Optimize the message queue for many active ports with few messages.

runtime/vm/message_handler.cc

 // Copyright (c) 2011, 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/message_handler.h"
+#include "vm/port.h"
 #include "vm/dart.h"
 
 namespace dart {
 
 DECLARE_FLAG(bool, trace_isolates);
 
 
 class MessageHandlerTask : public ThreadPool::Task {
  public:
   explicit MessageHandlerTask(MessageHandler* handler)
@@ skipping 127 matching lines @@
                 "\thandler:    %s\n"
                 "\tport:       %"Pd64"\n",
                 name(), message->dest_port());
     }
 
     // Release the monitor_ temporarily while we handle the message.
     // The monitor was acquired in MessageHandler::TaskCallback().
     monitor_.Exit();
     Message::Priority saved_priority = message->priority();
     result = HandleMessage(message);
-    // ASSERT(Isolate::Current() == NULL);
     monitor_.Enter();
-
     if (!result) {
       // If we hit an error, we're done processing messages.
       break;
     }
     if (!allow_multiple_normal_messages &&
         saved_priority == Message::kNormalPriority) {
       // Some callers want to process only one normal message and then quit.
       break;
     }
     message = DequeueMessage(min_priority);
@@ skipping 65 matching lines @@
 
 
 void MessageHandler::ClosePort(Dart_Port port) {
   MonitorLocker ml(&monitor_);
   if (FLAG_trace_isolates) {
     OS::Print("[-] Closing port:\n"
               "\thandler:    %s\n"
               "\tport:       %"Pd64"\n",
               name(), port);
   }
-  queue_->Flush(port);
-  oob_queue_->Flush(port);
 }
 
 
 void MessageHandler::CloseAllPorts() {
   MonitorLocker ml(&monitor_);
   if (FLAG_trace_isolates) {
     OS::Print("[-] Closing all ports:\n"
               "\thandler:    %s\n",
               name());
   }
-  queue_->FlushAll();
-  oob_queue_->FlushAll();
+  queue_->Clear();
+  oob_queue_->Clear();
 }
 
 
 void MessageHandler::increment_live_ports() {
   MonitorLocker ml(&monitor_);
 #if defined(DEBUG)
   CheckAccess();
 #endif
   live_ports_++;
 }
 
 
 void MessageHandler::decrement_live_ports() {
   MonitorLocker ml(&monitor_);
 #if defined(DEBUG)
   CheckAccess();
 #endif
   live_ports_--;
 }
 
 }  // namespace dart