-
Notifications
You must be signed in to change notification settings - Fork 0
/
network_layers.py
464 lines (416 loc) · 17 KB
/
network_layers.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
"""
network_layers.py
This has the main NetworkLayer class. This is inherited by the
RandomNoNetworkLayer, which was used for development of the game, the
NaiveNetworkLayer, which is the network layer that has no agreement
algorithm, and PartTimeNetworkLayer, which is the network layer that
uses Paxos for agreement. The utilities that this file uses are
defined in player_pb2, paxosmsg_pb2, and network_utils (the first two
are auto- generated by the protocol buffer package--the important part
is the protobuf structure that creates them, as defined in the .proto
files).
"""
import time, random
import socket as sock
import player_pb2 as pb
import paxosmsg_pb2 as pxb
from select import select
import cPickle
import time
from game_utils import GameState, Direction, Message
# handles setting up and using the network interfacing
from network_utils import *
message_dict = {}
class NetworkLayer(object):
"""
Responsible for handling networking operations. Provides an
interface for communicating with other players in the game. Must
be subclassed to be used.
"""
def broadcast_message(self, msg):
"""
Broadcast a message to other players.
Args:
msg: the message to broadcast
Return:
True if the message was successfully broadcast,
False otherwise.
"""
return False
def get_messages(self):
"""
Get queued incoming messages. Does not block to wait for
messages.
Return:
An Iterable of Messages
"""
return []
def start(self):
"""
Perform setup and block until the game is supposed to begin.
"""
while True:
pass
def stop(self):
"""
Perform teardown
"""
pass
class RandomNoNetworkLayer(NetworkLayer):
"""
A NetworkLayer implementation meant for user interface testing. It
does not actually do any network requests and it will generate
random moves for all players.
"""
def __init__(self, player, game):
self.player = player
self.game = game
self.message_queue = []
def broadcast_message(self, msg):
"""Pretend to broadcast the message."""
self.message_queue.append(msg)
return True
def get_messages(self):
"""
Yield the start messages and then yield a random message with
probability .05
"""
while True:
if len(self.message_queue) > 0:
yield self.message_queue.pop(0)
continue
if random.random() < .95:
raise StopIteration
else:
possible_players = [p for p in self.game.players_left
if p != self.player]
if len(possible_players) == 0:
raise StopIteration
p = possible_players[0]
if len(possible_players) > 1:
p = possible_players[random.randint(0,len(possible_players)-1)]
new_dir = Direction(random.randint(0,2))
new_t = time.time()
new_pos = self.game.state[p][-1]['pos']
yield Message.move(p, new_pos, new_dir)
def start(self):
"""Start the game immediately"""
pass
class NaiveNetworkLayer(NetworkLayer):
"""
A NetworkLayer implementation that uses simple message passing with
no agreement algorithm for game state. Should show liveness but might
show inconsistencies.
"""
def __init__(self, HOST=None):
self.HOST = HOST
# These get initialized in start
self.player = None
self.socks = None
self.addrs = None
def broadcast_message(self, msg):
"""
Send messages to all of the players
"""
network_msg = msg.serialize()
for i, s in enumerate(self.socks):
if s:
try:
s.send(network_msg)
except sock.error:
print 'lost connection to', i
self.socks[i] = None
return True
def get_messages(self):
"""
Get messages from all of the players
"""
msgs = []
net_msg = pb.GameMsg()
for s in self.socks:
if s:
try:
data = s.recv(1024)
if data:
msgs.append(Message.deserialize(data))
except IOError:
continue
return msgs
def start(self):
"""
Start up the TCP connections between all of the players for messaging. This is
handled through the network util functions. We return the player number of the
player who we set up. 4 players must join to continue.
"""
if (self.HOST):
self.player, self.socks, self.addrs = establish_tcp_connections(self.HOST)
else:
self.player, self.socks, self.addrs = coordinate_tcp_connections()
return self.player
class PartTimeNetworkLayer(NetworkLayer):
"""
A NetworkLayer implementation that uses Paxos }:-) for consistency with stable leaders and heartbeats.
