DvrBufferQueue: Add basic event callbacks

Currently, there is no guarantee of thread safty and on which thread
those callbacks are going to be fired.

Three new DVR APIs introduced:
1/ dvrReadBufferQueueSetBufferAvailableCallback
2/ dvrReadBufferQueueSetBufferRemovedCallback
3/ dvrReadBufferQueueHandleEvents

Bug: 36748012
Test: buffer_hub_queue-test, dvr_api-test
Change-Id: I79900c9d205f1808b02400b379c79adb366a1104

1 files changed, 18 insertions, 0 deletions

diff --git a/libs/vr/libbufferhubqueue/buffer_hub_queue_client.cpp b/libs/vr/libbufferhubqueue/buffer_hub_queue_client.cpp
index bba075d595..a53c8b001c 100644
--- a/libs/vr/libbufferhubqueue/buffer_hub_queue_client.cpp
+++ b/libs/vr/libbufferhubqueue/buffer_hub_queue_client.cpp
@@ -359,6 +359,10 @@ Status<void> BufferHubQueue::RemoveBuffer(size_t slot) {
       return ErrorStatus(-ret);
     }
 
+    // Trigger OnBufferRemoved callback if registered.
+    if (on_buffer_removed_)
+      on_buffer_removed_(buffers_[slot]);
+
     buffers_[slot] = nullptr;
     capacity_--;
   }
@@ -369,6 +373,11 @@ Status<void> BufferHubQueue::RemoveBuffer(size_t slot) {
 Status<void> BufferHubQueue::Enqueue(Entry entry) {
   if (!is_full()) {
     available_buffers_.Append(std::move(entry));
+
+    // Trigger OnBufferAvailable callback if registered.
+    if (on_buffer_available_)
+      on_buffer_available_();
+
     return {};
   } else {
     ALOGE("BufferHubQueue::Enqueue: Buffer queue is full!");
@@ -399,6 +408,15 @@ Status<std::shared_ptr<BufferHubBuffer>> BufferHubQueue::Dequeue(
   return {std::move(buffer)};
 }
 
+void BufferHubQueue::SetBufferAvailableCallback(
+    BufferAvailableCallback callback) {
+  on_buffer_available_ = callback;
+}
+
+void BufferHubQueue::SetBufferRemovedCallback(BufferRemovedCallback callback) {
+  on_buffer_removed_ = callback;
+}
+
 ProducerQueue::ProducerQueue(LocalChannelHandle handle)
     : BASE(std::move(handle)) {
   auto status = ImportQueue();