ceph/src/rocksdb/util/random.cc

   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
   7 #include "util/random.h"
   8
   9 #include <stdint.h>
  10 #include <string.h>
  11 #include <thread>
  12 #include <utility>
  13
  14 #include "port/likely.h"
  15 #include "util/thread_local.h"
  16
  17 #ifdef ROCKSDB_SUPPORT_THREAD_LOCAL
  18 #define STORAGE_DECL static __thread
  19 #else
  20 #define STORAGE_DECL static
  21 #endif
  22
  23 namespace ROCKSDB_NAMESPACE {
  24
  25 Random* Random::GetTLSInstance() {
  26   STORAGE_DECL Random* tls_instance;
  27   STORAGE_DECL std::aligned_storage<sizeof(Random)>::type tls_instance_bytes;
  28
  29   auto rv = tls_instance;
  30   if (UNLIKELY(rv == nullptr)) {
  31     size_t seed = std::hash<std::thread::id>()(std::this_thread::get_id());
  32     rv = new (&tls_instance_bytes) Random((uint32_t)seed);
  33     tls_instance = rv;
  34   }
  35   return rv;
  36 }
  37
  38 std::string Random::HumanReadableString(int len) {
  39   std::string ret;
  40   ret.resize(len);
  41   for (int i = 0; i < len; ++i) {
  42     ret[i] = static_cast<char>('a' + Uniform(26));
  43   }
  44   return ret;
  45 }
  46
  47 std::string Random::RandomString(int len) {
  48   std::string ret;
  49   ret.resize(len);
  50   for (int i = 0; i < len; i++) {
  51     ret[i] = static_cast<char>(' ' + Uniform(95));  // ' ' .. '~'
  52   }
  53   return ret;
  54 }
  55
  56 }  // namespace ROCKSDB_NAMESPACE