SF: Add TransactionHandler

- migrate transaction queueing and flushing into
  a new class and remove dependencies from
  other components.
- Add a filter interface for other components to
  participate in transactionready logic.

Test: presubmit
Bug: 238781169
Change-Id: Ia4da386cd72058126f6f765adafb9cb4d15b1d2b

13 files changed, 490 insertions, 326 deletions

diff --git a/libs/gui/LayerState.cpp b/libs/gui/LayerState.cpp
index 4d5978ccf7..2759c58fb1 100644
--- a/libs/gui/LayerState.cpp
+++ b/libs/gui/LayerState.cpp
@@ -634,7 +634,7 @@ bool layer_state_t::hasBufferChanges() const {
 }
 
 bool layer_state_t::hasValidBuffer() const {
-    return bufferData && (bufferData->buffer || bufferData->cachedBuffer.isValid());
+    return bufferData && (bufferData->hasBuffer() || bufferData->cachedBuffer.isValid());
 }
 
 status_t layer_state_t::matrix22_t::write(Parcel& output) const {
diff --git a/libs/gui/include/gui/fake/BufferData.h b/libs/gui/include/gui/fake/BufferData.h
new file mode 100644
index 0000000000..725d11c313
--- /dev/null
+++ b/libs/gui/include/gui/fake/BufferData.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <gui/LayerState.h>
+
+namespace android::fake {
+
+// Class which exposes buffer properties from BufferData without holding on to an actual buffer
+class BufferData : public android::BufferData {
+public:
+    BufferData(uint64_t bufferId, uint32_t width, uint32_t height, int32_t pixelFormat,
+               uint64_t outUsage)
+          : mBufferId(bufferId),
+            mWidth(width),
+            mHeight(height),
+            mPixelFormat(pixelFormat),
+            mOutUsage(outUsage) {}
+    bool hasBuffer() const override { return mBufferId != 0; }
+    bool hasSameBuffer(const android::BufferData& other) const override {
+        return getId() == other.getId() && frameNumber == other.frameNumber;
+    }
+    uint32_t getWidth() const override { return mWidth; }
+    uint32_t getHeight() const override { return mHeight; }
+    uint64_t getId() const override { return mBufferId; }
+    PixelFormat getPixelFormat() const override { return mPixelFormat; }
+    uint64_t getUsage() const override { return mOutUsage; }
+
+private:
+    uint64_t mBufferId;
+    uint32_t mWidth;
+    uint32_t mHeight;
+    int32_t mPixelFormat;
+    uint64_t mOutUsage;
+};
+
+} // namespace android::fake
diff --git a/services/surfaceflinger/Android.bp b/services/surfaceflinger/Android.bp
index b911ae75d4..809c80be0d 100644
--- a/services/surfaceflinger/Android.bp
+++ b/services/surfaceflinger/Android.bp
@@ -194,6 +194,7 @@ filegroup {
         "Tracing/TransactionTracing.cpp",
         "Tracing/TransactionProtoParser.cpp",
         "TransactionCallbackInvoker.cpp",
+        "TransactionHandler.cpp",
         "TunnelModeEnabledReporter.cpp",
     ],
 }
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 4ff86e5dd6..418056c22c 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -881,7 +881,9 @@ public:
 
     bool mPendingHWCDestroy{false};
 
-    bool backpressureEnabled() { return mDrawingState.flags & layer_state_t::eEnableBackpressure; }
+    bool backpressureEnabled() const {
+        return mDrawingState.flags & layer_state_t::eEnableBackpressure;
+    }
 
     bool setStretchEffect(const StretchEffect& effect);
     StretchEffect getStretchEffect() const;
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 3419721865..002a637899 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -129,14 +129,11 @@
 #include "LayerVector.h"
 #include "MutexUtils.h"
 #include "NativeWindowSurface.h"
-#include "RefreshRateOverlay.h"
 #include "RegionSamplingThread.h"
-#include "Scheduler/DispSyncSource.h"
 #include "Scheduler/EventThread.h"
 #include "Scheduler/LayerHistory.h"
 #include "Scheduler/Scheduler.h"
 #include "Scheduler/VsyncConfiguration.h"
-#include "Scheduler/VsyncController.h"
 #include "StartPropertySetThread.h"
 #include "SurfaceFlingerProperties.h"
 #include "SurfaceInterceptor.h"
@@ -775,6 +772,7 @@ chooseRenderEngineTypeViaSysProp() {
 void SurfaceFlinger::init() FTL_FAKE_GUARD(kMainThreadContext) {
     ALOGI(  "SurfaceFlinger's main thread ready to run. "
             "Initializing graphics H/W...");
+    addTransactionReadyFilters();
     Mutex::Autolock lock(mStateLock);
 
     // Get a RenderEngine for the given display / config (can't fail)
@@ -3691,122 +3689,117 @@ void SurfaceFlinger::setTransactionFlags(uint32_t mask, TransactionSchedule sche
     }
 }
 
-int SurfaceFlinger::flushPendingTransactionQueues(
-        std::vector<TransactionState>& transactions,
-        std::unordered_map<sp<IBinder>, uint64_t, SpHash<IBinder>>& bufferLayersReadyToPresent,
-        bool tryApplyUnsignaled) {
-    std::unordered_set<sp<IBinder>, SpHash<IBinder>> applyTokensWithUnsignaledTransactions;
-    int transactionsPendingBarrier = 0;
-    auto it = mPendingTransactionQueues.begin();
-    while (it != mPendingTransactionQueues.end()) {
-        auto& [applyToken, transactionQueue] = *it;
-        while (!transactionQueue.empty()) {
-            // if we are in LatchUnsignaledConfig::AutoSingleLayer
-            // then we should have only one applyToken for processing.
-            // so we can stop further transactions on this applyToken.
-            if (enableLatchUnsignaledConfig == LatchUnsignaledConfig::AutoSingleLayer &&
-                !applyTokensWithUnsignaledTransactions.empty()) {
-                ATRACE_NAME("stopTransactionProcessing");
-                break;
-            }
+TransactionHandler::TransactionReadiness SurfaceFlinger::transactionReadyTimelineCheck(
+        const TransactionHandler::TransactionFlushState& flushState) {
+    using TransactionReadiness = TransactionHandler::TransactionReadiness;
+    const auto& transaction = *flushState.transaction;
+    ATRACE_FORMAT("transactionIsReadyToBeApplied vsyncId: %" PRId64,
+                  transaction.frameTimelineInfo.vsyncId);
+    TimePoint desiredPresentTime = TimePoint::fromNs(transaction.desiredPresentTime);
+    // Do not present if the desiredPresentTime has not passed unless it is more than
+    // one second in the future. We ignore timestamps more than 1 second in the future
+    // for stability reasons.
+    if (!transaction.isAutoTimestamp && desiredPresentTime >= mExpectedPresentTime &&
+        desiredPresentTime < mExpectedPresentTime + 1s) {
+        ATRACE_NAME("not current");
+        return TransactionReadiness::NotReady;
+    }
 
