Added logutils module

src/shared/logutils/__init__.py

+#
+# Copyright (C) 2010-2013 Vinay Sajip. See LICENSE.txt for details.
+#
+"""
+The logutils package provides a set of handlers for the Python standard
+library's logging package.
+
+Some of these handlers are out-of-scope for the standard library, and
+so they are packaged here. Others are updated versions which have
+appeared in recent Python releases, but are usable with older versions
+of Python, and so are packaged here.
+"""
+import logging
+from string import Template
+
+__version__ = '0.3.3'
+
+class NullHandler(logging.Handler):
+    """
+    This handler does nothing. It's intended to be used to avoid the
+    "No handlers could be found for logger XXX" one-off warning. This is
+    important for library code, which may contain code to log events. If a user
+    of the library does not configure logging, the one-off warning might be
+    produced; to avoid this, the library developer simply needs to instantiate
+    a NullHandler and add it to the top-level logger of the library module or
+    package.
+    """
+
+    def handle(self, record):
+        """
+        Handle a record. Does nothing in this class, but in other
+        handlers it typically filters and then emits the record in a 
+        thread-safe way.
+        """
+        pass
+
+    def emit(self, record):
+        """
+        Emit a record. This does nothing and shouldn't be called during normal
+        processing, unless you redefine :meth:`~logutils.NullHandler.handle`.
+        """
+        pass
+
+    def createLock(self):
+        """
+        Since this handler does nothing, it has no underlying I/O to protect
+        against multi-threaded access, so this method returns `None`.
+        """
+        self.lock = None
+
+class PercentStyle(object):
+
+    default_format = '%(message)s'
+    asctime_format = '%(asctime)s'
+
+    def __init__(self, fmt):
+        self._fmt = fmt or self.default_format
+
+    def usesTime(self):
+        return self._fmt.find(self.asctime_format) >= 0
+
+    def format(self, record):
+        return self._fmt % record.__dict__
+
+class StrFormatStyle(PercentStyle):
+    default_format = '{message}'
+    asctime_format = '{asctime}'
+
+    def format(self, record):
+        return self._fmt.format(**record.__dict__)
+
+
+class StringTemplateStyle(PercentStyle):
+    default_format = '${message}'
+    asctime_format = '${asctime}'
+
+    def __init__(self, fmt):
+        self._fmt = fmt or self.default_format
+        self._tpl = Template(self._fmt)
+
+    def usesTime(self):
+        fmt = self._fmt
+        return fmt.find('$asctime') >= 0 or fmt.find(self.asctime_format) >= 0
+
+    def format(self, record):
+        return self._tpl.substitute(**record.__dict__)
+
+_STYLES = {
+    '%': PercentStyle,
+    '{': StrFormatStyle,
+    '$': StringTemplateStyle
+}
+
+class Formatter(logging.Formatter):
+    """
+    Subclasses Formatter in Pythons earlier than 3.2 in order to give
+    3.2 Formatter behaviour with respect to allowing %-, {} or $-
+    formatting.
+    """
+    def __init__(self, fmt=None, datefmt=None, style='%'):
+        """
+        Initialize the formatter with specified format strings.
+
+        Initialize the formatter either with the specified format string, or a
+        default as described above. Allow for specialized date formatting with
+        the optional datefmt argument (if omitted, you get the ISO8601 format).
+
+        Use a style parameter of '%', '{' or '$' to specify that you want to
+        use one of %-formatting, :meth:`str.format` (``{}``) formatting or
+        :class:`string.Template` formatting in your format string.
+        """
+        if style not in _STYLES:
+            raise ValueError('Style must be one of: %s' % ','.join(
+                             _STYLES.keys()))
+        self._style = _STYLES[style](fmt)
+        self._fmt = self._style._fmt
+        self.datefmt = datefmt
+
+    def usesTime(self):
+        """
+        Check if the format uses the creation time of the record.
+        """
+        return self._style.usesTime()
+
+    def formatMessage(self, record):
+        return self._style.format(record)
+
+    def format(self, record):
+        """
+        Format the specified record as text.
