Surface: add getRemovedBuffer API

This allows clients to optionally sign up to track
buffers going out of Surface.

Test: compile
Bug: 34461678
Change-Id: I8696b304c169099c872bd9ba783015c0f0dad73a

2 files changed, 53 insertions, 1 deletions

diff --git a/include/gui/Surface.h b/include/gui/Surface.h
index 62f6cadece..88ef010368 100644
--- a/include/gui/Surface.h
+++ b/include/gui/Surface.h
@@ -257,10 +257,25 @@ public:
     virtual int query(int what, int* value) const;
 
     virtual int connect(int api, const sp<IProducerListener>& listener);
+
+    // When reportBufferRemoval is true, clients must call getAndFlushRemovedBuffers to fetch
+    // GraphicBuffers removed from this surface after a dequeueBuffer, detachNextBuffer or
+    // attachBuffer call. This allows clients with their own buffer caches to free up buffers no
+    // longer in use by this surface.
+    virtual int connect(
+            int api, const sp<IProducerListener>& listener,
+            bool reportBufferRemoval);
     virtual int detachNextBuffer(sp<GraphicBuffer>* outBuffer,
             sp<Fence>* outFence);
     virtual int attachBuffer(ANativeWindowBuffer*);
 
+    // When client connects to Surface with reportBufferRemoval set to true, any buffers removed
+    // from this Surface will be collected and returned here. Once this method returns, these
+    // buffers will no longer be referenced by this Surface unless they are attached to this
+    // Surface later. The list of removed buffers will only be stored until the next dequeueBuffer,
+    // detachNextBuffer, or attachBuffer call.
+    status_t getAndFlushRemovedBuffers(std::vector<sp<GraphicBuffer>>* out);
+
 protected:
     enum { NUM_BUFFER_SLOTS = BufferQueueDefs::NUM_BUFFER_SLOTS };
     enum { DEFAULT_FORMAT = PIXEL_FORMAT_RGBA_8888 };
@@ -414,6 +429,9 @@ protected:
     // A cached copy of the FrameEventHistory maintained by the consumer.
     bool mEnableFrameTimestamps = false;
     std::unique_ptr<ProducerFrameEventHistory> mFrameEventHistory;
+
+    bool mReportRemovedBuffers = false;
+    std::vector<sp<GraphicBuffer>> mRemovedBuffers;
 };
 
 } // namespace android
diff --git a/libs/gui/Surface.cpp b/libs/gui/Surface.cpp
index 06fc31d16c..1149b8980b 100644
--- a/libs/gui/Surface.cpp
+++ b/libs/gui/Surface.cpp
@@ -505,7 +505,11 @@ int Surface::dequeueBuffer(android_native_buffer_t** buffer, int* fenceFd) {
          mFrameEventHistory->applyDelta(frameTimestamps);
     }
 
-    if ((result & IGraphicBufferProducer::BUFFER_NEEDS_REALLOCATION) || gbuf == 0) {
+    if ((result & IGraphicBufferProducer::BUFFER_NEEDS_REALLOCATION) || gbuf == nullptr) {
+        if (mReportRemovedBuffers && (gbuf != nullptr)) {
+            mRemovedBuffers.clear();
+            mRemovedBuffers.push_back(gbuf);
+        }
         result = mGraphicBufferProducer->requestBuffer(buf, &gbuf);
         if (result != NO_ERROR) {
             ALOGE("dequeueBuffer: IGraphicBufferProducer::requestBuffer failed: %d", result);
@@ -1075,10 +1079,16 @@ int Surface::connect(int api) {
 }
 
 int Surface::connect(int api, const sp<IProducerListener>& listener) {
+    return connect(api, listener, false);
+}
+
+int Surface::connect(
+        int api, const sp<IProducerListener>& listener, bool reportBufferRemoval) {
     ATRACE_CALL();
     ALOGV("Surface::connect");
     Mutex::Autolock lock(mMutex);
     IGraphicBufferProducer::QueueBufferOutput output;
+    mReportRemovedBuffers = reportBufferRemoval;
     int err = mGraphicBufferProducer->connect(listener, api, mProducerControlledByApp, &output);
     if (err == NO_ERROR) {
         mDefaultWidth = output.width;
@@ -1109,6 +1119,7 @@ int Surface::disconnect(int api, IGraphicBufferProducer::DisconnectMode mode) {
     ATRACE_CALL();
     ALOGV("Surface::disconnect");
     Mutex::Autolock lock(mMutex);
+    mRemovedBuffers.clear();
     mSharedBufferSlot = BufferItem::INVALID_BUFFER_SLOT;
     mSharedBufferHasBeenQueued = false;
     freeAllBuffers();
@@ -1156,9 +1167,16 @@ int Surface::detachNextBuffer(sp<GraphicBuffer>* outBuffer,
         *outFence = Fence::NO_FENCE;
     }
 
+    if (mReportRemovedBuffers) {
+        mRemovedBuffers.clear();
+    }
+
     for (int i = 0; i < NUM_BUFFER_SLOTS; i++) {
         if (mSlots[i].buffer != NULL &&
                 mSlots[i].buffer->handle == buffer->handle) {
+            if (mReportRemovedBuffers) {
+                mRemovedBuffers.push_back(mSlots[i].buffer);
+            }
             mSlots[i].buffer = NULL;
         }
     }
@@ -1184,6 +1202,10 @@ int Surface::attachBuffer(ANativeWindowBuffer* buffer)
         graphicBuffer->mGenerationNumber = priorGeneration;
         return result;
     }
+    if (mReportRemovedBuffers && (mSlots[attachedSlot].buffer != nullptr)) {
+        mRemovedBuffers.clear();
+        mRemovedBuffers.push_back(mSlots[attachedSlot].buffer);
+    }
     mSlots[attachedSlot].buffer = graphicBuffer;
 
     return NO_ERROR;
@@ -1617,4 +1639,16 @@ status_t Surface::getUniqueId(uint64_t* outId) const {
     return mGraphicBufferProducer->getUniqueId(outId);
 }
 
+status_t Surface::getAndFlushRemovedBuffers(std::vector<sp<GraphicBuffer>>* out) {
+    if (out == nullptr) {
+        ALOGE("%s: out must not be null!", __FUNCTION__);
+        return BAD_VALUE;
+    }
+
+    Mutex::Autolock lock(mMutex);
+    *out = mRemovedBuffers;
+    mRemovedBuffers.clear();
+    return OK;
+}
+
 }; // namespace android