Fix reuse of free blocks and delete global cache on VM shutdown.

runtime/vm/store_buffer.cc

 // Copyright (c) 2012, 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/store_buffer.h"
 
 #include "platform/assert.h"
 #include "vm/lockers.h"
 #include "vm/runtime_entry.h"
 
 namespace dart {
 
 DEFINE_LEAF_RUNTIME_ENTRY(void, StoreBufferBlockProcess, 1, Thread* thread) {
   thread->StoreBufferBlockProcess(true);
 }
 END_LEAF_RUNTIME_ENTRY
 
 
 StoreBuffer::List* StoreBuffer::global_empty_ = NULL;
 Mutex* StoreBuffer::global_mutex_ = NULL;
 
 
 void StoreBuffer::InitOnce() {
   global_empty_ = new List();
   global_mutex_ = new Mutex();
 }
 
 
+void StoreBuffer::ShutDown() {
+  delete global_empty_;
+  delete global_mutex_;
+}
+
+
 StoreBuffer::StoreBuffer() : mutex_(new Mutex()) {
 }
 
 
 StoreBuffer::~StoreBuffer() {
   Reset();
   delete mutex_;
 }
 
 
@@ skipping 59 matching lines @@
     }
   }
   return PopEmptyBlock();
 }
 
 
 StoreBufferBlock* StoreBuffer::PopEmptyBlock() {
   {
     MutexLocker ml(global_mutex_);
     if (!global_empty_->IsEmpty()) {
-      global_empty_->Pop();
+      return global_empty_->Pop();
     }
   }
   return new StoreBufferBlock();
 }
 
 
 StoreBufferBlock* StoreBuffer::PopNonEmptyBlock() {
   MutexLocker ml(mutex_);
   if (!full_.IsEmpty()) {
     return full_.Pop();
@@ skipping 50 matching lines @@
 
 
 void StoreBuffer::TrimGlobalEmpty() {
   DEBUG_ASSERT(global_mutex_->IsOwnedByCurrentThread());
   while (global_empty_->length() > kMaxGlobalEmpty) {
     delete global_empty_->Pop();
   }
 }
 
 }  // namespace dart