Support "break"/suspend command

src/debug.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2246 matching lines @@
 // public API.
 void Debugger::InvokeMessageHandler(MessageImpl message) {
   ScopedLock with(debugger_access_);
 
   if (message_handler_ != NULL) {
     message_handler_(message);
   }
 }
 
 
+static bool CompareAsciiWithUtf16(const char* s1, Vector<const uint16_t> s2) {
+  const char* p = s1;
+  int i = 0;
+  while (*p != '\0' && i < s2.length()) {
+    if (static_cast<uint16_t>(*p) != s2[i]) {
+      return false;
+    }
+    ++p;
+    ++i;
+  }
+
+  return *p == '\0' && i == s2.length();
+}
+
+
 // Puts a command coming from the public API on the queue.  Creates
 // a copy of the command string managed by the debugger.  Up to this
 // point, the command data was managed by the API client.  Called
 // by the API client thread.
 void Debugger::ProcessCommand(Vector<const uint16_t> command,
                               v8::Debug::ClientData* client_data) {
+  // First check for non-JSON command break. VM is supposed to be busy,
+  // so we cannot use it to handle JSON.
+  if (CompareAsciiWithUtf16("break", command)) {

[Mikhail Naganov, 2009/08/05 07:37:00]

FYI, an alternative to rolling out your own comparison function would be using
V8 strings:

Handle<String> request = Factory::NewStringFromTwoByte(command);
if (request->IsEqualTo(CStrVector("break")) {
...

+    PrintF("v8::Debug::DebugBreak()\n");
+    v8::Debug::DebugBreak();
+    return;
+  }
+
   // Need to cast away const.
   CommandMessage message = CommandMessage::New(
       Vector<uint16_t>(const_cast<uint16_t*>(command.start()),
                        command.length()),
       client_data);
   Logger::DebugTag("Put command on command_queue.");
   command_queue_.Put(message);
   command_received_->Signal();
 
   // Set the debug command break flag to have the command processed.
@@ skipping 279 matching lines @@
 
 
 void LockingCommandMessageQueue::Clear() {
   ScopedLock sl(lock_);
   queue_.Clear();
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal