ca26627ec4
This patch brings together oslo.cache, oslo.config, and stevedore to
provide pluggable, hierarchical catalogue caching for marconi proxy.
Here's the list of changes:
- add configuration/driver loading at the app level
- remove select from proxy storage driver - unnecessary intelligence
at storage layer
- node.weighted_select -> partition.weighted_select (clearer name)
- forwarding logic further refactored, placed in own module
- caching logic placed in lookup module
- selector passed down at app level to handle round-robin state
globally
* open to becoming configurable
- adds several TODOs for a better proxy
Change-Id: I3bc568315e685486d63cdce3ec278c89e3f2b2bc
Implements: blueprint placement-service
46 lines
1.5 KiB
Python
46 lines
1.5 KiB
Python
# Copyright (c) 2013 Rackspace Hosting, Inc.
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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
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# 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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"""partition: utilities for implementing partition selections."""
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import random
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def weighted_select(partitions):
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"""Select a partition from all the partitions passed in.
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:param partitions: gen({'name': ..., 'weight': ..., 'hosts': ...}, ...)
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:return: (name, hosts)
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"""
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acc = 0
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lookup = []
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# TODO(cpp-cabrera): the lookup table can be constructed once each time
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# an entry is added to/removed from the catalogue,
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# rather than each time a queue is created.
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# construct the (partition, weight) lookup table
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for p in partitions:
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acc += p['weight']
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lookup.append((p, acc))
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if not lookup:
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return None
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# select a partition from the lookup table
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selector = random.randint(0, acc - 1)
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last = 0
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for p, w in lookup:
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if last <= selector < w:
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return p
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last = w
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