+
+        The record's attribute dictionary is used as the operand to a
+        string formatting operation which yields the returned string.
+        Before formatting the dictionary, a couple of preparatory steps
+        are carried out. The message attribute of the record is computed
+        using LogRecord.getMessage(). If the formatting string uses the
+        time (as determined by a call to usesTime(), formatTime() is
+        called to format the event time. If there is exception information,
+        it is formatted using formatException() and appended to the message.
+        """
+        record.message = record.getMessage()
+        if self.usesTime():
+            record.asctime = self.formatTime(record, self.datefmt)
+        s = self.formatMessage(record)
+        if record.exc_info:
+            # Cache the traceback text to avoid converting it multiple times
+            # (it's constant anyway)
+            if not record.exc_text:
+                record.exc_text = self.formatException(record.exc_info)
+        if record.exc_text:
+            if s[-1:] != "\n":
+                s = s + "\n"
+            s = s + record.exc_text
+        return s
+
+
+class BraceMessage(object):
+    def __init__(self, fmt, *args, **kwargs):
+        self.fmt = fmt
+        self.args = args
+        self.kwargs = kwargs
+        self.str = None
+        
+    def __str__(self):
+        if self.str is None:
+            self.str = self.fmt.format(*self.args, **self.kwargs)
+        return self.str
+
+class DollarMessage(object):
+    def __init__(self, fmt, **kwargs):
+        self.fmt = fmt
+        self.kwargs = kwargs
+        self.str = None
+        
+    def __str__(self):
+        if self.str is None:
+            self.str = Template(self.fmt).substitute(**self.kwargs)
+        return self.str
+
+
+def hasHandlers(logger):
+    """
+    See if a logger has any handlers.
+    """
+    rv = False
+    while logger:
+        if logger.handlers:
+            rv = True
+            break
+        elif not logger.propagate:
+            break
+        else:
+            logger = logger.parent
+    return rv
+

src/shared/logutils/adapter.py

+#
+# Copyright (C) 2010-2013 Vinay Sajip. See LICENSE.txt for details.
+#
+import logging
+import logutils
+
+class LoggerAdapter(object):
+    """
+    An adapter for loggers which makes it easier to specify contextual
+    information in logging output.
+    """
+
+    def __init__(self, logger, extra):
+        """
+        Initialize the adapter with a logger and a dict-like object which
+        provides contextual information. This constructor signature allows
+        easy stacking of LoggerAdapters, if so desired.
+
+        You can effectively pass keyword arguments as shown in the
+        following example:
+
+        adapter = LoggerAdapter(someLogger, dict(p1=v1, p2="v2"))
+        """
+        self.logger = logger
+        self.extra = extra
+
+    def process(self, msg, kwargs):
+        """
+        Process the logging message and keyword arguments passed in to
+        a logging call to insert contextual information. You can either
+        manipulate the message itself, the keyword args or both. Return
+        the message and kwargs modified (or not) to suit your needs.
+
+        Normally, you'll only need to override this one method in a
+        LoggerAdapter subclass for your specific needs.
+        """
+        kwargs["extra"] = self.extra
+        return msg, kwargs
+
+    #
+    # Boilerplate convenience methods
+    #
+    def debug(self, msg, *args, **kwargs):
+        """
+        Delegate a debug call to the underlying logger.
+        """
+        self.log(logging.DEBUG, msg, *args, **kwargs)
+
+    def info(self, msg, *args, **kwargs):
+        """
+        Delegate an info call to the underlying logger.
+        """
+        self.log(logging.INFO, msg, *args, **kwargs)
+
+    def warning(self, msg, *args, **kwargs):
+        """
+        Delegate a warning call to the underlying logger.
+        """
+        self.log(logging.WARNING, msg, *args, **kwargs)
+
+    warn = warning
+
+    def error(self, msg, *args, **kwargs):
+        """
+        Delegate an error call to the underlying logger.
