ipc/chromium/src/base/revocable_store.h
author Josh Aas <joshmoz@gmail.com>
Thu, 18 Sep 2014 15:52:59 -0500
changeset 206112 d77733726cae101e5a1754e7507636bde4ca80c1
parent 198057 e4750e8e7a21c888d0623935a90efdc1fc4fb06e
child 206118 14fc678064b3d0a784198f81a9659caa9c2e2449
permissions -rw-r--r--
Bug 1063318: Switch Chromium IPC code to Mozilla's ref/auto ptr types. Also fix thread safety bug. r=nfroyd

// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_REVOCABLE_STORE_H_
#define BASE_REVOCABLE_STORE_H_

#include "base/basictypes.h"
#include "nsISupportsImpl.h"
#include "nsAutoPtr.h"

// |RevocableStore| is a container of items that can be removed from the store.
class RevocableStore {
 public:
  // A |StoreRef| is used to link the |RevocableStore| to its items.  There is
  // one StoreRef per store, and each item holds a reference to it.  If the
  // store wishes to revoke its items, it sets |store_| to null.  Items are
  // permitted to release their reference to the |StoreRef| when they no longer
  // require the store.
  class StoreRef MOZ_FINAL {
   public:
    NS_INLINE_DECL_THREADSAFE_REFCOUNTING(StoreRef)
    explicit StoreRef(RevocableStore* store) : store_(store) { }

    void set_store(RevocableStore* store) { store_ = store; }
    RevocableStore* store() const { return store_; }

   protected:
    ~StoreRef() {}
   private:
    RevocableStore* store_;

    DISALLOW_EVIL_CONSTRUCTORS(StoreRef);
  };

  // An item in the store.  On construction, the object adds itself to the
  // store.
  class Revocable {
   public:
    explicit Revocable(RevocableStore* store);
    ~Revocable();

    // This item has been revoked if it no longer has a pointer to the store.
    bool revoked() const { return !store_reference_->store(); }

  private:
    // We hold a reference to the store through this ref pointer.  We release
    // this reference on destruction.
    nsRefPtr<StoreRef> store_reference_;

    DISALLOW_EVIL_CONSTRUCTORS(Revocable);
  };

  RevocableStore();
  ~RevocableStore();

  // Revokes all the items in the store.
  void RevokeAll();

  // Returns true if there are no items in the store.
  bool empty() const { return count_ == 0; }

 private:
  friend class Revocable;

  // Adds an item to the store.  To add an item to the store, construct it
  // with a pointer to the store.
  void Add(Revocable* item);

  // This is the reference the unrevoked items in the store hold.
  nsRefPtr<StoreRef> owning_reference_;

  // The number of unrevoked items in the store.
  int count_;

  DISALLOW_EVIL_CONSTRUCTORS(RevocableStore);
};

#endif  // BASE_REVOCABLE_STORE_H_