-            auto& transaction = transactionQueue.front();
-            const auto ready =
-                    transactionIsReadyToBeApplied(transaction, transaction.frameTimelineInfo,
-                                                  transaction.isAutoTimestamp,
-                                                  TimePoint::fromNs(transaction.desiredPresentTime),
-                                                  transaction.originUid, transaction.states,
-                                                  bufferLayersReadyToPresent, transactions.size(),
-                                                  tryApplyUnsignaled);
-            ATRACE_INT("TransactionReadiness", static_cast<int>(ready));
-            if (ready == TransactionReadiness::NotReady) {
-                setTransactionFlags(eTransactionFlushNeeded);
-                break;
-            }
-            if (ready == TransactionReadiness::NotReadyBarrier) {
-                transactionsPendingBarrier++;
-                setTransactionFlags(eTransactionFlushNeeded);
-                break;
+    if (!mScheduler->isVsyncValid(mExpectedPresentTime, transaction.originUid)) {
+        ATRACE_NAME("!isVsyncValid");
+        return TransactionReadiness::NotReady;
+    }
+
+    // If the client didn't specify desiredPresentTime, use the vsyncId to determine the
+    // expected present time of this transaction.
+    if (transaction.isAutoTimestamp &&
+        frameIsEarly(mExpectedPresentTime, VsyncId{transaction.frameTimelineInfo.vsyncId})) {
+        ATRACE_NAME("frameIsEarly");
+        return TransactionReadiness::NotReady;
+    }
+    return TransactionReadiness::Ready;
+}
+
+TransactionHandler::TransactionReadiness SurfaceFlinger::transactionReadyBufferCheck(
+        const TransactionHandler::TransactionFlushState& flushState) {
+    using TransactionReadiness = TransactionHandler::TransactionReadiness;
+    auto ready = TransactionReadiness::Ready;
+    flushState.transaction->traverseStatesWithBuffersWhileTrue([&](const layer_state_t& s) -> bool {
+        sp<Layer> layer = Layer::fromHandle(s.surface).promote();
+        const auto& transaction = *flushState.transaction;
+        // check for barrier frames
+        if (s.bufferData->hasBarrier &&
+            ((layer->getDrawingState().frameNumber) < s.bufferData->barrierFrameNumber)) {
+            const bool willApplyBarrierFrame =
+                    flushState.bufferLayersReadyToPresent.contains(s.surface.get()) &&
+                    (flushState.bufferLayersReadyToPresent.get(s.surface.get()) >=
+                     s.bufferData->barrierFrameNumber);
+            if (!willApplyBarrierFrame) {
+                ATRACE_NAME("NotReadyBarrier");
+                ready = TransactionReadiness::NotReadyBarrier;
+                return false;
             }
-            transaction.traverseStatesWithBuffers([&](const layer_state_t& state) {
-                const bool frameNumberChanged = state.bufferData->flags.test(
-                        BufferData::BufferDataChange::frameNumberChanged);
-                if (frameNumberChanged) {
-                    bufferLayersReadyToPresent[state.surface] = state.bufferData->frameNumber;
-                } else {
-                    // Barrier function only used for BBQ which always includes a frame number
-                    bufferLayersReadyToPresent[state.surface] =
-                        std::numeric_limits<uint64_t>::max();
+        }
+
+        // If backpressure is enabled and we already have a buffer to commit, keep
+        // the transaction in the queue.
+        const bool hasPendingBuffer =
+                flushState.bufferLayersReadyToPresent.contains(s.surface.get());
+        if (layer->backpressureEnabled() && hasPendingBuffer && transaction.isAutoTimestamp) {
+            ATRACE_NAME("hasPendingBuffer");
+            ready = TransactionReadiness::NotReady;
+            return false;
+        }
+
+        // check fence status
+        const bool allowLatchUnsignaled = shouldLatchUnsignaled(layer, s, transaction.states.size(),
+                                                                flushState.firstTransaction);
+        ATRACE_FORMAT("%s allowLatchUnsignaled=%s", layer->getName().c_str(),
+                      allowLatchUnsignaled ? "true" : "false");
+
+        const bool acquireFenceChanged = s.bufferData &&
+                s.bufferData->flags.test(BufferData::BufferDataChange::fenceChanged) &&
+                s.bufferData->acquireFence;
+        const bool fenceSignaled =
+                (!acquireFenceChanged ||
+                 s.bufferData->acquireFence->getStatus() != Fence::Status::Unsignaled);
+        if (!fenceSignaled) {
+            if (!allowLatchUnsignaled) {
+                ready = TransactionReadiness::NotReady;
+                auto& listener = s.bufferData->releaseBufferListener;
+                if (listener &&
+                    (flushState.queueProcessTime - transaction.postTime) >
+                            std::chrono::nanoseconds(4s).count()) {
+                    mTransactionHandler.onTransactionQueueStalled(transaction, listener);
                 }
-            });
-            const bool appliedUnsignaled = (ready == TransactionReadiness::ReadyUnsignaled);
-            if (appliedUnsignaled) {
-                applyTokensWithUnsignaledTransactions.insert(transaction.applyToken);
+                return false;
             }
 
-            transactions.emplace_back(std::move(transaction));
-            transactionQueue.pop();
-            mPendingTransactionCount--;
-            ATRACE_INT("TransactionQueue", mPendingTransactionCount.load());
+            ready = enableLatchUnsignaledConfig == LatchUnsignaledConfig::AutoSingleLayer
+                    ? TransactionReadiness::ReadyUnsignaledSingle
+                    : TransactionReadiness::ReadyUnsignaled;
         }
+        return true;
+    });
+    ATRACE_INT("TransactionReadiness", static_cast<int>(ready));
+    return ready;
+}
 
