celery/celery/utils/compat.py

"""
celery.utils.compat
===================

Backward compatible implementations of features
only available in later Python versions.

"""
from __future__ import absolute_import

############## py3k #########################################################
import sys

try:
    from UserList import UserList       # noqa
except ImportError:
    from collections import UserList    # noqa

try:
    from UserDict import UserDict       # noqa
except ImportError:
    from collections import UserDict    # noqa

if sys.version_info >= (3, 0):
    from io import StringIO, BytesIO
    from .encoding import bytes_to_str

    class WhateverIO(StringIO):

        def write(self, data):
            StringIO.write(self, bytes_to_str(data))
else:
    try:
        from cStringIO import StringIO  # noqa
    except ImportError:
        from StringIO import StringIO   # noqa
    BytesIO = WhateverIO = StringIO     # noqa


############## collections.OrderedDict ######################################
try:
    from collections import OrderedDict
except ImportError:
    from ordereddict import OrderedDict  # noqa

############## logging.LoggerAdapter ########################################
import logging
try:
    import multiprocessing
except ImportError:
    multiprocessing = None  # noqa
import sys


def _checkLevel(level):
    if isinstance(level, int):
        rv = level
    elif str(level) == level:
        if level not in logging._levelNames:
            raise ValueError("Unknown level: %r" % level)
        rv = logging._levelNames[level]
    else:
        raise TypeError("Level not an integer or a valid string: %r" % level)
    return rv


class _CompatLoggerAdapter(object):

    def __init__(self, logger, extra):
        self.logger = logger
        self.extra = extra

    def setLevel(self, level):
        self.logger.level = _checkLevel(level)

    def process(self, msg, kwargs):
        kwargs["extra"] = self.extra
        return msg, kwargs

    def debug(self, msg, *args, **kwargs):
        self.log(logging.DEBUG, msg, *args, **kwargs)

    def info(self, msg, *args, **kwargs):
        self.log(logging.INFO, msg, *args, **kwargs)

    def warning(self, msg, *args, **kwargs):
        self.log(logging.WARNING, msg, *args, **kwargs)
    warn = warning

    def error(self, msg, *args, **kwargs):
        self.log(logging.ERROR, msg, *args, **kwargs)

    def exception(self, msg, *args, **kwargs):
        kwargs.setdefault("exc_info", 1)
        self.error(msg, *args, **kwargs)

    def critical(self, msg, *args, **kwargs):
        self.log(logging.CRITICAL, msg, *args, **kwargs)
    fatal = critical

    def log(self, level, msg, *args, **kwargs):
        if self.logger.isEnabledFor(level):
            msg, kwargs = self.process(msg, kwargs)
            self._log(level, msg, args, **kwargs)

    def makeRecord(self, name, level, fn, lno, msg, args, exc_info,
            func=None, extra=None):
        rv = logging.LogRecord(name, level, fn, lno, msg, args, exc_info, func)
        if extra is not None:
            for key, value in extra.items():
                if key in ("message", "asctime") or key in rv.__dict__:
                    raise KeyError(
                            "Attempt to override %r in LogRecord" % key)
                rv.__dict__[key] = value
        if multiprocessing is not None:
            rv.processName = multiprocessing.current_process()._name
        else:
            rv.processName = ""
        return rv

    def _log(self, level, msg, args, exc_info=None, extra=None):
        defcaller = "(unknown file)", 0, "(unknown function)"
        if logging._srcfile:
            # IronPython doesn't track Python frames, so findCaller
            # throws an exception on some versions of IronPython.
            # We trap it here so that IronPython can use logging.
            try:
                fn, lno, func = self.logger.findCaller()
            except ValueError:
                fn, lno, func = defcaller
        else:
            fn, lno, func = defcaller
        if exc_info:
            if not isinstance(exc_info, tuple):
                exc_info = sys.exc_info()
        record = self.makeRecord(self.logger.name, level, fn, lno, msg,
                                 args, exc_info, func, extra)
        self.logger.handle(record)

    def isEnabledFor(self, level):
        return self.logger.isEnabledFor(level)

    def addHandler(self, hdlr):
        self.logger.addHandler(hdlr)

    def removeHandler(self, hdlr):
        self.logger.removeHandler(hdlr)

    @property
    def level(self):
        return self.logger.level


try:
    from logging import LoggerAdapter
except ImportError:
    LoggerAdapter = _CompatLoggerAdapter  # noqa

############## itertools.izip_longest #######################################

try:
    from itertools import izip_longest
except ImportError:
    import itertools

    def izip_longest(*args, **kwds):  # noqa
        fillvalue = kwds.get("fillvalue")

        def sentinel(counter=([fillvalue] * (len(args) - 1)).pop):
            yield counter()     # yields the fillvalue, or raises IndexError

        fillers = itertools.repeat(fillvalue)
        iters = [itertools.chain(it, sentinel(), fillers)
                    for it in args]
        try:
            for tup in itertools.izip(*iters):
                yield tup
        except IndexError:
            pass


############## itertools.chain.from_iterable ################################
from itertools import chain


def _compat_chain_from_iterable(iterables):
    for it in iterables:
        for element in it:
            yield element

try:
    chain_from_iterable = getattr(chain, "from_iterable")
except AttributeError:
    chain_from_iterable = _compat_chain_from_iterable


############## logging.handlers.WatchedFileHandler ##########################
import os
from stat import ST_DEV, ST_INO
import platform as _platform

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)