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import os
import sys
import time
import signal
import logging
from gconf import gconf
from syncdutils import update_file, select, waitpid, set_term_handler
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)
# 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)
time.sleep(1)
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()
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