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/notreached.h" 13 #include "base/numerics/safe_conversions.h" 14 15 namespace base { 16 namespace { 17 18 // Maintains state for a BarrierClosure. 19 class BarrierInfo { 20 public: 21 BarrierInfo(size_t num_callbacks_left, OnceClosure done_closure); 22 BarrierInfo(const BarrierInfo&) = delete; 23 BarrierInfo& operator=(const BarrierInfo&) = delete; 24 void Run(); 25 26 private: 27 AtomicRefCount num_callbacks_left_; 28 OnceClosure done_closure_; 29 }; 30 BarrierInfo(size_t num_callbacks,OnceClosure done_closure)31BarrierInfo::BarrierInfo(size_t num_callbacks, OnceClosure done_closure) 32 : num_callbacks_left_(checked_cast<int>(num_callbacks)), 33 done_closure_(std::move(done_closure)) {} 34 Run()35void BarrierInfo::Run() { 36 DCHECK(!num_callbacks_left_.IsZero()); 37 if (!num_callbacks_left_.Decrement()) 38 std::move(done_closure_).Run(); 39 } 40 ShouldNeverRun()41void ShouldNeverRun() { 42 NOTREACHED(); 43 } 44 45 } // namespace 46 BarrierClosure(size_t num_callbacks_left,OnceClosure done_closure)47RepeatingClosure BarrierClosure(size_t num_callbacks_left, 48 OnceClosure done_closure) { 49 if (num_callbacks_left == 0) { 50 std::move(done_closure).Run(); 51 return BindRepeating(&ShouldNeverRun); 52 } 53 54 return BindRepeating(&BarrierInfo::Run, 55 std::make_unique<BarrierInfo>(num_callbacks_left, 56 std::move(done_closure))); 57 } 58 59 } // namespace base 60