[heap] pause/resume inline allocation observers around scavenge

test/cctest/test-spaces.cc

 // Copyright 2011 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 854 matching lines @@
     CHECK_EQ(observer1.count(), 20);
     CHECK_EQ(observer2.count(), 2);
 
     // Callback should stop getting called after an observer is removed.
     new_space->RemoveInlineAllocationObserver(&observer1);
 
     AllocateUnaligned(new_space, 384);
     CHECK_EQ(observer1.count(), 20);  // no more notifications.
     CHECK_EQ(observer2.count(), 3);   // this one is still active.
 
+    // Ensure that Pause/ResumeInlineAllocationObservers work correctly.
+    AllocateUnaligned(new_space, 48);
+    CHECK_EQ(observer2.count(), 3);
+    new_space->PauseInlineAllocationObservers();
+    CHECK_EQ(observer2.count(), 3);
+    AllocateUnaligned(new_space, 384);
+    CHECK_EQ(observer2.count(), 3);
+    new_space->ResumeInlineAllocationObservers();
+    CHECK_EQ(observer2.count(), 3);
+    // Coupled with the 48 bytes allocated before the pause, another 48 bytes
+    // allocated here should trigger a notification.
+    AllocateUnaligned(new_space, 48);
+    CHECK_EQ(observer2.count(), 4);
+
     new_space->RemoveInlineAllocationObserver(&observer2);
     AllocateUnaligned(new_space, 384);
     CHECK_EQ(observer1.count(), 20);
-    CHECK_EQ(observer2.count(), 3);
+    CHECK_EQ(observer2.count(), 4);
   }
   isolate->Dispose();
 }
 
 
 UNINITIALIZED_TEST(InlineAllocationObserverCadence) {
   v8::Isolate::CreateParams create_params;
   create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
   v8::Isolate* isolate = v8::Isolate::New(create_params);
   {
@@ skipping 18 matching lines @@
     new_space->RemoveInlineAllocationObserver(&observer2);
 
     CHECK_EQ(observer1.count(), 32);
     CHECK_EQ(observer2.count(), 28);
   }
   isolate->Dispose();
 }
 
 }  // namespace internal
 }  // namespace v8