+        """
+        self.log(logging.ERROR, msg, *args, **kwargs)
+
+    def exception(self, msg, *args, **kwargs):
+        """
+        Delegate an exception call to the underlying logger.
+        """
+        kwargs["exc_info"] = 1
+        self.log(logging.ERROR, msg, *args, **kwargs)
+
+    def critical(self, msg, *args, **kwargs):
+        """
+        Delegate a critical call to the underlying logger.
+        """
+        self.log(logging.CRITICAL, msg, *args, **kwargs)
+
+    def log(self, level, msg, *args, **kwargs):
+        """
+        Delegate a log call to the underlying logger, after adding
+        contextual information from this adapter instance.
+        """
+        if self.isEnabledFor(level):
+            msg, kwargs = self.process(msg, kwargs)
+            self.logger._log(level, msg, args, **kwargs)
+
+    def isEnabledFor(self, level):
+        """
+        Is this logger enabled for level 'level'?
+        """
+        if self.logger.manager.disable >= level:
+            return False
+        return level >= self.getEffectiveLevel()
+
+    def setLevel(self, level):
+        """
+        Set the specified level on the underlying logger.
+        """
+        self.logger.setLevel(level)
+
+    def getEffectiveLevel(self):
+        """
+        Get the effective level for the underlying logger.
+        """
+        return self.logger.getEffectiveLevel()
+
+    def hasHandlers(self):
+        """
+        See if the underlying logger has any handlers.
+        """
+        return logutils.hasHandlers(self.logger)
+

src/shared/logutils/colorize.py

+#
+# Copyright (C) 2010-2013 Vinay Sajip. All rights reserved.
+#
+import ctypes
+import logging
+import os
+
+try:
+    unicode
+except NameError:
+    unicode = None
+
+class ColorizingStreamHandler(logging.StreamHandler):
+    """
+    A stream handler which supports colorizing of console streams
+    under Windows, Linux and Mac OS X.
+
+    :param strm: The stream to colorize - typically ``sys.stdout``
+                 or ``sys.stderr``.
+    """
+    
+    # color names to indices
+    color_map = {
+        'black': 0,
+        'red': 1,
+        'green': 2,
+        'yellow': 3,
+        'blue': 4,
+        'magenta': 5,
+        'cyan': 6,
+        'white': 7,
+    }
+
+    #levels to (background, foreground, bold/intense)
+    if os.name == 'nt':
+        level_map = {
+            logging.DEBUG: (None, 'blue', True),
+            logging.INFO: (None, 'white', False),
+            logging.WARNING: (None, 'yellow', True),
+            logging.ERROR: (None, 'red', True),
+            logging.CRITICAL: ('red', 'white', True),
+        }
+    else:
+        "Maps levels to colour/intensity settings."
+        level_map = {
+            logging.DEBUG: (None, 'blue', False),
+            logging.INFO: (None, 'black', False),
+            logging.WARNING: (None, 'yellow', False),
+            logging.ERROR: (None, 'red', False),
+            logging.CRITICAL: ('red', 'white', True),
+        }
+
+    csi = '\x1b['
+    reset = '\x1b[0m'
+
+    @property
+    def is_tty(self):
+        "Returns true if the handler's stream is a terminal."
+        isatty = getattr(self.stream, 'isatty', None)
+        return isatty and isatty()
+
+    def emit(self, record):
+        try:
+            message = self.format(record)
+            stream = self.stream
+            if unicode and isinstance(message, unicode):
+                enc = getattr(stream, 'encoding', 'utf-8')
+                message = message.encode(enc, 'replace')
+            if not self.is_tty:
+                stream.write(message)
+            else:
+                self.output_colorized(message)
+            stream.write(getattr(self, 'terminator', '\n'))
+            self.flush()
+        except (KeyboardInterrupt, SystemExit):
+            raise
+        except:
+            self.handleError(record)
+
+    if os.name != 'nt':
+        def output_colorized(self, message):
+            """
+            Output a colorized message.
