CCF/include/ccf/ds/thread_ids.h

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the Apache 2.0 License.
#pragma once

#define FMT_HEADER_ONLY
#include <fmt/format.h>
#include <fmt/ostream.h>
#include <fmt/std.h>
#include <limits>
#include <map>
#include <thread>

namespace threading
{
  static constexpr size_t MAIN_THREAD_ID = 0;

  extern std::map<std::thread::id, uint16_t> thread_ids;
  static inline thread_local uint16_t thread_id =
    std::numeric_limits<uint16_t>::min();

  static inline uint16_t get_current_thread_id()
  {
    if (thread_id != std::numeric_limits<uint16_t>::min())
    {
      return thread_id;
    }

    if (thread_ids.empty())
    {
      return MAIN_THREAD_ID;
    }

    const auto tid = std::this_thread::get_id();
    const auto it = thread_ids.find(tid);
    if (it == thread_ids.end())
    {
      throw std::runtime_error(
        fmt::format("Accessed uninitialized thread_ids - ID {} unknown", tid));
    }

    thread_id = it->second;

    return thread_id;
  }
}