import logging
import MySQLdb
import os
from socket import inet_aton
from time import time
from neo.config import ConfigurationManager
from neo.protocol import Packet, ProtocolError, \
RUNNING_STATE, TEMPORARILY_DOWN_STATE, DOWN_STATE, BROKEN_STATE, \
INVALID_UUID, INVALID_OID, INVALID_TID, INVALID_PTID
from neo.node import NodeManager, MasterNode, StorageNode, ClientNode
from neo.event import EventManager
from neo.util import dump
from neo.connection import ListeningConnection, ClientConnection, ServerConnection
from neo.exception import ElectionFailure, PrimaryFailure
from neo.master.election import ElectionEventHandler
from neo.master.recovery import RecoveryEventHandler
from neo.pt import PartitionTable
class Application(object):
"""The master node application."""
def __init__(self, file, section):
config = ConfigurationManager(file, section)
self.num_replicas = config.getReplicas()
self.num_partitions = config.getPartitions()
self.name = config.getName()
logging.debug('the number of replicas is %d, the number of partitions is %d, the name is %s',
self.num_replicas, self.num_partitions, self.name)
self.server = config.getServer()
logging.debug('IP address is %s, port is %d', *(self.server))
# Exclude itself from the list.
self.master_node_list = [n for n in config.getMasterNodeList() if n != self.server]
logging.debug('master nodes are %s', self.master_node_list)
# Internal attributes.
self.em = EventManager()
self.nm = NodeManager()
self.pt = PartitionTable(self.num_partitions, self.num_replicas)
self.primary = None
self.primary_master_node = None
# XXX Generate an UUID for self. For now, just use a random string.
# Avoid an invalid UUID.
while 1:
uuid = os.urandom(16)
if uuid != INVALID_UUID:
break
self.uuid = uuid
# The last OID.
self.loid = INVALID_OID
# The last TID.
self.ltid = INVALID_TID
# The last Partition Table ID.
self.lptid = INVALID_PTID
# The target node's uuid to request next.
self.target_uuid = None
def run(self):
"""Make sure that the status is sane and start a loop."""
if self.num_replicas <= 0:
raise RuntimeError, 'replicas must be more than zero'
if self.num_partitions <= 0:
raise RuntimeError, 'partitions must be more than zero'
if len(self.name) == 0:
raise RuntimeError, 'cluster name must be non-empty'
for server in self.master_node_list:
self.nm.add(MasterNode(server = server))
# Make a listening port.
ListeningConnection(self.em, None, addr = self.server)
# Start the election of a primary master node.
self.electPrimary()
# Start a normal operation.
while 1:
try:
if self.primary:
self.playPrimaryRole()
else:
self.playSecondaryRole()
raise RuntimeError, 'should not reach here'
except (ElectionFailure, PrimaryFailure):
# Forget all connections.
for conn in self.em.getConnectionList():
if not isinstance(conn, ListeningConnection):
conn.close()
# Reelect a new primary master.
self.electPrimary(bootstrap = False)
def electPrimary(self, bootstrap = True):
"""Elect a primary master node.
The difficulty is that a master node must accept connections from
others while attempting to connect to other master nodes at the
same time. Note that storage nodes and client nodes may connect
to self as well as master nodes."""
logging.info('begin the election of a primary master')
self.unconnected_master_node_set = set()
self.negotiating_master_node_set = set()
handler = ElectionEventHandler(self)
em = self.em
nm = self.nm
# Make sure that every connection has the election event handler.
for conn in em.getConnectionList():
conn.setHandler(handler)
while 1:
t = 0
self.primary = None
self.primary_master_node = None
for node in nm.getMasterNodeList():
self.unconnected_master_node_set.add(node.getServer())
# For now, believe that every node should be available,
# since down or broken nodes may be already repaired.
node.setState(RUNNING_STATE)
self.negotiating_master_node_set.clear()
try:
while 1:
em.poll(1)
current_time = time()
if current_time >= t + 1:
t = current_time
# Expire temporarily down nodes. For now, assume that a node
# which is down for 60 seconds is really down, if this is a
# bootstrap. 60 seconds may sound too long, but this is reasonable
# when rebooting many cluster machines. Otherwise, wait for only
# 10 seconds, because stopping the whole cluster for a long time
# is a bad idea.
if bootstrap:
expiration = 60
else:
expiration = 10
for node in nm.getMasterNodeList():
if node.getState() == TEMPORARILY_DOWN_STATE \
and node.getLastStateChange() + expiration < current_time:
logging.info('%s:%d is down' % node.getServer())
node.setState(DOWN_STATE)
self.unconnected_master_node_set.discard(node.getServer())
# Try to connect to master nodes.
if self.unconnected_master_node_set:
for addr in list(self.unconnected_master_node_set):
ClientConnection(em, handler, addr = addr)
if len(self.unconnected_master_node_set) == 0 \
and len(self.negotiating_master_node_set) == 0:
break
# Now there are three situations:
# - I am the primary master
# - I am secondary but don't know who is primary
# - I am secondary and know who is primary
if self.primary is None:
# I am the primary.
self.primary = True
logging.info('I am the primary, so sending an announcement')
for conn in em.getConnectionList():
if isinstance(conn, ClientConnection):
p = Packet().announcePrimaryMaster(conn.getNextId())
conn.addPacket(p)
conn.abort()
closed = False
t = time()
while not closed:
em.poll(1)
closed = True
for conn in em.getConnectionList():
if isinstance(conn, ClientConnection):
closed = False
break
if t + 10 < time():
for conn in em.getConnectionList():
if isinstance(conn, ClientConnection):
conn.close()
closed = True
else:
# Wait for an announcement. If this is too long, probably
# the primary master is down.
t = time()
while self.primary_master_node is None:
em.poll(1)
if t + 10 < time():
raise ElectionFailure, 'no primary master elected'
# Now I need only a connection to the primary master node.
primary = self.primary_master_node
addr = primary.getServer()
for conn in em.getConnectionList():
if isinstance(conn, ServerConnection) \
or isinstance(conn, ClientConnection) \
and addr != conn.getAddress():
conn.close()
# But if there is no such connection, something wrong happened.
for conn in em.getConnectionList():
if isinstance(conn, ClientConnection) \
and addr == conn.getAddress():
break
else:
raise ElectionFailure, 'no connection remains to the primary'
return
except ElectionFailure, m:
logging.error('election failed; %s' % m)
# Ask all connected nodes to reelect a single primary master.
for conn in em.getConnectionList():
if isinstance(conn, ClientConnection):
conn.addPacket(Packet().reelectPrimaryMaster(conn.getNextId()))
conn.abort()
# Wait until the connections are closed.
self.primary = None
self.primary_master_node = None
closed = False
t = time()
while not closed:
try:
em.poll(1)
except ElectionFailure:
pass
closed = True
for conn in em.getConnectionList():
if isinstance(conn, ClientConnection):
# Still not closed.
closed = Falsed
break
if time() > t + 10:
# If too long, do not wait.
break
# Close all connections.
for conn in em.getConnectionList():
if not isinstance(conn, ListeningConnection):
conn.close()
bootstrap = False
def broadcastNodeInformation(self, node):
"""Broadcast a Notify Node Information packet."""
node_type = node.getNodeType()
state = node.getState()
uuid = node.getUUID()
ip_address, port = node.getServer()
if ip_address is None:
ip_address = '0.0.0.0'
if port is None:
port = 0
if node_type == CLIENT_NODE_TYPE:
# Only to master nodes and storage nodes.
for c in em.getConnectionList():
if c.getUUID() is not None:
n = nm.getNodeByUUID(c.getUUID())
if isinstance(n, (MasterNode, StorageNode)):
p = Packet()
node_list = (node_type, ip_address, port, uuid, state)
p.notifyNodeStateChange(c.getNextId(), node_list)
c.addPacket(p)
elif isinstance(node, (MasterNode, StorageNode)):
for c in em.getConnectionList():
if c.getUUID() is not None:
p = Packet()
node_list = (node_type, ip_address, port, uuid, state)
p.notifyNodeStateChange(c.getNextId(), node_list)
c.addPacket(p)
else:
raise Runtime, 'unknown node type'
def recoverStatus(self):
logging.info('begin the recovery of the status')
handler = RecoveryEventHandler(self)
em = self.em
nm = self.nm
# Make sure that every connection has the status recovery event handler.
for conn in em.getConnectionList():
conn.setHandler(handler)
prev_lptid = None
self.loid = INVALID_OID
self.ltid = INVALID_TID
self.lptid = None
while 1:
self.target_uuid = None
self.pt.clear()
if self.lptid is not None:
# I need to retrieve last ids again.
logging.debug('resending Ask Last IDs')
for conn in em.getConnectionList():
uuid = conn.getUUID()
if uuid is not None:
node = nm.getNodeByUUID(uuid)
if isinstance(node, StorageNode) \
and node.getState() == RUNNING_STATE:
p = Packet()
msg_id = conn.getNextId()
p.askLastIDs(msg_id)
conn.addPacket(p)
conn.expectMessage(msg_id)
# Wait for at least one storage node to appear.
while self.target_uuid is None:
em.poll(1)
# Wait a bit.
t = time()
while time() < t + 5:
em.poll(1)
# Now I have at least one to ask.
prev_lptid = self.lptid
node = nm.getNodeByUUID(uuid)
if node.getState() != RUNNING_STATE:
# Weird. It's dead.
logging.info('the target storage node is dead')
continue
for conn in em.getConnectionList():
if conn.getUUID() == self.lptid:
break
else:
# Why?
logging.info('no connection to the target storage node')
continue
if self.lptid == INVALID_PTID:
# This looks like the first time. So make a fresh table.
logging.debug('creating a new partition table')
self.pt.make(nm.getStorageNodeList())
else:
# Obtain a partition table. It is necessary to split this message
# because the packet size can be huge.
logging.debug('asking a partition table to %s:%d', *(node.getServer()))
start = 0
size = self.num_partitions
while size:
len = min(1000, size)
msg_id = conn.getNextId()
p = Packet()
p.askPartitionTable(msg_id, range(start, start + len))
conn.addPacket(p)
conn.expectMessage(msg_id)
size -= len
start += len
t = time()
while 1:
em.poll(1)
if node.getState() != RUNNING_STATE:
# Dead.
break
if self.pt.filled() or t + 30 < time():
break
if self.lptid != prev_lptid or not self.pt.filled():
# I got something newer or the target is dead.
continue
# Wait until the cluster gets operational or the Partition Table ID
# turns out to be not the latest.
logging.debug('waiting for the cluster to be operational')
while 1:
em.poll(1)
if self.pt.operational():
break
if self.lptid != prev_lptid:
break
if self.lptid != prev_lptid:
# I got something newer.
continue
break
def playPrimaryRole(self):
logging.info('play the primary role')
self.recoverStatus()
raise NotImplementedError
def playSecondaryRole(self):
logging.info('play the secondary role')
raise NotImplementedError