-        if (transactionQueue.empty()) {
-            it = mPendingTransactionQueues.erase(it);
-        } else {
-            it = std::next(it, 1);
-        }
-    }
-    return transactionsPendingBarrier;
+void SurfaceFlinger::addTransactionReadyFilters() {
+    mTransactionHandler.addTransactionReadyFilter(
+            std::bind(&SurfaceFlinger::transactionReadyTimelineCheck, this, std::placeholders::_1));
+    mTransactionHandler.addTransactionReadyFilter(
+            std::bind(&SurfaceFlinger::transactionReadyBufferCheck, this, std::placeholders::_1));
 }
 
 bool SurfaceFlinger::flushTransactionQueues(VsyncId vsyncId) {
     // to prevent onHandleDestroyed from being called while the lock is held,
     // we must keep a copy of the transactions (specifically the composer
     // states) around outside the scope of the lock
-    std::vector<TransactionState> transactions;
-    // Layer handles that have transactions with buffers that are ready to be applied.
-    std::unordered_map<sp<IBinder>, uint64_t, SpHash<IBinder>> bufferLayersReadyToPresent;
+    std::vector<TransactionState> transactions = mTransactionHandler.flushTransactions();
     {
         Mutex::Autolock _l(mStateLock);
-        {
-            while (!mLocklessTransactionQueue.isEmpty()) {
-                auto maybeTransaction = mLocklessTransactionQueue.pop();
-                if (!maybeTransaction.has_value()) {
-                    break;
-                }
-                auto transaction = maybeTransaction.value();
-                mPendingTransactionQueues[transaction.applyToken].push(std::move(transaction));
-            }
-
-            // Transactions with a buffer pending on a barrier may be on a different applyToken
-            // than the transaction which satisfies our barrier. In fact this is the exact use case
-            // that the primitive is designed for. This means we may first process
-            // the barrier dependent transaction, determine it ineligible to complete
-            // and then satisfy in a later inner iteration of flushPendingTransactionQueues.
-            // The barrier dependent transaction was eligible to be presented in this frame
-            // but we would have prevented it without case. To fix this we continually
-            // loop through flushPendingTransactionQueues until we perform an iteration
-            // where the number of transactionsPendingBarrier doesn't change. This way
-            // we can continue to resolve dependency chains of barriers as far as possible.
-            int lastTransactionsPendingBarrier = 0;
-            int transactionsPendingBarrier = 0;
-            do {
-                lastTransactionsPendingBarrier = transactionsPendingBarrier;
-                transactionsPendingBarrier =
-                        flushPendingTransactionQueues(transactions, bufferLayersReadyToPresent,
-                                                      /*tryApplyUnsignaled*/ false);
-            } while (lastTransactionsPendingBarrier != transactionsPendingBarrier);
-
-            // We collected all transactions that could apply without latching unsignaled buffers.
-            // If we are allowing latch unsignaled of some form, now it's the time to go over the
-            // transactions that were not applied and try to apply them unsignaled.
-            if (enableLatchUnsignaledConfig != LatchUnsignaledConfig::Disabled) {
-                flushPendingTransactionQueues(transactions, bufferLayersReadyToPresent,
-                                              /*tryApplyUnsignaled*/ true);
-            }
-
-            return applyTransactions(transactions, vsyncId);
-        }
+        return applyTransactions(transactions, vsyncId);
     }
 }
 
@@ -3833,7 +3826,7 @@ bool SurfaceFlinger::applyTransactions(std::vector<TransactionState>& transactio
 }
 
 bool SurfaceFlinger::transactionFlushNeeded() {
-    return !mPendingTransactionQueues.empty() || !mLocklessTransactionQueue.isEmpty();
+    return mTransactionHandler.hasPendingTransactions();
 }
 
 bool SurfaceFlinger::frameIsEarly(TimePoint expectedPresentTime, VsyncId vsyncId) const {
@@ -3859,7 +3852,7 @@ bool SurfaceFlinger::frameIsEarly(TimePoint expectedPresentTime, VsyncId vsyncId
 }
 
 bool SurfaceFlinger::shouldLatchUnsignaled(const sp<Layer>& layer, const layer_state_t& state,
-                                           size_t numStates, size_t totalTXapplied) const {
+                                           size_t numStates, bool firstTransaction) const {
     if (enableLatchUnsignaledConfig == LatchUnsignaledConfig::Disabled) {
         ALOGV("%s: false (LatchUnsignaledConfig::Disabled)", __func__);
         return false;
@@ -3878,9 +3871,9 @@ bool SurfaceFlinger::shouldLatchUnsignaled(const sp<Layer>& layer, const layer_s
     }
 
     if (enableLatchUnsignaledConfig == LatchUnsignaledConfig::AutoSingleLayer) {
-        if (totalTXapplied > 0) {
-            ALOGV("%s: false (LatchUnsignaledConfig::AutoSingleLayer; totalTXapplied=%zu)",
-                  __func__, totalTXapplied);
+        if (!firstTransaction) {
+            ALOGV("%s: false (LatchUnsignaledConfig::AutoSingleLayer; not first transaction)",
+                  __func__);
             return false;
         }
 
@@ -3904,116 +3897,6 @@ bool SurfaceFlinger::shouldLatchUnsignaled(const sp<Layer>& layer, const layer_s
     return true;
 }
 
