python-kombu 2.1.8-1 / usr / share / pyshared / kombu / utils / compat.py

"""
kombu.utils.compat
==================

Helps compatibility with older Python versions.

:copyright: (c) 2009 - 2012 by Ask Solem.
:license: BSD, see LICENSE for more details.

"""
import sys

############## collections.OrderedDict #######################################

import weakref
try:
    from collections import MutableMapping
except ImportError:
    from UserDict import DictMixin as MutableMapping  # noqa
from itertools import imap as _imap
from operator import eq as _eq


class _Link(object):
    """Doubly linked list."""
    __slots__ = 'prev', 'next', 'key', '__weakref__'


class CompatOrderedDict(dict, MutableMapping):
    """Dictionary that remembers insertion order"""
    # An inherited dict maps keys to values.
    # The inherited dict provides __getitem__, __len__, __contains__, and get.
    # The remaining methods are order-aware.
    # Big-O running times for all methods are the same as for regular
    # dictionaries.

    # The internal self.__map dictionary maps keys to links in a doubly
    # linked list.
    # The circular doubly linked list starts and ends with a sentinel element.
    # The sentinel element never gets deleted (this simplifies the algorithm).
    # The prev/next links are weakref proxies (to prevent circular
    # references).
    # Individual links are kept alive by the hard reference in self.__map.
    # Those hard references disappear when a key is deleted from
    # an OrderedDict.

    __marker = object()

    def __init__(self, *args, **kwds):
        """Initialize an ordered dictionary.

        Signature is the same as for regular dictionaries, but keyword
        arguments are not recommended because their insertion order is
        arbitrary.

        """
        if len(args) > 1:
            raise TypeError("expected at most 1 arguments, got %d" % (
                                len(args)))
        try:
            self.__root
        except AttributeError:
            # sentinel node for the doubly linked list
            self.__root = root = _Link()
            root.prev = root.next = root
            self.__map = {}
        self.update(*args, **kwds)

    def clear(self):
        "od.clear() -> None.  Remove all items from od."
        root = self.__root
        root.prev = root.next = root
        self.__map.clear()
        dict.clear(self)

    def __setitem__(self, key, value):
        "od.__setitem__(i, y) <==> od[i]=y"
        # Setting a new item creates a new link which goes at the end of the
        # linked list, and the inherited dictionary is updated with the new
        # key/value pair.
        if key not in self:
            self.__map[key] = link = _Link()
            root = self.__root
            last = root.prev
            link.prev, link.next, link.key = last, root, key
            last.next = root.prev = weakref.proxy(link)
        dict.__setitem__(self, key, value)

    def __delitem__(self, key):
        """od.__delitem__(y) <==> del od[y]"""
        # Deleting an existing item uses self.__map to find the
        # link which is then removed by updating the links in the
        # predecessor and successor nodes.
        dict.__delitem__(self, key)
        link = self.__map.pop(key)
        link.prev.next = link.next
        link.next.prev = link.prev

    def __iter__(self):
        """od.__iter__() <==> iter(od)"""
        # Traverse the linked list in order.
        root = self.__root
        curr = root.next
        while curr is not root:
            yield curr.key
            curr = curr.next

    def __reversed__(self):
        """od.__reversed__() <==> reversed(od)"""
        # Traverse the linked list in reverse order.
        root = self.__root
        curr = root.prev
        while curr is not root:
            yield curr.key
            curr = curr.prev

    def __reduce__(self):
        """Return state information for pickling"""
        items = [[k, self[k]] for k in self]
        tmp = self.__map, self.__root
        del(self.__map, self.__root)
        inst_dict = vars(self).copy()
        self.__map, self.__root = tmp
        if inst_dict:
            return (self.__class__, (items,), inst_dict)
        return self.__class__, (items,)

    def setdefault(self, key, default=None):
        try:
            return self[key]
        except KeyError:
            self[key] = default
        return default

    def update(self, other=(), **kwds):
        if isinstance(other, dict):
            for key in other:
                self[key] = other[key]
        elif hasattr(other, "keys"):
            for key in other.keys():
                self[key] = other[key]
        else:
            for key, value in other:
                self[key] = value
        for key, value in kwds.items():
            self[key] = value

    def pop(self, key, default=__marker):
        try:
            value = self[key]
        except KeyError:
            if default is self.__marker:
                raise
            return default
        else:
            del self[key]
            return value

    def values(self):
        return [self[key] for key in self]

    def items(self):
        return [(key, self[key]) for key in self]

    def itervalues(self):
        for key in self:
            yield self[key]

    def iteritems(self):
        for key in self:
            yield (key, self[key])

    def iterkeys(self):
        return iter(self)

    def keys(self):
        return list(self)

    def popitem(self, last=True):
        """od.popitem() -> (k, v)

        Return and remove a (key, value) pair.
        Pairs are returned in LIFO order if last is true or FIFO
        order if false.

