zuul/zk.py - github/openstack-infra/zuul - Gitiles

 #!/usr/bin/env python
 #
 # Licensed under the Apache License, Version 2.0 (the "License"); you may
 # not use this file except in compliance with the License. You may obtain
 # a copy of the License at
 #
 #      http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations
 # under the License.

 import json
 import logging
 import time
 from kazoo.client import KazooClient, KazooState
 from kazoo import exceptions as kze
 from kazoo.recipe.lock import Lock

 # States:
 # We are building this node but it is not ready for use.
 BUILDING = 'building'
 # The node is ready for use.
 READY = 'ready'
 # The node should be deleted.
 DELETING = 'deleting'

 STATES = set([BUILDING, READY, DELETING])


 class LockException(Exception):
     pass


 class ZooKeeperConnectionConfig(object):
     '''
     Represents the connection parameters for a ZooKeeper server.
     '''

     def __eq__(self, other):
         if isinstance(other, ZooKeeperConnectionConfig):
             if other.__dict__ == self.__dict__:
                 return True
         return False

     def __init__(self, host, port=2181, chroot=None):
         '''Initialize the ZooKeeperConnectionConfig object.

         :param str host: The hostname of the ZooKeeper server.
         :param int port: The port on which ZooKeeper is listening.
             Optional, default: 2181.
         :param str chroot: A chroot for this connection.  All
             ZooKeeper nodes will be underneath this root path.
             Optional, default: None.

         (one per server) defining the ZooKeeper cluster servers. Only
         the 'host' attribute is required.'.

         '''
         self.host = host
         self.port = port
         self.chroot = chroot or ''


 class ZooKeeper(object):
     '''
     Class implementing the ZooKeeper interface.

     This class uses the facade design pattern to keep common interaction
     with the ZooKeeper API simple and consistent for the caller, and
     limits coupling between objects. It allows for more complex interactions
     by providing direct access to the client connection when needed (though
     that is discouraged). It also provides for a convenient entry point for
     testing only ZooKeeper interactions.
     '''

     log = logging.getLogger("zuul.zk.ZooKeeper")

     REQUEST_ROOT = '/nodepool/requests'
     NODE_ROOT = '/nodepool/nodes'

     def __init__(self):
         '''
         Initialize the ZooKeeper object.
         '''
         self.client = None
         self._became_lost = False

     def _dictToStr(self, data):
         return json.dumps(data)

     def _strToDict(self, data):
         return json.loads(data)

     def _connection_listener(self, state):
         '''
         Listener method for Kazoo connection state changes.

         .. warning:: This method must not block.
         '''
         if state == KazooState.LOST:
             self.log.debug("ZooKeeper connection: LOST")
             self._became_lost = True
         elif state == KazooState.SUSPENDED:
             self.log.debug("ZooKeeper connection: SUSPENDED")
         else:
             self.log.debug("ZooKeeper connection: CONNECTED")

     @property
     def connected(self):
         return self.client.state == KazooState.CONNECTED

     @property
     def suspended(self):
         return self.client.state == KazooState.SUSPENDED

     @property
     def lost(self):
         return self.client.state == KazooState.LOST

     @property
     def didLoseConnection(self):
         return self._became_lost

     def resetLostFlag(self):
         self._became_lost = False

     def connect(self, host_list, read_only=False):
         '''
         Establish a connection with ZooKeeper cluster.

         Convenience method if a pre-existing ZooKeeper connection is not
         supplied to the ZooKeeper object at instantiation time.

         :param list host_list: A list of
             :py:class:`~nodepool.zk.ZooKeeperConnectionConfig` objects
             (one per server) defining the ZooKeeper cluster servers.
         :param bool read_only: If True, establishes a read-only connection.

         '''
         if self.client is None:
             self.client = KazooClient(hosts=host_list, read_only=read_only)
             self.client.add_listener(self._connection_listener)
             self.client.start()

     def disconnect(self):
         '''
         Close the ZooKeeper cluster connection.

