commit ae9668c1e1357a0b8e6812710dc05141a6c81666
author Tianyu Jiang <tianyuj@google.com> Fri Dec 07 15:14:47 2018 -0800
committer Tianyu Jiang <tianyuj@google.com> Sat Dec 08 06:10:19 2018 +0000
tree 0731bc2720cb7897bf980157f1df2096cd060272
parent 616aca2f670caf55c3b87fe53996a2e3bf99ab93

Explicitly clears signal upon OnProducerGained in consumer channels

And fix some unreadable code around buffer state
and a wrong-but-no-effect-yet fence return.

Bug: 120569702
Test: patch ag/4833259 and not see washing machine
Test: AHardwareBufferTest BufferHubBuffer_test
buffer_hub_queue_producer-test buffer_hub-test buffer_hub_queue-test
dvr_buffer_queue-test dvr_api-test libdvrtracking-test

Change-Id: I63b18a78ea05d2084b2ed29fbcaacbb652d48846

services/vr/bufferhubd/consumer_channel.cpp

diff --git a/services/vr/bufferhubd/consumer_channel.cpp b/services/vr/bufferhubd/consumer_channel.cpp
index f936e95..158ef9c 100644
--- a/services/vr/bufferhubd/consumer_channel.cpp
+++ b/services/vr/bufferhubd/consumer_channel.cpp
@@ -153,6 +153,17 @@
   }
 }
 
+void ConsumerChannel::OnProducerGained() {
+  // Clear the signal if exist. There is a possiblity that the signal still
+  // exist in consumer client when producer gains the buffer, e.g. newly added
+  // consumer fail to acquire the previous posted buffer in time. Then, when
+  // producer gains back the buffer, posts the buffer again and signal the
+  // consumer later, there won't be an signal change in eventfd, and thus,
+  // consumer will miss the posted buffer later. Thus, we need to clear the
+  // signal in consumer clients if the signal exist.
+  ClearAvailable();
+}
+
 void ConsumerChannel::OnProducerPosted() {
   acquired_ = false;
   released_ = false;

services/vr/bufferhubd/include/private/dvr/consumer_channel.h

diff --git a/services/vr/bufferhubd/include/private/dvr/consumer_channel.h b/services/vr/bufferhubd/include/private/dvr/consumer_channel.h
index de0f23c..5fb4ec1 100644
--- a/services/vr/bufferhubd/include/private/dvr/consumer_channel.h
+++ b/services/vr/bufferhubd/include/private/dvr/consumer_channel.h
@@ -26,6 +26,7 @@
   uint64_t client_state_mask() const { return client_state_mask_; }
   BufferInfo GetBufferInfo() const override;
 
+  void OnProducerGained();
   void OnProducerPosted();
   void OnProducerClosed();
 

services/vr/bufferhubd/producer_channel.cpp

diff --git a/services/vr/bufferhubd/producer_channel.cpp b/services/vr/bufferhubd/producer_channel.cpp
index ab1d94c..b541fb3 100644
--- a/services/vr/bufferhubd/producer_channel.cpp
+++ b/services/vr/bufferhubd/producer_channel.cpp
@@ -424,7 +424,7 @@
   // Signal any interested consumers. If there are none, the buffer will stay
   // in posted state until a consumer comes online. This behavior guarantees
   // that no frame is silently dropped.
-  for (auto consumer : consumer_channels_) {
+  for (auto& consumer : consumer_channels_) {
     consumer->OnProducerPosted();
   }
 
@@ -437,6 +437,9 @@
 
   ClearAvailable();
   post_fence_.close();
+  for (auto& consumer : consumer_channels_) {
+    consumer->OnProducerGained();
+  }
   return {std::move(returned_fence_)};
 }
 
@@ -533,7 +536,7 @@
 
   uint64_t current_buffer_state =
       buffer_state_->load(std::memory_order_acquire);
-  if (BufferHubDefs::IsClientReleased(current_buffer_state,
+  if (BufferHubDefs::IsBufferReleased(current_buffer_state &
                                       ~orphaned_consumer_bit_mask_)) {
     SignalAvailable();
     if (orphaned_consumer_bit_mask_) {
@@ -560,7 +563,7 @@
 
   uint64_t current_buffer_state =
       buffer_state_->load(std::memory_order_acquire);
-  if (BufferHubDefs::IsClientReleased(current_buffer_state,
+  if (BufferHubDefs::IsBufferReleased(current_buffer_state &
                                       ~orphaned_consumer_bit_mask_)) {
     SignalAvailable();
   }