mfbt/ReentrancyGuard.h
author Jan de Mooij <jdemooij@mozilla.com>
Sat, 12 Jan 2019 10:50:04 +0000
changeset 453631 cfa1c48c717048f00eb4811b5719cd716eb1e5b3
parent 448947 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1518753 part 5 - Stop using JSProtoKey for initial shapes. r=tcampbell I added this optimization in bug 1299107 to share more shapes across compartments. Unfortunately this doesn't play well with same-compartment realms (ICs can misbehave) because it relies on compartments being isolated from each other. I think we should remove this optimization: * Fixing the IC issue is impossible without deoptimizing everything. * I added it mainly for chrome globals. The shared-JSM-global work has eliminated the need for this there. * Same-compartment realms win memory back by eliminating CCWs etc. * It's quite a lot of complicated code. Differential Revision: https://phabricator.services.mozilla.com/D16170

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* Small helper class for asserting uses of a class are non-reentrant. */

#ifndef mozilla_ReentrancyGuard_h
#define mozilla_ReentrancyGuard_h

#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/GuardObjects.h"

namespace mozilla {

/* Useful for implementing containers that assert non-reentrancy */
class MOZ_RAII ReentrancyGuard {
  MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
#ifdef DEBUG
  bool& mEntered;
#endif

 public:
  template <class T>
#ifdef DEBUG
  explicit ReentrancyGuard(T& aObj MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
      : mEntered(aObj.mEntered)
#else
  explicit ReentrancyGuard(T& MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
#endif
  {
    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
#ifdef DEBUG
    MOZ_ASSERT(!mEntered);
    mEntered = true;
#endif
  }
  ~ReentrancyGuard() {
#ifdef DEBUG
    mEntered = false;
#endif
  }

 private:
  ReentrancyGuard(const ReentrancyGuard&) = delete;
  void operator=(const ReentrancyGuard&) = delete;
};

}  // namespace mozilla

#endif /* mozilla_ReentrancyGuard_h */