Introduce release buffer callback for BufferStateLayer

Currently BLAST clients use the TransactionCompleted callbacks to
determine when to release buffers. The TransactionCompleted callback
is overloaded. For transactions without buffers, the callback is
called when the transaction is applied on the server. If the
Transaction contains one or more buffers, the callback is called when
all the buffers are latched and ready to be presented. If we have
multiple buffers on multiple transactions, where one or more buffers
maybe dropped, the pending callbacks are called together. This may
delay signaling the client when a buffer can be released.

To fix this, we introduce a new buffer release callback that is
called as soon as a buffer is dropped by the server or when a new
buffer has been latched and the buffer will no longer be presented.
This new callback provides a graphic bufferid to identify the buffer
that can be released and a release fence to wait on.

BlastBufferQueue has been switched to use this new callback. Other
BLAST users continue to use the existing callback.

Test: go/wm-smoke
Test: atest ReleaseBufferCallbackTest
Bug: 178385281

Change-Id: Idd88e4994e543443198a5a8cfa0e3f5f67d5d482

1 files changed, 60 insertions, 47 deletions

diff --git a/libs/gui/BLASTBufferQueue.cpp b/libs/gui/BLASTBufferQueue.cpp
index 82c9268feb..f778232803 100644
--- a/libs/gui/BLASTBufferQueue.cpp
+++ b/libs/gui/BLASTBufferQueue.cpp
@@ -169,8 +169,6 @@ BLASTBufferQueue::BLASTBufferQueue(const std::string& name, const sp<SurfaceCont
 
     mNumAcquired = 0;
     mNumFrameAvailable = 0;
-    mPendingReleaseItem.item = BufferItem();
-    mPendingReleaseItem.releaseFence = nullptr;
 }
 
 BLASTBufferQueue::~BLASTBufferQueue() {
@@ -242,7 +240,6 @@ void BLASTBufferQueue::transactionCallback(nsecs_t /*latchTime*/, const sp<Fence
         std::unique_lock _lock{mMutex};
         ATRACE_CALL();
         BQA_LOGV("transactionCallback");
-        mInitialCallbackReceived = true;
 
         if (!stats.empty()) {
             mTransformHint = stats[0].transformHint;
@@ -255,38 +252,20 @@ void BLASTBufferQueue::transactionCallback(nsecs_t /*latchTime*/, const sp<Fence
                                             stats[0].frameEventStats.compositorTiming,
                                             stats[0].latchTime,
                                             stats[0].frameEventStats.dequeueReadyTime);
-        }
-        if (mPendingReleaseItem.item.mGraphicBuffer != nullptr) {
-            if (!stats.empty()) {
-                mPendingReleaseItem.releaseFence = stats[0].previousReleaseFence;
-            } else {
-                BQA_LOGE("Warning: no SurfaceControlStats returned in BLASTBufferQueue callback");
-                mPendingReleaseItem.releaseFence = nullptr;
+            currFrameNumber = stats[0].frameEventStats.frameNumber;
+
+            if (mTransactionCompleteCallback &&
+                currFrameNumber >= mTransactionCompleteFrameNumber) {
+                if (currFrameNumber > mTransactionCompleteFrameNumber) {
+                    BQA_LOGE("transactionCallback received for a newer framenumber=%" PRIu64
+                             " than expected=%" PRIu64,
+                             currFrameNumber, mTransactionCompleteFrameNumber);
+                }
+                transactionCompleteCallback = std::move(mTransactionCompleteCallback);
+                mTransactionCompleteFrameNumber = 0;
             }
-            mBufferItemConsumer->releaseBuffer(mPendingReleaseItem.item,
-                                               mPendingReleaseItem.releaseFence
-                                                       ? mPendingReleaseItem.releaseFence
-                                                       : Fence::NO_FENCE);
-            mNumAcquired--;
-            mPendingReleaseItem.item = BufferItem();
-            mPendingReleaseItem.releaseFence = nullptr;
-        }
-
-        if (mSubmitted.empty()) {
-            BQA_LOGE("ERROR: callback with no corresponding submitted buffer item");
         }
-        mPendingReleaseItem.item = std::move(mSubmitted.front());
-        mSubmitted.pop();
-
-        processNextBufferLocked(false /* useNextTransaction */);
 
