thread_affinity.h

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/*
  Copyright (c) 2020, 2024, Oracle and/or its affiliates.
 
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License, version 2.0,
  as published by the Free Software Foundation.
 
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  as designated in a particular file or component or in included license
  documentation.  The authors of MySQL hereby grant you an additional
  permission to link the program and your derivative works with the
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  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
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  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/
 
#ifndef MYSQLROUTER_IO_THREAD_AFFINITY_H
#define MYSQLROUTER_IO_THREAD_AFFINITY_H
 
#include <bitset>
#include <system_error>
#include <thread>
 
#if defined(__linux__)
#include <sched.h>  // CPU_SETSIZE
#elif defined(__FreeBSD__)
#include <sys/types.h>  // must be before sys/cpuset.h for cpusetid_t
 
#include <sys/cpuset.h>  // CPU_SETSIZE
#elif defined(_WIN32)
#include <Windows.h>
#endif
 
#include "mysql/harness/stdx/expected.h"
#include "mysqlrouter/io_component_export.h"
 
/**
 * manage thread affinity.
 */
class IO_COMPONENT_EXPORT ThreadAffinity {
 public:
#if defined(__linux__) || defined(__FreeBSD__)
  static constexpr const int max_cpus = CPU_SETSIZE;
#elif defined(_WIN32)
  static constexpr const int max_cpus = 64;
#else
  static constexpr const int max_cpus = 1024;
#endif
 
#if defined(_WIN32)
  using native_handle_type = HANDLE;
#else
  using native_handle_type = pthread_t;
#endif
 
  ThreadAffinity(native_handle_type thread_id) noexcept
      : thread_id_{thread_id} {}
 
  // get current thread's native handle
  static native_handle_type current_thread_handle() noexcept;
 
  // get CPU affinity
  stdx::expected<std::bitset<max_cpus>, std::error_code> affinity()
      const noexcept;
 
  // set CPU affinity
  stdx::expected<void, std::error_code> affinity(
      std::bitset<ThreadAffinity::max_cpus> cpus) const noexcept;
 
 private:
  native_handle_type thread_id_;
};
 
#endif