ParkingLot.cpp

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/*
 * Copyright 2017-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 <folly/synchronization/ParkingLot.h>

#include <array>

namespace folly {
namespace parking_lot_detail {

Bucket& Bucket::bucketFor(uint64_t key) {
  constexpr size_t const kNumBuckets = kIsMobile ? 256 : 4096;

  // Statically allocating this lets us use this in allocation-sensitive
  // contexts. This relies on the assumption that std::mutex won't dynamically
  // allocate memory, which we assume to be the case on Linux and iOS.
  static Indestructible<std::array<Bucket, kNumBuckets>> gBuckets;
  return (*gBuckets)[key % kNumBuckets];
}

std::atomic<uint64_t> idallocator{0};

} // namespace parking_lot_detail
} // namespace folly