commit 021d92e6b92a877b9c8a2d17761be8c2251ad7f6
author Jiwen 'Steve' Cai <jwcai@google.com> Thu Mar 16 21:07:00 2017 -0700
committer Jiwen 'Steve' Cai <jwcai@google.com> Fri Mar 17 15:46:02 2017 -0700
tree 5652a15697cebebf587c1107868b8493353592b7
parent 46f224d19d94324f5e09733c8a16a13a08dd9137

BufferItemConsumer: Add onBufferFreedListener

This callback can reliably notify its listener when a GraphicBuffer is
being freed at the consumer end of a BufferQueue. This is extremely
useful when user of BufferItemConsumer caches the GraphicBuffer, so they
can listen to this callback and clean up resource properly.

Bug: 35114769
Test: Built system, flash marlin (should have no functional change as
the listener is optional).
Change-Id: I591cfd3ece697b1b4fb3efbeff987c7960422d24

include/gui/BufferItemConsumer.h

diff --git a/include/gui/BufferItemConsumer.h b/include/gui/BufferItemConsumer.h
index ec77ec7..db7e944 100644
--- a/include/gui/BufferItemConsumer.h
+++ b/include/gui/BufferItemConsumer.h
@@ -37,6 +37,10 @@
   public:
     typedef ConsumerBase::FrameAvailableListener FrameAvailableListener;
 
+    struct BufferFreedListener : public virtual RefBase {
+        virtual void onBufferFreed(const wp<GraphicBuffer>& graphicBuffer) = 0;
+    };
+
     enum { DEFAULT_MAX_BUFFERS = -1 };
     enum { INVALID_BUFFER_SLOT = BufferQueue::INVALID_BUFFER_SLOT };
     enum { NO_BUFFER_AVAILABLE = BufferQueue::NO_BUFFER_AVAILABLE };
@@ -57,6 +61,10 @@
     // log messages.
     void setName(const String8& name);
 
+    // setBufferFreedListener sets the listener object that will be notified
+    // when an old buffer is being freed.
+    void setBufferFreedListener(const wp<BufferFreedListener>& listener);
+
     // Gets the next graphics buffer from the producer, filling out the
     // passed-in BufferItem structure. Returns NO_BUFFER_AVAILABLE if the queue
     // of buffers is empty, and INVALID_OPERATION if the maximum number of
@@ -81,6 +89,13 @@
     status_t releaseBuffer(const BufferItem &item,
             const sp<Fence>& releaseFence = Fence::NO_FENCE);
 
+   private:
+    void freeBufferLocked(int slotIndex) override;
+
+    // mBufferFreedListener is the listener object that will be called when
+    // an old buffer is being freed. If it is not NULL it will be called from
+    // freeBufferLocked.
+    wp<BufferFreedListener> mBufferFreedListener;
 };
 
 } // namespace android

libs/gui/BufferItemConsumer.cpp

diff --git a/libs/gui/BufferItemConsumer.cpp b/libs/gui/BufferItemConsumer.cpp
index 3491043..d9d50db 100644
--- a/libs/gui/BufferItemConsumer.cpp
+++ b/libs/gui/BufferItemConsumer.cpp
@@ -22,7 +22,7 @@
 #include <gui/BufferItem.h>
 #include <gui/BufferItemConsumer.h>
 
-//#define BI_LOGV(x, ...) ALOGV("[%s] " x, mName.string(), ##__VA_ARGS__)
+#define BI_LOGV(x, ...) ALOGV("[%s] " x, mName.string(), ##__VA_ARGS__)
 //#define BI_LOGD(x, ...) ALOGD("[%s] " x, mName.string(), ##__VA_ARGS__)
 //#define BI_LOGI(x, ...) ALOGI("[%s] " x, mName.string(), ##__VA_ARGS__)
 //#define BI_LOGW(x, ...) ALOGW("[%s] " x, mName.string(), ##__VA_ARGS__)
@@ -57,6 +57,12 @@
     mConsumer->setConsumerName(name);
 }
 
+void BufferItemConsumer::setBufferFreedListener(
+        const wp<BufferFreedListener>& listener) {
+    Mutex::Autolock _l(mMutex);
+    mBufferFreedListener = listener;
+}
+
 status_t BufferItemConsumer::acquireBuffer(BufferItem *item,
         nsecs_t presentWhen, bool waitForFence) {
     status_t err;
@@ -104,4 +110,14 @@
     return err;
 }
 
+void BufferItemConsumer::freeBufferLocked(int slotIndex) {
+    sp<BufferFreedListener> listener = mBufferFreedListener.promote();
+    if (listener != NULL && mSlots[slotIndex].mGraphicBuffer != NULL) {
+        // Fire callback if we have a listener registered and the buffer being freed is valid.
+        BI_LOGV("actually calling onBufferFreed");
+        listener->onBufferFreed(mSlots[slotIndex].mGraphicBuffer);
+    }
+    ConsumerBase::freeBufferLocked(slotIndex);
+}
+
 } // namespace android