Better IPC needed #3
Description
In order to really take use of the active mode / cluster mode / whatever, it should be possible to connect via socket to another host, and to a pre-spawned vw process. Currently this is impossible without fully forking the wabbit_wappa code.
That is, ActiveVWProcess currently has an initializer
def __init__(self, command, port=DEFAULT_PORT):
"""'command' is assumed to have the necessary options for use with this
class, which should be guaranteed in the calling context."""
# Launch the VW process, which we will communicate with only
# via its socket
self.vw_process = pexpect.spawn(command)
self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
connection_tries = 0
while connection_tries < MAX_CONNECTION_ATTEMPTS:
try:
self.sock.connect(('127.0.0.1', port))
break # Quit this loop once successful
except socket.error:
connection_tries += 1
time.sleep(CONNECTION_WAIT)
self.before = None
Which has at least 3 problems:
- it uses pexpect to spawn a process whose input is not read
- it always needs to spawn a new process
- it hardcodes '127.0.0.1' as the target address
The best solution could be to refactor the VW class to use way more functions, and use the factory pattern for creating the vw_process.