"""
def __init__(self, HOST=None):
self.HOST = HOST
# These get initialized in start
self.player = None
self.socks = None
self.addrs = None
def broadcast_message(self, msg):
"""
Send messages to all of the players
"""
message_dict[(msg.pos, msg.direction)] = time.time()
self.outbox.append(msg.serialize())
def _broadcast_message(self, msg):
"""
Put msg over all of the sockets
"""
for i, s in enumerate(self.socks):
if s:
try:
msg.from_uid = self.node.node_uid
msg.instance = self.instance
s.send(msg.SerializeToString())
except sock.error:
print 'lost connection to', i
self.socks[i] = None
return True
def _send_message(self, to, msg):
"""
Put msg to socket belonging to UID to
"""
try:
msg.from_uid = self.node.node_uid
msg.instance = self.instance
self.socks[to].send(msg.SerializeToString())
except sock.error:
print 'lost connection'
def get_messages(self):
"""
Get accepted messages from all of the players
"""
self.do_paxos()
inbox = self.inbox
self.inbox = []
return map(Message.deserialize, inbox)
def _get_messages(self):
"""
Read from all of the sockets
"""
msgs = []
for s in self.socks:
if s:
try:
data = s.recv(1024)
while data:
msg = pxb.msg()
msg.ParseFromString(data)
if msg.instance > self.instance:
print "OLD"
msgs.append((s,msg))
data = s.recv(1024)
except IOError:
continue
return msgs
def start(self):
"""
Start up the TCP connections between all of the players for messaging. This is
handled through the network util functions. We return the player number of the
player who we set up. 4 players must join to continue.
"""
if (self.HOST):
self.player, self.socks, self.addrs = establish_tcp_connections(self.HOST)
else:
self.player, self.socks, self.addrs = coordinate_tcp_connections()
self.call_part_time_parliament_to_order()
return self.player
def stop(self):
self.running = False
def call_part_time_parliament_to_order(self):
"""
Initialize Paxos algorithm, with self as Node # uid
"""
import paxos.functional
def status(*args):
print self.node.node_uid, args
class MyMessenger(paxos.functional.HeartbeatMessenger):
def __init__(_self): return super(MyMessenger,_self).__init__()
def send_prepare(_self, proposal_id):
'''
Broadcasts a Prepare message to all Acceptors
'''
status("Preparing", proposal_id)
msg = pxb.msg()
msg.type = pxb.PREPARE
msg.proposal_id = cPickle.dumps(proposal_id)
self._broadcast_message(msg)
def send_promise(_self, proposer_uid, proposal_id, previous_id, accepted_value):
'''
Sends a Promise message to the specified Proposer
'''
status("Promising", proposal_id, accepted_value)
msg = pxb.msg()
msg.type = pxb.PROMISE
msg.proposal_id = cPickle.dumps(proposal_id)
if previous_id:
msg.previous_id = cPickle.dumps(previous_id)
msg.value = cPickle.dumps(accepted_value)
self._send_message(proposer_uid, msg)
def send_accept(_self, proposal_id, proposal_value):
'''
Broadcasts an Accept! message to all Acceptors
'''
status("Accept!ing", proposal_id, proposal_value)
msg = pxb.msg()
msg.type = pxb.ACCEPT
msg.proposal_id = cPickle.dumps(proposal_id)
msg.value = cPickle.dumps(proposal_value)
self._broadcast_message(msg)
def send_accepted(_self, proposal_id, accepted_value):
'''
Broadcasts an Accepted message to all Learners
'''
status("Accepting", proposal_id, accepted_value)
msg = pxb.msg()
msg.type = pxb.ACCEPTED
msg.proposal_id = cPickle.dumps(proposal_id)
msg.value = cPickle.dumps(accepted_value)
self._broadcast_message(msg)
def on_resolution(_self, proposal_id, value):
'''
Called when a resolution is reached
'''
status("Accepted", proposal_id, value)
for v in value:
v = Message.deserialize(v)
if (v.pos, v.direction) in message_dict:
print "Time elapsed for accept", time.time() - message_dict[(v.pos, v.direction)]
self.inbox.extend(value)
self.incr_instance = True
def send_prepare_nack(_self, to_uid, proposal_id, promised_id):
'''
Sends a Prepare Nack message for the proposal to the specified node
'''
status("Prepare Nack", proposal_id, promised_id)
msg = pxb.msg()
msg.type = pxb.NACK_PREPARE
msg.proposal_id = cPickle.dumps(proposal_id)
msg.previous_id = cPickle.dumps(promised_id)
self._send_message(to_uid, msg)
def send_accept_nack(_self, to_uid, proposal_id, promised_id):
'''
Sends a Accept! Nack message for the proposal to the specified node
'''
status("Accept Nack", proposal_id, promised_id)
msg = pxb.msg()
msg.type = pxb.NACK_ACCEPT
msg.proposal_id = cPickle.dumps(proposal_id)
msg.previous_id = cPickle.dumps(promised_id)
self._send_message(to_uid, msg)
def on_leadership_acquired(_self):
'''
Called when leadership has been aquired. This is not a guaranteed
position. Another node may assume leadership at any time and it's
even possible that another may have successfully done so before this
callback is exectued. Use this method with care.