-auto SurfaceFlinger::transactionIsReadyToBeApplied(
-        TransactionState& transaction, const FrameTimelineInfo& info, bool isAutoTimestamp,
-        TimePoint desiredPresentTime, uid_t originUid, const Vector<ComposerState>& states,
-        const std::unordered_map<sp<IBinder>, uint64_t, SpHash<IBinder>>&
-                bufferLayersReadyToPresent,
-        size_t totalTXapplied, bool tryApplyUnsignaled) const -> TransactionReadiness {
-    ATRACE_FORMAT("transactionIsReadyToBeApplied vsyncId: %" PRId64, info.vsyncId);
-    // Do not present if the desiredPresentTime has not passed unless it is more than one second
-    // in the future. We ignore timestamps more than 1 second in the future for stability reasons.
-    if (!isAutoTimestamp && desiredPresentTime >= mExpectedPresentTime &&
-        desiredPresentTime < mExpectedPresentTime + 1s) {
-        ATRACE_NAME("not current");
-        return TransactionReadiness::NotReady;
-    }
-
-    if (!mScheduler->isVsyncValid(mExpectedPresentTime, originUid)) {
-        ATRACE_NAME("!isVsyncValid");
-        return TransactionReadiness::NotReady;
-    }
-
-    // If the client didn't specify desiredPresentTime, use the vsyncId to determine the expected
-    // present time of this transaction.
-    if (isAutoTimestamp && frameIsEarly(mExpectedPresentTime, VsyncId{info.vsyncId})) {
-        ATRACE_NAME("frameIsEarly");
-        return TransactionReadiness::NotReady;
-    }
-
-    bool fenceUnsignaled = false;
-    auto queueProcessTime = systemTime();
-    for (const ComposerState& state : states) {
-        const layer_state_t& s = state.state;
-
-        sp<Layer> layer = nullptr;
-        if (s.surface) {
-            layer = fromHandle(s.surface).promote();
-        } else if (s.hasBufferChanges()) {
-            ALOGW("Transaction with buffer, but no Layer?");
-            continue;
-        }
-        if (!layer) {
-            continue;
-        }
-
-        if (s.hasBufferChanges() && s.bufferData->hasBarrier &&
-            ((layer->getDrawingState().frameNumber) < s.bufferData->barrierFrameNumber)) {
-            const bool willApplyBarrierFrame =
-                (bufferLayersReadyToPresent.find(s.surface) != bufferLayersReadyToPresent.end()) &&
-                (bufferLayersReadyToPresent.at(s.surface) >= s.bufferData->barrierFrameNumber);
-            if (!willApplyBarrierFrame) {
-                ATRACE_NAME("NotReadyBarrier");
-                return TransactionReadiness::NotReadyBarrier;
-            }
-        }
-
-        const bool allowLatchUnsignaled = tryApplyUnsignaled &&
-                shouldLatchUnsignaled(layer, s, states.size(), totalTXapplied);
-        ATRACE_FORMAT("%s allowLatchUnsignaled=%s", layer->getName().c_str(),
-                      allowLatchUnsignaled ? "true" : "false");
-
-        const bool acquireFenceChanged = s.bufferData &&
-                s.bufferData->flags.test(BufferData::BufferDataChange::fenceChanged) &&
-                s.bufferData->acquireFence;
-        fenceUnsignaled = fenceUnsignaled ||
-                (acquireFenceChanged &&
-                 s.bufferData->acquireFence->getStatus() == Fence::Status::Unsignaled);
-
-        if (fenceUnsignaled && !allowLatchUnsignaled) {
-            if (!transaction.sentFenceTimeoutWarning &&
-                queueProcessTime - transaction.postTime > std::chrono::nanoseconds(4s).count()) {
-                transaction.sentFenceTimeoutWarning = true;
-                auto listener = s.bufferData->releaseBufferListener;
-                if (listener) {
-                    listener->onTransactionQueueStalled();
-                }
-            }
-
-            ATRACE_NAME("fence unsignaled");
-            return TransactionReadiness::NotReady;
-        }
-
-        if (s.hasBufferChanges()) {
-            // If backpressure is enabled and we already have a buffer to commit, keep the
-            // transaction in the queue.
-            const bool hasPendingBuffer = bufferLayersReadyToPresent.find(s.surface) !=
-                bufferLayersReadyToPresent.end();
-            if (layer->backpressureEnabled() && hasPendingBuffer && isAutoTimestamp) {
-                ATRACE_NAME("hasPendingBuffer");
-                return TransactionReadiness::NotReady;
-            }
-        }
-    }
-    return fenceUnsignaled ? TransactionReadiness::ReadyUnsignaled : TransactionReadiness::Ready;
-}
-
-void SurfaceFlinger::queueTransaction(TransactionState& state) {
-    mLocklessTransactionQueue.push(state);
-    mPendingTransactionCount++;
-    ATRACE_INT("TransactionQueue", mPendingTransactionCount.load());
-
-    const auto schedule = [](uint32_t flags) {
-        if (flags & eEarlyWakeupEnd) return TransactionSchedule::EarlyEnd;
-        if (flags & eEarlyWakeupStart) return TransactionSchedule::EarlyStart;
-        return TransactionSchedule::Late;
-    }(state.flags);
-
-    const auto frameHint = state.isFrameActive() ? FrameHint::kActive : FrameHint::kNone;
-
-    setTransactionFlags(eTransactionFlushNeeded, schedule, state.applyToken, frameHint);
-}
-
 status_t SurfaceFlinger::setTransactionState(
         const FrameTimelineInfo& frameTimelineInfo, const Vector<ComposerState>& states,
         const Vector<DisplayState>& displays, uint32_t flags, const sp<IBinder>& applyToken,
@@ -4064,7 +3947,16 @@ status_t SurfaceFlinger::setTransactionState(
     if (mTransactionTracing) {
         mTransactionTracing->addQueuedTransaction(state);
     }
-    queueTransaction(state);
+
+    const auto schedule = [](uint32_t flags) {
+        if (flags & eEarlyWakeupEnd) return TransactionSchedule::EarlyEnd;
+        if (flags & eEarlyWakeupStart) return TransactionSchedule::EarlyStart;
+        return TransactionSchedule::Late;
+    }(state.flags);
+
+    const auto frameHint = state.isFrameActive() ? FrameHint::kActive : FrameHint::kNone;
+    setTransactionFlags(eTransactionFlushNeeded, schedule, state.applyToken, frameHint);
+    mTransactionHandler.queueTransaction(std::move(state));
 
     return NO_ERROR;
 }
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index baaf41ec02..f4fb8de010 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -57,7 +57,6 @@
 #include <scheduler/Time.h>
 #include <ui/FenceResult.h>
 
-#include "ClientCache.h"
 #include "Display/DisplayMap.h"
 #include "Display/PhysicalDisplay.h"
 #include "DisplayDevice.h"
@@ -66,19 +65,17 @@
 #include "DisplayIdGenerator.h"
 #include "Effects/Daltonizer.h"
 #include "FlagManager.h"
-#include "FrameTracker.h"
 #include "LayerVector.h"
-#include "LocklessQueue.h"
 #include "Scheduler/RefreshRateConfigs.h"
 #include "Scheduler/RefreshRateStats.h"
 #include "Scheduler/Scheduler.h"
 #include "Scheduler/VsyncModulator.h"
 #include "SurfaceFlingerFactory.h"
 #include "ThreadContext.h"
-#include "TracedOrdinal.h"
 #include "Tracing/LayerTracing.h"
 #include "Tracing/TransactionTracing.h"
 #include "TransactionCallbackInvoker.h"
+#include "TransactionHandler.h"
 #include "TransactionState.h"
 
