def __init__(self, url):
self.url = url
# add callbacks to these to learn if we failed to connect
# (approximately) or if the ccnnection was unexpectedly lost
self.connectionFailed = defer.Deferred()
self.connectionLost = defer.Deferred()
self._listeners = set()
log.info("start read from %s", url)
# note: fullGraphReceived isn't guaranteed- the stream could
# start with patches
self._fullGraphReceived = False
self._eventSource = EventSource(url.toPython().encode("utf8"))
self._eventSource.protocol.delimiter = "\n"
self._eventSource.addEventListener("fullGraph", self._onFullGraph)
self._eventSource.addEventListener("patch", self._onPatch)
self._eventSource.onerror(self._onError)
origSet = self._eventSource.protocol.setFinishedDeferred
def sfd(d):
origSet(d)
d.addCallback(self._onDisconnect)
self._eventSource.protocol.setFinishedDeferred = sfd
class PatchSource(object):
"""wrap EventSource so it emits Patch objects and has an explicit stop method."""
def __init__(self, url):
self.url = url
# add callbacks to these to learn if we failed to connect
# (approximately) or if the ccnnection was unexpectedly lost
self.connectionFailed = defer.Deferred()
self.connectionLost = defer.Deferred()
self._listeners = set()
log.info("start read from %s", url)
# note: fullGraphReceived isn't guaranteed- the stream could
# start with patches
self._fullGraphReceived = False
self._eventSource = EventSource(url.toPython().encode("utf8"))
self._eventSource.protocol.delimiter = "\n"
self._eventSource.addEventListener("fullGraph", self._onFullGraph)
self._eventSource.addEventListener("patch", self._onPatch)
self._eventSource.onerror(self._onError)
origSet = self._eventSource.protocol.setFinishedDeferred
def sfd(d):
origSet(d)
d.addCallback(self._onDisconnect)
self._eventSource.protocol.setFinishedDeferred = sfd
def stats(self):
return {"url": self.url, "fullGraphReceived": self._fullGraphReceived}
def addPatchListener(self, func):
"""
func(patch, fullGraph=[true if the patch is the initial fullgraph])
"""
self._listeners.add(func)
def stop(self):
log.info("stop read from %s", self.url)
try:
self._eventSource.protocol.stopProducing() # needed?
except AttributeError:
pass
self._eventSource = None
def _onDisconnect(self, a):
log.debug("PatchSource._onDisconnect from %s", self.url)
# skip this if we're doing a stop?
self.connectionLost.callback(None)
def _onError(self, msg):
log.debug("PatchSource._onError from %s %r", self.url, msg)
if not self._fullGraphReceived:
self.connectionFailed.callback(msg)
else:
self.connectionLost.callback(msg)
def _onFullGraph(self, message):
try:
g = ConjunctiveGraph()
g.parse(StringInputSource(message), format="json-ld")
p = Patch(addGraph=g)
self._sendPatch(p, fullGraph=True)
except:
log.error(traceback.format_exc())
raise
self._fullGraphReceived = True
def _onPatch(self, message):
try:
p = patchFromJson(message)
self._sendPatch(p, fullGraph=False)
except:
log.error(traceback.format_exc())
raise
def _sendPatch(self, p, fullGraph):
log.debug("PatchSource %s received patch %s (fullGraph=%s)", self.url, p.shortSummary(), fullGraph)
for lis in self._listeners:
lis(p, fullGraph=fullGraph)
def __del__(self):
if self._eventSource:
raise ValueError
