def learner(db):
while True:
command = (yield)
try:
if command["action"] == "put":
log_info("setting db['%s'] to %s" % (command["key"], command["value"]))
db[command["key"]] = command["value"]
elif command["action"] == "incr":
db[command["key"]] = str(int(db[command["key"]]) + 1)
log_info("incrementing db['%s']" % command["key"])
elif command["action"] == "get":
# TODO only needs to execute on one
log_fail("db['%s'] is %s" % (command["key"], db[command["key"]]))
except KeyError:
log_fail("key %s is not in db" % command["key"])
def learner(db):
while True:
command = (yield)
try:
if command['action'] == 'put':
log_info("setting db['%s'] to %s" %
(command['key'], command['value']))
db[command['key']] = command['value']
elif command['action'] == 'incr':
db[command['key']] = str(int(db[command['key']]) + 1)
log_info("incrementing db['%s']" % command['key'])
elif command['action'] == 'get':
#TODO only needs to execute on one
log_fail("db['%s'] is %s" %
(command['key'], db[command['key']]))
except KeyError:
log_fail("key %s is not in db" % command['key'])
def client(request):
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
proposer = servers[1]
s_request = request.split()
if s_request[0] == 'get':
request = {'action': 'get',
'key': s_request[1]}
elif s_request[0] == 'incr':
request = {'action': 'incr',
'key': s_request[1]}
elif s_request[0] == 'put':
request = {'action': 'put',
'key': s_request[1],
'value': s_request[2]}
else:
log_fail("bad command: %s" % request)
sys.exit(-1)
request_msg = json.dumps({'request':request, 'protocol':'paxos'})
sock.sendto(request_msg, proposer)
# get_name_route: get_user_by_name
# delete_id_route: delete_user_by_id
# delete_name_route: delete_user_by_name
# delete_activity_route: delete_activity_by_activity_id
duplicated_flag = 0 #The duplicated_flag is used to skip the if loops for duplicated operation
for msgID in msgIDList: #This part of code tests for duplicates, if the msg_id is in the dictonary, skip if loops and send back original response
if msgID == request['msg_id']:
log_warning("REPLICATED msg_in: " + request['msg_id'])
qout.write(msgIDList[msgID])
duplicated_flag = 1
break
if duplicated_flag == 1: continue
if request['method'] == None:
log_fail("INVALID METHOD ID " + request['msg_id'])
continue
#print opnum of the request
log_back("###### EXPECTED OP# : " + str(nextTopNum))
log_back("!!!!!! REQUEST OP# : " + str(request['opnum']))
msg_out = Message() #creating empty message object for msg_out
key = request['msg_id'] #assigning msg_id to key
#print "line 413", key
method = request['method']
if method == constants.METHOD_POST_USER:
rqresult = create_user(table, request)
#rqresult['backend'] = args.suffix
write_out_msg(rqresult)
log_back("##### created user #####\n")
def paxos(learner):
state = 'waiting'
hnum = 0
nreceives = 0
client = None
request_q = deque()
current_i = None
while True:
if len(request_q) > 0 and state == 'waiting':
# adds fifo semantics to system
data, sock, addr = request_q.popleft()
else:
data, sock, addr = (yield)
if 'request' in data:
if state != 'waiting':
request_q.append((data, sock, addr))
log_warn('queue contains %s elements' % len(request_q))
continue
# we have been chosen as the proposer
# we need to check with all acceptors
log_verbose('coordinator received request, preparing %s' %
str(data))
client = addr
state = 'preparing'
nreceives = 0
current_i = hnum + 1
prep_msg = json.dumps({
'protocol': 'paxos',
'prepare': data['request'],
'i': hnum + 1
})
bcast(sock, prep_msg)
elif state == 'preparing':
if 'promise' in data and data['i'] == current_i:
nreceives += 1
if nreceives > (len(servers) / 2):
log_verbose('got more than n/2 promises, moving on')
state = 'accepting'
nreceives = 0
accept_msg = json.dumps({
'protocol': 'paxos',
'accept': data['promise'],
'i': hnum
})
bcast(sock, accept_msg)
elif 'nack' in data and data['i'] != current_i:
log_warn('caught (and ignored) old nack: %s\tcurrent i: %s' %
(data['i'], current_i))
elif 'nack' in data and data['i'] == current_i:
log_warn('falling back to waiting state from preparing')
log_fail('nack id: %s\thnum: %s' % (data['i'], hnum))
