Make type canonicalization thread safe

runtime/vm/isolate.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/isolate.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 #include "platform/assert.h"
 #include "platform/text_buffer.h"
@@ skipping 772 matching lines @@
       library_tag_handler_(NULL),
       api_state_(NULL),
       debugger_(NULL),
       resume_request_(false),
       last_resume_timestamp_(OS::GetCurrentTimeMillis()),
       has_compiled_code_(false),
       random_(),
       simulator_(NULL),
       mutex_(new Mutex()),
       symbols_mutex_(new Mutex()),
+      type_canonicalization_mutex_(new Mutex()),
       saved_stack_limit_(0),
       deferred_interrupts_mask_(0),
       deferred_interrupts_(0),
       stack_overflow_flags_(0),
       stack_overflow_count_(0),
       message_handler_(NULL),
       spawn_state_(NULL),
       is_runnable_(false),
       gc_prologue_callback_(NULL),
       gc_epilogue_callback_(NULL),
@@ skipping 43 matching lines @@
   if (FLAG_support_debugger) {
     delete debugger_;
   }
 #if defined(USING_SIMULATOR)
   delete simulator_;
 #endif
   delete mutex_;
   mutex_ = NULL;  // Fail fast if interrupts are scheduled on a dead isolate.
   delete symbols_mutex_;
   symbols_mutex_ = NULL;
+  delete type_canonicalization_mutex_;
+  type_canonicalization_mutex_ = NULL;
   delete message_handler_;
   message_handler_ = NULL;  // Fail fast if we send messages to a dead isolate.
   ASSERT(deopt_context_ == NULL);  // No deopt in progress when isolate deleted.
   delete spawn_state_;
   if (FLAG_support_service) {
     delete object_id_ring_;
   }
   object_id_ring_ = NULL;
   delete pause_loop_monitor_;
   pause_loop_monitor_ = NULL;
@@ skipping 1944 matching lines @@
 void IsolateSpawnState::DecrementSpawnCount() {
   ASSERT(spawn_count_monitor_ != NULL);
   ASSERT(spawn_count_ != NULL);
   MonitorLocker ml(spawn_count_monitor_);
   ASSERT(*spawn_count_ > 0);
   *spawn_count_ = *spawn_count_ - 1;
   ml.Notify();
 }
 
 }  // namespace dart