Coverage for scrapy/utils/trackref : 59%

"""This module provides some functions and classes to record and report 

references to live object instances. 

If you want live objects for a particular class to be tracked, you only have to 

subclass form object_ref (instead of object). Also, remember to turn on 

tracking by enabling the TRACK_REFS setting. 

About performance: This library has a minimal performance impact when enabled, 

and no performance penalty at all when disabled (as object_ref becomes just an 

alias to object in that case). 

""" 

import weakref, os 

from collections import defaultdict 

from time import time 

from operator import itemgetter 

from types import NoneType 

from scrapy.conf import settings 

live_refs = defaultdict(weakref.WeakKeyDictionary) 

class object_ref(object): 

    """Inherit from this class (instead of object) to a keep a record of live 

    instances""" 

    __slots__ = () 

    def __new__(cls, *args, **kwargs): 

        obj = object.__new__(cls) 

        live_refs[cls][obj] = time() 

        return obj 

37if not settings.getbool('TRACK_REFS'): 

    object_ref = object 

def format_live_refs(ignore=NoneType): 

    if object_ref is object: 

        return "The trackref module is disabled. Use TRACK_REFS setting to enable it." 

    s = "Live References" + os.linesep + os.linesep 

    now = time() 

    for cls, wdict in live_refs.iteritems(): 

        if not wdict: 

            continue 

        if issubclass(cls, ignore): 

            continue 

        oldest = min(wdict.itervalues()) 

        s += "%-30s %6d   oldest: %ds ago" % (cls.__name__, len(wdict), \ 

            now-oldest) + os.linesep 

    return s 

def print_live_refs(*a, **kw): 

    print format_live_refs(*a, **kw) 

def get_oldest(class_name): 

    for cls, wdict in live_refs.iteritems(): 

        if cls.__name__ == class_name: 

            if wdict: 

                return min(wdict.iteritems(), key=itemgetter(1))[0] 

def iter_all(class_name): 

    for cls, wdict in live_refs.iteritems(): 

        if cls.__name__ == class_name: 

            return wdict.iterkeys()