commit 65b8e8729104d4f7a379d72cdff06036b569dd9b
author Valerie Hau <vhau@google.com> Thu Feb 13 09:45:14 2020 -0800
committer Valerie Hau <vhau@google.com> Thu Feb 13 13:46:28 2020 -0800
tree 205d278308870205147536daa966dde9f915f87e
parent edd6bc95bbc71b94bd1d760c0ce8054cb521835f

Move maxAcquired back to 1 and set maxDequeued

BufferQueue internally already limits number of acquired buffers to be 1
more than the maxAcquired set.  We want to be able to acquire 2, so
setting back to 1.  Enable triple buffering through maxDequeuedCount.

Bug: 146345307
Test: build, boot, turn BLAST ON, run manually, libgui_test
Change-Id: I1deff382da3b37a2bde840802fdc4c10a8b868ed

libs/gui/BLASTBufferQueue.cpp

diff --git a/libs/gui/BLASTBufferQueue.cpp b/libs/gui/BLASTBufferQueue.cpp
index e2f5d31..4bbc855 100644
--- a/libs/gui/BLASTBufferQueue.cpp
+++ b/libs/gui/BLASTBufferQueue.cpp
@@ -19,6 +19,8 @@
 
 #define ATRACE_TAG ATRACE_TAG_GRAPHICS
 
+#include <cutils/properties.h>
+
 #include <gui/BLASTBufferQueue.h>
 #include <gui/BufferItemConsumer.h>
 #include <gui/GLConsumer.h>
@@ -99,7 +101,11 @@
         mHeight(height),
         mNextTransaction(nullptr) {
     BufferQueue::createBufferQueue(&mProducer, &mConsumer);
-    mConsumer->setMaxAcquiredBufferCount(MAX_ACQUIRED_BUFFERS);
+
+    int8_t disableTripleBuffer = property_get_bool("ro.sf.disable_triple_buffer", 0);
+    if (!disableTripleBuffer) {
+        mProducer->setMaxDequeuedBufferCount(2);
+    }
     mBufferItemConsumer =
             new BLASTBufferItemConsumer(mConsumer, AHARDWAREBUFFER_USAGE_GPU_FRAMEBUFFER, 1, true);
     static int32_t id = 0;
@@ -181,7 +187,7 @@
 
 void BLASTBufferQueue::processNextBufferLocked() {
     ATRACE_CALL();
-    if (mNumFrameAvailable == 0 || mNumAcquired == MAX_ACQUIRED_BUFFERS) {
+    if (mNumFrameAvailable == 0 || mNumAcquired == MAX_ACQUIRED_BUFFERS + 1) {
         return;
     }
 

libs/gui/include/gui/BLASTBufferQueue.h

diff --git a/libs/gui/include/gui/BLASTBufferQueue.h b/libs/gui/include/gui/BLASTBufferQueue.h
index d72eb5a..1b22df2 100644
--- a/libs/gui/include/gui/BLASTBufferQueue.h
+++ b/libs/gui/include/gui/BLASTBufferQueue.h
@@ -98,7 +98,9 @@
     std::mutex mMutex;
     std::condition_variable mCallbackCV;
 
-    static const int MAX_ACQUIRED_BUFFERS = 2;
+    // BufferQueue internally allows 1 more than
+    // the max to be acquired
+    static const int MAX_ACQUIRED_BUFFERS = 1;
 
     int32_t mNumFrameAvailable GUARDED_BY(mMutex);
     int32_t mNumAcquired GUARDED_BY(mMutex);