        """
        if not self:
            raise KeyError('dictionary is empty')
        if last:
            if sys.platform.startswith("java"):
                key = self.keys()[-1]
            else:
                key = reversed(self).next()
        else:
            key = iter(self).next()
        value = self.pop(key)
        return key, value

    def __repr__(self):
        "od.__repr__() <==> repr(od)"
        if not self:
            return '%s()' % (self.__class__.__name__,)
        return '%s(%r)' % (self.__class__.__name__, self.items())

    def copy(self):
        "od.copy() -> a shallow copy of od"
        return self.__class__(self)

    @classmethod
    def fromkeys(cls, iterable, value=None):
        """OD.fromkeys(S[, v]) -> New ordered dictionary with keys from S
        and values equal to v (which defaults to None)."""
        d = cls()
        for key in iterable:
            d[key] = value
        return d

    def __eq__(self, other):
        """od.__eq__(y) <==> od==y.  Comparison to another OD is
        order-sensitive while comparison to a regular mapping
        is order-insensitive."""
        if isinstance(other, OrderedDict):
            return len(self) == len(other) and \
                   all(_imap(_eq, self.iteritems(), other.iteritems()))
        return dict.__eq__(self, other)

    def __ne__(self, other):
        return not (self == other)

try:
    from collections import OrderedDict
except ImportError:
    OrderedDict = CompatOrderedDict  # noqa

############## queue.LifoQueue ##############################################
from Queue import Queue


class LifoQueue(Queue):

    def _init(self, maxsize):
        self.queue = []
        self.maxsize = maxsize

    def _qsize(self, len=len):
        return len(self.queue)

    def _put(self, item):
        self.queue.append(item)

    def _get(self):
        return self.queue.pop()

############## logging.handlers.WatchedFileHandler ##########################
import logging
import os
import platform as _platform

from stat import ST_DEV, ST_INO

if _platform.system() == "Windows":
    #since windows doesn't go with WatchedFileHandler use FileHandler instead
    WatchedFileHandler = logging.FileHandler
else:
    try:
        from logging.handlers import WatchedFileHandler
    except ImportError:
        class WatchedFileHandler(logging.FileHandler):  # noqa
            """
            A handler for logging to a file, which watches the file
            to see if it has changed while in use. This can happen because of
            usage of programs such as newsyslog and logrotate which perform
            log file rotation. This handler, intended for use under Unix,
            watches the file to see if it has changed since the last emit.
            (A file has changed if its device or inode have changed.)
            If it has changed, the old file stream is closed, and the file
            opened to get a new stream.

            This handler is not appropriate for use under Windows, because
            under Windows open files cannot be moved or renamed - logging
            opens the files with exclusive locks - and so there is no need
            for such a handler. Furthermore, ST_INO is not supported under
            Windows; stat always returns zero for this value.

            This handler is based on a suggestion and patch by Chad J.
            Schroeder.
            """
            def __init__(self, *args, **kwargs):
                logging.FileHandler.__init__(self, *args, **kwargs)

                if not os.path.exists(self.baseFilename):
                    self.dev, self.ino = -1, -1
                else:
                    stat = os.stat(self.baseFilename)
                    self.dev, self.ino = stat[ST_DEV], stat[ST_INO]

            def emit(self, record):
                """
                Emit a record.

                First check if the underlying file has changed, and if it
                has, close the old stream and reopen the file to get the
                current stream.
                """
                if not os.path.exists(self.baseFilename):
                    stat = None
                    changed = 1
                else:
                    stat = os.stat(self.baseFilename)
                    changed = ((stat[ST_DEV] != self.dev) or
                               (stat[ST_INO] != self.ino))
                if changed and self.stream is not None:
                    self.stream.flush()
                    self.stream.close()
                    self.stream = self._open()
                    if stat is None:
                        stat = os.stat(self.baseFilename)
                    self.dev, self.ino = stat[ST_DEV], stat[ST_INO]
                logging.FileHandler.emit(self, record)