forked from tkahnoski/polyp
/
gossip_handler.py
293 lines (278 loc) · 10.6 KB
/
gossip_handler.py
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#!/usr/bin/env python
import sys
from threading import Thread
import random
import time
sys.path.append('./gen-py')
import polyp_util
from polyp.ttypes import Endpoint
from polyp.gossip.ttypes import GossipSynMessage, GossipAckMessage, GossipAckBackMessage
from polyp.gossip.ttypes import NewStateMessage, GetStateMessage, ReturnStateMessage
from polyp.gossip.constants import FIRST_GEN
from polyp.gossip.ttypes import HeartBeatState, EndpointState, EndpointDigest, ApplicationState
VERB_SYN="syn"
VERB_ACK="ack"
VERB_ACKBACK="ackback"
VERB_NEWSTATE="newstate"
VERB_GETSTATE="getstate"
VERB_RETURNSTATE="returnstate"
RING_DELAY = 60.0 #Assume ring has stabilized after a minute
MAX_UNREACHABLE = 100
#TODO: Do some actual logging...
def debug_print(header,obj):
print >>sys.stderr, "-" * 80
print >>sys.stderr, time.strftime("%Y-%M-%d %H:%m:%S")
print >>sys.stderr, header
print >>sys.stderr, obj
#parse host:port lines into (host,port)
def read_seeds(stream):
seeds = []
for line in stream:
comments = line.split('#',1)
stripped = comments[0].strip()
if len(stripped) > 0:
cols = stripped.split(':',1)
seeds.append((cols[0],int(cols[1])) )
return seeds
class SynThread(Thread):
def __init__(self,gossiper,delay):
Thread.__init__(self,name="SynThread")
self.daemon = True
self.gossiper = gossiper
self.delay = delay
self.start()
def run(self):
while True:
time.sleep(self.delay)
self.gossiper.gossip_round()
def ep_pair(endpoint):
return (endpoint.address,endpoint.port)
class GossipHandler:
#Initialize gossiper and start thread to periodically gossip
#Requires generation number
def __init__(self,sending_service,local,generation,seeds=[],delay=4.0,auto_synch=True):
self.generation = generation
self.local = local
self.local_key = ep_pair(local)
self.version_counter = 1
self.heartbeat = HeartBeatState(generation,self.version_counter)
self.state = EndpointState(self.local,self.heartbeat,{})
self.endpoints = {}
self.endpoints[ep_pair(self.local)] = self.state
self.unreachable = []
self.quarantine = {}#{ep_pair(Endpoint) : time.time() of rejoin}
for seed in seeds:
if seed == self.local_key:
continue
self.endpoints[seed] = \
EndpointState(Endpoint(seed[0],seed[1]),HeartBeatState(FIRST_GEN,0),{})
self.living = []
self.outbound = sending_service
if auto_synch:
self.synThread = SynThread(self,delay)
def inc_version(self):
#TODO: lock
self.version_counter += 1
return self.version_counter
def add_unreachable(self,ep):
self.unreachable.append(ep)
print >>sys.stderr, ep, " is unreachable"
if len(self.unreachable) > MAX_UNREACHABLE:
x = self.unreachable.pop(0)
print >>sys.stderr, "Unreachable list is too big. Removed ", x
def add_quarantine(self,ep_key):
if ep_key in self.quarantine:
return
self.quarantine[ep_key] = time.time()
print >>sys.stderr, ep_key, " added to quarantine"
#Return true if endpoint is quarantined
#Note: this has has side effects!
def is_quarantined(self,ep):
if not ep in self.unreachable:
return False
ep_key = ep_pair(ep)
if not ep_key in self.quarantine:
self.add_quarantine(ep_key)
curTime = time.time()
if curTime - self.quarantine[ep_key] > RING_DELAY:
print >>sys.stderr, ep, " no longer quarantined"
self.quarantine.pop(ep_key)
self.unreachable.remove(ep)
return False
return True
def add_endpoint(self,epState):
if self.is_quarantined(epState.endpoint):
print >>sys.stderr, epState.endpoint, " is quarantined"
return
ep_key = ep_pair(epState.endpoint)
self.endpoints[ep_key] = epState
def syn(self,sender,syn_msg):
debug_print('syn:', syn_msg)
unknown, known = examine_digest_list(syn_msg.digests,self.endpoints)
ackMsg = GossipAckMessage(unknown,known)
self.send(sender,VERB_ACK,ackMsg)
def ack(self,sender,ack_msg):
debug_print('ack:', ack_msg)
self.update_states(ack_msg.known)
if len(ack_msg.requested) > 0:
unknown, known = examine_digest_list(ack_msg.requested,self.endpoints)
ackBackMsg = GossipAckBackMessage(known)
self.send(sender,VERB_ACKBACK,ackBackMsg)
def ackBack(self,sender,ack_back_msg):
debug_print('ack_back:', ack_back_msg)
self.update_states(ack_back_msg.known)
#Take a polyp Message and dispatch based on verb
def handleMessage(self,message):
#TODO: this needs to be fast
if message.header.verb == VERB_SYN:
synMsg = polyp_util.deserialize(GossipSynMessage(),message.body)
self.syn(message.header.sender,synMsg)
elif message.header.verb == VERB_ACK:
ackMsg = polyp_util.deserialize(GossipAckMessage(),message.body)
self.ack(message.header.sender,ackMsg)
elif message.header.verb == VERB_ACKBACK:
ackBackMsg = polyp_util.deserialize(
GossipAckBackMessage(),message.body)
self.ackBack(message.header.sender,ackBackMsg)
elif message.header.verb == VERB_NEWSTATE:
newStateMsg = polyp_util.deserialize(NewStateMessage(),message.body)
self.add_application_state(newStateMsg.key,newStateMsg.value)
elif message.header.verb == VERB_GETSTATE:
