mindspore2022/mindspore/ccsrc/dataset/util/service.cc

/**
 * Copyright 2019 Huawei Technologies Co., Ltd
 *
 * Licensed 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 "dataset/util/service.h"
#include <thread>

namespace mindspore {
namespace dataset {
Status Service::ServiceStart() {
  do {
    UniqueLock lck(&state_lock_);
    // No-op if it is already up or some other thread is
    // in the process of bring it up.
    if (state_ == STATE::kRunning || state_ == STATE::kStartInProg) {
      return Status::OK();
    }
    // If a stop is in progress, we line up after it
    // is done.
    if (state_ == STATE::kStopInProg) {
      std::this_thread::yield();
    } else {
      state_ = STATE::kStartInProg;
      // At this point, we will let go of the lock. This allow others to proceed.
      lck.Unlock();
      RETURN_IF_NOT_OK(DoServiceStart());
      // Lock again to change state.
      lck.Lock();
      state_ = STATE::kRunning;
      return Status::OK();
    }
  } while (true);
}

Status Service::ServiceStop() noexcept {
  do {
    UniqueLock lck(&state_lock_);
    // No-op if it is already stopped or some other thread is
    // in the process of shutting it down
    if (state_ == STATE::kStopped || state_ == STATE::kStopInProg) {
      return Status::OK();
    }
    // If a start is in progress, we line up after it
    // is done.
    if (state_ == STATE::kStartInProg) {
      std::this_thread::yield();
    } else {
      state_ = STATE::kStopInProg;
      // At this point, we will let go of the lock. This allows others to proceed.
      lck.Unlock();
      RETURN_IF_NOT_OK(DoServiceStop());
      // Lock again to change state.
      lck.Lock();
      state_ = STATE::kStopped;
      return Status::OK();
    }
  } while (true);
}
}  // namespace dataset
}  // namespace mindspore