+
+            On Linux and Mac OS X, this method just writes the
+            already-colorized message to the stream, since on these
+            platforms console streams accept ANSI escape sequences
+            for colorization. On Windows, this handler implements a
+            subset of ANSI escape sequence handling by parsing the
+            message, extracting the sequences and making Win32 API
+            calls to colorize the output.
+
+            :param message: The message to colorize and output.
+            """
+            self.stream.write(message)
+    else:
+        import re
+        ansi_esc = re.compile(r'\x1b\[((?:\d+)(?:;(?:\d+))*)m')
+
+        nt_color_map = {
+            0: 0x00,    # black
+            1: 0x04,    # red
+            2: 0x02,    # green
+            3: 0x06,    # yellow
+            4: 0x01,    # blue
+            5: 0x05,    # magenta
+            6: 0x03,    # cyan
+            7: 0x07,    # white
+        }
+
+        def output_colorized(self, message):
+            """
+            Output a colorized message.
+
+            On Linux and Mac OS X, this method just writes the
+            already-colorized message to the stream, since on these
+            platforms console streams accept ANSI escape sequences
+            for colorization. On Windows, this handler implements a
+            subset of ANSI escape sequence handling by parsing the
+            message, extracting the sequences and making Win32 API
+            calls to colorize the output.
+
+            :param message: The message to colorize and output.
+            """
+            parts = self.ansi_esc.split(message)
+            write = self.stream.write
+            h = None
+            fd = getattr(self.stream, 'fileno', None)
+            if fd is not None:
+                fd = fd()
+                if fd in (1, 2): # stdout or stderr
+                    h = ctypes.windll.kernel32.GetStdHandle(-10 - fd)
+            while parts:
+                text = parts.pop(0)
+                if text:
+                    write(text)
+                if parts:
+                    params = parts.pop(0)
+                    if h is not None:
+                        params = [int(p) for p in params.split(';')]
+                        color = 0
+                        for p in params:
+                            if 40 <= p <= 47:
+                                color |= self.nt_color_map[p - 40] << 4
+                            elif 30 <= p <= 37:
+                                color |= self.nt_color_map[p - 30]
+                            elif p == 1:
+                                color |= 0x08 # foreground intensity on
+                            elif p == 0: # reset to default color
+                                color = 0x07
+                            else:
+                                pass # error condition ignored
+                        ctypes.windll.kernel32.SetConsoleTextAttribute(h, color)
+
+    def colorize(self, message, record):
+        """
+        Colorize a message for a logging event.
+
+        This implementation uses the ``level_map`` class attribute to
+        map the LogRecord's level to a colour/intensity setting, which is
+        then applied to the whole message.
+
+        :param message: The message to colorize.
+        :param record: The ``LogRecord`` for the message.
+        """
+        if record.levelno in self.level_map:
+            bg, fg, bold = self.level_map[record.levelno]
+            params = []
+            if bg in self.color_map:
+                params.append(str(self.color_map[bg] + 40))
+            if fg in self.color_map:
+                params.append(str(self.color_map[fg] + 30))
+            if bold:
+                params.append('1')
+            if params:
+                message = ''.join((self.csi, ';'.join(params),
+                                   'm', message, self.reset))
+        return message
+
+    def format(self, record):
+        """
+        Formats a record for output.
+
+        This implementation colorizes the message line, but leaves
+        any traceback unolorized.
+        """
+        message = logging.StreamHandler.format(self, record)
+        if self.is_tty:
+            # Don't colorize any traceback
+            parts = message.split('\n', 1)
+            parts[0] = self.colorize(parts[0], record)
+            message = '\n'.join(parts)
+        return message
+

src/shared/logutils/http.py

+#
+# Copyright (C) 2010-2013 Vinay Sajip. See LICENSE.txt for details.
+#
+import logging
+
+class HTTPHandler(logging.Handler):
+    """
+    A class which sends records to a Web server, using either GET or
+    POST semantics.
+
+    :param host: The Web server to connect to.
+    :param url: The URL to use for the connection.
