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, 83 insertions, 1 deletions

diff --git a/libs/gui/SurfaceComposerClient.cpp b/libs/gui/SurfaceComposerClient.cpp
index c16a98f42f..11fe49039d 100644
--- a/libs/gui/SurfaceComposerClient.cpp
+++ b/libs/gui/SurfaceComposerClient.cpp
@@ -195,6 +195,17 @@ void TransactionCompletedListener::removeJankListener(const sp<JankDataListener>
     }
 }
 
+void TransactionCompletedListener::setReleaseBufferCallback(uint64_t graphicBufferId,
+                                                            ReleaseBufferCallback listener) {
+    std::scoped_lock<std::mutex> lock(mMutex);
+    mReleaseBufferCallbacks[graphicBufferId] = listener;
+}
+
+void TransactionCompletedListener::removeReleaseBufferCallback(uint64_t graphicBufferId) {
+    std::scoped_lock<std::mutex> lock(mMutex);
+    mReleaseBufferCallbacks.erase(graphicBufferId);
+}
+
 void TransactionCompletedListener::addSurfaceStatsListener(void* context, void* cookie,
         sp<SurfaceControl> surfaceControl, SurfaceStatsCallback listener) {
     std::lock_guard<std::mutex> lock(mMutex);
@@ -275,6 +286,20 @@ void TransactionCompletedListener::onTransactionCompleted(ListenerStats listener
                             .surfaceControls[surfaceStats.surfaceControl]
                             ->setTransformHint(surfaceStats.transformHint);
                 }
+                // If there is buffer id set, we look up any pending client release buffer callbacks
+                // and call them. This is a performance optimization when we have a transaction
+                // callback and a release buffer callback happening at the same time to avoid an
+                // additional ipc call from the server.
+                if (surfaceStats.previousBufferId) {
+                    ReleaseBufferCallback callback =
+                            popReleaseBufferCallbackLocked(surfaceStats.previousBufferId);
+                    if (callback) {
+                        callback(surfaceStats.previousBufferId,
+                                 surfaceStats.previousReleaseFence
+                                         ? surfaceStats.previousReleaseFence
+                                         : Fence::NO_FENCE);
+                    }
+                }
             }
 
             callbackFunction(transactionStats.latchTime, transactionStats.presentFence,
@@ -297,6 +322,32 @@ void TransactionCompletedListener::onTransactionCompleted(ListenerStats listener
     }
 }
 
+void TransactionCompletedListener::onReleaseBuffer(uint64_t graphicBufferId,
+                                                   sp<Fence> releaseFence) {
+    ReleaseBufferCallback callback;
+    {
+        std::scoped_lock<std::mutex> lock(mMutex);
+        callback = popReleaseBufferCallbackLocked(graphicBufferId);
+    }
+    if (!callback) {
+        ALOGE("Could not call release buffer callback, buffer not found %" PRIu64, graphicBufferId);
+        return;
+    }
+    callback(graphicBufferId, releaseFence);
+}
+
+ReleaseBufferCallback TransactionCompletedListener::popReleaseBufferCallbackLocked(
+        uint64_t graphicBufferId) {
+    ReleaseBufferCallback callback;
+    auto itr = mReleaseBufferCallbacks.find(graphicBufferId);
+    if (itr == mReleaseBufferCallbacks.end()) {
+        return nullptr;
+    }
+    callback = itr->second;
+    mReleaseBufferCallbacks.erase(itr);
+    return callback;
+}
+
 // ---------------------------------------------------------------------------
 
 void removeDeadBufferCallback(void* /*context*/, uint64_t graphicBufferId);
@@ -1219,17 +1270,20 @@ SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::setFrame
 }
 
 SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::setBuffer(
-        const sp<SurfaceControl>& sc, const sp<GraphicBuffer>& buffer) {
+        const sp<SurfaceControl>& sc, const sp<GraphicBuffer>& buffer,
+        ReleaseBufferCallback callback) {
     layer_state_t* s = getLayerState(sc);
     if (!s) {
         mStatus = BAD_INDEX;
         return *this;
     }
+    removeReleaseBufferCallback(s);
     s->what |= layer_state_t::eBufferChanged;
     s->buffer = buffer;
     if (mIsAutoTimestamp) {
         mDesiredPresentTime = systemTime();
     }
+    setReleaseBufferCallback(s, callback);
 
     registerSurfaceControlForCallback(sc);
 
@@ -1237,6 +1291,34 @@ SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::setBuffe
     return *this;
 }
 
+void SurfaceComposerClient::Transaction::removeReleaseBufferCallback(layer_state_t* s) {
+    if (!s->releaseBufferListener) {
+        return;
+    }
+
+    s->what &= ~static_cast<uint64_t>(layer_state_t::eReleaseBufferListenerChanged);
+    s->releaseBufferListener = nullptr;
+    TransactionCompletedListener::getInstance()->removeReleaseBufferCallback(s->buffer->getId());
+}
+
+void SurfaceComposerClient::Transaction::setReleaseBufferCallback(layer_state_t* s,
+                                                                  ReleaseBufferCallback callback) {
+    if (!callback) {
+        return;
+    }
+
+    if (!s->buffer) {
+        ALOGW("Transaction::setReleaseBufferCallback"
+              "ignored trying to set a callback on a null buffer.");
+        return;
+    }
+
+    s->what |= layer_state_t::eReleaseBufferListenerChanged;
+    s->releaseBufferListener = TransactionCompletedListener::getIInstance();
+    auto listener = TransactionCompletedListener::getInstance();
+    listener->setReleaseBufferCallback(s->buffer->getId(), callback);
+}
+
 SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::setAcquireFence(
         const sp<SurfaceControl>& sc, const sp<Fence>& fence) {
     layer_state_t* s = getLayerState(sc);