commit f1c675b33faeadc57f5d57a18d5e07bc644b0bad
author Lloyd Pique <lpique@google.com> Wed Sep 12 20:45:39 2018 -0700
committer Lloyd Pique <lpique@google.com> Fri Sep 21 17:56:10 2018 -0700
tree 34647152d45573d9e6aa4aec13a35096acb5dd25
parent ea0a5fb7c8dbeac40b2c4b22c4da86b234747eba

SF: Cleanups to use std::atomic/std::mutex

A few places in the code used "volatile". This patch removes the
volatile.

In most of the cases, the volatile value was converted to a std::atomic
value. The exception was Barrier where it was not actually necessary,
but there I converted the code to use std::mutex.

Bug: None
Test: atest SurfaceFlinger_test CtsViewTestCases
Change-Id: I7b4f5a7398a241db8201dc7f60d7c9cd41e32e1b

services/surfaceflinger/BufferQueueLayer.cpp

diff --git a/services/surfaceflinger/BufferQueueLayer.cpp b/services/surfaceflinger/BufferQueueLayer.cpp
index 4839bfb..521cdbf 100644
--- a/services/surfaceflinger/BufferQueueLayer.cpp
+++ b/services/surfaceflinger/BufferQueueLayer.cpp
@@ -207,8 +207,9 @@
 }
 
 std::optional<Region> BufferQueueLayer::latchSidebandStream(bool& recomputeVisibleRegions) {
-    if (android_atomic_acquire_cas(true, false, &mSidebandStreamChanged) == 0) {
-        // mSidebandStreamChanged was true
+    bool sidebandStreamChanged = true;
+    if (mSidebandStreamChanged.compare_exchange_strong(sidebandStreamChanged, false)) {
+        // mSidebandStreamChanged was changed to false
         // replicated in LayerBE until FE/BE is ready to be synchronized
         getBE().compositionInfo.hwc.sidebandStream = mConsumer->getSidebandStream();
         if (getBE().compositionInfo.hwc.sidebandStream != nullptr) {
@@ -259,7 +260,7 @@
             Mutex::Autolock lock(mQueueItemLock);
             mTimeStats.removeTimeRecord(getName().c_str(), mQueueItems[0].mFrameNumber);
             mQueueItems.removeAt(0);
-            android_atomic_dec(&mQueuedFrames);
+            mQueuedFrames--;
         }
         return BAD_VALUE;
     } else if (updateResult != NO_ERROR || mUpdateTexImageFailed) {
@@ -270,7 +271,7 @@
         if (queuedBuffer) {
             Mutex::Autolock lock(mQueueItemLock);
             mQueueItems.clear();
-            android_atomic_and(0, &mQueuedFrames);
+            mQueuedFrames = 0;
             mTimeStats.clearLayerRecord(getName().c_str());
         }
 
@@ -294,7 +295,7 @@
         while (mQueueItems[0].mFrameNumber != currentFrameNumber) {
             mTimeStats.removeTimeRecord(getName().c_str(), mQueueItems[0].mFrameNumber);
             mQueueItems.removeAt(0);
-            android_atomic_dec(&mQueuedFrames);
+            mQueuedFrames--;
         }
 
         const std::string layerName(getName().c_str());
@@ -306,7 +307,7 @@
 
     // Decrement the queued-frames count.  Signal another event if we
     // have more frames pending.
-    if ((queuedBuffer && android_atomic_dec(&mQueuedFrames) > 1) || mAutoRefresh) {
+    if ((queuedBuffer && mQueuedFrames.fetch_sub(1) > 1) || mAutoRefresh) {
         mFlinger->signalLayerUpdate();
     }
 
@@ -367,7 +368,7 @@
         }
 
         mQueueItems.push_back(item);
-        android_atomic_inc(&mQueuedFrames);
+        mQueuedFrames++;
 
         // Wake up any pending callbacks
         mLastFrameNumberReceived = item.mFrameNumber;
@@ -404,8 +405,9 @@
 }
 
 void BufferQueueLayer::onSidebandStreamChanged() {
-    if (android_atomic_release_cas(false, true, &mSidebandStreamChanged) == 0) {
-        // mSidebandStreamChanged was false
+    bool sidebandStreamChanged = false;
+    if (mSidebandStreamChanged.compare_exchange_strong(sidebandStreamChanged, true)) {
+        // mSidebandStreamChanged was changed to true
         mFlinger->signalLayerUpdate();
     }
 }