         You should call this method if you used connect() to establish a
         cluster connection.
         '''
         if self.client is not None and self.client.connected:
             self.client.stop()
             self.client.close()
             self.client = None

     def resetHosts(self, host_list):
         '''
         Reset the ZooKeeper cluster connection host list.

         :param list host_list: A list of
             :py:class:`~nodepool.zk.ZooKeeperConnectionConfig` objects
             (one per server) defining the ZooKeeper cluster servers.
         '''
         if self.client is not None:
             self.client.set_hosts(hosts=host_list)

     def submitNodeRequest(self, node_request, watcher):
         '''
         Submit a request for nodes to Nodepool.

         :param NodeRequest node_request: A NodeRequest with the
             contents of the request.

         :param callable watcher: A callable object that will be
             invoked each time the request is updated.  It is called
             with two arguments: (node_request, deleted) where
             node_request is the same argument passed to this method,
             and deleted is a boolean which is True if the node no
             longer exists (notably, this will happen on disconnection
             from ZooKeeper).  The watcher should return False when
             further updates are no longer necessary.
         '''
         priority = 100  # TODO(jeblair): integrate into nodereq

         data = node_request.toDict()
         data['created_time'] = time.time()

         path = '%s/%s-' % (self.REQUEST_ROOT, priority)
         path = self.client.create(path, self._dictToStr(data),
                                   makepath=True,
                                   sequence=True, ephemeral=True)
         reqid = path.split("/")[-1]
         node_request.id = reqid

         def callback(data, stat):
             if data:
                 data = self._strToDict(data)
                 node_request.updateFromDict(data)
                 request_nodes = node_request.nodeset.getNodes()
                 for i, nodeid in enumerate(data.get('nodes', [])):
                     node_path = '%s/%s' % (self.NODE_ROOT, nodeid)
                     node_data, node_stat = self.client.get(node_path)
                     node_data = self._strToDict(node_data)
                     request_nodes[i].id = nodeid
                     request_nodes[i].updateFromDict(node_data)
             deleted = (data is None)  # data *are* none
             return watcher(node_request, deleted)

         self.client.DataWatch(path, callback)

     def deleteNodeRequest(self, node_request):
         '''
         Delete a request for nodes.

         :param NodeRequest node_request: A NodeRequest with the
             contents of the request.
         '''

         path = '%s/%s' % (self.REQUEST_ROOT, node_request.id)
         try:
             self.client.delete(path)
         except kze.NoNodeError:
             pass

     def storeNode(self, node):
         '''Store the node.

         The node is expected to already exist and is updated in its
         entirety.

         :param Node node: The node to update.
         '''

         path = '%s/%s' % (self.NODE_ROOT, node.id)
         self.client.set(path, self._dictToStr(node.toDict()))

     def lockNode(self, node, blocking=True, timeout=None):
         '''
         Lock a node.

         This should be called as soon as a request is fulfilled and
         the lock held for as long as the node is in-use.  It can be
         used by nodepool to detect if Zuul has gone offline and the
         node should be reclaimed.

         :param Node node: The node which should be locked.
         '''

         lock_path = '%s/%s/lock' % (self.NODE_ROOT, node.id)
         try:
             lock = Lock(self.client, lock_path)
             have_lock = lock.acquire(blocking, timeout)
         except kze.LockTimeout:
             raise LockException(
                 "Timeout trying to acquire lock %s" % lock_path)

         # If we aren't blocking, it's possible we didn't get the lock
         # because someone else has it.
         if not have_lock:
             raise LockException("Did not get lock on %s" % lock_path)

         node.lock = lock

     def unlockNode(self, node):
         '''
         Unlock a node.

         The node must already have been locked.

