123 lines
4.9 KiB
Python
123 lines
4.9 KiB
Python
#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import uuid
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from oslo.config import cfg
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from heat.common import exception
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from heat.db import api as db_api
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from heat.openstack.common.gettextutils import _
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from heat.openstack.common import log as logging
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from heat.openstack.common.rpc import common as rpc_common
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from heat.openstack.common.rpc import proxy
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cfg.CONF.import_opt('engine_life_check_timeout', 'heat.common.config')
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logger = logging.getLogger(__name__)
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class StackLock(object):
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def __init__(self, context, stack, engine_id):
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self.context = context
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self.stack = stack
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self.engine_id = engine_id
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self.listener = None
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@staticmethod
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def engine_alive(context, engine_id):
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topic = engine_id
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rpc = proxy.RpcProxy(topic, "1.0")
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msg = rpc.make_msg("listening")
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try:
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return rpc.call(context, msg, topic=topic,
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timeout=cfg.CONF.engine_life_check_timeout)
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except rpc_common.Timeout:
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return False
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@staticmethod
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def generate_engine_id():
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return str(uuid.uuid4())
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def try_acquire(self):
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"""
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Try to acquire a stack lock, but don't raise an ActionInProgress
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exception or try to steal lock.
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"""
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return db_api.stack_lock_create(self.stack.id, self.engine_id)
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def acquire(self, retry=True):
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"""
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Acquire a lock on the stack.
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:param retry: When True, retry if lock was released while stealing.
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:type retry: boolean
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"""
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lock_engine_id = db_api.stack_lock_create(self.stack.id,
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self.engine_id)
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if lock_engine_id is None:
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logger.debug(_("Engine %(engine)s acquired lock on stack "
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"%(stack)s") % {'engine': self.engine_id,
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'stack': self.stack.id})
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return
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if lock_engine_id == self.engine_id or \
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self.engine_alive(self.context, lock_engine_id):
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logger.debug(_("Lock on stack %(stack)s is owned by engine "
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"%(engine)s") % {'stack': self.stack.id,
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'engine': lock_engine_id})
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raise exception.ActionInProgress(stack_name=self.stack.name,
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action=self.stack.action)
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else:
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logger.info(_("Stale lock detected on stack %(stack)s. Engine "
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"%(engine)s will attempt to steal the lock")
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% {'stack': self.stack.id, 'engine': self.engine_id})
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result = db_api.stack_lock_steal(self.stack.id, lock_engine_id,
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self.engine_id)
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if result is None:
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logger.info(_("Engine %(engine)s successfully stole the lock "
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"on stack %(stack)s")
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% {'engine': self.engine_id,
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'stack': self.stack.id})
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return
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elif result is True:
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if retry:
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logger.info(_("The lock on stack %(stack)s was released "
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"while engine %(engine)s was stealing it. "
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"Trying again") % {'stack': self.stack.id,
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'engine': self.engine_id})
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return self.acquire(retry=False)
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else:
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new_lock_engine_id = result
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logger.info(_("Failed to steal lock on stack %(stack)s. "
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"Engine %(engine)s stole the lock first")
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% {'stack': self.stack.id,
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'engine': new_lock_engine_id})
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raise exception.ActionInProgress(
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stack_name=self.stack.name, action=self.stack.action)
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def release(self, stack_id):
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"""Release a stack lock."""
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# Only the engine that owns the lock will be releasing it.
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result = db_api.stack_lock_release(stack_id, self.engine_id)
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if result is True:
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logger.warning(_("Lock was already released on stack %s!")
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% stack_id)
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else:
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logger.debug(_("Engine %(engine)s released lock on stack "
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"%(stack)s") % {'engine': self.engine_id,
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'stack': stack_id})
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