-        currFrameNumber = mPendingReleaseItem.item.mFrameNumber;
-        if (mTransactionCompleteCallback && mTransactionCompleteFrameNumber == currFrameNumber) {
-            transactionCompleteCallback = std::move(mTransactionCompleteCallback);
-            mTransactionCompleteFrameNumber = 0;
-        }
-
-        mCallbackCV.notify_all();
         decStrong((void*)transactionCallbackThunk);
     }
 
@@ -295,15 +274,46 @@ void BLASTBufferQueue::transactionCallback(nsecs_t /*latchTime*/, const sp<Fence
     }
 }
 
-void BLASTBufferQueue::processNextBufferLocked(bool useNextTransaction) {
+// Unlike transactionCallbackThunk the release buffer callback does not extend the life of the
+// BBQ. This is because if the BBQ is destroyed, then the buffers will be released by the client.
+// So we pass in a weak pointer to the BBQ and if it still alive, then we release the buffer.
+// Otherwise, this is a no-op.
+static void releaseBufferCallbackThunk(wp<BLASTBufferQueue> context, uint64_t graphicBufferId,
+                                       const sp<Fence>& releaseFence) {
+    sp<BLASTBufferQueue> blastBufferQueue = context.promote();
+    ALOGV("releaseBufferCallbackThunk graphicBufferId=%" PRIu64 " blastBufferQueue=%s",
+          graphicBufferId, blastBufferQueue ? "alive" : "dead");
+    if (blastBufferQueue) {
+        blastBufferQueue->releaseBufferCallback(graphicBufferId, releaseFence);
+    }
+}
+
+void BLASTBufferQueue::releaseBufferCallback(uint64_t graphicBufferId,
+                                             const sp<Fence>& releaseFence) {
     ATRACE_CALL();
-    BQA_LOGV("processNextBufferLocked useNextTransaction=%s", toString(useNextTransaction));
+    std::unique_lock _lock{mMutex};
+    BQA_LOGV("releaseBufferCallback graphicBufferId=%" PRIu64, graphicBufferId);
+
+    auto it = mSubmitted.find(graphicBufferId);
+    if (it == mSubmitted.end()) {
+        BQA_LOGE("ERROR: releaseBufferCallback without corresponding submitted buffer %" PRIu64,
+                 graphicBufferId);
+        return;
+    }
 
+    mBufferItemConsumer->releaseBuffer(it->second, releaseFence);
+    mSubmitted.erase(it);
+    mNumAcquired--;
+    processNextBufferLocked(false /* useNextTransaction */);
+    mCallbackCV.notify_all();
+}
+
+void BLASTBufferQueue::processNextBufferLocked(bool useNextTransaction) {
+    ATRACE_CALL();
     // If the next transaction is set, we want to guarantee the our acquire will not fail, so don't
     // include the extra buffer when checking if we can acquire the next buffer.
     const bool includeExtraAcquire = !useNextTransaction;
     if (mNumFrameAvailable == 0 || maxBuffersAcquired(includeExtraAcquire)) {
-        BQA_LOGV("processNextBufferLocked waiting for frame available or callback");
         mCallbackCV.notify_all();
         return;
     }
@@ -353,7 +363,7 @@ void BLASTBufferQueue::processNextBufferLocked(bool useNextTransaction) {
     }
 
     mNumAcquired++;
-    mSubmitted.push(bufferItem);
+    mSubmitted[buffer->getId()] = bufferItem;
 
     bool needsDisconnect = false;
     mBufferItemConsumer->getConnectionEvents(bufferItem.mFrameNumber, &needsDisconnect);
@@ -369,7 +379,10 @@ void BLASTBufferQueue::processNextBufferLocked(bool useNextTransaction) {
     mLastBufferScalingMode = bufferItem.mScalingMode;
     mLastAcquiredFrameNumber = bufferItem.mFrameNumber;
 
