[
https://issues.apache.org/jira/browse/BEAM-5428?focusedWorklogId=306402&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-306402
]
ASF GitHub Bot logged work on BEAM-5428:
----------------------------------------
Author: ASF GitHub Bot
Created on: 04/Sep/19 16:07
Start Date: 04/Sep/19 16:07
Worklog Time Spent: 10m
Work Description: mxm commented on pull request #9418: [BEAM-5428]
Implement cross-bundle user state caching in the Python SDK
URL: https://github.com/apache/beam/pull/9418#discussion_r320846304
##########
File path: sdks/python/apache_beam/runners/worker/statecache.py
##########
@@ -0,0 +1,105 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements. See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You 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.
+#
+
+"""A module for caching state reads/writes in Beam applications."""
+from __future__ import absolute_import
+
+import collections
+from threading import Lock
+
+
+class StateCache(object):
+ """ Cache for Beam state access, scoped by state key and cache_token.
+
+ For a given state_key, caches a (cache_token, value) tuple and allows to
+ a) read from the cache,
+ if the currently stored cache_token matches the provided
+ a) write to the cache,
+ storing the new value alongside with a cache token
+ c) append to the cache cache,
+ if the currently stored cache_token matches the provided
+
+ The operations on the cache are thread-safe for use by multiple workers.
+ """
+
+ def __init__(self, max_entries):
+ self._cache = self.LRUCache(max_entries, (None, None))
+ self._lock = Lock()
+
+ def get(self, state_key, cache_token):
+ assert cache_token and self.is_cache_enabled()
+ with self._lock:
+ token, value = self._cache.get(state_key)
+ return value if token == cache_token else None
+
+ def put(self, state_key, cache_token, value):
+ assert cache_token and self.is_cache_enabled()
+ with self._lock:
+ return self._cache.put(state_key, (cache_token, value))
+
+ def append(self, state_key, cache_token, elements):
+ assert cache_token and self.is_cache_enabled()
+ with self._lock:
+ token, value = self._cache.get(state_key)
+ if token != cache_token:
+ # Discard cached state if tokens do not match
+ value = []
Review comment:
Good catch. Have change it to expunge the cache in this case.
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Issue Time Tracking
-------------------
Worklog Id: (was: 306402)
Time Spent: 15h 20m (was: 15h 10m)
> Implement cross-bundle state caching.
> -------------------------------------
>
> Key: BEAM-5428
> URL: https://issues.apache.org/jira/browse/BEAM-5428
> Project: Beam
> Issue Type: Improvement
> Components: sdk-py-harness
> Reporter: Robert Bradshaw
> Assignee: Rakesh Kumar
> Priority: Major
> Time Spent: 15h 20m
> Remaining Estimate: 0h
>
> Tech spec:
> [https://docs.google.com/document/d/1BOozW0bzBuz4oHJEuZNDOHdzaV5Y56ix58Ozrqm2jFg/edit#heading=h.7ghoih5aig5m]
> Relevant document:
> [https://docs.google.com/document/d/1ltVqIW0XxUXI6grp17TgeyIybk3-nDF8a0-Nqw-s9mY/edit#|https://docs.google.com/document/d/1ltVqIW0XxUXI6grp17TgeyIybk3-nDF8a0-Nqw-s9mY/edit]
> Mailing list link:
> [https://lists.apache.org/thread.html/caa8d9bc6ca871d13de2c5e6ba07fdc76f85d26497d95d90893aa1f6@%3Cdev.beam.apache.org%3E]
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