earwigbot/earwigbot/bot.py

# -*- coding: utf-8  -*-
#
# Copyright (C) 2009-2012 by Ben Kurtovic <ben.kurtovic@verizon.net>
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is 
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

import logging
from threading import Lock, Thread, enumerate as enumerate_threads
from time import sleep, time

from earwigbot.config import BotConfig
from earwigbot.irc import Frontend, Watcher
from earwigbot.managers import CommandManager, TaskManager
from earwigbot.wiki import SitesDB

__all__ = ["Bot"]

class Bot(object):
    """
    The Bot class is the core of EarwigBot, essentially responsible for
    starting the various bot components and making sure they are all happy.

    EarwigBot has three components that can run independently of each other: an
    IRC front-end, an IRC watcher, and a wiki scheduler.
    * The IRC front-end runs on a normal IRC server and expects users to
      interact with it/give it commands.
    * The IRC watcher runs on a wiki recent-changes server and listens for
      edits. Users cannot interact with this part of the bot.
    * The wiki scheduler runs wiki-editing bot tasks in separate threads at
      user-defined times through a cron-like interface.
 
    The Bot() object is accessable from within commands and tasks as self.bot.
    This is the primary way to access data from other components of the bot.
    For example, our BotConfig object is accessable from bot.config, tasks
    can be started with bot.tasks.start(), and sites can be loaded from the
    wiki toolset with bot.wiki.get_site().
    """

    def __init__(self, root_dir, level=logging.INFO):
        self.config = BotConfig(root_dir, level)
        self.logger = logging.getLogger("earwigbot")
        self.commands = CommandManager(self)
        self.tasks = TaskManager(self)
        self.wiki = SitesDB(self.config)
        self.frontend = None
        self.watcher = None

        self.component_lock = Lock()
        self._keep_looping = True

        self.config.load()
        self.commands.load()
        self.tasks.load()

    def _start_irc_components(self):
        """Start the IRC frontend/watcher in separate threads if enabled."""
        if self.config.components.get("irc_frontend"):
            self.logger.info("Starting IRC frontend")
            self.frontend = Frontend(self)
            Thread(name="irc_frontend", target=self.frontend.loop).start()

        if self.config.components.get("irc_watcher"):
            self.logger.info("Starting IRC watcher")
            self.watcher = Watcher(self)
            Thread(name="irc_watcher", target=self.watcher.loop).start()

    def _start_wiki_scheduler(self):
        """Start the wiki scheduler in a separate thread if enabled."""
        def wiki_scheduler():
            while self._keep_looping:
                time_start = time()
                self.tasks.schedule()
                time_end = time()
                time_diff = time_start - time_end
                if time_diff < 60:  # Sleep until the next minute
                    sleep(60 - time_diff)

        if self.config.components.get("wiki_scheduler"):
            self.logger.info("Starting wiki scheduler")
            thread = Thread(name="wiki_scheduler", target=wiki_scheduler)
            thread.daemon = True  # Stop if other threads stop
            thread.start()

    def _stop_irc_components(self, msg):
        """Request the IRC frontend and watcher to stop if enabled."""
        if self.frontend:
            self.frontend.stop(msg)
        if self.watcher:
            self.watcher.stop(msg)

    def _stop_task_threads(self):
        """Notify the user of which task threads are going to be killed.

        Unfortunately, there is no method right now of stopping task threads
        safely. This is because there is no way to tell them to stop like the
        IRC components can be told; furthermore, they are run as daemons, and
        daemon threads automatically stop without calling any __exit__ or
        try/finally code when all non-daemon threads stop. They were originally
        implemented as regular non-daemon threads, but this meant there was no
        way to completely stop the bot if tasks were running, because all other
        threads would exit and threading would absorb KeyboardInterrupts.

        The advantage of this is that stopping the bot is truly guarenteed to
        *stop* the bot, while the disadvantage is that the tasks are given no
        advance warning of their forced shutdown.
        """
        tasks = []
        non_tasks = self.config.components.keys() + ["MainThread", "reminder"]
        for thread in enumerate_threads():
            if thread.name not in non_tasks and thread.is_alive():
                tasks.append(thread.name)
        if tasks:
            log = "The following tasks will be killed: {0}"
            self.logger.warn(log.format(" ".join(tasks)))

    def run(self):
        """Main entry point into running the bot.

        Starts all config-enabled components and then enters an idle loop,
        ensuring that all components remain online and restarting components
        that get disconnected from their servers.
        """
        self.logger.info("Starting bot")
        self._start_irc_components()
        self._start_wiki_scheduler()
        while self._keep_looping:
            with self.component_lock:
                if self.frontend and self.frontend.is_stopped():
                    self.logger.warn("IRC frontend has stopped; restarting")
                    self.frontend = Frontend(self)
                    Thread(name=name, target=self.frontend.loop).start()
                if self.watcher and self.watcher.is_stopped():
                    self.logger.warn("IRC watcher has stopped; restarting")
                    self.watcher = Watcher(self)
                    Thread(name=name, target=self.watcher.loop).start()
            sleep(2)

    def restart(self, msg=None):
        """Reload config, commands, tasks, and safely restart IRC components.

        This is thread-safe, and it will gracefully stop IRC components before
        reloading anything. Note that you can safely reload commands or tasks
        without restarting the bot with bot.commands.load() or
        bot.tasks.load(). These should not interfere with running components
        or tasks.

        If given, 'msg' will be used as our quit message.
        """
        if msg:
            self.logger.info('Restarting bot ("{0}")'.format(msg))
        else:
            self.logger.info("Restarting bot")
        with self.component_lock:
            self._stop_irc_components(msg)
            self.config.load()
            self.commands.load()
            self.tasks.load()
            self._start_irc_components()

    def stop(self, msg=None):
        """Gracefully stop all bot components.

        If given, 'msg' will be used as our quit message.
        """
        if msg:
            self.logger.info('Stopping bot ("{0}")'.format(msg))
        else:
            self.logger.info("Stopping bot")
        with self.component_lock:
            self._stop_irc_components(msg)
        self._keep_looping = False
        self._stop_task_threads()