newcron.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
Created by Attila Csipa <web2py@csipa.in.rs>
Modified by Massimo Di Pierro <mdipierro@cs.depaul.edu>
"""

import sys
import os
import threading
import logging
import time
import sched
import re
import datetime
import platform
import portalocker
import fileutils
import cPickle
from settings import global_settings

logger = logging.getLogger("web2py.cron")
_cron_stopping = False

def absolute_path_link(path):
    """
    Return an absolute path for the destination of a symlink

    """
    if os.path.islink(path):
        link = os.readlink(path)
        if not os.path.isabs(link):
            link = os.path.join(os.path.dirname(path), link)
    else:
        link = os.path.abspath(path)
    return link

def stopcron():
    "graceful shutdown of cron"
    global _cron_stopping
    _cron_stopping = True

class extcron(threading.Thread):

    def __init__(self, applications_parent):
        threading.Thread.__init__(self)
        self.setDaemon(False)
        self.path = applications_parent
        crondance(self.path, 'external', startup=True)

    def run(self):
        if not _cron_stopping:
            logger.debug('external cron invocation')
            crondance(self.path, 'external', startup=False)

class hardcron(threading.Thread):

    def __init__(self, applications_parent):
        threading.Thread.__init__(self)
        self.setDaemon(True)
        self.path = applications_parent
        crondance(self.path, 'hard', startup=True)

    def launch(self):
        if not _cron_stopping:
            logger.debug('hard cron invocation')
            crondance(self.path, 'hard', startup = False)

    def run(self):
        s = sched.scheduler(time.time, time.sleep)
        logger.info('Hard cron daemon started')
        while not _cron_stopping:
            now = time.time()
            s.enter(60 - now % 60, 1, self.launch, ())
            s.run()

class softcron(threading.Thread):

    def __init__(self, applications_parent):
        threading.Thread.__init__(self)
        self.path = applications_parent
        crondance(self.path, 'soft', startup=True)

    def run(self):
        if not _cron_stopping:
            logger.debug('soft cron invocation')
            crondance(self.path, 'soft', startup=False)

class Token(object):

    def __init__(self,path):
        self.path = os.path.join(path, 'cron.master')
        if not os.path.exists(self.path):
            fileutils.write_file(self.path, '', 'wb')
        self.master = None
        self.now = time.time()

    def acquire(self,startup=False):
        """
        returns the time when the lock is acquired or
        None if cron already running

        lock is implemented by writing a pickle (start, stop) in cron.master
        start is time when cron job starts and stop is time when cron completed
        stop == 0 if job started but did not yet complete
        if a cron job started within less than 60 seconds, acquire returns None
        if a cron job started before 60 seconds and did not stop,
        a warning is issue "Stale cron.master detected"
        """
        if portalocker.LOCK_EX is None:
            logger.warning('WEB2PY CRON: Disabled because no file locking')
            return None
        self.master = open(self.path,'rb+')
        try:
            ret = None
            portalocker.lock(self.master,portalocker.LOCK_EX)
            try:
                (start, stop) =  cPickle.load(self.master)
            except:
                (start, stop) = (0, 1)
            if startup or self.now - start > 59.99:
                ret = self.now
                if not stop:
                    # this happens if previous cron job longer than 1 minute
                    logger.warning('WEB2PY CRON: Stale cron.master detected')
                logger.debug('WEB2PY CRON: Acquiring lock')
                self.master.seek(0)
                cPickle.dump((self.now,0),self.master)
        finally:
            portalocker.unlock(self.master)
        if not ret:
            # do this so no need to release
            self.master.close()
        return ret

    def release(self):
        """
        this function writes into cron.master the time when cron job
        was completed
        """
        if not self.master.closed:
            portalocker.lock(self.master,portalocker.LOCK_EX)
            logger.debug('WEB2PY CRON: Releasing cron lock')
            self.master.seek(0)
            (start, stop) =  cPickle.load(self.master)
            if start == self.now: # if this is my lock
                self.master.seek(0)
                cPickle.dump((self.now,time.time()),self.master)
            portalocker.unlock(self.master)
            self.master.close()


def rangetolist(s, period='min'):
    retval = []
    if s.startswith('*'):
        if period == 'min':
            s = s.replace('*', '0-59', 1)
        elif period == 'hr':
            s = s.replace('*', '0-23', 1)
        elif period == 'dom':
            s = s.replace('*', '1-31', 1)
        elif period == 'mon':
            s = s.replace('*', '1-12', 1)
        elif period == 'dow':
            s = s.replace('*', '0-6', 1)
    m = re.compile(r'(\d+)-(\d+)/(\d+)')
    match = m.match(s)
    if match:
        for i in range(int(match.group(1)), int(match.group(2)) + 1):
            if i % int(match.group(3)) == 0:
                retval.append(i)
    return retval