+    :param method: The HTTP method to use. GET and POST are supported.
+    :param secure: set to True if HTTPS is to be used.
+    :param credentials: Set to a username/password tuple if desired. If
+                        set, a Basic authentication header is sent. WARNING:
+                        if using credentials, make sure `secure` is `True`
+                        to avoid sending usernames and passwords in
+                        cleartext over the wire.
+    """
+    def __init__(self, host, url, method="GET", secure=False, credentials=None):
+        """
+        Initialize an instance.
+        """
+        logging.Handler.__init__(self)
+        method = method.upper()
+        if method not in ["GET", "POST"]:
+            raise ValueError("method must be GET or POST")
+        self.host = host
+        self.url = url
+        self.method = method
+        self.secure = secure
+        self.credentials = credentials
+
+    def mapLogRecord(self, record):
+        """
+        Default implementation of mapping the log record into a dict
+        that is sent as the CGI data. Overwrite in your class.
+        Contributed by Franz Glasner.
+        
+        :param record: The record to be mapped.
+        """
+        return record.__dict__
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        Send the record to the Web server as a percent-encoded dictionary
+
+        :param record: The record to be emitted.
+        """
+        try:
+            import http.client, urllib.parse
+            host = self.host
+            if self.secure:
+                h = http.client.HTTPSConnection(host)
+            else:
+                h = http.client.HTTPConnection(host)
+            url = self.url
+            data = urllib.parse.urlencode(self.mapLogRecord(record))
+            if self.method == "GET":
+                if (url.find('?') >= 0):
+                    sep = '&'
+                else:
+                    sep = '?'
+                url = url + "%c%s" % (sep, data)
+            h.putrequest(self.method, url)
+            # support multiple hosts on one IP address...
+            # need to strip optional :port from host, if present
+            i = host.find(":")
+            if i >= 0:
+                host = host[:i]
+            h.putheader("Host", host)
+            if self.method == "POST":
+                h.putheader("Content-type",
+                            "application/x-www-form-urlencoded")
+                h.putheader("Content-length", str(len(data)))
+            if self.credentials:
+                import base64
+                s = ('u%s:%s' % self.credentials).encode('utf-8')
+                s = 'Basic ' + base64.b64encode(s).strip()
+                h.putheader('Authorization', s)
+            h.endheaders(data if self.method == "POST" else None)
+            h.getresponse()    #can't do anything with the result
+        except (KeyboardInterrupt, SystemExit):
+            raise
+        except:
+            self.handleError(record)
+

src/shared/logutils/queue.py

+#
+# Copyright (C) 2010-2013 Vinay Sajip. See LICENSE.txt for details.
+#
+"""
+This module contains classes which help you work with queues. A typical
+application is when you want to log from performance-critical threads, but
+where the handlers you want to use are slow (for example,
+:class:`~logging.handlers.SMTPHandler`). In that case, you can create a queue,
+pass it to a :class:`QueueHandler` instance and use that instance with your
+loggers. Elsewhere, you can instantiate a :class:`QueueListener` with the same
+queue and some slow handlers, and call :meth:`~QueueListener.start` on it.
+This will start monitoring the queue on a separate thread and call all the
+configured handlers *on that thread*, so that your logging thread is not held
+up by the slow handlers.
+
+Note that as well as in-process queues, you can use these classes with queues
+from the :mod:`multiprocessing` module.
+
+**N.B.** This is part of the standard library since Python 3.2, so the
+version here is for use with earlier Python versions.
+"""
+import logging
+try:
+    import Queue as queue
+except ImportError:
+    import queue
+import threading
+
+class QueueHandler(logging.Handler):
+    """
+    This handler sends events to a queue. Typically, it would be used together
+    with a multiprocessing Queue to centralise logging to file in one process
+    (in a multi-process application), so as to avoid file write contention
+    between processes.
+    
+    :param queue: The queue to send `LogRecords` to.
+    """
+
+    def __init__(self, queue):
+        """
+        Initialise an instance, using the passed queue.
