heron/common/src/cpp/threads/spcountdownlatch.cpp

/**
 * 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.
 */

#include "threads/spcountdownlatch.h"

CountDownLatch::CountDownLatch(sp_uint32 count) : count_(count) {}

CountDownLatch::~CountDownLatch() {}

bool CountDownLatch::wait(sp_uint32 target, const std::chrono::seconds& duration) {
  std::unique_lock<std::mutex> m(mutex_);
  // If the count is greater than target, then wait until the count reaches the value of target.
  // Else return immediately.
  if (std::chrono::seconds::zero() == duration) {
    while (count_ > target) {
      cond_.wait(m);
    }
  } else {
    if (count_ > target) {
      return cond_.wait_for(m, duration, [this, &target]{return count_ <= target;});
    }
  }
  return true;
}

void CountDownLatch::countDown() {
  std::unique_lock<std::mutex> m(mutex_);

  // Nothing to do if count is already 0
  if (count_ == 0) return;

  // Decrement count.
  count_--;
  //  Notify all blocked threads: give them a chance to compare (count_ and target)
  cond_.notify_all();
}

sp_uint32 CountDownLatch::getCount() {
  std::unique_lock<std::mutex> m(mutex_);
  return count_;
}