base/barrier_closure.cc

   1 // Copyright 2013 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 #include "base/barrier_closure.h"
   6
   7 #include "base/atomic_ref_count.h"
   8 #include "base/bind.h"
   9
  10 namespace {
  11
  12 // Maintains state for a BarrierClosure.
  13 class BarrierInfo {
  14  public:
  15   BarrierInfo(int num_callbacks_left, const base::Closure& done_closure);
  16   void Run();
  17
  18  private:
  19   base::AtomicRefCount num_callbacks_left_;
  20   base::Closure done_closure_;
  21 };
  22
  23 BarrierInfo::BarrierInfo(int num_callbacks, const base::Closure& done_closure)
  24     : num_callbacks_left_(num_callbacks),
  25       done_closure_(done_closure) {
  26 }
  27
  28 void BarrierInfo::Run() {
  29   DCHECK(!base::AtomicRefCountIsZero(&num_callbacks_left_));
  30   if (!base::AtomicRefCountDec(&num_callbacks_left_)) {
  31     base::Closure done_closure = done_closure_;
  32     done_closure_.Reset();
  33     done_closure.Run();
  34   }
  35 }
  36
  37 }  // namespace
  38
  39 namespace base {
  40
  41 base::Closure BarrierClosure(int num_callbacks_left,
  42                              const base::Closure& done_closure) {
  43   DCHECK_GE(num_callbacks_left, 0);
  44
  45   if (num_callbacks_left == 0)
  46     done_closure.Run();
  47
  48   return base::Bind(&BarrierInfo::Run,
  49                     base::Owned(
  50                         new BarrierInfo(num_callbacks_left, done_closure)));
  51 }
  52
  53 }  // namespace base