Serializer enable/disable flags need thread safety.

src/serialize.cc

Index: src/serialize.cc
diff --git a/src/serialize.cc b/src/serialize.cc
index b271fa2a0fdb50adbf02daa4d45ebe394905291a..42c6d698c7af3c79fc247a91d4c4b7fff0362720 100644
--- a/src/serialize.cc
+++ b/src/serialize.cc
@@ -649,10 +649,7 @@ ExternalReferenceDecoder::~ExternalReferenceDecoder() {
   DeleteArray(encodings_);
 }
 
-
-bool Serializer::serialization_enabled_ = false;
-bool Serializer::too_late_to_enable_now_ = false;
-
+Atomic32 Serializer::serialization_state_ = SERIALIZER_STATE_UNINITIALIZED;

[Hannes Payer (out of office), 2014/04/17 09:48:10]

AtomicWord

[mvstanton, 2014/04/17 14:18:29]

Done.

 
 class CodeAddressMap: public CodeEventLogger {
  public:
@@ -765,22 +762,33 @@ class CodeAddressMap: public CodeEventLogger {
 CodeAddressMap* Serializer::code_address_map_ = NULL;
 
 
-void Serializer::Enable(Isolate* isolate) {
-  if (!serialization_enabled_) {
-    ASSERT(!too_late_to_enable_now_);
-  }
-  if (serialization_enabled_) return;
-  serialization_enabled_ = true;
+void Serializer::RequestEnable(Isolate* isolate) {
   isolate->InitializeLoggingAndCounters();
   code_address_map_ = new CodeAddressMap(isolate);
 }
 
 
-void Serializer::Disable() {
-  if (!serialization_enabled_) return;
-  serialization_enabled_ = false;
-  delete code_address_map_;
-  code_address_map_ = NULL;
+void Serializer::InitializeOncePerProcess() {
+  ASSERT(NoBarrier_Load(&serialization_state_) ==
+         SERIALIZER_STATE_UNINITIALIZED);
+  SerializationState state = code_address_map_
+      ? SERIALIZER_STATE_ENABLED
+      : SERIALIZER_STATE_DISABLED;
+  NoBarrier_Store(&serialization_state_, state);

[Hannes Payer (out of office), 2014/04/17 09:48:10]

Can we have a comment here why this works and why no barrier loads/stores are
fine.
Can there by a enable/disable race?

[mvstanton, 2014/04/17 14:18:29]

Yes, done, and no.

+}
+
+
+void Serializer::TearDown() {
+  ASSERT(NoBarrier_Load(&serialization_state_) !=
+         SERIALIZER_STATE_UNINITIALIZED);
+  if (code_address_map_) {
+    ASSERT(NoBarrier_Load(&serialization_state_) ==
+           SERIALIZER_STATE_ENABLED);
+    delete code_address_map_;
+    code_address_map_ = NULL;
+  }
+
+  NoBarrier_Store(&serialization_state_, SERIALIZER_STATE_UNINITIALIZED);

[Hannes Payer (out of office), 2014/04/17 09:48:10]

The assumption is that this method is just invoked by one thread, right?
Otherwise it wouldn't work. Please add a comment to explain the global picture.

[mvstanton, 2014/04/17 14:18:29]

Good point, done.

 }