pid_file.h

/*
 *     .============.
 *    //  M A K E  / \
 *   //  C++ DEV  /   \
 *  //  E A S Y  /  \/ \
 * ++ ----------.  \/\  .
 *  \\     \     \ /\  /
 *   \\     \     \   /
 *    \\     \     \ /
 *     -============'
 *
 * Copyright (c) 2018 Hevake and contributors, all rights reserved.
 *
 * This file is part of cpp-tbox (https://github.com/cpp-main/cpp-tbox)
 * Use of this source code is governed by MIT license that can be found
 * in the LICENSE file in the root of the source tree. All contributing
 * project authors may be found in the CONTRIBUTORS.md file in the root
 * of the source tree.
 */
/**
 * pid 文件类
 *
 * 通常一个服务程序在运行时会创建一个pid文件。
 * pid 文件有两个使用场景：
 * 1. 记录当前服务程序的进程号，以便其它程序能给该进程发送信号
 * 2. 防止多个服务进程同时运行，导致资源抢占异常
 *
 * 该 PidFile 类使用比较简单
 *
 * int main() {
 *   PidFile pid("/var/my_server.pid");
 *   if (!pid.lock()) {
 *     //! 获取不到 pid 文件的写权限，应当主动结束进程
 *     return 0;
 *   }
 *
 *   //! 正常的服务业务逻辑
 * }
 */
#ifndef TBOX_PID_FILE_H_20211221
#define TBOX_PID_FILE_H_20211221

#include <string>
#include <tbox/base/defines.h>

namespace tbox {
namespace util {

class PidFile {
  public:
    PidFile();
    virtual ~PidFile();

    NONCOPYABLE(PidFile);

    bool lock(const std::string &pid_filename);
    bool unlock();

  private:
    std::string pid_filename_;
    int fd_ = -1;
};

}
}

#endif //TBOX_PID_FILE_H_20211221