140 lines
4.5 KiB
Python
140 lines
4.5 KiB
Python
# Copyright 2013 Red Hat, Inc.
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#
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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 abc
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import collections
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import threading
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from oslo_log import log as logging
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from oslo_utils import timeutils
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from oslo_messaging._drivers import common
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LOG = logging.getLogger(__name__)
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class Pool(object, metaclass=abc.ABCMeta):
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"""A thread-safe object pool.
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Modelled after the eventlet.pools.Pool interface, but designed to be safe
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when using native threads without the GIL.
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Resizing is not supported.
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"""
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def __init__(self, max_size=4, min_size=2, ttl=1200, on_expire=None):
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super(Pool, self).__init__()
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self._min_size = min_size
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self._max_size = max_size
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self._item_ttl = ttl
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self._current_size = 0
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self._cond = threading.Condition()
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self._items = collections.deque()
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self._on_expire = on_expire
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def expire(self):
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"""Remove expired items from left (the oldest item) to
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right (the newest item).
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"""
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with self._cond:
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while len(self._items) > self._min_size:
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try:
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ttl_watch, item = self._items.popleft()
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if ttl_watch.expired():
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self._on_expire and self._on_expire(item)
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self._current_size -= 1
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else:
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self._items.appendleft((ttl_watch, item))
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return
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except IndexError:
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break
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def put(self, item):
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"""Return an item to the pool."""
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with self._cond:
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ttl_watch = timeutils.StopWatch(duration=self._item_ttl)
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ttl_watch.start()
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self._items.append((ttl_watch, item))
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self._cond.notify()
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def get(self, retry=None):
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"""Return an item from the pool, when one is available.
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This may cause the calling thread to block.
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"""
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with self._cond:
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while True:
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try:
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ttl_watch, item = self._items.pop()
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self.expire()
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return item
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except IndexError:
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pass
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if self._current_size < self._max_size:
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self._current_size += 1
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break
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LOG.warning("Connection pool limit exceeded: "
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"current size %s surpasses max "
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"configured rpc_conn_pool_size %s",
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self._current_size, self._max_size)
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self._cond.wait()
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# We've grabbed a slot and dropped the lock, now do the creation
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try:
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return self.create(retry=retry)
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except Exception:
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with self._cond:
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self._current_size -= 1
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raise
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def iter_free(self):
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"""Iterate over free items."""
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while True:
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try:
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_, item = self._items.pop()
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yield item
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except IndexError:
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return
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@abc.abstractmethod
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def create(self, retry=None):
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"""Construct a new item."""
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class ConnectionPool(Pool):
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"""Class that implements a Pool of Connections."""
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def __init__(self, conf, max_size, min_size, ttl, url, connection_cls):
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self.connection_cls = connection_cls
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self.conf = conf
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self.url = url
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super(ConnectionPool, self).__init__(max_size, min_size, ttl,
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self._on_expire)
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def _on_expire(self, connection):
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connection.close()
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LOG.debug("Idle connection has expired and been closed."
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" Pool size: %d" % len(self._items))
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def create(self, purpose=common.PURPOSE_SEND, retry=None):
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LOG.debug('Pool creating new connection')
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return self.connection_cls(self.conf, self.url, purpose, retry=retry)
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def empty(self):
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for item in self.iter_free():
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item.close()
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