ipc/chromium/src/base/revocable_store.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style license that can be
   5 // found in the LICENSE file.
   6
   7 #ifndef BASE_REVOCABLE_STORE_H_
   8 #define BASE_REVOCABLE_STORE_H_
   9
  10 #include "base/basictypes.h"
  11 #include "nsISupportsImpl.h"
  12
  13 // |RevocableStore| is a container of items that can be removed from the store.
  14 class RevocableStore {
  15  public:
  16   // A |StoreRef| is used to link the |RevocableStore| to its items.  There is
  17   // one StoreRef per store, and each item holds a reference to it.  If the
  18   // store wishes to revoke its items, it sets |store_| to null.  Items are
  19   // permitted to release their reference to the |StoreRef| when they no longer
  20   // require the store.
  21   class StoreRef final {
  22    public:
  23     NS_INLINE_DECL_THREADSAFE_REFCOUNTING(StoreRef)
  24     explicit StoreRef(RevocableStore* aStore) : store_(aStore) {}
  25
  26     void set_store(RevocableStore* aStore) { store_ = aStore; }
  27     RevocableStore* store() const { return store_; }
  28
  29    protected:
  30     ~StoreRef() {}
  31
  32    private:
  33     RevocableStore* store_;
  34
  35     DISALLOW_EVIL_CONSTRUCTORS(StoreRef);
  36   };
  37
  38   // An item in the store.  On construction, the object adds itself to the
  39   // store.
  40   class Revocable {
  41    public:
  42     explicit Revocable(RevocableStore* store);
  43     ~Revocable() = default;
  44
  45     // This item has been revoked if it no longer has a pointer to the store.
  46     bool revoked() const { return !store_reference_->store(); }
  47
  48    private:
  49     // We hold a reference to the store through this ref pointer.  We release
  50     // this reference on destruction.
  51     RefPtr<StoreRef> store_reference_;
  52
  53     DISALLOW_EVIL_CONSTRUCTORS(Revocable);
  54   };
  55
  56   RevocableStore();
  57   ~RevocableStore();
  58
  59   // Revokes all the items in the store.
  60   void RevokeAll();
  61
  62  private:
  63   friend class Revocable;
  64
  65   // Adds an item to the store.  To add an item to the store, construct it
  66   // with a pointer to the store.
  67   void Add(Revocable* item);
  68
  69   // This is the reference the unrevoked items in the store hold.
  70   RefPtr<StoreRef> owning_reference_;
  71
  72   DISALLOW_EVIL_CONSTRUCTORS(RevocableStore);
  73 };
  74
  75 #endif  // BASE_REVOCABLE_STORE_H_