Viewing file:  Journal.py (2.29 KB) -rw-r--r--
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import logging
_logger = logging.getLogger(__name__)
from rdflib.Graph import QuotedGraph
from rdflib.events import Event, Dispatcher
from rdflib.store import TripleAddedEvent, TripleRemovedEvent, StoreCreatedEvent
class JournalWriter(object):
"""
Writes a journal of the store events.
"""
def __init__(self, store, stream=None, filename=None):
if stream is None:
assert filename, "Must specify either stream or filename"
stream = file(filename, "ab")
dispatcher = store.dispatcher
dispatcher.subscribe(TripleAddedEvent, self.journal_event)
dispatcher.subscribe(TripleRemovedEvent, self.journal_event)
dispatcher.subscribe(StoreCreatedEvent, self.journal_event)
self._dumps = store.node_pickler.dumps
self._write = stream.write
def journal_event(self, event):
self._write(self._dumps(event))
self._write("\n\n")
class JournalReader(object):
"""
Reads a journal of store events into a store.
"""
def __init__(self, store, filename):
self.stream = file(filename, "rb")
self.store = store
dispatcher = Dispatcher()
dispatcher.subscribe(TripleAddedEvent, self.add)
dispatcher.subscribe(TripleRemovedEvent, self.remove)
dispatcher.subscribe(StoreCreatedEvent, self.store_created)
loads = store.node_pickler.loads
dispatch = dispatcher.dispatch
lines = []
for line in self.stream:
if line=="\n":
try:
event = loads("".join(lines))
dispatch(event)
lines = []
except Exception, e:
_logger.exception(e)
_logger.debug("lines: '%s'" % lines)
lines = []
else:
lines.append(line)
def add(self, event):
context = event.context
quoted = isinstance(context, QuotedGraph)
self.store.add(event.triple, context, quoted)
def remove(self, event):
self.store.remove(event.triple, event.context)
def store_created(self, event):
n = len(self.store)
if n>0:
_logger.warning("Store not empty for 'store created'. Contains '%s' assertions" % n)
# TODO: clear store
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