def recv_acceptrequest(self, msg, instance):
"""Update instance state appropriately based upon msg.
(b) If an acceptor receives an accept request for a proposal numbered n, it
accepts the proposal unless it has already responded to a prepare request
having a number greater than n.
"""
if msg['prop_num'] >= instance['acceptor_prepare_prop_num']:
dbprint("Instance %d: accepting prop %s (current is %s)"
% (instance['instance_id'],
msg['prop_num'],
instance['acceptor_cur_prop_num']),
level=4)
instance['acceptor_cur_prop_num'] = msg.prop_num
instance['acceptor_cur_prop_value'] = msg.prop_value
self.writeAll(Msg({
"msg_type": "acceptnotify",
"prop_num": msg.prop_num,
"prop_value": msg.prop_value,
"instance_id": instance['instance_id']
}))
else:
if config.NACKS_ENABLED:
d = {
'msg_type': 'nack_acceptrequest',
'prop_num': msg['prop_num'],
'instance_id': instance['instance_id'],
}
if config.NACKS_ENABLED == 2:
d['prev_prop_num'] = instance['acceptor_cur_prop_num']
d['prev_prop_value'] = instance['acceptor_cur_prop_value']
self.writeMessage(msg['uid'], Msg(d))
def process(self, tx_id, d):
"""Process an operation that's been passed up through Paxos."""
dbprint("processing op %r, tx id %d" % (d, tx_id), level=4)
assert tx_id == self.tx_version+1, "process: tx_id %d != tx_version+1: %d" % (tx_id, self.tx_version+1)
self.history.append((tx_id, d))
assert isinstance(d, dict), "process: %s is not a dict" % (d,)
if self.lock_holder is not None:
if self.lock_holder != d['uid']:
dbprint("ignoring op '%s', lock held by %s" % (d, self.lock_holder), level=3)
self.tx_version = tx_id
return
op = d['type']
if op == "nop":
pass
elif op == "attemptlock":
self.process_lock(d)
elif op == "unlock":
self.process_unlock(d)
elif op == "db_op":
self.process_op(d)
if tx_id in self.waiters:
for d in self.waiters[tx_id]:
d.callback(tx_id)
del self.waiters[tx_id]
self.tx_version = tx_id
def process(self, tx_id, d):
"""Process an operation that's been passed up through Paxos."""
dbprint("processing op %r, tx id %d" % (d, tx_id), level=4)
assert tx_id == self.tx_version + 1, "process: tx_id %d != tx_version+1: %d" % (
tx_id, self.tx_version + 1)
self.history.append((tx_id, d))
assert isinstance(d, dict), "process: %s is not a dict" % (d, )
if self.lock_holder is not None:
if self.lock_holder != d['uid']:
dbprint("ignoring op '%s', lock held by %s" %
(d, self.lock_holder),
level=3)
self.tx_version = tx_id
return
op = d['type']
if op == "nop":
pass
elif op == "attemptlock":
self.process_lock(d)
elif op == "unlock":
self.process_unlock(d)
elif op == "db_op":
self.process_op(d)
if tx_id in self.waiters:
for d in self.waiters[tx_id]:
d.callback(tx_id)
del self.waiters[tx_id]
self.tx_version = tx_id
def recv_acceptrequest(self, msg, instance):
"""Update instance state appropriately based upon msg.
(b) If an acceptor receives an accept request for a proposal numbered n, it
accepts the proposal unless it has already responded to a prepare request
having a number greater than n.
"""
if msg['prop_num'] >= instance['acceptor_prepare_prop_num']:
dbprint("Instance %d: accepting prop %s (current is %s)" %
(instance['instance_id'], msg['prop_num'],
instance['acceptor_cur_prop_num']),
level=4)
instance['acceptor_cur_prop_num'] = msg.prop_num
instance['acceptor_cur_prop_value'] = msg.prop_value
self.writeAll(
Msg({
"msg_type": "acceptnotify",
"prop_num": msg.prop_num,
"prop_value": msg.prop_value,
"instance_id": instance['instance_id']
}))
else:
if config.NACKS_ENABLED:
d = {
'msg_type': 'nack_acceptrequest',
'prop_num': msg['prop_num'],
'instance_id': instance['instance_id'],
}
if config.NACKS_ENABLED == 2:
d['prev_prop_num'] = instance['acceptor_cur_prop_num']
d['prev_prop_value'] = instance['acceptor_cur_prop_value']
self.writeMessage(msg['uid'], Msg(d))
def value_learned(self, instance):
assert instance['status'] == "completed"
dbprint("passing TX(%s, %s) up" %
(instance['instance_id'], instance['value']),
level=3)
self.manager._passup_tx((instance['instance_id'], instance['value']))
return instance
def writeMessage(self, uid, msg):
dbprint("Sent %s message to %s\n%s\n" % (msg['msg_type'], uid, msg),
level=1)
msg.contents['uid'] = self.uid
msg = msg.serialize()
addr = self.hosts[uid]
self.transport.write(msg, addr)
def recv_acceptnotify(self, msg, instance):
"""Update instance state appropriately based upon msg.
