An exploration into the different behaviors of handles.

handles_gc_behavior.cpp

#include "v8.h"
#include "stdio.h"
using namespace v8;
void PrintlnWeakReferenceCallback(Persistent<Value> value, void * parameters) {
  printf("->invoking weak reference callback\n"); fflush(stdout);
  value.Dispose();
}

int main(int argc, char **args) {
  Persistent<Context> cxt(Context::New());
  Persistent<Object> p;
  cxt->Enter();
  {
    HandleScope hs;
    printf("Creating a New Object\n");
    p = Persistent<Object>::New(Object::New());
  }
  cxt->Exit();
  cxt.Dispose();
  while (!V8::IdleNotification()) {}
  printf("  Empty? %d\n", p.IsEmpty());
  printf("  NearDeath? %d\n", p.IsNearDeath());
  printf("  IsWeak? %d\n", p.IsWeak());
  printf("Making handle weak.\n");
  p.MakeWeak(0, PrintlnWeakReferenceCallback);
  while (!V8::IdleNotification()) {}
  printf("  Empty? %d\n", p.IsEmpty());
  printf("  NearDeath? %d\n", p.IsNearDeath());
  printf("  IsWeak? %d\n", p.IsWeak());
  printf("Disposing of the handle\n");
  p.Dispose();
  while (!V8::IdleNotification()) {}
  printf("  Empty? %d\n", p.IsEmpty());
  printf("  NearDeath? %d\n", p.IsNearDeath());
  printf("  IsWeak? %d\n", p.IsWeak());
  printf("Clearing the handle\n");
  p.Clear();
  while (!V8::IdleNotification()) {}
  printf("  Empty? %d\n", p.IsEmpty());
  printf("  NearDeath? %d\n", p.IsNearDeath());
  printf("  IsWeak? %d\n", p.IsWeak());
  return 0;
}

output.txt

Creating a New Object
  Empty? 0
  NearDeath? 0
  IsWeak? 0
Making handle weak.
  Empty? 0
  NearDeath? 0
  IsWeak? 1
Disposing of the handle
  Empty? 0
  NearDeath? 0
  IsWeak? 0
Clearing the handle
  Empty? 1
  NearDeath? 0
  IsWeak? 0