Allura/allura/lib/decorators.py

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import inspect
import sys
import json
import logging
from collections import defaultdict
from urllib import unquote

from decorator import decorator
from tg.decorators import before_validate
from tg import request, redirect
from webob import exc
from pylons import tmpl_context as c

from allura.lib import helpers as h
from allura.lib import utils


def task(*args, **kw):
    """Decorator that adds a ``.post()`` function to the decorated callable.

    Calling <original_callable>.post(*args, **kw) queues the callable for
    execution by a background worker process. All parameters must be
    BSON-serializable.

    Example usage:

    @task
    def myfunc():
        pass

    @task(notifications_disabled=True)
    def myotherfunc():
        # No email notifications will be sent for c.project during this task
        pass

    """
    def task_(func):
        def post(*args, **kwargs):
            delay = kwargs.pop('delay', 0)
            project = getattr(c, 'project', None)
            cm = (h.notifications_disabled if project and
                  kw.get('notifications_disabled') else h.null_contextmanager)
            with cm(project):
                from allura import model as M
                return M.MonQTask.post(func, args, kwargs, delay=delay)
        # if decorating a class, have to make it a staticmethod
        # or it gets a spurious cls argument
        func.post = staticmethod(post) if inspect.isclass(func) else post
        return func
    if len(args) == 1 and callable(args[0]):
        return task_(args[0])
    return task_


class event_handler(object):

    '''Decorator to register event handlers'''
    listeners = defaultdict(set)

    def __init__(self, *topics):
        self.topics = topics

    def __call__(self, func):
        for t in self.topics:
            self.listeners[t].add(func)
        return func


class require_post(object):

    def __init__(self, redir=None):
        self.redir = redir

    def __call__(self, func):
        def check_method(remainder, params):
            if request.method != 'POST':
                if self.redir is not None:
                    redirect(self.redir)
                raise exc.HTTPMethodNotAllowed(headers={'Allow': 'POST'})
        before_validate(check_method)(func)
        return func


class log_action(object):  # pragma no cover

    def __init__(self,
                 logger=None,
                 level=logging.INFO,
                 msg=None,
                 *args, **kwargs):
        if logger is None:
            logger = logging
        self._logger = logger
        self._level = level
        self._msg = msg
        self._args = args
        self._kwargs = kwargs
        self._extra_proto = dict(
            user=None,
            user_id=None,
            source=None,
            project_name=None,
            group_id=None)

    def __call__(self, func):
        self._func = func
        self._extra_proto.update(action=func.__name__)
        if self._msg is None:
            self._msg = func.__name__
        result = lambda *args, **kwargs: self._wrapper(*args, **kwargs)
        # assert not hasattr(func, 'decoration')
        if hasattr(func, 'decoration'):
            result.decoration = func.decoration
        return result

    def _wrapper(self, *args, **kwargs):
        result = None
        try:
            try:
                result = self._func(*args, **kwargs)
            except exc.HTTPServerError:
                raise
            except exc.HTTPException, e:
                result = e
            args = self._args
            kwargs = self._kwargs
            extra = kwargs.setdefault('extra', {})
            extra.update(self._make_extra(result))
            self._logger.log(self._level, self._msg,
                             *self._args, **self._kwargs)
            return result
        except:
            args = self._args
            kwargs = self._kwargs
            extra = kwargs.setdefault('extra', {})
            extra.update(self._make_extra(result))
            kwargs['exc_info'] = sys.exc_info()
            self._logger.log(logging.ERROR, self._msg,
                             *self._args, **self._kwargs)
            raise

    def _make_extra(self, result=None):
        '''Create a dict of extra items to be added to a log record
        '''
        extra = self._extra_proto.copy()
        # Save the client IP address
        extra.update(client_ip=utils.ip_address(request))
        # Save the user info
        user = getattr(request, 'user', None)
        if user:
            extra.update(user=user.username,
                         user_id=user.id)
        # Save the project info
        if (result
                and isinstance(result, dict)
                and 'p' in result
                and result['p'] is not None):
            extra.update(
                source=result['p']['source'],
                project_name=result['p']['shortname'],
                group_id=result['p'].get('sf_id'))
        # Log the referer cookie if it exists
        referer_link = request.cookies.get('referer_link')
        if referer_link:
            referer_link = unquote(referer_link)
            try:
                referer_link = json.loads(referer_link)
            except ValueError:
                pass
        extra['referer_link'] = referer_link
        return extra


def Property(function):
    '''Decorator to easily assign descriptors based on sub-function names
    See <http://code.activestate.com/recipes/410698-property-decorator-for-python-24/>
    '''
    keys = 'fget', 'fset', 'fdel'
    func_locals = {'doc': function.__doc__}

    def probeFunc(frame, event, arg):
        if event == 'return':
            locals = frame.f_locals
            func_locals.update(dict((k, locals.get(k)) for k in keys))
            sys.settrace(None)
        return probeFunc
    sys.settrace(probeFunc)
    function()
    return property(**func_locals)


def getattr_(obj, name, default_thunk):
    "Similar to .setdefault in dictionaries."
    try:
        return getattr(obj, name)
    except AttributeError:
        default = default_thunk()
        setattr(obj, name, default)
        return default


@decorator
def memoize(func, *args):
    """
    Cache the method's result, for the given args
    """
    dic = getattr_(func, "memoize_dic", dict)
    # memoize_dic is created at the first call
    if args in dic:
        return dic[args]
    else:
        result = func(*args)
        dic[args] = result
        return result