From c4a40c1c522bb6607fb436d81c9ff32947a37328 Mon Sep 17 00:00:00 2001
From: Vishnu Nair <vishnun@google.com>
Date: Wed, 23 Dec 2020 09:14:32 -0800
Subject: Added mergeWithNextTransaction to BlastBufferQueue

Resurrected abandoned cl Ife2a8c9dbcfac7a5c3b294f64bc8dce40231f652

This is to support SurfaceView synchronizing transactions with
ViewRootImpl. Currently, when SurfaceView gets a callback from
PositionUpdateListener, it asks ViewRootImpl whether it's
waiting on a sync transactions. If so, it will add the SV transactions
to the sync transactions. Otherwise, it will apply the transaction on
its own.

By adding the new function mergeWithNextTransaction, SV can call into
BlastBufferQueue and send its own transaction without having to know
whether VRI is in a blast sync. As long as blast is enabled, it can
always send its transaction to the BlastBufferQueue, which will apply it
when the VRI frame comes in.

Test: open bubbles with sv blast
Test: atest SurfaceViewSyncTest
Bug: 175594838
Change-Id: I1d1b6eb3bbcaa844f430dd3a2f7cfbe59e558909
---
 libs/gui/BLASTBufferQueue.cpp | 44 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 2 deletions(-)

(limited to 'libs/gui/BLASTBufferQueue.cpp')

diff --git a/libs/gui/BLASTBufferQueue.cpp b/libs/gui/BLASTBufferQueue.cpp
index 3415d9db61..ee5552f20e 100644
--- a/libs/gui/BLASTBufferQueue.cpp
+++ b/libs/gui/BLASTBufferQueue.cpp
@@ -151,6 +151,19 @@ BLASTBufferQueue::BLASTBufferQueue(const std::string& name, const sp<SurfaceCont
     mPendingReleaseItem.releaseFence = nullptr;
 }
 
+BLASTBufferQueue::~BLASTBufferQueue() {
+    if (mPendingTransactions.empty()) {
+        return;
+    }
+    BQA_LOGE("Applying pending transactions on dtor %d",
+             static_cast<uint32_t>(mPendingTransactions.size()));
+    SurfaceComposerClient::Transaction t;
+    for (auto& [targetFrameNumber, transaction] : mPendingTransactions) {
+        t.merge(std::move(transaction));
+    }
+    t.apply();
+}
+
 void BLASTBufferQueue::update(const sp<SurfaceControl>& surface, uint32_t width, uint32_t height) {
     std::unique_lock _lock{mMutex};
     mSurfaceControl = surface;
@@ -312,6 +325,7 @@ void BLASTBufferQueue::processNextBufferLocked(bool useNextTransaction) {
     incStrong((void*)transactionCallbackThunk);
 
     mLastBufferScalingMode = bufferItem.mScalingMode;
+    mLastAcquiredFrameNumber = bufferItem.mFrameNumber;
 
     t->setBuffer(mSurfaceControl, buffer);
     t->setDataspace(mSurfaceControl, static_cast<ui::Dataspace>(bufferItem.mDataSpace));
@@ -341,14 +355,29 @@ void BLASTBufferQueue::processNextBufferLocked(bool useNextTransaction) {
         mAutoRefresh = bufferItem.mAutoRefresh;
     }
 
+    auto mergeTransaction =
+            [&t, currentFrameNumber = bufferItem.mFrameNumber](
+                    std::tuple<uint64_t, SurfaceComposerClient::Transaction> pendingTransaction) {
+                auto& [targetFrameNumber, transaction] = pendingTransaction;
+                if (currentFrameNumber < targetFrameNumber) {
+                    return false;
+                }
+                t->merge(std::move(transaction));
+                return true;
+            };
+
+    mPendingTransactions.erase(std::remove_if(mPendingTransactions.begin(),
+                                              mPendingTransactions.end(), mergeTransaction),
+                               mPendingTransactions.end());
+
     if (applyTransaction) {
         t->apply();
     }
 
     BQA_LOGV("processNextBufferLocked size=%dx%d mFrameNumber=%" PRIu64
-             " applyTransaction=%s mTimestamp=%" PRId64,
+             " applyTransaction=%s mTimestamp=%" PRId64 " mPendingTransactions.size=%d",
              mSize.width, mSize.height, bufferItem.mFrameNumber, toString(applyTransaction),
-             bufferItem.mTimestamp);
+             bufferItem.mTimestamp, static_cast<uint32_t>(mPendingTransactions.size()));
 }
 
 Rect BLASTBufferQueue::computeCrop(const BufferItem& item) {
@@ -487,6 +516,17 @@ sp<Surface> BLASTBufferQueue::getSurface(bool includeSurfaceControlHandle) {
     return new BBQSurface(mProducer, true, scHandle, this);
 }
 
+void BLASTBufferQueue::mergeWithNextTransaction(SurfaceComposerClient::Transaction* t,
+                                                uint64_t frameNumber) {
+    std::lock_guard _lock{mMutex};
+    if (mLastAcquiredFrameNumber >= frameNumber) {
+        // Apply the transaction since we have already acquired the desired frame.
+        t->apply();
+    } else {
+        mPendingTransactions.emplace_back(frameNumber, std::move(*t));
+    }
+}
+
 // Maintains a single worker thread per process that services a list of runnables.
 class AsyncWorker : public Singleton<AsyncWorker> {
 private:
-- 
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