         :param Node node: The node which should be unlocked.
         '''

         if node.lock is None:
             raise LockException("Node %s does not hold a lock" % (node,))
         node.lock.release()
         node.lock = None
	#!/usr/bin/env python
	#
	# Licensed under the Apache License, Version 2.0 (the "License"); you may
	# not use this file except in compliance with the License. You may obtain
	# a copy of the License at
	#
	# http://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
	# License for the specific language governing permissions and limitations
	# under the License.

	import json
	import logging
	import time
	from kazoo.client import KazooClient, KazooState
	from kazoo import exceptions as kze
	from kazoo.recipe.lock import Lock

	# States:
	# We are building this node but it is not ready for use.
	BUILDING = 'building'
	# The node is ready for use.
	READY = 'ready'
	# The node should be deleted.
	DELETING = 'deleting'

	STATES = set([BUILDING, READY, DELETING])


	class LockException(Exception):
	pass


	class ZooKeeperConnectionConfig(object):
	'''
	Represents the connection parameters for a ZooKeeper server.
	'''

	def __eq__(self, other):
	if isinstance(other, ZooKeeperConnectionConfig):
	if other.__dict__ == self.__dict__:
	return True
	return False

	def __init__(self, host, port=2181, chroot=None):
	'''Initialize the ZooKeeperConnectionConfig object.

	:param str host: The hostname of the ZooKeeper server.
	:param int port: The port on which ZooKeeper is listening.
	Optional, default: 2181.
	:param str chroot: A chroot for this connection. All
	ZooKeeper nodes will be underneath this root path.
	Optional, default: None.

	(one per server) defining the ZooKeeper cluster servers. Only
	the 'host' attribute is required.'.

	'''
	self.host = host
	self.port = port
	self.chroot = chroot or ''


	class ZooKeeper(object):
	'''
	Class implementing the ZooKeeper interface.

	This class uses the facade design pattern to keep common interaction
	with the ZooKeeper API simple and consistent for the caller, and
	limits coupling between objects. It allows for more complex interactions
	by providing direct access to the client connection when needed (though
	that is discouraged). It also provides for a convenient entry point for
	testing only ZooKeeper interactions.
	'''

	log = logging.getLogger("zuul.zk.ZooKeeper")

	REQUEST_ROOT = '/nodepool/requests'
	NODE_ROOT = '/nodepool/nodes'

	def __init__(self):
	'''
	Initialize the ZooKeeper object.
	'''
	self.client = None
	self._became_lost = False

	def _dictToStr(self, data):
	return json.dumps(data)

	def _strToDict(self, data):
	return json.loads(data)

	def _connection_listener(self, state):
	'''
	Listener method for Kazoo connection state changes.

	.. warning:: This method must not block.
	'''
	if state == KazooState.LOST:
	self.log.debug("ZooKeeper connection: LOST")
	self._became_lost = True
	elif state == KazooState.SUSPENDED:
	self.log.debug("ZooKeeper connection: SUSPENDED")
	else:
	self.log.debug("ZooKeeper connection: CONNECTED")

	@property
	def connected(self):
	return self.client.state == KazooState.CONNECTED

	@property
	def suspended(self):
	return self.client.state == KazooState.SUSPENDED

	@property
	def lost(self):
	return self.client.state == KazooState.LOST

	@property
	def didLoseConnection(self):
	return self._became_lost

	def resetLostFlag(self):
	self._became_lost = False

	def connect(self, host_list, read_only=False):
	'''
	Establish a connection with ZooKeeper cluster.

	Convenience method if a pre-existing ZooKeeper connection is not
	supplied to the ZooKeeper object at instantiation time.

	:param list host_list: A list of
	:py:class:`~nodepool.zk.ZooKeeperConnectionConfig` objects
	(one per server) defining the ZooKeeper cluster servers.
	:param bool read_only: If True, establishes a read-only connection.

	'''
	if self.client is None:
	self.client = KazooClient(hosts=host_list, read_only=read_only)
	self.client.add_listener(self._connection_listener)
	self.client.start()

	def disconnect(self):
	'''
	Close the ZooKeeper cluster connection.