+        """
+        logging.Handler.__init__(self)
+        self.queue = queue
+
+    def enqueue(self, record):
+        """
+        Enqueue a record.
+
+        The base implementation uses :meth:`~queue.Queue.put_nowait`. You may
+        want to override this method if you want to use blocking, timeouts or
+        custom queue implementations.
+        
+        :param record: The record to enqueue.
+        """
+        self.queue.put_nowait(record)
+
+    def prepare(self, record):
+        """
+        Prepares a record for queuing. The object returned by this method is
+        enqueued.
+
+        The base implementation formats the record to merge the message
+        and arguments, and removes unpickleable items from the record
+        in-place.
+
+        You might want to override this method if you want to convert
+        the record to a dict or JSON string, or send a modified copy
+        of the record while leaving the original intact.
+        
+        :param record: The record to prepare.
+        """
+        # The format operation gets traceback text into record.exc_text
+        # (if there's exception data), and also puts the message into
+        # record.message. We can then use this to replace the original
+        # msg + args, as these might be unpickleable. We also zap the
+        # exc_info attribute, as it's no longer needed and, if not None,
+        # will typically not be pickleable.
+        self.format(record)
+        record.msg = record.message
+        record.args = None
+        record.exc_info = None
+        return record
+
+    def emit(self, record):
+        """
+        Emit a record.
+
+        Writes the LogRecord to the queue, preparing it for pickling first.
+        
+        :param record: The record to emit.
+        """
+        try:
+            self.enqueue(self.prepare(record))
+        except (KeyboardInterrupt, SystemExit):
+            raise
+        except:
+            self.handleError(record)
+
+class QueueListener(object):
+    """
+    This class implements an internal threaded listener which watches for
+    LogRecords being added to a queue, removes them and passes them to a
+    list of handlers for processing.
+            
+    :param record: The queue to listen to.
+    :param handlers: The handlers to invoke on everything received from
+                     the queue.
+    """
+    _sentinel = None
+
+    def __init__(self, queue, *handlers):
+        """
+        Initialise an instance with the specified queue and
+        handlers.
+        """
+        self.queue = queue
+        self.handlers = handlers
+        self._stop = threading.Event()
+        self._thread = None
+
+    def dequeue(self, block):
+        """
+        Dequeue a record and return it, optionally blocking.
+
+        The base implementation uses :meth:`~queue.Queue.get`. You may want to
+        override this method if you want to use timeouts or work with custom
+        queue implementations.
+        
+        :param block: Whether to block if the queue is empty. If `False` and
+                      the queue is empty, an :class:`~queue.Empty` exception
+                      will be thrown.
+        """
+        return self.queue.get(block)
+
+    def start(self):
+        """
+        Start the listener.
+
+        This starts up a background thread to monitor the queue for
+        LogRecords to process.
+        """
+        self._thread = t = threading.Thread(target=self._monitor)
+        t.setDaemon(True)
+        t.start()
+
+    def prepare(self , record):
+        """
+        Prepare a record for handling.
+
+        This method just returns the passed-in record. You may want to
+        override this method if you need to do any custom marshalling or
+        manipulation of the record before passing it to the handlers.
+        
+        :param record: The record to prepare.
+        """
+        return record
+
+    def handle(self, record):
+        """
+        Handle a record.
+
+        This just loops through the handlers offering them the record
+        to handle.
+
+        :param record: The record to handle.
+        """
+        record = self.prepare(record)
+        for handler in self.handlers:
+            handler.handle(record)
+
+    def _monitor(self):
+        """
+        Monitor the queue for records, and ask the handler
+        to deal with them.
+
+        This method runs on a separate, internal thread.
+        The thread will terminate if it sees a sentinel object in the queue.
+        """
+        q = self.queue
+        has_task_done = hasattr(q, 'task_done')
+        while not self._stop.isSet():
+            try:
+                record = self.dequeue(True)
+                if record is self._sentinel:
+                    break
+                self.handle(record)
+                if has_task_done:
+                    q.task_done()
+            except queue.Empty:
+                pass
+        # There might still be records in the queue.
