Eliminate busy waiting for debugger connection

runtime/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/dartutils.h"
 #include "bin/socket.h"
 #include "bin/thread.h"
 #include "bin/utils.h"
 
 #include "platform/globals.h"
 #include "platform/json.h"
 #include "platform/thread.h"
 #include "platform/utils.h"
 
 #include "include/dart_api.h"
 
 
 int DebuggerConnectionHandler::listener_fd_ = -1;
 int DebuggerConnectionHandler::debugger_fd_ = -1;
+dart::Monitor DebuggerConnectionHandler::is_connected_;
 MessageBuffer* DebuggerConnectionHandler::msgbuf_ = NULL;
 
 bool DebuggerConnectionHandler::handler_started_ = false;
 
 
 // TODO(hausner): Need better error handling.
 #define ASSERT_NOT_ERROR(handle)                                               \
   ASSERT(!Dart_IsError(handle))
 
 
@@ skipping 171 matching lines @@
     ASSERT_NOT_ERROR(res);
     ASSERT(Dart_IsString(func_name));
     const char* func_name_chars;
     Dart_StringToCString(func_name, &func_name_chars);
     msg.Printf("%s { \"functionName\" : \"%s\" , ",
               i > 0 ? "," : "",
               func_name_chars);
     ASSERT(Dart_IsString(script_url));
     const char* script_url_chars;
     Dart_StringToCString(script_url, &script_url_chars);
-    msg.Printf("\"location\": { \"scriptId\": \"%s\", \"lineNumber\": %d }}",
+    msg.Printf("\"location\": { \"url\": \"%s\", \"lineNumber\": %d }}",
                script_url_chars, line_number);
   }
   msg.Printf("]}}");
   Socket::Write(debugger_fd_, msg.buf(), msg.length());
   ASSERT(IsValidJSON(msg.buf()));
 }
 
 
 void DebuggerConnectionHandler::BreakpointHandler(Dart_Breakpoint bpt,
                                                   Dart_StackTrace trace) {
-  // TODO(hausner): rather than busy-waiting, block on the pipe to the
-  // debugger thread and wait until a debugger connection has been
-  // established.
-  while (!IsConnected()) {
-    // Busy wait.
+  {
+    MonitorLocker ml(&is_connected_);
+    while (!IsConnected()) {
+      printf("Waiting for debugger connection...\n");
+      dart::Monitor::WaitResult res = ml.Wait(dart::Monitor::kNoTimeout);
+      ASSERT(res == dart::Monitor::kNotified);
+    }
   }
   SendBreakpointEvent(bpt, trace);
   HandleMessages();
   if (!msgbuf_->Alive()) {
     CloseDbgConnection();
   }
 }
 
 
 void DebuggerConnectionHandler::AcceptDbgConnection(int debugger_fd) {
   debugger_fd_ = debugger_fd;
   ASSERT(msgbuf_ == NULL);
   msgbuf_ = new MessageBuffer(debugger_fd_);
+  {
+    MonitorLocker ml(&is_connected_);
+    ml.Notify();
+  }
 }
 
 void DebuggerConnectionHandler::CloseDbgConnection() {
   if (debugger_fd_ >= 0) {
     // TODO(hausner): need a Socket::Close() function.
   }
   if (msgbuf_ != NULL) {
     delete msgbuf_;
     msgbuf_ = NULL;
   }
@@ skipping 11 matching lines @@
 
   handler_started_ = true;
   DebuggerConnectionImpl::StartHandler(port_number);
   Dart_SetBreakpointHandler(BreakpointHandler);
 }
 
 
 DebuggerConnectionHandler::~DebuggerConnectionHandler() {
   CloseDbgConnection();
 }