earwigbot/bot/tasks/__init__.py

# -*- coding: utf-8  -*-

"""
EarwigBot's Wiki Task Manager

This package provides the wiki bot "tasks" EarwigBot runs. Here in __init__,
you can find some functions used to load and run these tasks.
"""

import time
import traceback
import threading
import os

import config

__all__ = ["load", "schedule", "start"]

# Store loaded tasks as a dict where the key is the task name and the value is
# an instance of the task class:
_tasks = {}

def _load_class_from_file(f):
    """Look in a given file for the task class."""
    global _tasks

    module = f[:-3]  # strip .py from end
    try:
        exec "from wiki.tasks import %s as m" % module
    except:  # importing the file failed for some reason...
        print "Couldn't load task file %s:" % f
        traceback.print_exc()
        return
    try:
        task_class = m.Task
    except:
        print "Couldn't find or get task class in file %s:" % f
        traceback.print_exc()
        return
    task_name = task_class.task_name
    _tasks[task_name] = task_class()
    print "Added task %s from bot/tasks/%s..." % (task_name, f)

def _wrapper(task, **kwargs):
    """Wrapper for task classes: run the task and catch any errors."""
    try:
        task.run(**kwargs)
    except:
        print "Task '{0}' raised an exception and had to stop:".format(task.task_name)
        traceback.print_exc()
    else:
        print "Task '{0}' finished without error.".format(task.task_name)

def load():
    """Load all valid task classes from bot/tasks/, and add them to the
    _tasks variable."""
    files = os.listdir(os.path.join("bot", "tasks"))
    files.sort()  # alphabetically sort all files in wiki/tasks/
    for f in files:
        if not os.path.isfile(os.path.join("bot", "tasks", f)):
            continue  # ignore non-files
        if f.startswith("_") or not f.endswith(".py"):
            continue  # ignore non-python files or files beginning with an _
        load_class_from_file(f)
    print "Found %s tasks: %s." % (len(_tasks), ', '.join(_tasks.keys()))

def schedule(now=time.gmtime()):
    """Start all tasks that are supposed to be run at a given time."""
    tasks = config.schedule(now.tm_min, now.tm_hour, now.tm_mday, now.tm_mon,
            now.tm_wday)  # get list of tasks to run this turn

    for task in tasks:
        if isinstance(task, list):     # they've specified kwargs
            start(task[0], **task[1])  # so pass those to start_task
        else:  # otherwise, just pass task_name
            start(task)

def start(task_name, **kwargs):
    """Start a given task in a new thread. Pass args to the task's run()
    function."""
    print "Starting task '{0}' in a new thread...".format(task_name)

    try:
        task = _tasks[task_name]
    except KeyError:
        print ("Couldn't find task '{0}': bot/tasks/{0}.py does not exist.").format(task_name)
        return

    task_thread = threading.Thread(target=lambda: _wrapper(task, **kwargs))
    task_thread.name = "{0} ({1})".format(task_name, time.strftime("%b %d %H:%M:%S"))

    # stop bot task threads automagically if the main bot stops
    task_thread.daemon = True

    task_thread.start()