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Diffstat (limited to 'src/mailman/core/switchboard.py')
| -rw-r--r-- | src/mailman/core/switchboard.py | 269 |
1 files changed, 269 insertions, 0 deletions
diff --git a/src/mailman/core/switchboard.py b/src/mailman/core/switchboard.py new file mode 100644 index 000000000..5d9eb65ce --- /dev/null +++ b/src/mailman/core/switchboard.py @@ -0,0 +1,269 @@ +# Copyright (C) 2001-2011 by the Free Software Foundation, Inc. +# +# This file is part of GNU Mailman. +# +# GNU Mailman is free software: you can redistribute it and/or modify it under +# the terms of the GNU General Public License as published by the Free +# Software Foundation, either version 3 of the License, or (at your option) +# any later version. +# +# GNU Mailman is distributed in the hope that it will be useful, but WITHOUT +# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or +# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for +# more details. +# +# You should have received a copy of the GNU General Public License along with +# GNU Mailman. If not, see <http://www.gnu.org/licenses/>. + +"""Queing and dequeuing message/metadata pickle files. + +Messages are represented as email.message.Message objects (or an instance ofa +subclass). Metadata is represented as a Python dictionary. For every +message/metadata pair in a queue, a single file containing two pickles is +written. First, the message is written to the pickle, then the metadata +dictionary is written. +""" + +from __future__ import absolute_import, unicode_literals + +__metaclass__ = type +__all__ = [ + 'Switchboard', + ] + + +import os +import time +import email +import pickle +import cPickle +import hashlib +import logging + +from zope.interface import implements + +from mailman.config import config +from mailman.email.message import Message +from mailman.interfaces.switchboard import ISwitchboard +from mailman.utilities.filesystem import makedirs +from mailman.utilities.string import expand + + +# 20 bytes of all bits set, maximum hashlib.sha.digest() value +shamax = 0xffffffffffffffffffffffffffffffffffffffffL +# Small increment to add to time in case two entries have the same time. This +# prevents skipping one of two entries with the same time until the next pass. +DELTA = .0001 +# We count the number of times a file has been moved to .bak and recovered. +# In order to prevent loops and a message flood, when the count reaches this +# value, we move the file to the bad queue as a .psv. +MAX_BAK_COUNT = 3 + +elog = logging.getLogger('mailman.error') + + + +class Switchboard: + implements(ISwitchboard) + + @staticmethod + def initialize(): + """Initialize the global switchboards for input/output.""" + for conf in config.qrunner_configs: + name = conf.name.split('.')[-1] + assert name not in config.switchboards, ( + 'Duplicate qrunner name: {0}'.format(name)) + substitutions = config.paths + substitutions['name'] = name + path = expand(conf.path, substitutions) + config.switchboards[name] = Switchboard(name, path) + + def __init__(self, name, queue_directory, + slice=None, numslices=1, recover=False): + """Create a switchboard object. + + :param name: The queue name. + :type name: str + :param queue_directory: The queue directory. + :type queue_directory: str + :param slice: The slice number for this switchboard, or None. If not + None, it must be [0..`numslices`). + :type slice: int or None + :param numslices: The total number of slices to split this queue + directory into. It must be a power of 2. + :type numslices: int + :param recover: True if backup files should be recovered. + :type recover: bool + """ + assert (numslices & (numslices - 1)) == 0, ( + 'Not a power of 2: {0}'.format(numslices)) + self.name = name + self.queue_directory = queue_directory + # If configured to, create the directory if it doesn't yet exist. + if config.create_paths: + makedirs(self.queue_directory, 0770) + # Fast track for no slices + self._lower = None + self._upper = None + # BAW: test performance and end-cases of this algorithm + if numslices <> 1: + self._lower = ((shamax + 1) * slice) / numslices + self._upper = (((shamax + 1) * (slice + 1)) / numslices) - 1 + if recover: + self.recover_backup_files() + + def enqueue(self, _msg, _metadata=None, **_kws): + """See `ISwitchboard`.""" + if _metadata is None: + _metadata = {} + # Calculate the SHA hexdigest of the message to get a unique base + # filename. We're also going to use the digest as a hash into the set + # of parallel qrunner processes. + data = _metadata.copy() + data.update(_kws) + listname = data.get('listname', '--nolist--') + # Get some data for the input to the sha hash. + now = time.time() + if data.get('_plaintext'): + protocol = 0 + msgsave = cPickle.dumps(str(_msg), protocol) + else: + protocol = pickle.HIGHEST_PROTOCOL + msgsave = cPickle.dumps(_msg, protocol) + # listname