getStateMsg = polyp_util.deserialize(GetStateMessage(),message.body)
self.get_state(message.header.sender,getStateMsg)
elif message.header.verb == VERB_RETURNSTATE:
returnStateMsg = polyp_util.deserialize(ReturnStateMessage(),message.body)
self.return_state(message.header.sender,returnStateMsg)
def add_application_state(self,key,value):
version = self.inc_version()
state = ApplicationState(key,value,self.generation,version)
debug_print("newstate:",state)
self.state.info[key] = state
return state
def get_state(self,sender,stateMsg):
endpoints = stateMsg.endpoints
to_send = []
if len(endpoints) == 0:
to_send = self.endpoints.values()
else:
for ep in endpoints:
ep_key = ep_pair(ep)
state = self.endpoints.get(ep_key)
to_send.append(state)
self.send(sender,"returnstate",ReturnStateMessage(to_send))
def return_state(self,sender,statemsg):
print "Status from %s:%s" % (sender.address, sender.port)
for ep_state in statemsg.states:
endpoint = ep_state.endpoint
heartbeat = ep_state.heartbeat
print endpoint.address, ':', endpoint.port
print "\tgeneration: %s\tversion:%s" % (heartbeat.generation, heartbeat.version)
print "\t", ep_state.info
def send_random(self,endpoints,message,msg_verb):
if len(endpoints) == 1:
return
chosen = random.choice(endpoints)
if chosen == self.local_key:
eps = endpoints[:]
eps.remove(self.local_key)
chosen = random.choice(eps)
print >>sys.stderr, 'sending syn to ', chosen
contact = Endpoint(chosen[0],chosen[1])
self.send(contact, msg_verb, message)
def send(self,contact, msg_verb, message):
try:
self.outbound.get(contact).send_obj("gossip",msg_verb,message)
except (Exception), e:
print >>sys.stderr, e
self.endpoints.pop(ep_pair(contact))
self.add_unreachable(contact)
print >>sys.stderr, "Removed ep"
def gossip_round(self):
self.heartbeat.version = self.inc_version()
debug_print('Gossip round %d ' % self.heartbeat.version,self.endpoints)
if len(self.endpoints) == 1:
print >>sys.stderr, 'No one to gossip to :-('
return
digests = self.make_random_digests()
synMsg = GossipSynMessage(digests)
self.send_random(self.endpoints.keys(),synMsg,VERB_SYN)
#TODO: gossip to seed, gossip to unreachable
def make_random_digests(self):
#Assume we have lock
sample_size = min(len(self.endpoints),31)
rand_endpoints = random.sample(self.endpoints.values(),sample_size)
if not self.state in rand_endpoints:
rand_endpoints.append(self.state)
return [EndpointDigest(x.endpoint,
max_generation(x),
max_version(x))
for x in rand_endpoints]
def update_states(self,epStates):
for state in epStates:
if state.endpoint == self.local:
continue
ep_key = ep_pair(state.endpoint)
local_ep = self.endpoints.get(ep_key)
if local_ep is None:
#TODO
# notifications?
self.add_endpoint(state)
elif local_ep.heartbeat.generation < state.heartbeat.generation:
self.endpoints[ep_key] = state
#TODO: notifications?
elif local_ep.heartbeat.generation == state.heartbeat.generation \
and max_version(local_ep) < max_version(state):
update_ep_state(local_ep,state)
def max_version(state):
states = state.info.values()[:]
states.append(state.heartbeat)
return max(states,key=lambda x: x.version).version
def max_generation(state):
states = state.info.values()[:]
states.append(state.heartbeat)
return max(states,key=lambda x: x.generation).generation
#Return a new endpoint state
def get_bigger_states(epState,version):
states = filter(lambda x: x[1].version > version, epState.info.items())
return EndpointState(epState.endpoint, epState.heartbeat,dict(states))
#Return tuple of states that need updating and known states
def examine_digest_list(remote_digests,localEpMap):
unknown = []
knownStates = []
for digest in remote_digests:
remote_gen = digest.generation
remote_v = digest.version
ep_key = (digest.endpoint.address,digest.endpoint.port)
epState = localEpMap.get(ep_key)
if not epState is None:
local_gen = max_generation(epState)
local_v = max_version(epState)
if remote_gen == local_gen and remote_v == local_v:
continue
if remote_gen > local_gen:
unknown.append(digest.endpoint,remote_gen,0)
elif remote_gen < local_gen:
knownStates.append(get_bigger_states(epState,0))
elif remote_v > local_v:
unknown.append(
EndpointDigest(digest.endpoint,remote_gen,local_v))
elif remote_v < local_v:
knownStates.append(get_bigger_states(epState,remote_v))
else:
unknown.append(EndpointDigest(digest.endpoint,remote_gen,0))
return (unknown,knownStates)
#Mutate current state in place with changes from latest
#States must not be None
def update_ep_state(current_state,latest_state):
current_state.heartbeat = latest_state.heartbeat
current_map = current_state.info
latest_map = latest_state.info
for k, latest_v in latest_map.items():
current_v = current_map.get(k)
if current_v is None:
current_map[k] = latest_v
elif current_v.generation < latest_v.generation:
current_map[k] = latest_v
elif current_v.generation == latest_v.generation \
and current_v.version < latest_v.version:
current_map[k] = latest_v