# -*- coding: utf-8 -*-

import sys, os, time, atexit

from signal import SIGTERM

class Daemon:

    def __init__(self, pidfile, stderr='/data/deamon_err.log', stdout='/data/deamon_out.log', stdin='/dev/null'):

        self.stdin = stdin

        self.stdout = stdout

        self.stderr = stderr

        self.pidfile = pidfile

    def _daemonize(self):

        #脱离父进程

        try:

            pid = os.fork()

            if pid > 0:

                sys.exit(0)

        except OSError, e:

            sys.stderr.write("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))

            sys.exit(1)

        #脱离终端

        os.setsid()

        #修改当前工作目录

        os.chdir("/")

        #重设文件创建权限

        os.umask(0)

        #第二次fork，禁止进程重新打开控制终端

        try:

            pid = os.fork()

            if pid > 0:

                sys.exit(0)

        except OSError, e:

            sys.stderr.write("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))

            sys.exit(1)

        sys.stdout.flush()

        sys.stderr.flush()

        si = file(self.stdin, 'r')

        so = file(self.stdout, 'a+')

        se = file(self.stderr, 'a+', 0)

        #重定向标准输入/输出/错误

        os.dup2(si.fileno(), sys.stdin.fileno())

        os.dup2(so.fileno(), sys.stdout.fileno())

        os.dup2(se.fileno(), sys.stderr.fileno())

        #注册程序退出时的函数，即删掉pid文件

        atexit.register(self.delpid)

        pid = str(os.getpid())

        file(self.pidfile,'w+').write("%s\n" % pid)

    def delpid(self):

        os.remove(self.pidfile)

    def start(self):

        """

        Start the daemon

        """

        # Check for a pidfile to see if the daemon already runs

        try:

            pf = file(self.pidfile,'r')

            pid = int(pf.read().strip())

            pf.close()

        except IOError:

            pid = None

        if pid:

            message = "pidfile %s already exist. Daemon already running?\n"

            sys.stderr.write(message % self.pidfile)

            sys.exit(1)

        # Start the daemon

        self._daemonize()

        self._run()

    def stop(self):

        # Get the pid from the pidfile

        try:

            pf = file(self.pidfile,'r')

            pid = int(pf.read().strip())

            pf.close()

        except IOError:

            pid = None

        if not pid:

            message = "pidfile %s does not exist. Daemon not running?\n"

            sys.stderr.write(message % self.pidfile)

            return # not an error in a restart

        # Try killing the daemon process

        try:

            while 1:

                os.kill(pid, SIGTERM)

                time.sleep(0.1)

        except OSError, err:

            err = str(err)

            if err.find("No such process") > 0:

                if os.path.exists(self.pidfile):

                    os.remove(self.pidfile)

            else:

                print str(err)

                sys.exit(1)

    def restart(self):

        self.stop()

        self.start()

    def _run(self):

class MyDaemon(Daemon):

    def __init__(self, pidfile):

        mod_daemon.Daemon.__init__(self,pidfile)

        task_mgr_log = time.strftime('%Y%m%d') + '.log'

        self.logger = mod_logger.logger(task_mgr_log)

    def _run(self):

            self.logger.debug("begin sleep")

            time.sleep(20)

            self.logger.debug("end sleep")

if __name__ == "__main__":

    daemon = MyDaemon('/tmp/daemon-example.pid')

    if len(sys.argv) == 2:

        if 'start' == sys.argv[1]:

            print 'start daemon'

            daemon.start()

        elif 'stop' == sys.argv[1]:

            print 'stop daemon'

            daemon.stop()

        elif 'restart' == sys.argv[1]:

            print 'restart daemon'

            daemon.restart()

        else:

            print "Unknown command"

            sys.exit(2)

        sys.exit(0)

    else:

        print "usage: %s start|stop|restart" % sys.argv[0]

        sys.exit(2)