	You should call this method if you used connect() to establish a
	cluster connection.
	'''
	if self.client is not None and self.client.connected:
	self.client.stop()
	self.client.close()
	self.client = None

	def resetHosts(self, host_list):
	'''
	Reset the ZooKeeper cluster connection host list.

	:param list host_list: A list of
	:py:class:`~nodepool.zk.ZooKeeperConnectionConfig` objects
	(one per server) defining the ZooKeeper cluster servers.
	'''
	if self.client is not None:
	self.client.set_hosts(hosts=host_list)

	def submitNodeRequest(self, node_request, watcher):
	'''
	Submit a request for nodes to Nodepool.

	:param NodeRequest node_request: A NodeRequest with the
	contents of the request.

	:param callable watcher: A callable object that will be
	invoked each time the request is updated. It is called
	with two arguments: (node_request, deleted) where
	node_request is the same argument passed to this method,
	and deleted is a boolean which is True if the node no
	longer exists (notably, this will happen on disconnection
	from ZooKeeper). The watcher should return False when
	further updates are no longer necessary.
	'''
	priority = 100 # TODO(jeblair): integrate into nodereq

	data = node_request.toDict()
	data['created_time'] = time.time()

	path = '%s/%s-' % (self.REQUEST_ROOT, priority)
	path = self.client.create(path, self._dictToStr(data),
	makepath=True,
	sequence=True, ephemeral=True)
	reqid = path.split("/")[-1]
	node_request.id = reqid

	def callback(data, stat):
	if data:
	data = self._strToDict(data)
	node_request.updateFromDict(data)
	request_nodes = node_request.nodeset.getNodes()
	for i, nodeid in enumerate(data.get('nodes', [])):
	node_path = '%s/%s' % (self.NODE_ROOT, nodeid)
	node_data, node_stat = self.client.get(node_path)
	node_data = self._strToDict(node_data)
	request_nodes[i].id = nodeid
	request_nodes[i].updateFromDict(node_data)
	deleted = (data is None) # data are none
	return watcher(node_request, deleted)

	self.client.DataWatch(path, callback)

	def deleteNodeRequest(self, node_request):
	'''
	Delete a request for nodes.

	:param NodeRequest node_request: A NodeRequest with the
	contents of the request.
	'''

	path = '%s/%s' % (self.REQUEST_ROOT, node_request.id)
	try:
	self.client.delete(path)
	except kze.NoNodeError:
	pass

	def storeNode(self, node):
	'''Store the node.

	The node is expected to already exist and is updated in its
	entirety.

	:param Node node: The node to update.
	'''

	path = '%s/%s' % (self.NODE_ROOT, node.id)
	self.client.set(path, self._dictToStr(node.toDict()))

	def lockNode(self, node, blocking=True, timeout=None):
	'''
	Lock a node.

	This should be called as soon as a request is fulfilled and
	the lock held for as long as the node is in-use. It can be
	used by nodepool to detect if Zuul has gone offline and the
	node should be reclaimed.

	:param Node node: The node which should be locked.
	'''

	lock_path = '%s/%s/lock' % (self.NODE_ROOT, node.id)
	try:
	lock = Lock(self.client, lock_path)
	have_lock = lock.acquire(blocking, timeout)
	except kze.LockTimeout:
	raise LockException(
	"Timeout trying to acquire lock %s" % lock_path)

	# If we aren't blocking, it's possible we didn't get the lock
	# because someone else has it.
	if not have_lock:
	raise LockException("Did not get lock on %s" % lock_path)

	node.lock = lock

	def unlockNode(self, node):
	'''
	Unlock a node.

	The node must already have been locked.

	:param Node node: The node which should be unlocked.
	'''

	if node.lock is None:
	raise LockException("Node %s does not hold a lock" % (node,))
	node.lock.release()
	node.lock = None