1 files changed, 64 insertions, 32 deletions

diff --git a/libs/gui/BLASTBufferQueue.cpp b/libs/gui/BLASTBufferQueue.cpp
index e9149f3a3e..55703214a5 100644
--- a/libs/gui/BLASTBufferQueue.cpp
+++ b/libs/gui/BLASTBufferQueue.cpp
@@ -407,18 +407,9 @@ void BLASTBufferQueue::releaseBufferCallback(
 
     // Release all buffers that are beyond the ones that we need to hold
     while (mPendingRelease.size() > numPendingBuffersToHold) {
-        const auto releaseBuffer = mPendingRelease.front();
+        const auto releasedBuffer = mPendingRelease.front();
         mPendingRelease.pop_front();
-        auto it = mSubmitted.find(releaseBuffer.callbackId);
-        if (it == mSubmitted.end()) {
-            BQA_LOGE("ERROR: releaseBufferCallback without corresponding submitted buffer %s",
-                     releaseBuffer.callbackId.to_string().c_str());
-            return;
-        }
-        mNumAcquired--;
-        BQA_LOGV("released %s", releaseBuffer.callbackId.to_string().c_str());
-        mBufferItemConsumer->releaseBuffer(it->second, releaseBuffer.releaseFence);
-        mSubmitted.erase(it);
+        releaseBuffer(releasedBuffer.callbackId, releasedBuffer.releaseFence);
         // Don't process the transactions here if mWaitForTransactionCallback is set. Instead, let
         // onFrameAvailable handle processing them since it will merge with the syncTransaction.
         if (!mWaitForTransactionCallback) {
@@ -432,6 +423,20 @@ void BLASTBufferQueue::releaseBufferCallback(
     mCallbackCV.notify_all();
 }
 
+void BLASTBufferQueue::releaseBuffer(const ReleaseCallbackId& callbackId,
+                                     const sp<Fence>& releaseFence) {
+    auto it = mSubmitted.find(callbackId);
+    if (it == mSubmitted.end()) {
+        BQA_LOGE("ERROR: releaseBufferCallback without corresponding submitted buffer %s",
+                 callbackId.to_string().c_str());
+        return;
+    }
+    mNumAcquired--;
+    BQA_LOGV("released %s", callbackId.to_string().c_str());
+    mBufferItemConsumer->releaseBuffer(it->second, releaseFence);
+    mSubmitted.erase(it);
+}
+
 void BLASTBufferQueue::acquireNextBufferLocked(
         const std::optional<SurfaceComposerClient::Transaction*> transaction) {
     ATRACE_CALL();
@@ -589,34 +594,57 @@ void BLASTBufferQueue::acquireAndReleaseBuffer() {
     mBufferItemConsumer->releaseBuffer(bufferItem, bufferItem.mFence);
 }
 
+void BLASTBufferQueue::flushAndWaitForFreeBuffer(std::unique_lock<std::mutex>& lock) {
+    if (mWaitForTransactionCallback && mNumFrameAvailable > 0) {
+        // We are waiting on a previous sync's transaction callback so allow another sync
+        // transaction to proceed.
+        //
+        // We need to first flush out the transactions that were in between the two syncs.
+        // We do this by merging them into mSyncTransaction so any buffer merging will get
+        // a release callback invoked. The release callback will be async so we need to wait
+        // on max acquired to make sure we have the capacity to acquire another buffer.
+        if (maxBuffersAcquired(false /* includeExtraAcquire */)) {
+            BQA_LOGD("waiting to flush shadow queue...");
+            mCallbackCV.wait(lock);
+        }
+        while (mNumFrameAvailable > 0) {
+            // flush out the shadow queue
+            acquireAndReleaseBuffer();
+        }
+    }
+
+    while (maxBuffersAcquired(false /* includeExtraAcquire */)) {
+        BQA_LOGD("waiting for free buffer.");
+        mCallbackCV.wait(lock);
+    }
+}
+
 void BLASTBufferQueue::onFrameAvailable(const BufferItem& item) {
     ATRACE_CALL();
     std::unique_lock _lock{mMutex};
 
     const bool syncTransactionSet = mSyncTransaction != nullptr;
     BQA_LOGV("onFrameAvailable-start syncTransactionSet=%s", boolToString(syncTransactionSet));
+
     if (syncTransactionSet) {
-        if (mWaitForTransactionCallback) {
-            // We are waiting on a previous sync's transaction callback so allow another sync
-            // transaction to proceed.
-            //
-            // We need to first flush out the transactions that were in between the two syncs.
-            // We do this by merging them into mSyncTransaction so any buffer merging will get
-            // a release callback invoked. The release callback will be async so we need to wait
-            // on max acquired to make sure we have the capacity to acquire another buffer.
-            if (maxBuffersAcquired(false /* includeExtraAcquire */)) {
-                BQA_LOGD("waiting to flush shadow queue...");
-                mCallbackCV.wait(_lock);
-            }
-            while (mNumFrameAvailable > 0) {
-                // flush out the shadow queue
-                acquireAndReleaseBuffer();
+        bool mayNeedToWaitForBuffer = true;
+        // If we are going to re-use the same mSyncTransaction, release the buffer that may already
+        // be set in the Transaction. This is to allow us a free slot early to continue processing
+        // a new buffer.
+        if (!mAcquireSingleBuffer) {
+            auto bufferData = mSyncTransaction->getAndClearBuffer(mSurfaceControl);
+            if (bufferData) {
+                BQA_LOGD("Releasing previous buffer when syncing: framenumber=%" PRIu64,
+                         bufferData->frameNumber);
+                releaseBuffer(bufferData->releaseCallbackId, bufferData->acquireFence);
+                // Because we just released a buffer, we know there's no need to wait for a free
+                // buffer.
+                mayNeedToWaitForBuffer = false;
             }
         }
 
-        while (maxBuffersAcquired(false /* includeExtraAcquire */)) {
-            BQA_LOGD("waiting for free buffer.");
-            mCallbackCV.wait(_lock);
+        if (mayNeedToWaitForBuffer) {
+            flushAndWaitForFreeBuffer(_lock);
         }
     }
 
@@ -629,8 +657,10 @@ void BLASTBufferQueue::onFrameAvailable(const BufferItem& item) {
              boolToString(syncTransactionSet));
 
     if (syncTransactionSet) {
-        acquireNextBufferLocked(std::move(mSyncTransaction));
-        mSyncTransaction = nullptr;
+        acquireNextBufferLocked(mSyncTransaction);
+        if (mAcquireSingleBuffer) {
+            mSyncTransaction = nullptr;
+        }
         mWaitForTransactionCallback = true;
     } else if (!mWaitForTransactionCallback) {
         acquireNextBufferLocked(std::nullopt);
@@ -652,9 +682,11 @@ void BLASTBufferQueue::onFrameCancelled(const uint64_t bufferId) {
     mDequeueTimestamps.erase(bufferId);
 };
 
-void BLASTBufferQueue::setSyncTransaction(SurfaceComposerClient::Transaction* t) {
+void BLASTBufferQueue::setSyncTransaction(SurfaceComposerClient::Transaction* t,
+                                          bool acquireSingleBuffer) {
     std::lock_guard _lock{mMutex};
     mSyncTransaction = t;
+    mAcquireSingleBuffer = mSyncTransaction ? acquireSingleBuffer : true;
 }
 
 bool BLASTBufferQueue::rejectBuffer(const BufferItem& item) {