src/third_party/v8/test/mjsunit/harmony/weakrefs/unregister-inside-cleanup2.js

// Copyright 2018 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.

// Flags: --harmony-weak-refs --expose-gc --noincremental-marking

let cleanup_call_count = 0;
let cleanup_holdings_count = 0;
let cleanup = function(holdings) {
  // See which target we're cleaning up and unregister the other one.
  if (holdings == 1) {
    let success = fg.unregister(key2);
    assertTrue(success);
  } else {
    assertSame(holdings, 2);
    let success = fg.unregister(key1);
    assertTrue(success);
  }
  ++cleanup_holdings_count;
  ++cleanup_call_count;
}

let fg = new FinalizationRegistry(cleanup);
let key1 = {"k": "first key"};
let key2 = {"k": "second key"};
// Create two objects and register them in the FinalizationRegistry. The objects
// need to be inside a closure so that we can reliably kill them!

(function() {
  let object1 = {};
  fg.register(object1, 1, key1);
  let object2 = {};
  fg.register(object2, 2, key2);

  // object1 and object2 go out of scope.
})();

// This GC will reclaim target objects and schedule cleanup.
gc();
assertEquals(0, cleanup_call_count);

// Assert that the cleanup function was called and cleaned up one holdings (but not the other one).
let timeout_func = function() {
  assertEquals(1, cleanup_call_count);
  assertEquals(1, cleanup_holdings_count);
}

setTimeout(timeout_func, 0);