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

runtime/vm/message.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.h"
 
 namespace dart {
 
 MessageQueue::MessageQueue() {
   head_ = NULL;
   tail_ = NULL;
 }
 
 
 MessageQueue::~MessageQueue() {
   // Ensure that all pending messages have been released.
-#if defined(DEBUG)
+  Clear();
   ASSERT(head_ == NULL);
-#endif
 }
 
 
 void MessageQueue::Enqueue(Message* msg) {
   // Make sure messages are not reused.
   ASSERT(msg->next_ == NULL);
   if (head_ == NULL) {
     // Only element in the queue.
     ASSERT(tail_ == NULL);
     head_ = msg;
@@ skipping 17 matching lines @@
     }
 #if defined(DEBUG)
     result->next_ = result;  // Make sure to trigger ASSERT in Enqueue.
 #endif  // DEBUG
     return result;
   }
   return NULL;
 }
 
 
-void MessageQueue::Flush(Dart_Port port) {
-  Message* cur = head_;
-  Message* prev = NULL;
-  while (cur != NULL) {
-    Message* next = cur->next_;
-    // If the message matches, then remove it from the queue and delete it.
-    if (cur->dest_port() == port) {
-      if (prev != NULL) {
-        prev->next_ = next;
-      } else {
-        head_ = next;
-      }
-      delete cur;
-    } else {
-      // Move prev forward.
-      prev = cur;
-    }
-    // Advance to the next message in the queue.
-    cur = next;
-  }
-  tail_ = prev;
-}
-
-
-void MessageQueue::FlushAll() {
+void MessageQueue::Clear() {
   Message* cur = head_;
   head_ = NULL;
   tail_ = NULL;
   while (cur != NULL) {
     Message* next = cur->next_;
     delete cur;
     cur = next;
   }
 }
 
 
 }  // namespace dart