[futex] Allow debugger to break in the middle of a futexWait

src/debug/debug.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/debug/debug.h"
 
 #include "src/api.h"
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 2258 matching lines @@
   // Ignore debug break if debugger is not active.
   if (!is_active()) return;
 
   StackLimitCheck check(isolate_);
   if (check.HasOverflowed()) return;
 
   { JavaScriptFrameIterator it(isolate_);
     DCHECK(!it.done());
     Object* fun = it.frame()->function();
     if (fun && fun->IsJSFunction()) {
+      HandleScope scope(isolate_);
       // Don't stop in builtin functions.
-      if (!JSFunction::cast(fun)->IsSubjectToDebugging()) return;
-      GlobalObject* global = JSFunction::cast(fun)->context()->global_object();
+      Handle<JSFunction> jsfun(JSFunction::cast(fun));

[Yang, 2015/08/27 06:27:25]

I think it might be cleaner to just pass in an optional parameter from
FutexEmulation::Wait through Execution::HandleInterrupts to here, stating that
the interrupt comes from futex wait.

[binji, 2015/08/31 21:25:18]

Done.

+      if (!jsfun->IsSubjectToDebugging()) {
+        // Make an exception for futexWait.
+        Handle<String> name(String::cast(jsfun->shared()->name()));
+        if (!String::Equals(name, isolate_->factory()->futexWait_string())) {
+          return;
+        }
+      }
+      GlobalObject* global = jsfun->context()->global_object();
       // Don't stop in debugger functions.
       if (IsDebugGlobal(global)) return;
     }
   }
 
   // Collect the break state before clearing the flags.
   bool debug_command_only = isolate_->stack_guard()->CheckDebugCommand() &&
                             !isolate_->stack_guard()->CheckDebugBreak();
 
   isolate_->stack_guard()->ClearDebugBreak();
@@ skipping 321 matching lines @@
 }
 
 
 void LockingCommandMessageQueue::Clear() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
   queue_.Clear();
 }
 
 }  // namespace internal
 }  // namespace v8