-    t->setBuffer(mSurfaceControl, buffer);
+    auto releaseBufferCallback =
+            std::bind(releaseBufferCallbackThunk, wp<BLASTBufferQueue>(this) /* callbackContext */,
+                      std::placeholders::_1, std::placeholders::_2);
+    t->setBuffer(mSurfaceControl, buffer, releaseBufferCallback);
     t->setDataspace(mSurfaceControl, static_cast<ui::Dataspace>(bufferItem.mDataSpace));
     t->setHdrMetadata(mSurfaceControl, bufferItem.mHdrMetadata);
     t->setSurfaceDamageRegion(mSurfaceControl, bufferItem.mSurfaceDamage);
@@ -427,9 +440,12 @@ void BLASTBufferQueue::processNextBufferLocked(bool useNextTransaction) {
     }
 
     BQA_LOGV("processNextBufferLocked size=%dx%d mFrameNumber=%" PRIu64
-             " applyTransaction=%s mTimestamp=%" PRId64 " mPendingTransactions.size=%d",
+             " applyTransaction=%s mTimestamp=%" PRId64 "%s mPendingTransactions.size=%d"
+             " graphicBufferId=%" PRIu64,
              mSize.width, mSize.height, bufferItem.mFrameNumber, toString(applyTransaction),
-             bufferItem.mTimestamp, static_cast<uint32_t>(mPendingTransactions.size()));
+             bufferItem.mTimestamp, bufferItem.mIsAutoTimestamp ? "(auto)" : "",
+             static_cast<uint32_t>(mPendingTransactions.size()),
+             bufferItem.mGraphicBuffer->getId());
 }
 
 Rect BLASTBufferQueue::computeCrop(const BufferItem& item) {
@@ -444,18 +460,17 @@ void BLASTBufferQueue::onFrameAvailable(const BufferItem& item) {
     std::unique_lock _lock{mMutex};
 
     const bool nextTransactionSet = mNextTransaction != nullptr;
-    BQA_LOGV("onFrameAvailable framenumber=%" PRIu64 " nextTransactionSet=%s mFlushShadowQueue=%s",
-             item.mFrameNumber, toString(nextTransactionSet), toString(mFlushShadowQueue));
-
-    if (nextTransactionSet || mFlushShadowQueue) {
+    if (nextTransactionSet) {
         while (mNumFrameAvailable > 0 || maxBuffersAcquired(false /* includeExtraAcquire */)) {
             BQA_LOGV("waiting in onFrameAvailable...");
             mCallbackCV.wait(_lock);
         }
     }
-    mFlushShadowQueue = false;
     // add to shadow queue
     mNumFrameAvailable++;
+
+    BQA_LOGV("onFrameAvailable framenumber=%" PRIu64 " nextTransactionSet=%s", item.mFrameNumber,
+             toString(nextTransactionSet));
     processNextBufferLocked(nextTransactionSet /* useNextTransaction */);
 }
 
@@ -514,14 +529,12 @@ void BLASTBufferQueue::setTransactionCompleteCallback(
 }
 
 // Check if we have acquired the maximum number of buffers.
-// As a special case, we wait for the first callback before acquiring the second buffer so we
-// can ensure the first buffer is presented if multiple buffers are queued in succession.
 // Consumer can acquire an additional buffer if that buffer is not droppable. Set
 // includeExtraAcquire is true to include this buffer to the count. Since this depends on the state
 // of the buffer, the next acquire may return with NO_BUFFER_AVAILABLE.
 bool BLASTBufferQueue::maxBuffersAcquired(bool includeExtraAcquire) const {
     int maxAcquiredBuffers = MAX_ACQUIRED_BUFFERS + (includeExtraAcquire ? 2 : 1);
-    return mNumAcquired == maxAcquiredBuffers || (!mInitialCallbackReceived && mNumAcquired == 1);
+    return mNumAcquired == maxAcquiredBuffers;
 }
 
 class BBQSurface : public Surface {