state = 'waiting'
nreceives = 0
elif state == 'accepting':
if 'accepted' in data and data['i'] == current_i:
nreceives += 1
if nreceives > (len(servers) / 2):
log_verbose('successfully got more than n/2 accepts')
success_msg = json.dumps({
'protocol': 'paxos',
'success': True
})
sock.sendto(success_msg, client)
state = 'waiting'
nreceives = 0
current_i = None
client = None
elif 'nack' in data and data['i'] != current_i:
log_warn('caught (and ignored) old nack: %s\tcurrent i: %s' %
(data['i'], current_i))
elif 'nack' in data and data['i'] == current_i:
log_warn('falling back to waiting state from accepting')
log_fail('possible inconsistency')
log_fail('nack id: %s\thnum: %s' % (data['i'], hnum))
state = 'waiting'
nreceives = 0
if 'prepare' in data:
if data['i'] > hnum:
hnum = data['i']
response = json.dumps({
'protocol': 'paxos',
'promise': data['prepare'],
'i': data['i']
})
else:
log_warn('got prepare for number less than hnum')
response = json.dumps({'protocol': 'paxos', 'nack': data['i']})
sock.sendto(response, addr)
elif 'accept' in data:
if data['i'] == hnum:
learner.send(data['accept'])
response = json.dumps({
'protocol': 'paxos',
'accepted': data['accept'],
'i': hnum
})
else:
log_warn('got accept for number other than hnum')
log_fail('possible inconsistency')
response = json.dumps({'protocol': 'paxos', 'nack': data['i']})
sock.sendto(response, addr)
def paxos(learner):
state = "waiting"
hnum = 0
nreceives = 0
client = None
request_q = deque()
current_i = None
while True:
if len(request_q) > 0 and state == "waiting":
# adds fifo semantics to system
data, sock, addr = request_q.popleft()
else:
data, sock, addr = (yield)
if "request" in data:
if state != "waiting":
request_q.append((data, sock, addr))
log_warn("queue contains %s elements" % len(request_q))
continue
# we have been chosen as the proposer
# we need to check with all acceptors
log_verbose("coordinator received request, preparing %s" % str(data))
client = addr
state = "preparing"
nreceives = 0
current_i = hnum + 1
prep_msg = json.dumps({"protocol": "paxos", "prepare": data["request"], "i": hnum + 1})
bcast(sock, prep_msg)
elif state == "preparing":
if "promise" in data and data["i"] == current_i:
nreceives += 1
if nreceives > (len(servers) / 2):
log_verbose("got more than n/2 promises, moving on")
state = "accepting"
nreceives = 0
accept_msg = json.dumps({"protocol": "paxos", "accept": data["promise"], "i": hnum})
bcast(sock, accept_msg)
elif "nack" in data and data["i"] != current_i:
log_warn("caught (and ignored) old nack: %s\tcurrent i: %s" % (data["i"], current_i))
elif "nack" in data and data["i"] == current_i:
log_warn("falling back to waiting state from preparing")
log_fail("nack id: %s\thnum: %s" % (data["i"], hnum))
state = "waiting"
nreceives = 0
elif state == "accepting":
if "accepted" in data and data["i"] == current_i:
nreceives += 1
if nreceives > (len(servers) / 2):
log_verbose("successfully got more than n/2 accepts")
success_msg = json.dumps({"protocol": "paxos", "success": True})
sock.sendto(success_msg, client)
state = "waiting"
nreceives = 0
current_i = None
client = None
elif "nack" in data and data["i"] != current_i:
log_warn("caught (and ignored) old nack: %s\tcurrent i: %s" % (data["i"], current_i))
elif "nack" in data and data["i"] == current_i:
log_warn("falling back to waiting state from accepting")
log_fail("possible inconsistency")
log_fail("nack id: %s\thnum: %s" % (data["i"], hnum))
state = "waiting"
nreceives = 0
if "prepare" in data:
if data["i"] > hnum:
hnum = data["i"]
response = json.dumps({"protocol": "paxos", "promise": data["prepare"], "i": data["i"]})
else:
log_warn("got prepare for number less than hnum")
response = json.dumps({"protocol": "paxos", "nack": data["i"]})
sock.sendto(response, addr)
elif "accept" in data:
if data["i"] == hnum:
learner.send(data["accept"])
response = json.dumps({"protocol": "paxos", "accepted": data["accept"], "i": hnum})
else:
log_warn("got accept for number other than hnum")
log_fail("possible inconsistency")
response = json.dumps({"protocol": "paxos", "nack": data["i"]})
sock.sendto(response, addr)
