down-integrate internal changes

1 files changed, 13 insertions, 5 deletions

diff --git a/src/google/protobuf/map_field.cc b/src/google/protobuf/map_field.cc
index fd40c0d8..6ff1936e 100644
--- a/src/google/protobuf/map_field.cc
+++ b/src/google/protobuf/map_field.cc
@@ -104,14 +104,18 @@ void MapFieldBase::SetRepeatedDirty() { state_ = STATE_MODIFIED_REPEATED; }
 void* MapFieldBase::MutableRepeatedPtrField() const { return repeated_field_; }
 
 void MapFieldBase::SyncRepeatedFieldWithMap() const {
-  Atomic32 state = google::protobuf::internal::NoBarrier_Load(&state_);
+  // "Acquire" insures the operation after SyncRepeatedFieldWithMap won't get
+  // executed before state_ is checked.
+  Atomic32 state = google::protobuf::internal::Acquire_Load(&state_);
   if (state == STATE_MODIFIED_MAP) {
     mutex_.Lock();
     // Double check state, because another thread may have seen the same state
     // and done the synchronization before the current thread.
     if (state_ == STATE_MODIFIED_MAP) {
       SyncRepeatedFieldWithMapNoLock();
-      google::protobuf::internal::NoBarrier_Store(&state_, CLEAN);
+      // "Release" insures state_ can only be changed "after"
+      // SyncRepeatedFieldWithMapNoLock is finished.
+      google::protobuf::internal::Release_Store(&state_, CLEAN);
     }
     mutex_.Unlock();
   }
@@ -119,19 +123,23 @@ void MapFieldBase::SyncRepeatedFieldWithMap() const {
 
 void MapFieldBase::SyncRepeatedFieldWithMapNoLock() const {
   if (repeated_field_ == NULL) {
-    repeated_field_ = Arena::Create<RepeatedPtrField<Message> >(arena_, arena_);
+    repeated_field_ = Arena::CreateMessage<RepeatedPtrField<Message> >(arena_);
   }
 }
 
 void MapFieldBase::SyncMapWithRepeatedField() const {
-  Atomic32 state = google::protobuf::internal::NoBarrier_Load(&state_);
+  // "Acquire" insures the operation after SyncMapWithRepeatedField won't get
+  // executed before state_ is checked.
+  Atomic32 state = google::protobuf::internal::Acquire_Load(&state_);
   if (state == STATE_MODIFIED_REPEATED) {
     mutex_.Lock();
     // Double check state, because another thread may have seen the same state
     // and done the synchronization before the current thread.
     if (state_ == STATE_MODIFIED_REPEATED) {
       SyncMapWithRepeatedFieldNoLock();
-      google::protobuf::internal::NoBarrier_Store(&state_, CLEAN);
+      // "Release" insures state_ can only be changed "after"
+      // SyncRepeatedFieldWithMapNoLock is finished.
+      google::protobuf::internal::Release_Store(&state_, CLEAN);
     }
     mutex_.Unlock();
   }