 #include <atomic>
@@ -341,6 +338,7 @@ private:
     friend class RegionSamplingThread;
     friend class LayerRenderArea;
     friend class LayerTracing;
+    friend class SurfaceComposerAIDL;
 
     // For unit tests
     friend class TestableSurfaceFlinger;
@@ -729,11 +727,13 @@ private:
     bool flushTransactionQueues(VsyncId) REQUIRES(kMainThreadContext);
     // Returns true if there is at least one transaction that needs to be flushed
     bool transactionFlushNeeded();
-
-    int flushPendingTransactionQueues(
-            std::vector<TransactionState>& transactions,
-            std::unordered_map<sp<IBinder>, uint64_t, SpHash<IBinder>>& bufferLayersReadyToPresent,
-            bool tryApplyUnsignaled) REQUIRES(mStateLock) REQUIRES(kMainThreadContext);
+    void addTransactionReadyFilters();
+    TransactionHandler::TransactionReadiness transactionReadyTimelineCheck(
+            const TransactionHandler::TransactionFlushState& flushState)
+            REQUIRES(kMainThreadContext);
+    TransactionHandler::TransactionReadiness transactionReadyBufferCheck(
+            const TransactionHandler::TransactionFlushState& flushState)
+            REQUIRES(kMainThreadContext);
 
     uint32_t setClientStateLocked(const FrameTimelineInfo&, ComposerState&,
                                   int64_t desiredPresentTime, bool isAutoTimestamp,
@@ -751,23 +751,9 @@ private:
 
     void commitOffscreenLayers();
 
-    enum class TransactionReadiness {
-        NotReady,
-        NotReadyBarrier,
-        Ready,
-        ReadyUnsignaled,
-    };
-    TransactionReadiness transactionIsReadyToBeApplied(
-            TransactionState&, const FrameTimelineInfo&, bool isAutoTimestamp,
-            TimePoint desiredPresentTime, uid_t originUid, const Vector<ComposerState>&,
-            const std::unordered_map<sp<IBinder>, uint64_t, SpHash<IBinder>>&
-                    bufferLayersReadyToPresent,
-            size_t totalTXapplied, bool tryApplyUnsignaled) const REQUIRES(mStateLock)
-            REQUIRES(kMainThreadContext);
-
     static LatchUnsignaledConfig getLatchUnsignaledConfig();
     bool shouldLatchUnsignaled(const sp<Layer>& layer, const layer_state_t&, size_t numStates,
-                               size_t totalTXapplied) const;
+                               bool firstTransaction) const;
     bool applyTransactions(std::vector<TransactionState>& transactions, VsyncId)
             REQUIRES(mStateLock);
     uint32_t setDisplayStateLocked(const DisplayState& s) REQUIRES(mStateLock);
@@ -1094,7 +1080,6 @@ private:
     status_t CheckTransactCodeCredentials(uint32_t code);
 
     // Add transaction to the Transaction Queue
-    void queueTransaction(TransactionState& state);
 
     /*
      * Generic Layer Metadata
@@ -1256,10 +1241,6 @@ private:
     uint32_t mTexturePoolSize = 0;
     std::vector<uint32_t> mTexturePool;
 
-    std::unordered_map<sp<IBinder>, std::queue<TransactionState>, IListenerHash>
-            mPendingTransactionQueues;
-    LocklessQueue<TransactionState> mLocklessTransactionQueue;
-    std::atomic<size_t> mPendingTransactionCount = 0;
     std::atomic<size_t> mNumLayers = 0;
 
     // to linkToDeath
@@ -1415,7 +1396,7 @@ private:
         bool early = false;
     } mPowerHintSessionMode;
 
-    friend class SurfaceComposerAIDL;
+    TransactionHandler mTransactionHandler;
 };
 
 class SurfaceComposerAIDL : public gui::BnSurfaceComposer {
diff --git a/services/surfaceflinger/Tracing/TransactionProtoParser.h b/services/surfaceflinger/Tracing/TransactionProtoParser.h
index 872a901b21..2232bb9cb1 100644
--- a/services/surfaceflinger/Tracing/TransactionProtoParser.h
+++ b/services/surfaceflinger/Tracing/TransactionProtoParser.h
@@ -15,6 +15,7 @@
  */
 #pragma once
 
+#include <gui/fake/BufferData.h>
 #include <layerproto/TransactionProto.h>
 #include <utils/RefBase.h>
 
@@ -43,35 +44,6 @@ struct TracingLayerState : layer_state_t {
     TracingLayerCreationArgs args;
 };
 
