1 // Copyright 2013 The Chromium Authors 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/functional/bind.h" 11 #include "base/memory/ptr_util.h" 12 #include "base/numerics/safe_conversions.h" 13 14 namespace base { 15 namespace { 16 17 // Maintains state for a BarrierClosure. 18 class BarrierInfo { 19 public: 20 BarrierInfo(size_t num_callbacks_left, OnceClosure done_closure); 21 BarrierInfo(const BarrierInfo&) = delete; 22 BarrierInfo& operator=(const BarrierInfo&) = delete; 23 void Run(); 24 25 private: 26 AtomicRefCount num_callbacks_left_; 27 OnceClosure done_closure_; 28 }; 29 BarrierInfo(size_t num_callbacks,OnceClosure done_closure)30BarrierInfo::BarrierInfo(size_t num_callbacks, OnceClosure done_closure) 31 : num_callbacks_left_(checked_cast<int>(num_callbacks)), 32 done_closure_(std::move(done_closure)) {} 33 Run()34void BarrierInfo::Run() { 35 DCHECK(!num_callbacks_left_.IsZero()); 36 if (!num_callbacks_left_.Decrement()) 37 std::move(done_closure_).Run(); 38 } 39 ShouldNeverRun()40void ShouldNeverRun() { 41 CHECK(false); 42 } 43 44 } // namespace 45 BarrierClosure(size_t num_callbacks_left,OnceClosure done_closure)46RepeatingClosure BarrierClosure(size_t num_callbacks_left, 47 OnceClosure done_closure) { 48 if (num_callbacks_left == 0) { 49 std::move(done_closure).Run(); 50 return BindRepeating(&ShouldNeverRun); 51 } 52 53 return BindRepeating(&BarrierInfo::Run, 54 std::make_unique<BarrierInfo>(num_callbacks_left, 55 std::move(done_closure))); 56 } 57 58 } // namespace base 59