If the proposal has been accepted by a quorum, it's completed.
"""
# if we've already learnt it's been accepted, there's no need to
# deal with it any more
if instance['status'] == "completed":
return
s = instance['learner_accepted'].setdefault(msg['prop_num'], set())
s.add(msg['uid'])
if len(s) >= self.quorum_size:
dbprint("Instance %d: learnt value %s (prop %s)"
% (instance['instance_id'],
msg['prop_value'],
msg['prop_num']),
level=4)
instance['status'] = "completed"
instance['value'] = msg['prop_value']
assert not instance['callback'].called, "completion error 1: %s: %s" % (msg, instance)
instance['callback'].callback(instance)
def datagramReceived(self, msg, host):
"""Called when a message is received by a specific agent.
"""
self._msgs.append((msg, host))
try:
m = parse_message(msg)
# If we haven't heard this host before, add them to the record
if m['uid'] not in self.hosts and m['uid'] != self.uid:
self.addHost(m['uid'], host)
t = m['msg_type']
dbprint("Got %s message from %s\n%s\n" % (m['msg_type'], host, m), level=1)
if m['instance_id'] is not None:
i = m['instance_id']
if i not in self.instances:
if i >= self.current_instance_number:
self.current_instance_number = i+1
self.instances[i] = self.create_instance(i)
else:
assert i < self.current_instance_number, "known but oddly large instance number %s (%s)" % (i, self.current_instance_number)
instance = self.instances[i]
if instance['status'] == 'completed':
dbprint("dropping msg as instance %s is already completed" % i, level=2)
return
else:
instance = None
method = getattr(self, "recv_%s" % t)
method(m, instance)
except (InvalidMessageException, KeyError), e:
dbprint("%s received invalid message %s (%s)" % (self, msg, e), level=4)
raise
def recv_acceptnotify(self, msg, instance):
"""Update instance state appropriately based upon msg.
If the proposal has been accepted by a quorum, it's completed.
"""
# if we've already learnt it's been accepted, there's no need to
# deal with it any more
if instance['status'] == "completed":
return
s = instance['learner_accepted'].setdefault(msg['prop_num'], set())
s.add(msg['uid'])
if len(s) >= self.quorum_size:
dbprint(
"Instance %d: learnt value %s (prop %s)" %
(instance['instance_id'], msg['prop_value'], msg['prop_num']),
level=4)
instance['status'] = "completed"
instance['value'] = msg['prop_value']
assert not instance[
'callback'].called, "completion error 1: %s: %s" % (msg,
instance)
instance['callback'].callback(instance)
def chase_up(self, instance_id):
dbprint("chasing up instance %s" % instance_id, level=2)
if instance_id not in self.instances:
dbprint("chase up: haven't heard of %s yet, starting again" % instance_id, level=2)
self.instances[i] = self.create_instance(instance_id)
self.proposer_start(i, "nop", restart=False)
else:
dbprint("chase up: already heard of %s, being mean anyway" % instance_id, level=2)
i = self.instances[instance_id]
self.proposer_start(i, "nop", restart=False)
def chase_up(self, instance_id):
dbprint("chasing up instance %s" % instance_id, level=2)
if instance_id not in self.instances:
dbprint("chase up: haven't heard of %s yet, starting again" %
instance_id,
level=2)
self.instances[i] = self.create_instance(instance_id)
self.proposer_start(i, "nop", restart=False)
else:
dbprint("chase up: already heard of %s, being mean anyway" %
instance_id,
level=2)
i = self.instances[instance_id]
self.proposer_start(i, "nop", restart=False)
def recv_promise(self, msg, instance):
"""Update instance state appropriately based upon msg.
(a) If the proposer receives a response to its prepare requests (numbered n)
from a majority of acceptors, then it sends an accept request to each of those
acceptors for a proposal numbered n with a value v, where v is the value of
the highest-numbered proposal among the responses, or if the responses reported
no proposals, a value of its own choosing.
"""
# If this is an old message or we're in the wrong state, ignore
if msg['prop_num'] != instance['last_tried']:# or instance['status'] != "trying":
dbprint("proposer ignoring msg %s, not appropriate (%s)"
% (msg, instance),
level=1)
return
instance['quorum'].add(msg['uid'])
if msg['prev_prop_value'] is not None:
if msg['prev_prop_num'] > instance['proposer_prev_prop_num']:
dbprint("loading old prop value of %s (num %s)"
% (msg['prev_prop_value'], msg['prev_prop_num']),
level=2)
instance['proposer_prev_prop_num'] = msg['prev_prop_num']
instance['proposer_prev_prop_value'] = msg['prev_prop_value']
else:
dbprint("ignoring old prop value of %s (num %s) for prop %s"
% (msg['prev_prop_value'],
msg['prev_prop_num'],
instance['proposer_prev_prop_value']),
level=2)
if len(instance['quorum']) >= self.quorum_size:
# If this is the message that tips us over the edge and we
# finally accept the proposal, deal with it appropriately.
if instance['status'] == 'trying':
self.poll(instance, msg['prop_num'])
def recv_promise(self, msg, instance):
"""Update instance state appropriately based upon msg.