+        while True:
+            try:
+                record = self.dequeue(False)
+                if record is self._sentinel:
+                    break
+                self.handle(record)
+                if has_task_done:
+                    q.task_done()
+            except queue.Empty:
+                break
+
+    def enqueue_sentinel(self):
+        """
+        Writes a sentinel to the queue to tell the listener to quit. This
+        implementation uses ``put_nowait()``.  You may want to override this
+        method if you want to use timeouts or work with custom queue
+        implementations.
+        """
+        self.queue.put_nowait(self._sentinel)
+
+    def stop(self):
+        """
+        Stop the listener.
+
+        This asks the thread to terminate, and then waits for it to do so.
+        Note that if you don't call this before your application exits, there
+        may be some records still left on the queue, which won't be processed.
+        """
+        self._stop.set()
+        self.enqueue_sentinel()
+        self._thread.join()
+        self._thread = None
+

src/shared/logutils/redis.py

+#
+# Copyright (C) 2011-2013 Vinay Sajip. See LICENSE.txt for details.
+#
+"""
+This module contains classes which help you work with Redis queues.
+"""
+
+from logutils.queue import QueueHandler, QueueListener
+try:
+    import cPickle as pickle
+except ImportError:
+    import pickle
+
+class RedisQueueHandler(QueueHandler):
+    """
+    A QueueHandler implementation which pushes pickled
+    records to a Redis queue using a specified key.
+    
+    :param key: The key to use for the queue. Defaults to
+                "python.logging".
+    :param redis: If specified, this instance is used to
+                  communicate with a Redis instance.
+    :param limit: If specified, the queue is restricted to
+                  have only this many elements.
+    """
+    def __init__(self, key='python.logging', redis=None, limit=0):
+        if redis is None:
+            from redis import Redis
+            redis = Redis()
+        self.key = key
+        assert limit >= 0
+        self.limit = limit
+        QueueHandler.__init__(self, redis)
+        
+    def enqueue(self, record):
+        s = pickle.dumps(vars(record))
+        self.queue.rpush(self.key, s)
+        if self.limit:
+            self.queue.ltrim(self.key, -self.limit, -1)
+
+class RedisQueueListener(QueueListener):
+    """
+    A QueueListener implementation which fetches pickled
+    records from a Redis queue using a specified key.
+    
+    :param key: The key to use for the queue. Defaults to
+                "python.logging".
+    :param redis: If specified, this instance is used to
+                  communicate with a Redis instance.
+    """
+    def __init__(self, *handlers, **kwargs):
+        redis = kwargs.get('redis')
+        if redis is None:
+            from redis import Redis
+            redis = Redis()
+        self.key = kwargs.get('key', 'python.logging')
+        QueueListener.__init__(self, redis, *handlers)
+
+    def dequeue(self, block):
+        """
+        Dequeue and return a record.
+        """
+        if block:
+            s = self.queue.blpop(self.key)[1]
+        else:
+            s = self.queue.lpop(self.key)        
+        if not s:
+            record = None
+        else:
+            record = pickle.loads(s)
+        return record
+
+    def enqueue_sentinel(self):
+        self.queue.rpush(self.key, '')
+

src/shared/logutils/testing.py

+#
+# Copyright (C) 2010-2013 Vinay Sajip. See LICENSE.txt for details.
+#
+import logging
+from logging.handlers import BufferingHandler
+
+class TestHandler(BufferingHandler):
+    """
+    This handler collects records in a buffer for later inspection by
+    your unit test code.
+    
+    :param matcher: The :class:`~logutils.testing.Matcher` instance to
+                    use for matching.
+    """
+    def __init__(self, matcher):
+        # BufferingHandler takes a "capacity" argument
+        # so as to know when to flush. As we're overriding
+        # shouldFlush anyway, we can set a capacity of zero.
+        # You can call flush() manually to clear out the
+        # buffer.
