39e7fef87b
It can be quite useful to allow the lock that the pool uses to be specified to be something other than the default threading lock class/type. This can be especially useful when eventlet (or gevent or other) are used which have there own special lock type that connects into there event-loop.
115 lines
3.6 KiB
Python
115 lines
3.6 KiB
Python
# Copyright 2015 Yahoo.com
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import collections
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import contextlib
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import sys
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import threading
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import six
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class ObjectPool(object):
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"""A pool of objects that release/creates/destroys as needed."""
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def __init__(self, obj_creator,
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after_remove=None, max_size=None,
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lock_generator=None):
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self._used_objs = collections.deque()
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self._free_objs = collections.deque()
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self._obj_creator = obj_creator
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if lock_generator is None:
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self._lock = threading.Lock()
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else:
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self._lock = lock_generator()
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self._after_remove = after_remove
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max_size = max_size or 2 ** 31
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if not isinstance(max_size, six.integer_types) or max_size < 0:
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raise ValueError('"max_size" must be a positive integer')
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self.max_size = max_size
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@property
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def used(self):
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return tuple(self._used_objs)
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@property
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def free(self):
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return tuple(self._free_objs)
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@contextlib.contextmanager
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def get_and_release(self, destroy_on_fail=False):
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obj = self.get()
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try:
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yield obj
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except Exception:
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exc_info = sys.exc_info()
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if not destroy_on_fail:
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self.release(obj)
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else:
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self.destroy(obj)
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six.reraise(exc_info[0], exc_info[1], exc_info[2])
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self.release(obj)
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def get(self):
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with self._lock:
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if not self._free_objs:
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curr_count = len(self._used_objs)
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if curr_count >= self.max_size:
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raise RuntimeError("Too many objects,"
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" %s >= %s" % (curr_count,
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self.max_size))
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obj = self._obj_creator()
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self._used_objs.append(obj)
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return obj
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else:
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obj = self._free_objs.pop()
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self._used_objs.append(obj)
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return obj
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def destroy(self, obj, silent=True):
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was_dropped = False
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with self._lock:
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try:
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self._used_objs.remove(obj)
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was_dropped = True
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except ValueError:
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if not silent:
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raise
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if was_dropped and self._after_remove is not None:
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self._after_remove(obj)
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def release(self, obj, silent=True):
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with self._lock:
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try:
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self._used_objs.remove(obj)
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self._free_objs.append(obj)
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except ValueError:
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if not silent:
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raise
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def clear(self):
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if self._after_remove is not None:
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needs_destroy = []
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with self._lock:
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needs_destroy.extend(self._used_objs)
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needs_destroy.extend(self._free_objs)
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self._free_objs.clear()
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self._used_objs.clear()
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for obj in needs_destroy:
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self._after_remove(obj)
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else:
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with self._lock:
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self._free_objs.clear()
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self._used_objs.clear()
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