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# Copyright (C) 2008, One Laptop Per Child
#
# 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
import logging
import os
import gobject
from semanticstore import layoutmanager
from semanticstore.layoutmanager import MAX_QUERY_LIMIT
from semanticstore.metadatastore import OLPC_TERMS
from semanticxo.sparql import SPARQL
_VALUE_UID = 0
_VALUE_TIMESTAMP = 1
_VALUE_TITLE = 2
# 3 reserved for version support
_VALUE_FILESIZE = 4
_VALUE_CREATION_TIME = 5
_PREFIX_NONE = 'N'
_PREFIX_FULL_VALUE = 'F'
_PREFIX_UID = 'Q'
_PREFIX_ACTIVITY = 'A'
_PREFIX_ACTIVITY_ID = 'I'
_PREFIX_MIME_TYPE = 'M'
_PREFIX_KEEP = 'K'
# Force a flush every _n_ changes to the db
_FLUSH_THRESHOLD = 20
# Force a flush after _n_ seconds since the last change to the db
_FLUSH_TIMEOUT = 5
_PROPERTIES_NOT_TO_INDEX = ['timestamp', 'preview']
_MAX_RESULTS = int(2 ** 31 - 1)
_QUERY_TERMS = ['uid', 'activity', 'activity_id', 'mime_type', 'timestamp', 'filesize', 'creation_time']
class Enquire(object):
def __init__(self):
self._graph_patterns = []
pass
def parse_query(self, query_dict, query_string):
logging.debug('[IDX] parse_query %r %r', query_dict, query_string)
patterns = []
query_dict = dict(query_dict)
# Full text search
if query_string is not None:
# TODO Do something with a regexp in title
pass
# Properties based search
for name, value in query_dict.items():
if name in _QUERY_TERMS:
pattern = "?entry <%s> \"%s\"." % (OLPC_TERMS[name], value)
patterns.append(pattern)
else:
logging.warning('Unknown term: %r=%r', name, value)
# Get all the entries
if not patterns:
pattern = "?entry <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <%s>." % OLPC_TERMS['DSObject']
patterns.append(pattern)
# Add a pattern to get the UID
patterns.append("?entry <%s> ?uid." % OLPC_TERMS['uid'])
# Save the query
self._graph_patterns = patterns
logging.debug('[IDX] patterns %r', [str(q) for q in patterns])
def set_sort_by_value(self, name, incremental):
# TODO Convert order by into SPARQL ORDER BY clause (map word to URI and adjust +-)
pass
def get_set(self, offset, limit):
sparql = SPARQL()
query = "SELECT ?uid WHERE {\n %s \n}" % "\n".join(self._graph_patterns)
results = []
for result in sparql.execute_select(query):
results.append(result['uid'])
return results
class IndexStore(object):
'''
Index metadata and provide rich query facilities on it.
'''
def __init__(self):
self._url = '127.0.0.1:8080'
self._database = None
self._flush_timeout = None
self._pending_writes = 0
self._index_updated_path = os.path.join(
layoutmanager.get_instance().get_root_path(), 'index_updated')
def open_index(self):
pass
def close_index(self):
"""Close index database if it is open."""
if not self._database:
return
self._flush(True)
self._database = None
def remove_index(self):
index_path = layoutmanager.get_instance().get_index_path()
if not os.path.exists(index_path):
return
for f in os.listdir(index_path):
os.remove(os.path.join(index_path, f))
def contains(self, uid):
enquire = Enquire()
enquire.parse_query({'uid' : uid}, None)
query_result = enquire.get_set(0, 1)
return len(query_result) == 1
def store(self, uid, properties):
logging.debug('[IDX] store ' + uid)
# TODO needed ?
def find(self, query):
logging.debug('[IDX] find ' + str(query))
offset = query.pop('offset', 0)
limit = query.pop('limit', MAX_QUERY_LIMIT)
order_by = query.pop('order_by', [])
query_string = query.pop('query', None)
enquire = Enquire()
enquire.parse_query(query, query_string)
if not order_by:
order_by = '+timestamp'
else:
order_by = order_by[0]
if order_by == '+timestamp':
enquire.set_sort_by_value(_VALUE_TIMESTAMP, True)
elif order_by == '-timestamp':
enquire.set_sort_by_value(_VALUE_TIMESTAMP, False)
elif order_by == '+title':
enquire.set_sort_by_value(_VALUE_TITLE, True)
elif order_by == '-title':
enquire.set_sort_by_value(_VALUE_TITLE, False)
elif order_by == '+filesize':
enquire.set_sort_by_value(_VALUE_FILESIZE, True)
elif order_by == '-filesize':
enquire.set_sort_by_value(_VALUE_FILESIZE, False)
elif order_by == '+creation_time':
enquire.set_sort_by_value(_VALUE_CREATION_TIME, True)
elif order_by == '-creation_time':
enquire.set_sort_by_value(_VALUE_CREATION_TIME, False)
else:
logging.warning('Unsupported property for sorting: %s', order_by)
query_result = enquire.get_set(offset, limit)
total_count = len(query_result)
logging.debug('[IDX] query result %r' % query_result)
uids = []
for hit in query_result:
uids.append(hit) #.split(",")[1][1:-1]
return (uids, total_count)
def delete(self, uid):
# TODO Needed ?
#self._database.delete_document(_PREFIX_FULL_VALUE + _PREFIX_UID + uid)
#self._flush()
pass
def get_activities(self):
logging.debug('[IDX] get_activities')
activities = []
#prefix = _PREFIX_FULL_VALUE + _PREFIX_ACTIVITY
#for term in self._database.allterms(prefix):
# activities.append(term.term[len(prefix):])
return activities
def flush(self):
self._flush(True)
def get_index_updated(self):
return os.path.exists(self._index_updated_path)
index_updated = property(get_index_updated)
def _set_index_updated(self, index_updated):
if index_updated != self.index_updated:
if index_updated:
index_updated_file = open(self._index_updated_path, 'w')
# index_updated = True will happen every
# indexstore._FLUSH_TIMEOUT seconds, so it is ok to fsync
os.fsync(index_updated_file.fileno())
index_updated_file.close()
else:
os.remove(self._index_updated_path)
def _flush_timeout_cb(self):
self._flush(True)
return False
def _flush(self, force=False):
"""Called after any database mutation"""
logging.debug('IndexStore.flush: force=%r _pending_writes=%r',
force, self._pending_writes)
self._set_index_updated(False)
if self._flush_timeout is not None:
gobject.source_remove(self._flush_timeout)
self._flush_timeout = None
self._pending_writes += 1
if force or self._pending_writes > _FLUSH_THRESHOLD:
self._pending_writes = 0
self._set_index_updated(True)
else:
self._flush_timeout = gobject.timeout_add_seconds(_FLUSH_TIMEOUT,
self._flush_timeout_cb)
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