Fix race condition when posting debugger messages to the message queue

bin/dbg_connection.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 "bin/dbg_connection.h"
 #include "bin/dbg_message.h"
 #include "bin/dartutils.h"
 #include "bin/socket.h"
 #include "bin/thread.h"
 #include "bin/utils.h"
@@ skipping 209 matching lines @@
       i++;
     }
     if (!is_handled) {
       // Check if this is an isolate specific command.
       int32_t cmd_idx = DbgMsgQueueList::LookupIsolateCommand(r.ValueChars(),
                                                               r.ValueLen());
       if (cmd_idx != DbgMsgQueueList::kInvalidCommand) {
         // Get debug message queue corresponding to isolate.
         // TODO(asiva): Once we have support for including the isolate id
         // in the debug wire protocol we need to read the isolate id and
-        // pass it down to GetIsolateMsgQueue to get the appropriate debug
-        // message queue.
-        DbgMsgQueue* queue =
-            DbgMsgQueueList::GetIsolateMsgQueue(ILLEGAL_ISOLATE_ID);
-        ASSERT(queue != NULL);
-        queue->AddMessage(cmd_idx, msgbuf_->buf(), r.EndOfObject(), debug_fd_);
+        // pass it down to AddIsolateMessage.
+        if (!DbgMsgQueueList::AddIsolateMessage(ILLEGAL_ISOLATE_ID,
+                                                cmd_idx,
+                                                msgbuf_->buf(),
+                                                r.EndOfObject(),
+                                                debug_fd_)) {
+          SendError(debug_fd_, MessageId(), "Invalid isolate specified");
+        }
         msgbuf_->PopMessage();
         continue;
       }
 
       // This is an unrecognized command, report error and move on to next.
       printf("unrecognized command received: '%s'\n", msgbuf_->buf());
       HandleUnknownMsg();
       msgbuf_->PopMessage();
     }
   }
@@ skipping 124 matching lines @@
 
 void DebuggerConnectionHandler::HandleInterruptCmd(DbgMessage* in_msg) {
   MessageParser msg_parser(in_msg->buffer(), in_msg->buffer_len());
   int msg_id = msg_parser.MessageId();
   Dart_IsolateId isolate_id =
       static_cast<Dart_IsolateId>(msg_parser.GetIntParam("isolateId"));
   if (isolate_id == ILLEGAL_ISOLATE_ID || Dart_GetIsolate(isolate_id) == NULL) {
     in_msg->SendErrorReply(msg_id, "Invalid isolate specified");
     return;
   }
-  DbgMsgQueue* queue = DbgMsgQueueList::GetIsolateMsgQueue(isolate_id);
-  ASSERT(queue != NULL);
-  queue->InterruptIsolate();
+  if (!DbgMsgQueueList::InterruptIsolate(isolate_id)) {
+    in_msg->SendErrorReply(msg_id, "Invalid isolate specified");
+    return;
+  }
   dart::TextBuffer msg(64);
   msg.Printf("{ \"id\": %d }", msg_id);
   in_msg->SendReply(&msg);
 }
 
 
 void DebuggerConnectionHandler::HandleIsolatesListCmd(DbgMessage* in_msg) {
   MessageParser msg_parser(in_msg->buffer(), in_msg->buffer_len());
   int msg_id = msg_parser.MessageId();
   ASSERT(msg_id >= 0);
@@ skipping 24 matching lines @@
   ASSERT(singleton_handler != NULL);
   return singleton_handler;
 }
 
 
 bool DebuggerConnectionHandler::IsConnected() {
   // TODO(asiva): Support multiple debugger connections.
   // Return true if a connection has been established.
   return singleton_handler != NULL;
 }