chrome/browser/sync_file_system/drive_backend/callback_tracker.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_CALLBACK_TRACKER_H_
   6 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_CALLBACK_TRACKER_H_
   7
   8 #include <map>
   9
  10 #include "base/bind.h"
  11 #include "base/callback_forward.h"
  12 #include "base/memory/weak_ptr.h"
  13 #include "chrome/browser/sync_file_system/drive_backend/callback_tracker_internal.h"
  14
  15 namespace sync_file_system {
  16 namespace drive_backend {
  17
  18 // A helper class to ensure one-shot callback to be called exactly once.
  19 //
  20 // Usage:
  21 //   class Foo {
  22 //    private:
  23 //     CallbackTracker callback_tracker_;
  24 //   };
  25 //
  26 //   void DoSomethingAsync(const SomeCallbackType& callback) {
  27 //     base::Closure abort_case_handler = base::Bind(callback, ABORT_ERROR);
  28 //
  29 //     SomeCallbackType wrapped_callback =
  30 //         callback_tracker_.Register(
  31 //             abort_case_handler, callback);
  32 //
  33 //     // The body of the operation goes here.
  34 //   }
  35 class CallbackTracker {
  36  public:
  37   typedef std::map<internal::AbortHelper*, base::Closure> AbortClosureByHelper;
  38
  39   CallbackTracker();
  40   ~CallbackTracker();
  41
  42   // Returns a wrapped callback.
  43   // Upon AbortAll() call, CallbackTracker invokes |abort_closure| and voids all
  44   // wrapped callbacks returned by Register().
  45   // Invocation of the wrapped callback unregisters |callback| from
  46   // CallbackTracker.
  47   template <typename T>
  48   base::Callback<T> Register(const base::Closure& abort_closure,
  49                              const base::Callback<T>& callback) {
  50     internal::AbortHelper* helper = new internal::AbortHelper(this);
  51     helpers_[helper] = abort_closure;
  52     return base::Bind(&internal::InvokeAndInvalidateHelper<T>::Run,
  53                       helper->AsWeakPtr(), callback);
  54   }
  55
  56   void AbortAll();
  57
  58  private:
  59   friend class internal::AbortHelper;
  60
  61   scoped_ptr<internal::AbortHelper> PassAbortHelper(
  62       internal::AbortHelper* helper);
  63
  64   AbortClosureByHelper helpers_;  // Owns AbortHelpers.
  65
  66   DISALLOW_COPY_AND_ASSIGN(CallbackTracker);
  67 };
  68
  69 }  // namespace drive_backend
  70 }  // namespace sync_file_system
  71
  72 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_CALLBACK_TRACKER_H_