ceph/src/rocksdb/third-party/folly/folly/synchronization/ParkingLot.cpp

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5
   6 #include <folly/synchronization/ParkingLot.h>
   7
   8 #include <array>
   9
  10 namespace folly {
  11 namespace parking_lot_detail {
  12
  13 Bucket& Bucket::bucketFor(uint64_t key) {
  14   constexpr size_t const kNumBuckets = 4096;
  15
  16   // Statically allocating this lets us use this in allocation-sensitive
  17   // contexts. This relies on the assumption that std::mutex won't dynamically
  18   // allocate memory, which we assume to be the case on Linux and iOS.
  19   static Indestructible<std::array<Bucket, kNumBuckets>> gBuckets;
  20   return (*gBuckets)[key % kNumBuckets];
  21 }
  22
  23 std::atomic<uint64_t> idallocator{0};
  24
  25 } // namespace parking_lot_detail
  26 } // namespace folly