-// Class which exposes buffer properties from BufferData without holding on to the actual buffer
-// handle.
-class BufferDataStub : public BufferData {
-public:
-    BufferDataStub(uint64_t bufferId, uint32_t width, uint32_t height, int32_t pixelFormat,
-                   uint64_t outUsage)
-          : mBufferId(bufferId),
-            mWidth(width),
-            mHeight(height),
-            mPixelFormat(pixelFormat),
-            mOutUsage(outUsage) {}
-    bool hasBuffer() const override { return mBufferId != 0; }
-    bool hasSameBuffer(const BufferData& other) const override {
-        return getId() == other.getId() && frameNumber == other.frameNumber;
-    }
-    uint32_t getWidth() const override { return mWidth; }
-    uint32_t getHeight() const override { return mHeight; }
-    uint64_t getId() const override { return mBufferId; }
-    PixelFormat getPixelFormat() const override { return mPixelFormat; }
-    uint64_t getUsage() const override { return mOutUsage; }
-
-private:
-    uint64_t mBufferId;
-    uint32_t mWidth;
-    uint32_t mHeight;
-    int32_t mPixelFormat;
-    uint64_t mOutUsage;
-};
-
 class TransactionProtoParser {
 public:
     // Utility class to map handles to ids and buffers to buffer properties without pulling
@@ -87,7 +59,7 @@ public:
         virtual std::shared_ptr<BufferData> getGraphicData(uint64_t bufferId, uint32_t width,
                                                            uint32_t height, int32_t pixelFormat,
                                                            uint64_t usage) const {
-            return std::make_shared<BufferDataStub>(bufferId, width, height, pixelFormat, usage);
+            return std::make_shared<fake::BufferData>(bufferId, width, height, pixelFormat, usage);
         }
         virtual void getGraphicBufferPropertiesFromCache(client_cache_t /* cachedBuffer */,
                                                          uint64_t* /* outBufferId */,
diff --git a/services/surfaceflinger/TransactionHandler.cpp b/services/surfaceflinger/TransactionHandler.cpp
new file mode 100644
index 0000000000..6c6a487b67
--- /dev/null
+++ b/services/surfaceflinger/TransactionHandler.cpp
@@ -0,0 +1,188 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// #define LOG_NDEBUG 0
+#undef LOG_TAG
+#define LOG_TAG "TransactionHandler"
+#define ATRACE_TAG ATRACE_TAG_GRAPHICS
+
+#include <cutils/trace.h>
+#include <utils/Log.h>
+
+#include "TransactionHandler.h"
+
+namespace android {
+
+void TransactionHandler::queueTransaction(TransactionState&& state) {
+    mLocklessTransactionQueue.push(std::move(state));
+    mPendingTransactionCount.fetch_add(1);
+    ATRACE_INT("TransactionQueue", static_cast<int>(mPendingTransactionCount.load()));
+}
+
+std::vector<TransactionState> TransactionHandler::flushTransactions() {
+    while (!mLocklessTransactionQueue.isEmpty()) {
+        auto maybeTransaction = mLocklessTransactionQueue.pop();
+        if (!maybeTransaction.has_value()) {
+            break;
+        }
+        auto transaction = maybeTransaction.value();
+        mPendingTransactionQueues[transaction.applyToken].emplace(std::move(transaction));
+    }
+
+    // Collect transaction that are ready to be applied.
+    std::vector<TransactionState> transactions;
+    TransactionFlushState flushState;
+    flushState.queueProcessTime = systemTime();
+    // Transactions with a buffer pending on a barrier may be on a different applyToken
+    // than the transaction which satisfies our barrier. In fact this is the exact use case
+    // that the primitive is designed for. This means we may first process
+    // the barrier dependent transaction, determine it ineligible to complete
+    // and then satisfy in a later inner iteration of flushPendingTransactionQueues.
+    // The barrier dependent transaction was eligible to be presented in this frame
+    // but we would have prevented it without case. To fix this we continually
+    // loop through flushPendingTransactionQueues until we perform an iteration
+    // where the number of transactionsPendingBarrier doesn't change. This way
+    // we can continue to resolve dependency chains of barriers as far as possible.
+    int lastTransactionsPendingBarrier = 0;
+    int transactionsPendingBarrier = 0;
+    do {
+        lastTransactionsPendingBarrier = transactionsPendingBarrier;
+        // Collect transactions that are ready to be applied.
+        transactionsPendingBarrier = flushPendingTransactionQueues(transactions, flushState);
+    } while (lastTransactionsPendingBarrier != transactionsPendingBarrier);
+
+    mPendingTransactionCount.fetch_sub(transactions.size());
+    ATRACE_INT("TransactionQueue", static_cast<int>(mPendingTransactionCount.load()));
+    return transactions;
+}
+
+TransactionHandler::TransactionReadiness TransactionHandler::applyFilters(
+        TransactionFlushState& flushState) {
+    auto ready = TransactionReadiness::Ready;
+    for (auto& filter : mTransactionReadyFilters) {
+        auto perFilterReady = filter(flushState);
+        switch (perFilterReady) {
+            case TransactionReadiness::NotReady:
+            case TransactionReadiness::NotReadyBarrier:
+                return perFilterReady;
+
+            case TransactionReadiness::ReadyUnsignaled:
+            case TransactionReadiness::ReadyUnsignaledSingle:
+                // If one of the filters allows latching an unsignaled buffer, latch this ready
+                // state.
+                ready = perFilterReady;
+                break;
+            case TransactionReadiness::Ready:
+                continue;
+        }
+    }
+    return ready;
+}
+
+int TransactionHandler::flushPendingTransactionQueues(std::vector<TransactionState>& transactions,
+                                                      TransactionFlushState& flushState) {
+    int transactionsPendingBarrier = 0;
+    auto it = mPendingTransactionQueues.begin();
+    while (it != mPendingTransactionQueues.end()) {
+        auto& queue = it->second;
+        IBinder* queueToken = it->first.get();
+
+        // if we have already flushed a transaction with an unsignaled buffer then stop queue
+        // processing
+        if (std::find(flushState.queuesWithUnsignaledBuffers.begin(),
+                      flushState.queuesWithUnsignaledBuffers.end(),
+                      queueToken) != flushState.queuesWithUnsignaledBuffers.end()) {
+            continue;
+        }
+
+        while (!queue.empty()) {
+            auto& transaction = queue.front();
+            flushState.transaction = &transaction;
+            auto ready = applyFilters(flushState);
+            if (ready == TransactionReadiness::NotReadyBarrier) {
+                transactionsPendingBarrier++;
+                break;
+            } else if (ready == TransactionReadiness::NotReady) {
+                break;
+            }
+
+            // Transaction is ready move it from the pending queue.
+            flushState.firstTransaction = false;
+            removeFromStalledTransactions(transaction.id);
+            transactions.emplace_back(std::move(transaction));
+            queue.pop();
+
+            // If the buffer is unsignaled, then we don't want to signal other transactions using
+            // the buffer as a barrier.
+            auto& readyToApplyTransaction = transactions.back();
+            if (ready == TransactionReadiness::Ready) {
+                readyToApplyTransaction.traverseStatesWithBuffers([&](const layer_state_t& state) {
+                    const bool frameNumberChanged = state.bufferData->flags.test(
+                            BufferData::BufferDataChange::frameNumberChanged);
+                    if (frameNumberChanged) {
+                        flushState.bufferLayersReadyToPresent
+                                .emplace_or_replace(state.surface.get(),
+                                                    state.bufferData->frameNumber);
+                    } else {
+                        // Barrier function only used for BBQ which always includes a frame number.
+                        // This value only used for barrier logic.
+                        flushState.bufferLayersReadyToPresent
+                                .emplace_or_replace(state.surface.get(),
+                                                    std::numeric_limits<uint64_t>::max());
+                    }
+                });
+            } else if (ready == TransactionReadiness::ReadyUnsignaledSingle) {
+                // Track queues with a flushed unsingaled buffer.
+                flushState.queuesWithUnsignaledBuffers.emplace_back(queueToken);
+                break;
+            }
+        }
+
+        if (queue.empty()) {
+            it = mPendingTransactionQueues.erase(it);
+        } else {
+            it = std::next(it, 1);
+        }
+    }
+    return transactionsPendingBarrier;
+}
+
+void TransactionHandler::addTransactionReadyFilter(TransactionFilter&& filter) {
+    mTransactionReadyFilters.emplace_back(std::move(filter));
+}
+
+bool TransactionHandler::hasPendingTransactions() {
+    return !mPendingTransactionQueues.empty() || !mLocklessTransactionQueue.isEmpty();
+}
+
+void TransactionHandler::onTransactionQueueStalled(const TransactionState& transaction,
+                                                   sp<ITransactionCompletedListener>& listener) {
+    if (std::find(mStalledTransactions.begin(), mStalledTransactions.end(), transaction.id) !=
+        mStalledTransactions.end()) {
+        return;
+    }
+
+    mStalledTransactions.push_back(transaction.id);
+    listener->onTransactionQueueStalled();
+}
+
+void TransactionHandler::removeFromStalledTransactions(uint64_t id) {
+    auto it = std::find(mStalledTransactions.begin(), mStalledTransactions.end(), id);
+    if (it != mStalledTransactions.end()) {
+        mStalledTransactions.erase(it);
+    }
+}
+} // namespace android
\ No newline at end of file
diff --git a/services/surfaceflinger/TransactionHandler.h b/services/surfaceflinger/TransactionHandler.h
new file mode 100644
index 0000000000..237b48d55f
--- /dev/null
+++ b/services/surfaceflinger/TransactionHandler.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <semaphore.h>
+#include <cstdint>
+#include <mutex>
+#include <queue>
+#include <thread>
+#include <vector>
+
+#include <LocklessQueue.h>
+#include <TransactionState.h>
+#include <android-base/thread_annotations.h>
+#include <ftl/small_map.h>
+#include <ftl/small_vector.h>
+
+namespace android {
+class TransactionHandler {
+public:
+    struct TransactionFlushState {
+        const TransactionState* transaction;
+        bool firstTransaction = true;
+        nsecs_t queueProcessTime = 0;
+        // Layer handles that have transactions with buffers that are ready to be applied.
+        ftl::SmallMap<IBinder* /* binder address */, uint64_t /* framenumber */, 15>
+                bufferLayersReadyToPresent = {};
+        ftl::SmallVector<IBinder* /* queueToken */, 15> queuesWithUnsignaledBuffers;
+    };
+    enum class TransactionReadiness {
+        NotReady,
+        NotReadyBarrier,
+        Ready,
+        ReadyUnsignaled,
+        ReadyUnsignaledSingle,
+    };
+    using TransactionFilter = std::function<TransactionReadiness(const TransactionFlushState&)>;
+
+    bool hasPendingTransactions();
+    std::vector<TransactionState> flushTransactions();
+    void addTransactionReadyFilter(TransactionFilter&&);
+    void queueTransaction(TransactionState&&);
+    void onTransactionQueueStalled(const TransactionState&, sp<ITransactionCompletedListener>&);
+    void removeFromStalledTransactions(uint64_t transactionId);
+
+private:
+    // For unit tests
+    friend class TestableSurfaceFlinger;
+
+    int flushPendingTransactionQueues(std::vector<TransactionState>&, TransactionFlushState&);
+    TransactionReadiness applyFilters(TransactionFlushState&);
+    std::unordered_map<sp<IBinder>, std::queue<TransactionState>, IListenerHash>
+            mPendingTransactionQueues;
+    LocklessQueue<TransactionState> mLocklessTransactionQueue;
+    std::atomic<size_t> mPendingTransactionCount = 0;
+    ftl::SmallVector<TransactionFilter, 2> mTransactionReadyFilters;
+    std::vector<uint64_t> mStalledTransactions;
+};
+
+} // namespace android
diff --git a/services/surfaceflinger/TransactionState.h b/services/surfaceflinger/TransactionState.h
index 95eb503327..3cbfe811ea 100644
--- a/services/surfaceflinger/TransactionState.h
+++ b/services/surfaceflinger/TransactionState.h
@@ -64,6 +64,15 @@ struct TransactionState {
         }
     }
 
