def crawl(self, path=".", xtr=None, done=0):
     """ generate a CHANGELOG file consumable by process_change """
     if path == ".":
         self.open()
         self.crawls += 1
     if not xtr:
         # get the root stime and use it for all comparisons
         xtr = self.xtime(".", self.slave)
         if isinstance(xtr, int):
             if xtr != ENOENT:
                 raise GsyncdError("slave is corrupt")
             xtr = self.minus_infinity
     xtl = self.xtime(path)
     if isinstance(xtl, int):
         raise GsyncdError("master is corrupt")
     if xtr == xtl:
         if path == ".":
             self.close()
         return
     self.xtime_reversion_hook(path, xtl, xtr)
     logging.debug("entering " + path)
     dem = self.master.server.entries(path)
     pargfid = self.master.server.gfid(path)
     if isinstance(pargfid, int):
         logging.warn("skipping directory %s" % (path))
     for e in dem:
         bname = e
         e = os.path.join(path, e)
         st = self.lstat(e)
         if isinstance(st, int):
             logging.warn("%s got purged in the interim.." % e)
             continue
         gfid = self.master.server.gfid(e)
         if isinstance(gfid, int):
             logging.warn("skipping entry %s.." % (e))
             continue
         xte = self.xtime(e)
         if isinstance(xte, int):
             raise GsyncdError("master is corrupt")
         if not self.need_sync(e, xte, xtr):
             continue
         mo = st.st_mode
         if stat.S_ISDIR(mo):
             self.write_entry_change("E", [gfid, "MKDIR", escape(os.path.join(pargfid, bname))])
             self.crawl(e, xtr)
         elif stat.S_ISREG(mo):
             self.write_entry_change("E", [gfid, "CREATE", escape(os.path.join(pargfid, bname))])
             self.write_entry_change("D", [gfid])
         elif stat.S_ISLNK(mo):
             self.write_entry_change("E", [gfid, "SYMLINK", escape(os.path.join(pargfid, bname))])
         else:
             logging.info("ignoring %s" % e)
     if path == ".":
         logging.info("processing xsync changelog %s" % self.fname())
         self.close()
         self.process([self.fname()], done)
         self.upd_stime(xtl)

 def get_url(self, canonical=False, escaped=False):
     if canonical:
         pa = self.canonical_path()
     else:
         pa = self.path
     u = "://".join((self.scheme(), pa))
     if escaped:
         u = syncdutils.escape(u)
     return u

 def get_url(self, canonical=False, escaped=False):
     """format self's url in various styles"""
     if canonical:
         pa = self.canonical_path()
     else:
         pa = self.path
     u = "://".join((self.scheme, pa))
     if escaped:
         u = syncdutils.escape(u)
     return u

 def section(self, rx=False):
     peers = self.peers
     if not peers:
         peers = ['.', '.']
         rx = True
     if rx:
         st = 'peersrx'
     else:
         st = 'peers'
     return ' '.join([st] + [escape(u) for u in peers])

 def section(self, rx=False):
     """get the section name of the section representing .peers
     in .config"""
     peers = self.peers
     if not peers:
         peers = ['.', '.']
         rx = True
     if rx:
         return ' '.join(['peersrx'] + [escape(u) for u in peers])
     else:
         return ' '.join(['peers'] + [u.split(':')[-1] for u in peers])

 def section(self, rx=False):
     """get the section name of the section representing .peers in .config"""
     peers = self.peers
     if not peers:
         peers = ['.', '.']
         rx = True
     if rx:
         st = 'peersrx'
     else:
         st = 'peers'
     return ' '.join([st] + [escape(u) for u in peers])

 def _set_checkpt_param(cls, chkpt, prm, val, xtimish=True):
     """use config backend to store a parameter associated
        with checkpoint @chkpt"""
     if xtimish:
         val = cls.serialize_xtime(val)
     gconf.configinterface.set("checkpoint_" + prm, "%s:%s" % (escape(chkpt), val))

    def monitor(self, w, argv, cpids):
        """the monitor loop

        Basic logic is a blantantly simple blunt heuristics:
        if spawned client survives 60 secs, it's considered OK.
        This servers us pretty well as it's not vulneralbe to
        any kind of irregular behavior of the child...

