//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.

//  This source code is licensed under both the GPLv2 (found in the

//  COPYING file in the root directory) and Apache 2.0 License

//  (found in the LICENSE.Apache file in the root directory).

//

#include "util/random.h"

#include <climits>

#include <cstdint>

#include <cstring>

#include <thread>

#include <utility>

#include "port/likely.h"

#include "util/aligned_storage.h"

#include "util/thread_local.h"

#define STORAGE_DECL static thread_local

namespace ROCKSDB_NAMESPACE {

Random* Random::GetTLSInstance() {

  STORAGE_DECL Random* tls_instance;

  STORAGE_DECL aligned_storage<Random>::type tls_instance_bytes;

  auto rv = tls_instance;

  if (UNLIKELY(rv == nullptr)) {

    size_t seed = std::hash<std::thread::id>()(std::this_thread::get_id());

    rv = new (&tls_instance_bytes) Random((uint32_t)seed);

    tls_instance = rv;

  }

  return rv;

}

std::string Random::HumanReadableString(int len) {

  std::string ret;

  ret.resize(len);

  for (int i = 0; i < len; ++i) {

    ret[i] = static_cast<char>('a' + Uniform(26));

  }

  return ret;

}

std::string Random::RandomString(int len) {

  std::string ret;

  ret.resize(len);

  for (int i = 0; i < len; i++) {

    ret[i] = static_cast<char>(' ' + Uniform(95));  // ' ' .. '~'

  }

  return ret;

}

std::string Random::RandomBinaryString(int len) {

  std::string ret;

  ret.resize(len);

  for (int i = 0; i < len; i++) {

    ret[i] = static_cast<char>(Uniform(CHAR_MAX));

  }

  return ret;

}

}  // namespace ROCKSDB_NAMESPACE