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 <utility>
   8
   9 #include "base/atomic_ref_count.h"
  10 #include "base/bind.h"
  11 #include "base/memory/ptr_util.h"
  12
  13 namespace base {
  14 namespace {
  15
  16 // Maintains state for a BarrierClosure.
  17 class BarrierInfo {
  18  public:
  19   BarrierInfo(int num_callbacks_left, OnceClosure done_closure);
  20   void Run();
  21
  22  private:
  23   AtomicRefCount num_callbacks_left_;
  24   OnceClosure done_closure_;
  25 };
  26
  27 BarrierInfo::BarrierInfo(int num_callbacks, OnceClosure done_closure)
  28     : num_callbacks_left_(num_callbacks),
  29       done_closure_(std::move(done_closure)) {}
  30
  31 void BarrierInfo::Run() {
  32   DCHECK(!num_callbacks_left_.IsZero());
  33   if (!num_callbacks_left_.Decrement())
  34     std::move(done_closure_).Run();
  35 }
  36
  37 }  // namespace
  38
  39 RepeatingClosure BarrierClosure(int num_callbacks_left,
  40                                 OnceClosure done_closure) {
  41   DCHECK_GE(num_callbacks_left, 0);
  42
  43   if (num_callbacks_left == 0)
  44     std::move(done_closure).Run();
  45
  46   return BindRepeating(
  47       &BarrierInfo::Run,
  48       Owned(new BarrierInfo(num_callbacks_left, std::move(done_closure))));
  49 }
  50
  51 }  // namespace base