caffe2/core/context.cc

/**
 * Copyright (c) 2016-present, Facebook, Inc.
 *
 * 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 "caffe2/core/context.h"

#include <atomic>
#if defined(_MSC_VER)
#include <process.h>
#endif

namespace caffe2 {

uint32_t RandomNumberSeed() {
  // Originally copied from folly::randomNumberSeed (at 418ad4)
  // modified to use chrono instead of sys/time.h
  static std::atomic<uint32_t> seedInput(0);
  auto tv = std::chrono::system_clock::now().time_since_epoch();
  uint64_t usec = static_cast<uint64_t>(
      std::chrono::duration_cast<std::chrono::microseconds>(tv).count());
  uint32_t tv_sec = usec / 1000000;
  uint32_t tv_usec = usec % 1000000;
  const uint32_t kPrime0 = 51551;
  const uint32_t kPrime1 = 61631;
  const uint32_t kPrime2 = 64997;
  const uint32_t kPrime3 = 111857;
  return kPrime0 * (seedInput++) + kPrime1 * static_cast<uint32_t>(getpid()) +
      kPrime2 * tv_sec + kPrime3 * tv_usec;
}

} // namespace caffe2