| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License. |
| #pragma once |
| |
| #include "kudu/gutil/macros.h" |
| #include "kudu/util/condition_variable.h" |
| #include "kudu/util/mutex.h" |
| #include "kudu/util/thread_restrictions.h" |
| |
| namespace kudu { |
| |
| // Implementation of pthread-style Barriers. |
| class Barrier { |
| public: |
| // Initialize the barrier with the given initial count. |
| explicit Barrier(int count) : |
| cond_(&mutex_), |
| count_(count), |
| initial_count_(count) { |
| DCHECK_GT(count, 0); |
| } |
| |
| ~Barrier() { |
| } |
| |
| // Wait until all threads have reached the barrier. |
| // Once all threads have reached the barrier, the barrier is reset |
| // to the initial count. |
| void Wait() { |
| ThreadRestrictions::AssertWaitAllowed(); |
| MutexLock l(mutex_); |
| if (--count_ == 0) { |
| count_ = initial_count_; |
| cycle_count_++; |
| cond_.Broadcast(); |
| return; |
| } |
| |
| int initial_cycle = cycle_count_; |
| while (cycle_count_ == initial_cycle) { |
| cond_.Wait(); |
| } |
| } |
| |
| private: |
| Mutex mutex_; |
| ConditionVariable cond_; |
| int count_; |
| uint32_t cycle_count_ = 0; |
| const int initial_count_; |
| DISALLOW_COPY_AND_ASSIGN(Barrier); |
| }; |
| |
| } // namespace kudu |