        ... well, except for one: if children is hung up on
        waiting for some event, it can survive aeons, still
        will be defunct. So we tweak the above logic to
        expect the worker to send us a signal within 60 secs
        (in the form of closing its end of a pipe). The worker
        does this when it's done with the setup stage
        ready to enter the service loop (note it's the setup
        stage which is vulnerable to hangs -- the full
        blown worker blows up on EPIPE if the net goes down,
        due to the keep-alive thread)
        """

        self.set_state(self.ST_INIT, w)
        ret = 0

        def nwait(p, o=0):
            p2, r = waitpid(p, o)
            if not p2:
                return
            return r

        def exit_signalled(s):
            """ child teminated due to receipt of SIGUSR1 """
            return (os.WIFSIGNALED(s) and (os.WTERMSIG(s) == signal.SIGUSR1))

        def exit_status(s):
            if os.WIFEXITED(s):
                return os.WEXITSTATUS(s)
            return 1
        conn_timeout = int(gconf.connection_timeout)
        while ret in (0, 1):
            logging.info('-' * conn_timeout)
            logging.info('starting gsyncd worker')
            pr, pw = os.pipe()
            cpid = os.fork()
            if cpid == 0:
                os.close(pr)
                os.execv(sys.executable, argv + ['--feedback-fd', str(pw),
                                                 '--local-path', w[0],
                                                 '--local-id',
                                                 '.' + escape(w[0]),
                                                 '--resource-remote', w[1]])
            self.lock.acquire()
            cpids.add(cpid)
            self.lock.release()
            os.close(pw)
            t0 = time.time()
            so = select((pr,), (), (), conn_timeout)[0]
            os.close(pr)
            if so:
                ret = nwait(cpid, os.WNOHANG)
                if ret is not None:
                    logging.info("worker(%s) died before establishing "
                                 "connection" % w[0])
                else:
                    logging.debug("worker(%s) connected" % w[0])
                    while time.time() < t0 + conn_timeout:
                        ret = nwait(cpid, os.WNOHANG)
                        if ret is not None:
                            logging.info("worker(%s) died in startup "
                                         "phase" % w[0])
                            break
                        time.sleep(1)
            else:
                logging.info("worker(%s) not confirmed in %d sec, "
                             "aborting it" % (w[0], conn_timeout))
                os.kill(cpid, signal.SIGKILL)
                ret = nwait(cpid)
            if ret is None:
                self.set_state(self.ST_STABLE, w)
                ret = nwait(cpid)
            if exit_signalled(ret):
                ret = 0
            else:
                ret = exit_status(ret)
                if ret in (0, 1):
                    self.set_state(self.ST_FAULTY, w)
            time.sleep(10)
        self.set_state(self.ST_INCON, w)
        return ret

#.........这里部分代码省略.........
            # Spawn the worker and agent in lock to avoid fd leak
            self.lock.acquire()

            logging.info('-' * conn_timeout)
            logging.info('starting gsyncd worker')

            # Couple of pipe pairs for RPC communication b/w
            # worker and changelog agent.

            # read/write end for agent
            (ra, ww) = os.pipe()
            # read/write end for worker
            (rw, wa) = os.pipe()

            # spawn the agent process
            apid = os.fork()
            if apid == 0:
                os.close(rw)
                os.close(ww)
                os.execv(sys.executable, argv + ['--local-path', w[0],
                                                 '--agent',
                                                 '--rpc-fd',
                                                 ','.join([str(ra), str(wa),
                                                           str(rw), str(ww)])])
            pr, pw = os.pipe()
            cpid = os.fork()
            if cpid == 0:
                os.close(pr)
                os.close(ra)
                os.close(wa)
                os.execv(sys.executable, argv + ['--feedback-fd', str(pw),
                                                 '--local-path', w[0],
                                                 '--local-id',
                                                 '.' + escape(w[0]),
                                                 '--rpc-fd',
                                                 ','.join([str(rw), str(ww),
                                                           str(ra), str(wa)]),
                                                 '--subvol-num', str(w[2])] +
                         (['--is-hottier'] if w[3] else []) +
                         ['--resource-remote', remote_host])

            cpids.add(cpid)
            agents.add(apid)
            os.close(pw)

            # close all RPC pipes in monitor
            os.close(ra)
            os.close(wa)
            os.close(rw)
            os.close(ww)
            self.lock.release()

            t0 = time.time()
            so = select((pr,), (), (), conn_timeout)[0]
            os.close(pr)

            if so:
                ret = nwait(cpid, os.WNOHANG)
                ret_agent = nwait(apid, os.WNOHANG)

                if ret_agent is not None:
                    # Agent is died Kill Worker
                    logging.info("Changelog Agent died, "
                                 "Aborting Worker(%s)" % w[0])
                    errno_wrap(os.kill, [cpid, signal.SIGKILL], [ESRCH])
                    nwait(cpid)

