Allura/allura/command/taskd.py

import os
import time
import Queue
from datetime import datetime, timedelta
import signal
import sys

import faulthandler
import pylons
from paste.deploy import loadapp
from paste.deploy.converters import asint
from webob import Request

import base

faulthandler.enable()


class TaskdCommand(base.Command):
    summary = 'Task server'
    parser = base.Command.standard_parser(verbose=True)
    parser.add_option('--only', dest='only', type='string', default=None,
                      help='only handle tasks of the given name(s) (can be comma-separated list)')

    def command(self):
        self.basic_setup()
        self.keep_running = True
        self.restart_when_done = False
        base.log.info('Starting taskd, pid %s' % os.getpid())
        signal.signal(signal.SIGHUP, self.graceful_restart)
        signal.signal(signal.SIGTERM, self.graceful_stop)
        signal.signal(signal.SIGUSR1, self.log_current_task)
        # restore default behavior of not interrupting system calls
        # see http://docs.python.org/library/signal.html#signal.siginterrupt
        # and http://linux.die.net/man/3/siginterrupt
        signal.siginterrupt(signal.SIGHUP, False)
        signal.siginterrupt(signal.SIGTERM, False)
        signal.siginterrupt(signal.SIGUSR1, False)
        self.worker()

    def graceful_restart(self, signum, frame):
        base.log.info('taskd pid %s recieved signal %s preparing to do a graceful restart' % (os.getpid(), signum))
        self.keep_running = False
        self.restart_when_done = True

    def graceful_stop(self, signum, frame):
        base.log.info('taskd pid %s recieved signal %s preparing to do a graceful stop' % (os.getpid(), signum))
        self.keep_running = False

    def log_current_task(self, signum, frame):
        base.log.info('taskd pid %s is currently handling task %s' % (os.getpid(), getattr(self, 'task', None)))

    def worker(self):
        from allura import model as M
        name = '%s pid %s' % (os.uname()[1], os.getpid())
        wsgi_app = loadapp('config:%s#task' % self.args[0],relative_to=os.getcwd())
        poll_interval = asint(pylons.config.get('monq.poll_interval', 10))
        only = self.options.only
        if only:
            only = only.split(',')

        # errors get logged via regular logging and also recorded into the mongo task record
        # so this is generally not needed, and only present to avoid errors within
        # weberror's ErrorMiddleware if the default error stream (stderr?) doesn't work
        wsgi_error_log = open(pylons.config.get('taskd.wsgi_log', '/dev/null'), 'a')

        def start_response(status, headers, exc_info=None):
            pass

        def waitfunc_amqp():
            try:
                return pylons.g.amq_conn.queue.get(timeout=poll_interval)
            except Queue.Empty:
                return None

        def waitfunc_noq():
            time.sleep(poll_interval)

        def check_running(func):
            if self.keep_running:
                return func()
            else:
                return None

        if pylons.g.amq_conn:
            waitfunc = waitfunc_amqp
        else:
            waitfunc = waitfunc_noq
        waitfunc = check_running(waitfunc)
        while self.keep_running:
            if pylons.g.amq_conn:
                pylons.g.amq_conn.reset()
            try:
                while self.keep_running:
                    self.task = M.MonQTask.get(
                            process=name,
                            waitfunc=waitfunc,
                            only=only)
                    if self.task:
                        # Build the (fake) request
                        r = Request.blank('/--%s--/' % self.task.task_name,
                                          {'task': self.task,
                                           'wsgi.errors': wsgi_error_log,  # ErrorMiddleware records error details here
                                           })
                        list(wsgi_app(r.environ, start_response))
                        self.task = None
            except Exception as e:
                if self.keep_running:
                    base.log.exception('taskd error %s; pausing for 10s before taking more tasks' % e)
                    time.sleep(10)
                else:
                    base.log.exception('taskd error %s' % e)
            finally:
                wsgi_error_log.flush()
        base.log.info('taskd pid %s stopping gracefully.' % os.getpid())

        if self.restart_when_done:
            base.log.info('taskd pid %s restarting itself' % os.getpid())
            os.execv(sys.argv[0], sys.argv)


class TaskCommand(base.Command):
    summary = 'Task command'
    parser = base.Command.standard_parser(verbose=True)
    parser.add_option('-s', '--state', dest='state', default='ready',
                      help='state of processes to examine')
    parser.add_option('-t', '--timeout', dest='timeout', type=int, default=60,
                      help='timeout (in seconds) for busy tasks')
    min_args = 2
    max_args = None
    usage = '<ini file> [list|retry|purge|timeout|commit]'

    def command(self):
        self.basic_setup()
        cmd = self.args[1]
        tab = dict(
            list=self._list,
            retry=self._retry,
            purge=self._purge,
            timeout=self._timeout,
            commit=self._commit)
        tab[cmd]()

    def _list(self):
        '''List tasks'''
        from allura import model as M
        base.log.info('Listing tasks of state %s', self.options.state)
        if self.options.state == '*':
            q = dict()
        else:
            q = dict(state=self.options.state)
        for t in M.MonQTask.query.find(q):
            print t

    def _retry(self):
        '''Retry tasks in an error state'''
        from allura import model as M
        base.log.info('Retry tasks in error state')
        M.MonQTask.query.update(
            dict(state='error'),
            {'$set': dict(state='ready')},
            multi=True)

    def _purge(self):
        '''Purge completed tasks'''
        from allura import model as M
        base.log.info('Purge complete/forget tasks')
        M.MonQTask.query.remove(
            dict(state='complete', result_type='forget'))

    def _timeout(self):
        '''Reset tasks that have been busy too long to 'ready' state'''
        from allura import model as M
        base.log.info('Reset tasks stuck for %ss or more', self.options.timeout)
        cutoff = datetime.utcnow() - timedelta(seconds=self.options.timeout)
        M.MonQTask.timeout_tasks(cutoff)

    def _commit(self):
        '''Schedule a SOLR commit'''
        from allura.tasks import index_tasks
        base.log.info('Commit to solr')
        index_tasks.commit.post()