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#
# Copyright (C) 2006 Robey Pointer <robey@lag.net>
#
# This program 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 2 of the License, or
# (at your option) any later version.
#
# This program 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 this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
"""
indexing of the comment text of revisions, for fast searching.
two separate 'shelve' files are created:
- recorded: revid -> 1 (if the revid is indexed)
- index: 3-letter substring -> list(revids)
"""
import logging
import os
import re
import shelve
import threading
from loggerhead import util
from loggerhead.util import decorator
log = logging.getLogger("loggerhead.controllers")
# if any substring index reaches this many revids, replace the entry with
# an ALL marker -- it's not worth an explicit index.
ALL_THRESHOLD = 1000
ALL = 'ALL'
@decorator
def with_lock(unbound):
def locked(self, *args, **kw):
self._lock.acquire()
try:
return unbound(self, *args, **kw)
finally:
self._lock.release()
return locked
def normalize_string(s):
"""
remove any punctuation and normalize all whitespace to a single space.
"""
s = util.to_utf8(s).lower()
# remove apostrophes completely.
s = re.sub(r"'", '', s)
# convert other garbage into space
s = re.sub(r'[^\w\d]', ' ', s)
# compress multiple spaces into one.
s = re.sub(r'\s{2,}', ' ', s)
# and finally remove leading/trailing whitespace
s = s.strip()
return s
class TextIndex (object):
def __init__(self, history, cache_path):
self.history = history
if not os.path.exists(cache_path):
os.mkdir(cache_path)
recorded_filename = os.path.join(cache_path, 'textindex-recorded')
index_filename = os.path.join(cache_path, 'textindex')
self._recorded = shelve.open(recorded_filename, 'c', protocol=2)
self._index = shelve.open(index_filename, 'c', protocol=2)
self._lock = threading.RLock()
log.info('Using search index; %d entries.', len(self._recorded))
@with_lock
def is_indexed(self, revid):
return self._recorded.get(util.to_utf8(revid), None) is not None
@with_lock
def __len__(self):
return len(self._recorded)
@with_lock
def flush(self):
self._recorded.sync()
self._index.sync()
@with_lock
def index_change(self, change):
"""
currently, only indexes the 'comment' field.
"""
comment = normalize_string(change.comment)
if len(comment) < 3:
return
for i in xrange(len(comment) - 2):
sub = comment[i:i + 3]
revid_set = self._index.get(sub, None)
if revid_set is None:
revid_set = set()
elif revid_set == ALL:
# this entry got too big
continue
revid_set.add(change.revid)
if len(revid_set) > ALL_THRESHOLD:
revid_set = ALL
self._index[sub] = revid_set
self._recorded[util.to_utf8(change.revid)] = True
return
@with_lock
def find(self, text, revid_list=None):
text = normalize_string(text)
if len(text) < 3:
return []
total_set = None
if revid_list is not None:
total_set = set(revid_list)
seen_all = False
for i in xrange(len(text) - 2):
sub = text[i:i + 3]
revid_set = self._index.get(sub, None)
if revid_set is None:
# zero matches, stop here.
return []
if revid_set == ALL:
# skip
seen_all = True
continue
if total_set is None:
total_set = revid_set
else:
total_set.intersection_update(revid_set)
if len(total_set) == 0:
return []
# tricky: if seen_all is True, one of the substring indices was ALL
# (in other words, unindexed), so our results are actually a superset
# of the exact answer.
#
# if we cared, we could do a direct match on the result set and cull
# out any that aren't actually matches. for now, i'm gonna say that
# we DON'T care, and if one of the substrings hit ALL, there's a small
# chance that we'll give a few false positives, and we don't care.
return total_set
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