def run(self):
if self.is_forwarder:
spawn_greenlet(Forwarder, self.name, self.pid)
else:
self.publisher = Publisher(self.name, self.pid)
self.subscriber = Subscriber(self.on_message_callback, self.name, self.pid)
spawn_greenlet(self.subscriber.serve_forever)
class IPCAPI(object):
""" API through which IPC is performed.
"""
def __init__(self,
is_forwarder,
name=None,
on_message_callback=None,
pid=None):
self.is_forwarder = is_forwarder
self.name = name
self.on_message_callback = on_message_callback
self.pid = pid
def run(self):
if self.is_forwarder:
spawn_greenlet(Forwarder, self.name, self.pid)
else:
self.publisher = Publisher(self.name, self.pid)
self.subscriber = Subscriber(self.on_message_callback, self.name,
self.pid)
spawn_greenlet(self.subscriber.serve_forever)
def publish(self, payload):
self.publisher.publish(payload)
def _get_response(self,
fifo,
buffer_size,
fifo_ignore_err=fifo_ignore_err,
empty=('', None)):
try:
buff = StringIO()
data = object(
) # Just a sentinel because '' or None are expected from os.read
while data not in empty:
data = os.read(fifo, 1)
buff.write(data)
response = buff.getvalue()
status = response[:IPC.STATUS.LENGTH]
response = response[IPC.STATUS.LENGTH +
1:] # Add 1 to account for the separator
is_success = status == IPC.STATUS.SUCCESS
if is_success:
response = loads(response) if response else ''
buff.close()
return is_success, response
except OSError, e:
if e.errno not in fifo_ignore_err:
raise
def _get_pid_publisher(self, cluster_name, server_name, target_pid):
# We do no have a publisher connected to that PID, so we need to create it ..
if target_pid not in self.pid_publishers:
# Create a publisher and sleep for a moment until it connects to the other socket
publisher = Publisher(self.get_endpoint_name(cluster_name, server_name, target_pid), self.pid)
# We can tolerate it because it happens only the very first time our PID invokes target_pid
sleep(0.1)
# We can now store it for later use
self.pid_publishers[target_pid] = publisher
# At this point we are sure we have a publisher for target PID
return self.pid_publishers[target_pid]