Add a flag to d8 to invoke weak callbacks

src/d8.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.
 
 
 // Defined when linking against shared lib on Windows.
 #if defined(USING_V8_SHARED) && !defined(V8_SHARED)
 #define V8_SHARED
 #endif
 
@@ skipping 1172 matching lines @@
 #ifndef V8_SHARED
 i::Thread::Options SourceGroup::GetThreadOptions() {
   // On some systems (OSX 10.6) the stack size default is 0.5Mb or less
   // which is not enough to parse the big literal expressions used in tests.
   // The stack size should be at least StackGuard::kLimitSize + some
   // OS-specific padding for thread startup code.  2Mbytes seems to be enough.
   return i::Thread::Options("IsolateThread", 2 * MB);
 }
 
 
+void SuggestivelyAskForAggressiveGC() {
+  if (Shell::options.send_idle_notification) {
+    const int kLongIdlePauseInMs = 1000;
+    V8::ContextDisposedNotification();
+    V8::IdleNotification(kLongIdlePauseInMs);
+  }
+  if (Shell::options.invoke_weak_callbacks) {
+    // By sending a low memory notifications, we will try hard to collect
+    // all garbage and will therefore also invoke all weak callbacks of
+    // actually unreachable persistent handles.
+    V8::LowMemoryNotification();
+  }
+}
+
+
 void SourceGroup::ExecuteInThread() {
   Isolate* isolate = Isolate::New();
   do {
     next_semaphore_.Wait();
     {
       Isolate::Scope iscope(isolate);
       {
         HandleScope scope(isolate);
         PerIsolateData data(isolate);
         Local<Context> context = Shell::CreateEvaluationContext(isolate);
         {
           Context::Scope cscope(context);
           PerIsolateData::RealmScope realm_scope(PerIsolateData::Get(isolate));
           Execute(isolate);
         }
       }
-      if (Shell::options.send_idle_notification) {
-        const int kLongIdlePauseInMs = 1000;
-        V8::ContextDisposedNotification();
-        V8::IdleNotification(kLongIdlePauseInMs);
-      }
+      SuggestivelyAskForAggressiveGC();
     }
     done_semaphore_.Signal();
   } while (!Shell::options.last_run);
+
   isolate->Dispose();
 }
 
 
 void SourceGroup::StartExecuteInThread() {
   if (thread_ == NULL) {
     thread_ = new IsolateThread(this);
     thread_->Start();
   }
   next_semaphore_.Signal();
@@ skipping 40 matching lines @@
       argv[i] = NULL;
     } else if (strcmp(argv[i], "--shell") == 0) {
       options.interactive_shell = true;
       argv[i] = NULL;
     } else if (strcmp(argv[i], "--test") == 0) {
       options.test_shell = true;
       argv[i] = NULL;
     } else if (strcmp(argv[i], "--send-idle-notification") == 0) {
       options.send_idle_notification = true;
       argv[i] = NULL;
+    } else if (strcmp(argv[i], "--invoke-weak-callbacks") == 0) {
+      options.invoke_weak_callbacks = true;
+      // TODO(jochen) See issue 3351
+      options.send_idle_notification = true;
+      argv[i] = NULL;
     } else if (strcmp(argv[i], "-f") == 0) {
       // Ignore any -f flags for compatibility with other stand-alone
       // JavaScript engines.
       continue;
     } else if (strcmp(argv[i], "--isolate") == 0) {
 #ifdef V8_SHARED
       printf("D8 with shared library does not support multi-threading\n");
       return false;
 #endif  // V8_SHARED
       options.num_isolates++;
@@ skipping 68 matching lines @@
         InstallUtilityScript(isolate);
       }
 #endif  // !V8_SHARED
     }
     {
       Context::Scope cscope(context);
       PerIsolateData::RealmScope realm_scope(PerIsolateData::Get(isolate));
       options.isolate_sources[0].Execute(isolate);
     }
   }
-  if (options.send_idle_notification) {
-    const int kLongIdlePauseInMs = 1000;
-    V8::ContextDisposedNotification();
-    V8::IdleNotification(kLongIdlePauseInMs);
-  }
+  SuggestivelyAskForAggressiveGC();
 
 #ifndef V8_SHARED
   for (int i = 1; i < options.num_isolates; ++i) {
     options.isolate_sources[i].WaitForThread();
   }
 #endif  // !V8_SHARED
   return 0;
 }
 
 
@@ skipping 162 matching lines @@
 }
 
 }  // namespace v8
 
 
 #ifndef GOOGLE3
 int main(int argc, char* argv[]) {
   return v8::Shell::Main(argc, argv);
 }
 #endif