+        BufferingHandler.__init__(self, 0)
+        self.formatted = []
+        self.matcher = matcher
+
+    def shouldFlush(self):
+        """
+        Should the buffer be flushed?
+
+        This returns `False` - you'll need to flush manually, usually after
+        your unit test code checks the buffer contents against your
+        expectations.
+        """
+        return False
+
+    def emit(self, record):
+        """
+        Saves the `__dict__` of the record in the `buffer` attribute,
+        and the formatted records in the `formatted` attribute.
+
+        :param record: The record to emit.
+        """
+        self.formatted.append(self.format(record))
+        self.buffer.append(record.__dict__)
+
+    def flush(self):
+        """
+        Clears out the `buffer` and `formatted` attributes.
+        """
+        BufferingHandler.flush(self)
+        self.formatted = []
+
+    def matches(self, **kwargs):
+        """
+        Look for a saved dict whose keys/values match the supplied arguments.
+
+        Return `True` if found, else `False`.
+        
+        :param kwargs: A set of keyword arguments whose names are LogRecord
+                       attributes and whose values are what you want to 
+                       match in a stored LogRecord.
+        """
+        result = False
+        for d in self.buffer:
+            if self.matcher.matches(d, **kwargs):
+                result = True
+                break
+        #if not result:
+        #    print('*** matcher failed completely on %d records' % len(self.buffer))
+        return result
+
+    def matchall(self, kwarglist):
+        """
+        Accept a list of keyword argument values and ensure that the handler's
+        buffer of stored records matches the list one-for-one.
+
+        Return `True` if exactly matched, else `False`.
+        
+        :param kwarglist: A list of keyword-argument dictionaries, each of
+                          which will be passed to :meth:`matches` with the
+                          corresponding record from the buffer.
+        """
+        if self.count != len(kwarglist):
+            result = False
+        else:
+            result = True
+            for d, kwargs in zip(self.buffer, kwarglist):
+                if not self.matcher.matches(d, **kwargs):
+                    result = False
+                    break
+        return result
+
+    @property
+    def count(self):
+        """
+        The number of records in the buffer.
+        """
+        return len(self.buffer)
+
+class Matcher(object):
+    """
+    This utility class matches a stored dictionary of
+    :class:`logging.LogRecord` attributes with keyword arguments
+    passed to its :meth:`~logutils.testing.Matcher.matches` method.
+    """
+    
+    _partial_matches = ('msg', 'message')
+    """
+    A list of :class:`logging.LogRecord` attribute names which
+    will be checked for partial matches. If not in this list,
+    an exact match will be attempted.
+    """
+    
+    def matches(self, d, **kwargs):
+        """
+        Try to match a single dict with the supplied arguments.
+
+        Keys whose values are strings and which are in self._partial_matches
+        will be checked for partial (i.e. substring) matches. You can extend
+        this scheme to (for example) do regular expression matching, etc.
+        
+        Return `True` if found, else `False`.
+
+        :param kwargs: A set of keyword arguments whose names are LogRecord
+                       attributes and whose values are what you want to 
+                       match in a stored LogRecord.
+        """
+        result = True
+        for k in kwargs:
+            v = kwargs[k]
+            dv = d.get(k)
+            if not self.match_value(k, dv, v):
+                #print('*** matcher failed: %s, %r, %r' % (k, dv, v))
+                result = False
+                break
+        return result
+
+    def match_value(self, k, dv, v):
+        """
+        Try to match a single stored value (dv) with a supplied value (v).
+
+        Return `True` if found, else `False`.
+
+        :param k: The key value (LogRecord attribute name).
+        :param dv: The stored value to match against.
+        :param v: The value to compare with the stored value.
+        """
+        if type(v) != type(dv):
+            result = False
+        elif type(dv) is not str or k not in self._partial_matches:
+            result = (v == dv)
+        else:
+            result = dv.find(v) >= 0
+        #if not result:
+        #    print('*** matcher failed on %s: %r vs. %r' % (k, dv, v))
+        return result
+