import os import sys import time import signal import logging from gconf import gconf from syncdutils import update_file, select, waitpid class Monitor(object): """class which spawns and manages gsyncd workers""" def __init__(self): self.state = None def set_state(self, state): """set the state that can be used by external agents like glusterd for status reporting""" if state == self.state: return self.state = state logging.info('new state: %s' % state) if getattr(gconf, 'state_file', None): update_file(gconf.state_file, lambda f: f.write(state + '\n')) def monitor(self): """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) """ def sigcont_handler(*a): """ Re-init logging and send group kill signal """ md = gconf.log_metadata logging.shutdown() lcls = logging.getLoggerClass() lcls.setup(label=md.get('saved_label'), **md) pid = os.getpid() os.kill(-pid, signal.SIGUSR1) signal.signal(signal.SIGUSR1, lambda *a: ()) signal.signal(signal.SIGCONT, sigcont_handler) argv = sys.argv[:] for o in ('-N', '--no-daemon', '--monitor'): while o in argv: argv.remove(o) argv.extend(('-N', '-p', '')) argv.insert(0, os.path.basename(sys.executable)) self.set_state('starting...') 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)]) 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) os.kill(cpid, signal.SIGKILL) ret = nwait(cpid) if ret == None: self.set_state('OK') ret = nwait(cpid) if exit_signalled(ret): ret = 0 else: ret = exit_status(ret) if ret in (0,1): self.set_state('faulty') time.sleep(10) self.set_state('inconsistent') return ret def monitor(): """oh yeah, actually Monitor is used as singleton, too""" return Monitor().monitor()