import os import sys import time import signal import logging import uuid import xml.etree.ElementTree as XET from subprocess import PIPE from resource import Popen, FILE, GLUSTER, SSH from threading import Lock from gconf import gconf from syncdutils import update_file, select, waitpid, set_term_handler, is_host_local, GsyncdError from syncdutils import escape, Thread, finalize, memoize class Volinfo(object): def __init__(self, vol, host='localhost', prelude=[]): po = Popen(prelude + ['gluster', '--xml', '--remote-host=' + host, 'volume', 'info', vol], stdout=PIPE, stderr=PIPE) vix = po.stdout.read() po.wait() po.terminate_geterr() vi = XET.fromstring(vix) if vi.find('opRet').text != '0': if prelude: via = '(via %s) ' % prelude.join(' ') else: via = ' ' raise GsyncdError('getting volume info of %s%s failed with errorcode %s', (vol, via, vi.find('opErrno').text)) self.tree = vi self.volume = vol self.host = host def get(self, elem): return self.tree.findall('.//' + elem) @property @memoize def bricks(self): def bparse(b): host, dirp = b.text.split(':', 2) return {'host': host, 'dir': dirp} return [ bparse(b) for b in self.get('brick') ] @property @memoize def uuid(self): ids = self.get('id') if len(ids) != 1: raise GsyncdError("volume info of %s obtained from %s: ambiguous uuid", self.volume, self.host) return ids[0].text class Monitor(object): """class which spawns and manages gsyncd workers""" ST_INIT = 'Initializing...' ST_STABLE = 'Stable' ST_FAULTY = 'faulty' ST_INCON = 'inconsistent' _ST_ORD = [ST_STABLE, ST_INIT, ST_FAULTY, ST_INCON] def __init__(self): self.lock = Lock() self.state = {} def set_state(self, state, w=None): """set the state that can be used by external agents like glusterd for status reporting""" computestate = lambda: self.state and self._ST_ORD[max(self._ST_ORD.index(s) for s in self.state.values())] if w: self.lock.acquire() old_state = computestate() self.state[w] = state state = computestate() self.lock.release() if state != old_state: self.set_state(state) else: logging.info('new state: %s' % state) if getattr(gconf, 'state_file', None): update_file(gconf.state_file, lambda f: f.write(state + '\n')) @staticmethod def terminate(): # relax one SIGTERM by setting a handler that sets back # standard handler set_term_handler(lambda *a: set_term_handler()) # give a chance to graceful exit os.kill(-os.getpid(), signal.SIGTERM) 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 != None: logging.debug("worker died before establishing connection") else: logging.debug("worker seems to be connected (?? racy check)") while time.time() < t0 + conn_timeout: ret = nwait(cpid, os.WNOHANG) if ret != None: logging.debug("worker died in startup phase") break time.sleep(1) else: logging.debug("worker not confirmed in %d sec, aborting it" % \ conn_timeout) self.terminate() time.sleep(1) os.kill(cpid, signal.SIGKILL) ret = nwait(cpid) if ret == 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 def multiplex(self, wspx, suuid): argv = sys.argv[:] for o in ('-N', '--no-daemon', '--monitor'): while o in argv: argv.remove(o) argv.extend(('-N', '-p', '', '--slave-id', suuid)) argv.insert(0, os.path.basename(sys.executable)) cpids = set() ta = [] for wx in wspx: def wmon(w): cpid, _ = self.monitor(w, argv, cpids) terminate() time.sleep(1) self.lock.acquire() for cpid in cpids: os.kill(cpid, signal.SIGKILL) self.lock.release() finalize(exval=1) t = Thread(target = wmon, args=[wx]) t.start() ta.append(t) for t in ta: t.join() def distribute(*resources): master, slave = resources mvol = Volinfo(master.volume, master.host) logging.debug('master bricks: ' + repr(mvol.bricks)) prelude = [] si = slave if isinstance(slave, SSH): prelude = gconf.ssh_command.split() + [slave.remote_addr] si = slave.inner_rsc logging.debug('slave SSH gateway: ' + slave.remote_addr) if isinstance(si, FILE): sbricks = {'host': 'localhost', 'dir': si.path} suuid = uuid.uuid5(uuid.NAMESPACE_URL, slave.get_url(canonical=True)) elif isinstance(si, GLUSTER): svol = Volinfo(si.volume, si.host, prelude) sbricks = svol.bricks suuid = svol.uuid else: raise GsyncdError("unkown slave type " + slave.url) logging.info('slave bricks: ' + repr(sbricks)) if isinstance(si, FILE): slaves = [ slave.url ] else: slavenodes = set(b['host'] for b in sbricks) if isinstance(slave, SSH) and not gconf.isolated_slave: rap = SSH.parse_ssh_address(slave) slaves = [ 'ssh://' + rap['user'] + '@' + h + ':' + si.url for h in slavenodes ] else: slavevols = [ h + ':' + si.volume for h in slavenodes ] if isinstance(slave, SSH): slaves = [ 'ssh://' + rap.remote_addr + ':' + v for v in slavevols ] else: slaves = slavevols workerspex = [ (brick['dir'], slaves[idx % len(slaves)]) for idx, brick in enumerate(mvol.bricks) if is_host_local(brick['host']) ] logging.info('worker specs: ' + repr(workerspex)) return workerspex, suuid def monitor(*resources): """oh yeah, actually Monitor is used as singleton, too""" return Monitor().multiplex(*distribute(*resources))