(a) If the proposer receives a response to its prepare requests (numbered n)
from a majority of acceptors, then it sends an accept request to each of those
acceptors for a proposal numbered n with a value v, where v is the value of
the highest-numbered proposal among the responses, or if the responses reported
no proposals, a value of its own choosing.
"""
# If this is an old message or we're in the wrong state, ignore
if msg['prop_num'] != instance[
'last_tried']: # or instance['status'] != "trying":
dbprint("proposer ignoring msg %s, not appropriate (%s)" %
(msg, instance),
level=1)
return
instance['quorum'].add(msg['uid'])
if msg['prev_prop_value'] is not None:
if msg['prev_prop_num'] > instance['proposer_prev_prop_num']:
dbprint("loading old prop value of %s (num %s)" %
(msg['prev_prop_value'], msg['prev_prop_num']),
level=2)
instance['proposer_prev_prop_num'] = msg['prev_prop_num']
instance['proposer_prev_prop_value'] = msg['prev_prop_value']
else:
dbprint("ignoring old prop value of %s (num %s) for prop %s" %
(msg['prev_prop_value'], msg['prev_prop_num'],
instance['proposer_prev_prop_value']),
level=2)
if len(instance['quorum']) >= self.quorum_size:
# If this is the message that tips us over the edge and we
# finally accept the proposal, deal with it appropriately.
if instance['status'] == 'trying':
self.poll(instance, msg['prop_num'])
def datagramReceived(self, msg, host):
"""Called when a message is received by a specific agent.
"""
self._msgs.append((msg, host))
try:
m = parse_message(msg)
# If we haven't heard this host before, add them to the record
if m['uid'] not in self.hosts and m['uid'] != self.uid:
self.addHost(m['uid'], host)
t = m['msg_type']
dbprint("Got %s message from %s\n%s\n" % (m['msg_type'], host, m),
level=1)
if m['instance_id'] is not None:
i = m['instance_id']
if i not in self.instances:
if i >= self.current_instance_number:
self.current_instance_number = i + 1
self.instances[i] = self.create_instance(i)
else:
assert i < self.current_instance_number, "known but oddly large instance number %s (%s)" % (
i, self.current_instance_number)
instance = self.instances[i]
if instance['status'] == 'completed':
dbprint(
"dropping msg as instance %s is already completed" % i,
level=2)
return
else:
instance = None
method = getattr(self, "recv_%s" % t)
method(m, instance)
except (InvalidMessageException, KeyError), e:
dbprint("%s received invalid message %s (%s)" % (self, msg, e),
level=4)
raise
def writeAll(self, msg):
dbprint("%s sent message %s to all" % (self, msg), level=1)
for uid in self.hosts:
self.writeMessage(uid, msg)
def value_learned(self, instance):
assert instance['status'] == "completed"
dbprint("passing TX(%s, %s) up" % (instance['instance_id'], instance['value']), level=3)
self.manager._passup_tx((instance['instance_id'], instance['value']))
return instance
def process_unlock(self, d):
"""Handle someone requesting to take the global lock"""
guid = d['uid']
dbprint("unlock: released by %s" % guid, level=3)
self.lock_holder = None
def process_op(self, d):
try:
op = parse_op(d)
op.perform_op(self.db)
except InvalidOp, e:
dbprint("Invalid op (%s)" % e)
def process_lock(self, d):
"""Handle someone requesting to take the global lock"""
guid = d['uid']
dbprint("lock: taken by %s" % guid, level=3)
self.lock_holder = guid
def process_unlock(self, d):
"""Handle someone requesting to take the global lock"""
guid = d['uid']
dbprint("unlock: released by %s" % guid, level=3)
self.lock_holder = None
def addHost(self, uid, host):
dbprint("Adding node %s (%s)" % (uid, host), level=3)
self.hosts[uid] = host
self.quorum_size = (len(self.hosts)+1) // 2
def process_lock(self, d):
"""Handle someone requesting to take the global lock"""
guid = d['uid']
dbprint("lock: taken by %s" % guid, level=3)
self.lock_holder = guid
def process_op(self, d):
try:
op = parse_op(d)
op.perform_op(self.db)
except InvalidOp, e:
dbprint("Invalid op (%s)" % e)
def addHost(self, uid, host):
dbprint("Adding node %s (%s)" % (uid, host), level=3)
self.hosts[uid] = host
self.quorum_size = (len(self.hosts) + 1) // 2
def writeMessage(self, uid, msg):
dbprint("Sent %s message to %s\n%s\n" % (msg['msg_type'], uid, msg), level=1)
msg.contents['uid'] = self.uid
msg = msg.serialize()
addr = self.hosts[uid]
self.transport.write(msg, addr)
def writeAll(self, msg):
dbprint("%s sent message %s to all" % (self, msg), level=1)
for uid in self.hosts:
self.writeMessage(uid, msg)
