // buffers in non-async mode. This flag is set during connect when both the
+    // producer and consumer are controlled by application.
+    bool mQueueBufferCanDrop;
+
     // mDefaultBufferFormat can be set so it will override the buffer format
     // when it isn't specified in dequeueBuffer.
     PixelFormat mDefaultBufferFormat;
diff --git a/libs/gui/include/gui/IGraphicBufferProducer.h b/libs/gui/include/gui/IGraphicBufferProducer.h
index 887654e05b..2f8a154faa 100644
--- a/libs/gui/include/gui/IGraphicBufferProducer.h
+++ b/libs/gui/include/gui/IGraphicBufferProducer.h
@@ -584,6 +584,10 @@ public:
     // non-blocking mode and its corresponding spare buffer (which is used to
     // ensure a buffer is always available).
     //
+    // N.B. queueBuffer will stop buffer dropping behavior if timeout is
+    // strictly positive. If timeout is zero or negative, previous buffer
+    // dropping behavior will not be changed.
+    //
     // Return of a value other than NO_ERROR means an error has occurred:
     // * BAD_VALUE - Failure to adjust the number of available slots. This can
     //               happen because of trying to allocate/deallocate the async