def parsecronline(line):
    task = {}
    if line.startswith('@reboot'):
        line=line.replace('@reboot', '-1 * * * *')
    elif line.startswith('@yearly'):
        line=line.replace('@yearly', '0 0 1 1 *')
    elif line.startswith('@annually'):
        line=line.replace('@annually', '0 0 1 1 *')
    elif line.startswith('@monthly'):
        line=line.replace('@monthly', '0 0 1 * *')
    elif line.startswith('@weekly'):
        line=line.replace('@weekly', '0 0 * * 0')
    elif line.startswith('@daily'):
        line=line.replace('@daily', '0 0 * * *')
    elif line.startswith('@midnight'):
        line=line.replace('@midnight', '0 0 * * *')
    elif line.startswith('@hourly'):
        line=line.replace('@hourly', '0 * * * *')
    params = line.strip().split(None, 6)
    if len(params) < 7:
        return None
    daysofweek={'sun':0,'mon':1,'tue':2,'wed':3,'thu':4,'fri':5,'sat':6}
    for (s, id) in zip(params[:5], ['min', 'hr', 'dom', 'mon', 'dow']):
        if not s in [None, '*']:
            task[id] = []
            vals = s.split(',')
            for val in vals:
                if val != '-1' and '-' in val and '/' not in val:
                    val = '%s/1' % val
                if '/' in val:
                    task[id] += rangetolist(val, id)
                elif val.isdigit() or val=='-1':
                    task[id].append(int(val))
                elif id=='dow' and val[:3].lower() in daysofweek:
                    task[id].append(daysofweek(val[:3].lower()))
    task['user'] = params[5]
    task['cmd'] = params[6]
    return task


class cronlauncher(threading.Thread):

    def __init__(self, cmd, shell=True):
        threading.Thread.__init__(self)
        if platform.system() == 'Windows':
            shell = False
        elif isinstance(cmd,list):
            cmd = ' '.join(cmd)
        self.cmd = cmd
        self.shell = shell

    def run(self):
        import subprocess
        proc = subprocess.Popen(self.cmd,
                                stdin=subprocess.PIPE,
                                stdout=subprocess.PIPE,
                                stderr=subprocess.PIPE,
                                shell=self.shell)
        (stdoutdata,stderrdata) = proc.communicate()
        if proc.returncode != 0:
            logger.warning(
                'WEB2PY CRON Call returned code %s:\n%s' % \
                    (proc.returncode, stdoutdata+stderrdata))
        else:
            logger.debug('WEB2PY CRON Call returned success:\n%s' \
                              % stdoutdata)

def crondance(applications_parent, ctype='soft', startup=False):
    apppath = os.path.join(applications_parent,'applications')
    cron_path = os.path.join(applications_parent)
    token = Token(cron_path)
    cronmaster = token.acquire(startup=startup)
    if not cronmaster:
        return
    now_s = time.localtime()
    checks=(('min',now_s.tm_min),
            ('hr',now_s.tm_hour),
            ('mon',now_s.tm_mon),
            ('dom',now_s.tm_mday),
            ('dow',(now_s.tm_wday+1)%7))

    apps = [x for x in os.listdir(apppath)
            if os.path.isdir(os.path.join(apppath, x))]

    full_apath_links = set()

    for app in apps:
        if _cron_stopping:
            break;
        apath = os.path.join(apppath,app)

        # if app is a symbolic link to other app, skip it
        full_apath_link = absolute_path_link(apath)
        if full_apath_link in full_apath_links:
            continue
        else:
            full_apath_links.add(full_apath_link)

        cronpath = os.path.join(apath, 'cron')
        crontab = os.path.join(cronpath, 'crontab')
        if not os.path.exists(crontab):
            continue
        try:
            cronlines = fileutils.readlines_file(crontab, 'rt')
            lines = [x.strip() for x in cronlines if x.strip() and not x.strip().startswith('#')]
            tasks = [parsecronline(cline) for cline in lines]
        except Exception, e:
            logger.error('WEB2PY CRON: crontab read error %s' % e)
            continue

        for task in tasks:
            if _cron_stopping:
                break;
            commands = [sys.executable]
            w2p_path = fileutils.abspath('web2py.py', gluon=True)
            if os.path.exists(w2p_path):
                commands.append(w2p_path)
            if global_settings.applications_parent != global_settings.gluon_parent:
                commands.extend(('-f', global_settings.applications_parent))
            citems = [(k in task and not v in task[k]) for k,v in checks]
            task_min= task.get('min',[])
            if not task:
                continue
            elif not startup and task_min == [-1]:
                continue
            elif task_min != [-1] and reduce(lambda a,b: a or b, citems):
                continue
            logger.info('WEB2PY CRON (%s): %s executing %s in %s at %s' \
                             % (ctype, app, task.get('cmd'),
                                os.getcwd(), datetime.datetime.now()))
            action, command, models = False, task['cmd'], ''
            if command.startswith('**'):
                (action,models,command) = (True,'',command[2:])
            elif command.startswith('*'):
                (action,models,command) = (True,'-M',command[1:])
            else:
                action=False
            if action and command.endswith('.py'):
                commands.extend(('-J',                # cron job
                                 models,              # import models?
                                 '-S', app,           # app name
                                 '-a', '"<recycle>"', # password
                                 '-R', command))      # command
                shell = True
            elif action:
                commands.extend(('-J',                  # cron job
                                 models,                # import models?
                                 '-S', app+'/'+command, # app name
                                 '-a', '"<recycle>"'))  # password
                shell = True
            else:
                commands = command
                shell = False
            try:
                cronlauncher(commands, shell=shell).start()
            except Exception, e:
                logger.warning(
                    'WEB2PY CRON: Execution error for %s: %s' \
                        % (task.get('cmd'), e))
    token.release()