The safe way to guarantee leadership is to use a full Paxos instance
whith the resolution value being the UID of the leader node. To avoid
potential issues arising from timing and/or failure, the election
result may be restricted to a certain time window. Prior to the end of
the window the leader may attempt to re-elect itself to extend it's
term in office.
'''
status("I'm the leader!")
def send_heartbeat(_self, leader_proposal_id):
'''
Sends a heartbeat message to all nodes
'''
status("My heart still beats", leader_proposal_id)
msg = pxb.msg()
msg.type = pxb.HEARTBEAT
msg.proposal_id = cPickle.dumps(leader_proposal_id)
self._broadcast_message(msg)
def schedule(_self, msec_delay, func_obj):
'''
While leadership is held, this method is called by pulse() to schedule
the next call to pulse(). If this method is not overridden appropriately,
subclasses must use the on_leadership_acquired()/on_leadership_lost() callbacks
to ensure that pulse() is called every hb_period while leadership is held.
'''
self.node.next_hb = time.time() + msec_delay
def on_leadership_lost(_self):
'''
Called when loss of leadership is detected
'''
status("I'm not the leader :(")
def on_leadership_change(_self, prev_leader_uid, new_leader_uid):
'''
Called when a change in leadership is detected. Either UID may
be None.
'''
status("Leader change", prev_leader_uid, new_leader_uid)
self.messenger = MyMessenger()
self.node = paxos.functional.HeartbeatNode(self.messenger, self.player, len(self.socks)/2 + 1)
self.inbox = []
self.outbox = []
self.instance = 1
self.incr_instance = False
def do_paxos(self):
"""
Main Paxos loop
"""
for s,msg in self._get_messages():
if msg.proposal_id:
proposal_id = paxos.functional.ProposalID._make(cPickle.loads(str(msg.proposal_id)))
self.node.next_proposal_number = max(self.node.next_proposal_number, proposal_id.number + 1)
if msg.previous_id:
previous_id = paxos.functional.ProposalID._make(cPickle.loads(str(msg.previous_id)))
if msg.type == pxb.PREPARE:
self.node.recv_prepare(msg.from_uid, proposal_id)
elif msg.type == pxb.PROMISE:
previous_id = None
accepted_value = cPickle.loads(str(msg.value))
self.node.recv_promise(msg.from_uid, proposal_id, previous_id, accepted_value)
elif msg.type == pxb.ACCEPT:
self.node.recv_accept_request(msg.from_uid, proposal_id, cPickle.loads(str(msg.value)))
elif msg.type == pxb.ACCEPTED:
self.node.recv_accepted(msg.from_uid, proposal_id, cPickle.loads(str(msg.value)))
elif msg.type == pxb.NACK_PREPARE:
self.node.recv_prepare_nack(msg.from_uid, proposal_id, previous_id)
elif msg.type == pxb.NACK_ACCEPT:
self.node.recv_accept_nack(msg.from_uid, proposal_id, previous_id)
elif msg.type == pxb.HEARTBEAT:
self.node.recv_heartbeat(msg.from_uid, proposal_id)
elif msg.type == pxb.REQUEST:
if self.node.leader:
self.outbox.extend(cPickle.loads(str(msg.value)))
else:
status("Dropping request")
else:
raise NotImplementedError
if not self.incr_instance:
if self.outbox:
if self.node.leader and not self.node.proposed_value:
self.node.proposed_value = self.outbox
self.node.prepare()
elif not self.node.leader:
msg = pxb.msg()
msg.type = pxb.REQUEST
msg.value = cPickle.dumps(self.outbox)
self.outbox = []
self._broadcast_message(msg)
self.node.persisted()
if self.node.leader and self.node.next_hb <= time.time():
self.node.pulse()
else:
self.node = paxos.functional.HeartbeatNode(self.messenger, self.player, len(self.socks)/2 + 1, self.node.leader_uid)
self.node.next_hb = time.time()
self.instance += 1
self.incr_instance = False
self.paxos = do_paxos
if self.player == 1:
self.node.prepare()
def do_paxos(self):
return self.paxos(self)