src/mailman/mta/bulk.py

   1 # Copyright (C) 2009 by the Free Software Foundation, Inc.
   2 #
   3 # This file is part of GNU Mailman.
   4 #
   5 # GNU Mailman is free software: you can redistribute it and/or modify it under
   6 # the terms of the GNU General Public License as published by the Free
   7 # Software Foundation, either version 3 of the License, or (at your option)
   8 # any later version.
   9 #
  10 # GNU Mailman is distributed in the hope that it will be useful, but WITHOUT
  11 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12 # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13 # more details.
  14 #
  15 # You should have received a copy of the GNU General Public License along with
  16 # GNU Mailman.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 """Bulk message delivery."""
  19
  20 from __future__ import absolute_import, unicode_literals
  21
  22 __metaclass__ = type
  23 __all__ = [
  24     'BulkDelivery',
  25     ]
  26
  27
  28 from mailman.mta.base import BaseDelivery
  29
  30
  31 # A mapping of top-level domains to bucket numbers.  The zeroth bucket is
  32 # reserved for everything else.  At one time, these were the most common
  33 # domains.
  34 CHUNKMAP = dict(
  35     com=1,
  36     net=2,
  37     org=2,
  38     edu=3,
  39     us=3,
  40     ca=3,
  41     )
  42
  43
  44 \f
  45 class BulkDelivery(BaseDelivery):
  46     """Deliver messages to the MSA in as few sessions as possible."""
  47
  48     def __init__(self, max_recipients=None):
  49         """See `BaseDelivery`.
  50
  51         :param max_recipients: The maximum number of recipients per delivery
  52             chunk.  None, zero or less means to group all recipients into one
  53             big chunk.
  54         :type max_recipients: integer
  55         """
  56         super(BulkDelivery, self).__init__()
  57         self._max_recipients = (max_recipients
  58                                 if max_recipients is not None
  59                                 else 0)
  60
  61     def chunkify(self, recipients):
  62         """Split a set of recipients into chunks.
  63
  64         The `max_recipients` argument given to the constructor specifies the
  65         maximum number of recipients in each chunk.
  66
  67         :param recipients: The set of recipient email addresses
  68         :type recipients: sequence of email address strings
  69         :return: A list of chunks, where each chunk is a set containing no
  70             more than `max_recipients` number of addresses.  The chunk can
  71             contain fewer, and no packing is guaranteed.
  72         :rtype: list of sets of strings
  73         """
  74         if self._max_recipients <= 0:
  75             yield set(recipients)
  76             return
  77         # This algorithm was originally suggested by Chuq Von Rospach.  Start
  78         # by splitting the recipient addresses into top-level domain buckets,
  79         # using the "most common" domains.  Everything else ends up in the
  80         # zeroth bucket.
  81         by_bucket = {}
  82         for address in recipients:
  83             localpart, at, domain = address.partition('@')
  84             domain_parts = domain.split('.')
  85             bucket_number = CHUNKMAP.get(domain_parts[-1], 0)
  86             by_bucket.setdefault(bucket_number, set()).add(address)
  87         # Fill chunks by sorting the tld values by length.
  88         chunk = set()
  89         for tld_chunk in sorted(by_bucket.values(), key=len, reverse=True):
  90             while tld_chunk:
  91                 chunk.add(tld_chunk.pop())
  92                 if len(chunk) == self._max_recipients:
  93                     yield chunk
  94                     chunk = set()
  95             # Every tld bucket starts a new chunk, but only if non-empty
  96             if len(chunk) > 0:
  97                 yield chunk
  98                 chunk = set()
  99         # Be sure to include the last chunk, but only if it's non-empty.
 100         if len(chunk) > 0:
 101             yield chunk
 102
 103     def deliver(self, mlist, msg, msgdata):
 104         """See `IMailTransportAgentDelivery`."""
 105         refused = {}
 106         for recipients in self.chunkify(msgdata.get('recipients', set())):
 107             chunk_refused = self._deliver_to_recipients(
 108                 mlist, msg, msgdata, recipients)
 109             refused.update(chunk_refused)
 110         return refused
 111