+    template <typename Visitor>
+    void traverseStatesWithBuffersWhileTrue(Visitor&& visitor) const {
+        for (const auto& [state] : states) {
+            if (state.hasBufferChanges() && state.hasValidBuffer() && state.surface) {
+                if (!visitor(state)) return;
+            }
+        }
+    }
+
     // TODO(b/185535769): Remove FrameHint. Instead, reset the idle timer (of the relevant physical
     // display) on the main thread if commit leads to composite. Then, RefreshRateOverlay should be
     // able to setFrameRate once, rather than for each transaction.
diff --git a/services/surfaceflinger/fuzzer/surfaceflinger_fuzzers_utils.h b/services/surfaceflinger/fuzzer/surfaceflinger_fuzzers_utils.h
index 370b23c7ce..49dd80ede7 100644
--- a/services/surfaceflinger/fuzzer/surfaceflinger_fuzzers_utils.h
+++ b/services/surfaceflinger/fuzzer/surfaceflinger_fuzzers_utils.h
@@ -728,8 +728,10 @@ public:
         return mFlinger->setPowerModeInternal(display, mode);
     }
 
-    auto &getTransactionQueue() { return mFlinger->mLocklessTransactionQueue; }
-    auto &getPendingTransactionQueue() { return mFlinger->mPendingTransactionQueues; }
+    auto &getTransactionQueue() { return mFlinger->mTransactionHandler.mLocklessTransactionQueue; }
+    auto &getPendingTransactionQueue() {
+        return mFlinger->mTransactionHandler.mPendingTransactionQueues;
+    }
 
     auto setTransactionState(
             const FrameTimelineInfo &frameTimelineInfo, const Vector<ComposerState> &states,
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index e1a0eeb7fe..7b319f52c5 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -417,8 +417,13 @@ public:
         return mFlinger->SurfaceFlinger::getDisplayNativePrimaries(displayToken, primaries);
     }
 
-    auto& getTransactionQueue() { return mFlinger->mLocklessTransactionQueue; }
-    auto& getPendingTransactionQueue() { return mFlinger->mPendingTransactionQueues; }
+    auto& getTransactionQueue() { return mFlinger->mTransactionHandler.mLocklessTransactionQueue; }
+    auto& getPendingTransactionQueue() {
+        return mFlinger->mTransactionHandler.mPendingTransactionQueues;
+    }
+    size_t getPendingTransactionCount() {
+        return mFlinger->mTransactionHandler.mPendingTransactionCount.load();
+    }
 
     auto setTransactionState(
             const FrameTimelineInfo& frameTimelineInfo, const Vector<ComposerState>& states,
diff --git a/services/surfaceflinger/tests/unittests/TransactionApplicationTest.cpp b/services/surfaceflinger/tests/unittests/TransactionApplicationTest.cpp
index b4030b3617..db438b70ab 100644
--- a/services/surfaceflinger/tests/unittests/TransactionApplicationTest.cpp
+++ b/services/surfaceflinger/tests/unittests/TransactionApplicationTest.cpp
@@ -14,7 +14,6 @@
  * limitations under the License.
  */
 