is unicode but the input to the hash function must be an + # 8-bit string (eventually, a bytes object). + hashfood = msgsave + listname.encode('utf-8') + repr(now) + # Encode the current time into the file name for FIFO sorting. The + # file name consists of two parts separated by a '+': the received + # time for this message (i.e. when it first showed up on this system) + # and the sha hex digest. + rcvtime = data.setdefault('received_time', now) + filebase = repr(rcvtime) + '+' + hashlib.sha1(hashfood).hexdigest() + filename = os.path.join(self.queue_directory, filebase + '.pck') + tmpfile = filename + '.tmp' + # Always add the metadata schema version number + data['version'] = config.QFILE_SCHEMA_VERSION + # Filter out volatile entries. Use .keys() so that we can mutate the + # dictionary during the iteration. + for k in data.keys(): + if k.startswith('_'): + del data[k] + # We have to tell the dequeue() method whether to parse the message + # object or not. + data['_parsemsg'] = (protocol == 0) + # Write to the pickle file the message object and metadata. + with open(tmpfile, 'w') as fp: + fp.write(msgsave) + cPickle.dump(data, fp, protocol) + fp.flush() + os.fsync(fp.fileno()) + os.rename(tmpfile, filename) + return filebase + + def dequeue(self, filebase): + """See `ISwitchboard`.""" + # Calculate the filename from the given filebase. + filename = os.path.join(self.queue_directory, filebase + '.pck') + backfile = os.path.join(self.queue_directory, filebase + '.bak') + # Read the message object and metadata. + with open(filename) as fp: + # Move the file to the backup file name for processing. If this + # process crashes uncleanly the .bak file will be used to + # re-instate the .pck file in order to try again. + os.rename(filename, backfile) + msg = cPickle.load(fp) + data = cPickle.load(fp) + if data.get('_parsemsg'): + # Calculate the original size of the text now so that we won't + # have to generate the message later when we do size restriction + # checking. + original_size = len(msg) + msg = email.message_from_string(msg, Message) + msg.original_size = original_size + data['original_size'] = original_size + return msg, data + + def finish(self, filebase, preserve=False): + """See `ISwitchboard`.""" + bakfile = os.path.join(self.queue_directory, filebase + '.bak') + try: + if preserve: + bad_dir = config.switchboards['bad'].queue_directory + psvfile = os.path.join(bad_dir, filebase + '.psv') + os.rename(bakfile, psvfile) + else: + os.unlink(bakfile) + except EnvironmentError: + elog.exception( + 'Failed to unlink/preserve backup file: %s', bakfile) + + @property + def files(self): + """See `ISwitchboard`.""" + return self.get_files() + + def get_files(self, extension='.pck'): + """See `ISwitchboard`.""" + times = {} + lower = self._lower + upper = self._upper + for f in os.listdir(self.queue_directory): + # By ignoring anything that doesn't end in .pck, we ignore + # tempfiles and avoid a race condition. + filebase, ext = os.path.splitext(f) + if ext <> extension: + continue + when, digest = filebase.split('+', 1) + # Throw out any files which don't match our bitrange. BAW: test + # performance and end-cases of this algorithm. MAS: both + # comparisons need to be <= to get complete range. + if lower is None or (lower <= long(digest, 16) <= upper): + key = float(when) + while key in times: + key += DELTA + times[key] = filebase + # FIFO sort + return [times[key] for key in sorted(times)] + + def recover_backup_files(self): + """See `ISwitchboard`.""" + # Move all .bak files in our slice to .pck. It's impossible for both + # to exist at the same time, so the move is enough to ensure that our + # normal dequeuing process will handle them. We keep count in + # _bak_count in the metadata of the number of times we recover this + # file. When the count reaches MAX_BAK_COUNT, we move the .bak file + # to a .psv file in the bad queue. + for filebase in self.get_files('.bak'): + src = os.path.join(self.queue_directory, filebase + '.bak') + dst = os.path.join(self.queue_directory, filebase + '.pck') + fp = open(src, 'rb+') + try: + try: + msg = cPickle.load(fp) + data_pos = fp.tell() + data = cPickle.load(fp) + except Exception as error: + # If unpickling throws any exception, just log and + # preserve this entry + elog.error('Unpickling .bak exception: %s\n' + 'Preserving file: %s', error, filebase) + self.finish(filebase, preserve=True) + else: + data['_bak_count'] = data.get('_bak_count', 0) + 1 + fp.seek(data_pos) + if data.get('_parsemsg'): + protocol = 0 + else: + protocol = 1 + cPickle.dump(data, fp, protocol) + fp.truncate() + fp.flush() + os.fsync(fp.fileno()) + if data['_bak_count'] >= MAX_BAK_COUNT: + elog.error('.bak file max count, preserving file: %s', + filebase) + self.finish(filebase, preserve=True) + else: + os.rename(src, dst) + finally: + fp.close() |