cpython/Demo/pdist/client.py

"""RPC Client module."""

import sys
import socket
import pickle
import __builtin__
import os


# Default verbosity (0 = silent, 1 = print connections, 2 = print requests too)
VERBOSE = 1


class Client:
	
	"""RPC Client class.  No need to derive a class -- it's fully generic."""
	
	def __init__(self, address, verbose = VERBOSE):
		if type(address) == type(0):
			address = ('', address)
		self._address = address
		self._verbose = verbose
		if self._verbose: print "Connecting to %s ..." % repr(address)
		self._socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
		self._socket.connect(address)
		if self._verbose: print "Connected."
		self._lastid = 0 # Last id for which a reply has been received
		self._nextid = 1 # Id of next request
		self._replies = {} # Unprocessed replies
		self._rf = self._socket.makefile('r')
		self._wf = self._socket.makefile('w')
		self._methods = self._call('.methods')
	
	def __del__(self):
		self._close()
	
	def _close(self):
		if self._rf: self._rf.close()
		self._rf = None
		if self._wf: self._wf.close()
		self._wf = None
		if self._socket: self._socket.close()
		self._socket = None
	
	def __getattr__(self, name):
		if name in self._methods:
			method = _stub(self, name)
			setattr(self, name, method) # XXX circular reference
			return method
		raise AttributeError, name
	
	def _setverbose(self, verbose):
		self._verbose = verbose
	
	def _call(self, name, *args):
		return self._vcall(name, args)
	
	def _vcall(self, name, args):
		return self._recv(self._vsend(name, args))
	
	def _send(self, name, *args):
		return self._vsend(name, args)
	
	def _send_noreply(self, name, *args):
		return self._vsend(name, args, 0)
	
	def _vsend_noreply(self, name, args):
		return self._vsend(name, args, 0)
	
	def _vsend(self, name, args, wantreply = 1):
		id = self._nextid
		self._nextid = id+1
		if not wantreply: id = -id
		request = (name, args, id)
		if self._verbose > 1: print "sending request: %s" % repr(request)
		wp = pickle.Pickler(self._wf)
		wp.dump(request)
		return id
	
	def _recv(self, id):
		exception, value, rid = self._vrecv(id)
		if rid != id:
			raise RuntimeError, "request/reply id mismatch: %d/%d" % (id, rid)
		if exception is None:
			return value
		x = exception
		if hasattr(__builtin__, exception):
			x = getattr(__builtin__, exception)
		elif exception in ('posix.error', 'mac.error'):
			x = os.error
		if x == exception:
			exception = x
		raise exception, value		
	
	def _vrecv(self, id):
		self._flush()
		if self._replies.has_key(id):
			if self._verbose > 1: print "retrieving previous reply, id = %d" % id
			reply = self._replies[id]
			del self._replies[id]
			return reply
		aid = abs(id)
		while 1:
			if self._verbose > 1: print "waiting for reply, id = %d" % id
			rp = pickle.Unpickler(self._rf)
			reply = rp.load()
			del rp
			if self._verbose > 1: print "got reply: %s" % repr(reply)
			rid = reply[2]
			arid = abs(rid)
			if arid == aid:
				if self._verbose > 1: print "got it"
				return reply
			self._replies[rid] = reply
			if arid > aid:
				if self._verbose > 1: print "got higher id, assume all ok"
				return (None, None, id)
	
	def _flush(self):
		self._wf.flush()


class _stub:
	
	"""Helper class for Client -- each instance serves as a method of the client."""
	
	def __init__(self, client, name):
		self._client = client
		self._name = name
	
	def __call__(self, *args):
		return self._client._vcall(self._name, args)