-
 #undef LOG_TAG
 #define LOG_TAG "CompositionTest"
 
@@ -22,12 +21,17 @@
 #include <compositionengine/mock/DisplaySurface.h>
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
+#include <gui/LayerState.h>
 #include <gui/SurfaceComposerClient.h>
+#include <gui/fake/BufferData.h>
 #include <log/log.h>
 #include <ui/MockFence.h>
 #include <utils/String8.h>
+#include <vector>
+#include <binder/Binder.h>
 
 #include "TestableSurfaceFlinger.h"
+#include "TransactionHandler.h"
 #include "mock/MockEventThread.h"
 #include "mock/MockVsyncController.h"
 
@@ -78,6 +82,7 @@ public:
         mFlinger.setupScheduler(std::unique_ptr<mock::VsyncController>(mVsyncController),
                                 std::unique_ptr<mock::VSyncTracker>(mVSyncTracker),
                                 std::move(eventThread), std::move(sfEventThread));
+        mFlinger.flinger()->addTransactionReadyFilters();
     }
 
     TestableSurfaceFlinger mFlinger;
@@ -314,7 +319,10 @@ public:
 
     ComposerState createComposerState(int layerId, sp<Fence> fence, uint64_t what) {
         ComposerState state;
-        state.state.bufferData = std::make_shared<BufferData>();
+        state.state.bufferData =
+                std::make_shared<fake::BufferData>(/* bufferId */ 123L, /* width */ 1,
+                                                   /* height */ 2, /* pixelFormat */ 0,
+                                                   /* outUsage */ 0);
         state.state.bufferData->acquireFence = std::move(fence);
         state.state.layerId = layerId;
         state.state.surface =
@@ -361,7 +369,7 @@ public:
         }
         mFlinger.flushTransactionQueues();
         EXPECT_TRUE(mFlinger.getTransactionQueue().isEmpty());
-        EXPECT_EQ(expectedTransactionsPending, mFlinger.getPendingTransactionQueue().size());
+        EXPECT_EQ(expectedTransactionsPending, mFlinger.getPendingTransactionCount());
     }
 };
 
@@ -413,7 +421,9 @@ TEST_F(LatchUnsignaledAutoSingleLayerTest, Flush_KeepsUnSignaledInTheQueue_NonBu
                                   {
                                           createComposerState(kLayerId,
                                                               fence(Fence::Status::Unsignaled),
-                                                              layer_state_t::eCropChanged),
+                                                              layer_state_t::eCropChanged |
+                                                                      layer_state_t::
+                                                                              eBufferChanged),
                                   });
     setTransactionStates({unsignaledTransaction}, kExpectedTransactionsPending);
 }
@@ -536,41 +546,6 @@ TEST_F(LatchUnsignaledAutoSingleLayerTest,
                          kExpectedTransactionsPending);
 }
 
-TEST_F(LatchUnsignaledAutoSingleLayerTest, UnsignaledNotAppliedWhenThereAreSignaled_SignaledFirst) {
-    const sp<IBinder> kApplyToken1 =
-            IInterface::asBinder(TransactionCompletedListener::getIInstance());
-    const sp<IBinder> kApplyToken2 = sp<BBinder>::make();
-    const sp<IBinder> kApplyToken3 = sp<BBinder>::make();
-    const auto kLayerId1 = 1;
-    const auto kLayerId2 = 2;
-    const auto kExpectedTransactionsPending = 1u;
-
-    const auto signaledTransaction =
-            createTransactionInfo(kApplyToken1,
-                                  {
-                                          createComposerState(kLayerId1,
-                                                              fence(Fence::Status::Signaled),
-                                                              layer_state_t::eBufferChanged),
-                                  });
-    const auto signaledTransaction2 =
-            createTransactionInfo(kApplyToken2,
-                                  {
-                                          createComposerState(kLayerId1,
-                                                              fence(Fence::Status::Signaled),
-                                                              layer_state_t::eBufferChanged),
-                                  });
-    const auto unsignaledTransaction =
-            createTransactionInfo(kApplyToken3,
-                                  {
-                                          createComposerState(kLayerId2,
-                                                              fence(Fence::Status::Unsignaled),
-                                                              layer_state_t::eBufferChanged),
-                                  });
-
-    setTransactionStates({signaledTransaction, signaledTransaction2, unsignaledTransaction},
-                         kExpectedTransactionsPending);
-}
-
 TEST_F(LatchUnsignaledAutoSingleLayerTest, Flush_KeepsTransactionInTheQueueSameApplyToken) {
     const sp<IBinder> kApplyToken =
             IInterface::asBinder(TransactionCompletedListener::getIInstance());
@@ -798,7 +773,7 @@ TEST_F(LatchUnsignaledDisabledTest, Flush_KeepInTheUnsignaledTheQueue) {
             IInterface::asBinder(TransactionCompletedListener::getIInstance());
     const auto kLayerId1 = 1;
     const auto kLayerId2 = 2;
-    const auto kExpectedTransactionsPending = 1u;
+    const auto kExpectedTransactionsPending = 2u;
 
     const auto unsignaledTransaction =
             createTransactionInfo(kApplyToken,
@@ -1004,4 +979,16 @@ TEST_F(LatchUnsignaledAlwaysTest, LatchUnsignaledWhenEarlyOffset) {
     setTransactionStates({unsignaledTransaction}, kExpectedTransactionsPending);
 }
 
+TEST(TransactionHandlerTest, QueueTransaction) {
+    TransactionHandler handler;
+    TransactionState transaction;
+    transaction.applyToken = sp<BBinder>::make();
+    transaction.id = 42;
+    handler.queueTransaction(std::move(transaction));
+    std::vector<TransactionState> transactionsReadyToBeApplied = handler.flushTransactions();
+
+    EXPECT_EQ(transactionsReadyToBeApplied.size(), 1u);
+    EXPECT_EQ(transactionsReadyToBeApplied.front().id, 42u);
+}
+
 } // namespace android