    def crawl(self, path='.', xtr=None, done=0):
        """ generate a CHANGELOG file consumable by process_change """
        if path == '.':
            self.open()
            self.crawls += 1
        if not xtr:
            # get the root stime and use it for all comparisons
            xtr = self.xtime('.', self.slave)
            if isinstance(xtr, int):
                if xtr != ENOENT:
                    raise GsyncdError('slave is corrupt')
                xtr = self.minus_infinity
        xtl = self.xtime(path)
        if isinstance(xtl, int):
            raise GsyncdError('master is corrupt')
        if xtr == xtl:
            if path == '.':
                self.close()
            return
        self.xtime_reversion_hook(path, xtl, xtr)
        logging.debug("entering " + path)
        dem = self.master.server.entries(path)
        pargfid = self.master.server.gfid(path)
        if isinstance(pargfid, int):
            logging.warn('skipping directory %s' % (path))
        for e in dem:
            bname = e
            e = os.path.join(path, e)
            st = lstat(e)
            if isinstance(st, int):
                logging.warn('%s got purged in the interim..' % e)
                continue
            gfid = self.master.server.gfid(e)
            if isinstance(gfid, int):
                logging.warn('skipping entry %s..' % (e))
                continue
            xte = self.xtime(e)
            if isinstance(xte, int):
                raise GsyncdError('master is corrupt')
            if not self.need_sync(e, xte, xtr):
                continue
            mo = st.st_mode
            if stat.S_ISDIR(mo):
                self.write_entry_change("E", [gfid, 'MKDIR', escape(os.path.join(pargfid, bname))])
                self.crawl(e, xtr)
            elif stat.S_ISLNK(mo):
                rl = errno_wrap(os.readlink, [en], [ENOENT])
                if isinstance(rl, int):
                    continue
                self.write_entry_change("E", [gfid, 'SYMLINK', escape(os.path.join(pargfid, bname)), rl])
            else:
                # if a file has a hardlink, create a Changelog entry as 'LINK' so the slave
                # side will decide if to create the new entry, or to create link.
                if st.st_nlink == 1:
                    self.write_entry_change("E", [gfid, 'MKNOD', escape(os.path.join(pargfid, bname))])
                else:
                    self.write_entry_change("E", [gfid, 'LINK', escape(os.path.join(pargfid, bname))])
                if stat.S_ISREG(mo):
                    self.write_entry_change("D", [gfid])

        if path == '.':
            logging.info('processing xsync changelog %s' % self.fname())
            self.close()
            self.process([self.fname()], done)
            self.upd_stime(xtl)

#.........这里部分代码省略.........
    p.add_argument("--debug", action="store_true")

    # Delete
    p = sp.add_parser("delete")
    p.add_argument("master", help="Master Volume Name")
    p.add_argument("slave", help="Slave")
    p.add_argument("-c", "--config-file", help="Config File")
    p.add_argument('--path', dest='paths', action="append")
    p.add_argument("--reset-sync-time", action="store_true",
                   help="Reset Sync Time")
    p.add_argument("--debug", action="store_true")

    # Parse arguments
    args = parser.parse_args()

    # Extra template values, All arguments are already part of template
    # variables, use this for adding extra variables
    extra_tmpl_args = {}

    # Add First/Primary Slave host, user and volume
    if getattr(args, "slave", None) is not None:
        hostdata, slavevol = args.slave.split("::")
        hostdata = hostdata.split("@")
        slavehost = hostdata[-1]
        slaveuser = "root"
        if len(hostdata) == 2:
            slaveuser = hostdata[0]
        extra_tmpl_args["primary_slave_host"] = slavehost
        extra_tmpl_args["slaveuser"] = slaveuser
        extra_tmpl_args["slavevol"] = slavevol

    # Add Bricks encoded path
    if getattr(args, "local_path", None) is not None:
        extra_tmpl_args["local_id"] = escape(args.local_path)

    # Add Master Bricks encoded path(For Slave)
    if getattr(args, "master_brick", None) is not None:
        extra_tmpl_args["master_brick_id"] = escape(args.master_brick)

    # Load configurations
    config_file = getattr(args, "config_file", None)

    # Subcmd accepts config file argument but not passed
    # Set default path for config file in that case
    # If an subcmd accepts config file then it also accepts
    # master and Slave arguments.
    if config_file is None and hasattr(args, "config_file"):
        config_file = "%s/geo-replication/%s_%s_%s/gsyncd.conf" % (
            GLUSTERD_WORKDIR,
            args.master,
            extra_tmpl_args["primary_slave_host"],
            extra_tmpl_args["slavevol"])

    # If Config file path not exists, log error and continue using default conf
    config_file_error_msg = None
    if config_file is not None and not os.path.exists(config_file):
        # Logging not yet initialized, create the error message to
        # log later and reset the config_file to None
        config_file_error_msg = lf(
            "Session config file not exists, using the default config",
            path=config_file)
        config_file = None

    rconf.config_file = config_file

    # Override gconf values from argument values only if it is slave gsyncd