Commit b0cb2e02 authored by Shane Kerr's avatar Shane Kerr
Browse files

Some initial work on a boss process.



git-svn-id: svn://bind10.isc.org/svn/bind10/branches/f2f200910@154 e5f2f494-b856-4b98-b285-d166d9295462
parent 0a6b3fc6
#! /bin/sh
PYTHON_EXEC=/usr/bin/python3.0
BIND10_PATH=.
cd ${BIND10_PATH}
exec ${PYTHON_EXEC} -O bind10.py $*
"""\
This file implements the Boss of Bind (BoB, or bob) program.
It's purpose is to start up the BIND 10 system, and then manage the
processes, by starting, stopping, and restarting processes that exit.
To start the system, it first runs the c-channel program (msgq), then
connects to that. It then runs the configuration manager, and reads
its own configuration. Then it proceeds to starting other modules.
The Python subprocess module is used for starting processes, but
because this is not efficient for managing groups of processes,
SIGCHLD signals are caught and processed using the signal module.
Most of the logic is contained in the BoB class. However, since Python
requires that signal processing happen in the main thread, we do
signal handling outside of that class, in the code running for
__main__.
"""
import subprocess
import signal
import os
import sys
import re
import errno
import time
from optparse import OptionParser, OptionValueError
#import ISC
# This is the version that gets displayed to the user.
__version__ = "v20091028 (Paving the DNS Parking Lot)"
class BoB:
"""Boss of BIND class."""
def __init__(self, c_channel_port="9912", verbose=False):
"""Initialize the Boss of BIND. This is a singleton (only one
can run).
The c_channel_port specifies the TCP/IP port that the msgq
process listens on. If verbose is True, then the boss reports
what it is doing.
"""
self.c_channel_port = c_channel_port
self.processes = {}
self.dead_processes = {}
self.component_processes = {}
self.verbose = True
def startup(self):
"""Start the BoB instance.
Returns None if successful, otherwise an string describing the
problem.
"""
if self.verbose:
sys.stdout.write("Starting msgq using port %s\n" % self.c_channel_port)
c_channel_env = { "ISC_MSGQ_PORT": self.c_channel_port, }
try:
c_channel = subprocess.Popen("msgq",
stdin=subprocess.PIPE,
stdout=subprocess.PIPE,
close_fds=True,
env=c_channel_env,)
except:
return "Unable to start msgq"
self.processes[c_channel.pid] = c_channel
if self.verbose:
sys.stdout.write("Started msgq with PID %d\n" % c_channel.pid)
return None
def stop_process(self, process):
"""Stop the given process, friendly-like."""
# XXX nothing yet
pass
def shutdown(self):
"""Stop the BoB instance."""
if self.verbose:
sys.stdout.write("Stopping the server.\n")
# first try using the BIND 10 request to stop
unstopped_processes = []
for process in self.processes.values():
if not self.stop_process(process):
unstopped_processes.append(process)
# next try sending a SIGTERM
processes_to_stop = unstopped_processes
unstopped_processes = []
for process in processes_to_stop:
if self.verbose:
sys.stdout.write("Sending SIGTERM to process %d.\n" % process.pid)
try:
process.terminate()
except OSError as o:
# ignore these (usually ESRCH because the child
# finally exited)
pass
time.sleep(0.1) # XXX: some delay probably useful... how much is uncertain
for process in processes_to_stop:
(pid, exit_status) = os.waitpid(process.pid, os.WNOHANG)
if pid == 0:
unstopped_processes.append(process)
# finally, send a SIGKILL (unmaskable termination)
processes_to_stop = unstopped_processes
for process in processes_to_stop:
if self.verbose:
sys.stdout.write("Sending SIGKILL to process %d.\n" % process.pid)
try:
process.kill()
except OSError as o:
# ignore these (usually ESRCH because the child
# finally exited)
pass
if self.verbose:
sys.stdout.write("All processes ended, server done.\n")
def reap(self, pid, exit_status):
"""The process specified by pid has exited with the value
exit_status, so perform any action necessary (cleanup,
restart, and so on).
"""
process = self.processes.pop(pid)
self.dead_processes[process.pid] = process
if self.verbose:
sys.stdout.write("Process %d died.\n" % pid)
if __name__ == "__main__":
def reaper(signal_number, stack_frame):
"""A child process has died (SIGCHLD received)."""
global boss_of_bind
while True:
try:
(pid, exit_status) = os.waitpid(-1, os.WNOHANG)
except OSError as o:
if o.errno == errno.ECHILD: break
raise
if pid == 0: break
boss_of_bind.reap(pid, exit_status)
def get_signame(signal_number):
"""Return the symbolic name for a signal."""
for sig in dir(signal):
if sig.startswith("SIG") and sig[3].isalnum():
if getattr(signal, sig) == signal_number:
return sig
return "Unknown signal %d" % signal_number
def fatal_signal(signal_number, stack_frame):
"""We need to exit (SIGINT or SIGTERM received)."""
global boss_of_bind
global options
if options.verbose:
sys.stdout.write("Received %s.\n" % get_signame(signal_number))
signal.signal(signal.SIGCHLD, signal.SIG_DFL)
if boss_of_bind:
boss_of_bind.shutdown()
sys.exit(0)
def check_port(option, opt_str, value, parser):
if not re.match('^(6553[0-5]|655[0-2]\d|65[0-4]\d\d|6[0-4]\d{3}|[1-5]\d{4}|[1-9]\d{0,3}|0)$', value):
raise OptionValueError("%s requires a port number (0-65535)" % opt_str)
parser.values.msgq_port = value
parser = OptionParser(version=__version__)
parser.add_option("-v", "--verbose", dest="verbose", action="store_true",
help="display more about what is going on")
parser.add_option("-m", "--msgq-port", dest="msgq_port", type="string",
action="callback", callback=check_port, default="9912",
help="port the msgq daemon will use")
(options, args) = parser.parse_args()
if options.verbose:
sys.stdout.write("BIND 10 %s\n" % __version__)
# TODO: set process name, perhaps by:
# http://code.google.com/p/procname/
# http://github.com/lericson/procname/
signal.signal(signal.SIGCHLD, reaper)
signal.siginterrupt(signal.SIGCHLD, False)
signal.signal(signal.SIGINT, fatal_signal)
signal.signal(signal.SIGTERM, fatal_signal)
boss_of_bind = BoB(options.msgq_port, options.verbose)
startup_result = boss_of_bind.startup()
if startup_result:
sys.stderr.write("Error on startup: %s\n" % startup_result)
sys.exit(1)
while True:
time.sleep(1)
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