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https://issues.apache.org/jira/browse/BEAM-8537?focusedWorklogId=371301&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-371301
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ASF GitHub Bot logged work on BEAM-8537:
----------------------------------------
Author: ASF GitHub Bot
Created on: 14/Jan/20 02:37
Start Date: 14/Jan/20 02:37
Worklog Time Spent: 10m
Work Description: boyuanzz commented on pull request #10375: [BEAM-8537]
Provide WatermarkEstimator to track watermark
URL: https://github.com/apache/beam/pull/10375#discussion_r366128556
##########
File path: sdks/python/apache_beam/io/watermark_estimators.py
##########
@@ -0,0 +1,101 @@
+#
+# 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 collection of WatermarkEstimator implementations that SplittableDoFns
+can use."""
+
+from __future__ import absolute_import
+
+from apache_beam.io.iobase import WatermarkEstimator
+from apache_beam.utils.timestamp import Timestamp
+
+
+class MonotonicWatermarkEstimator(WatermarkEstimator):
+ """A WatermarkEstimator which assumes that timestamps of all ouput records
+ are increasing monotonically.
+ """
+ def __init__(self, timestamp):
+ """For a new tracking <element, restriction> pair, the initial value
+ should be None. When resuming from residual, the initial timestamp should
+ be the same timestamp as the estimated watermark from primary.
+ """
+ self._watermark = timestamp
+
+ def observe_timestamp(self, timestamp):
+ if self._watermark is None:
+ self._watermark = timestamp
+ else:
+ if timestamp < self._watermark:
+ raise ValueError('A MonotonicWatermarkEstimator expects output '
+ 'timestamp to be increasing monotonically.')
Review comment:
The `MonotonicWatermarkEstimator.observe_timestamp()` expects the timestamp
of output_record. For me, conceptually it's a timestamp.
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Issue Time Tracking
-------------------
Worklog Id: (was: 371301)
Time Spent: 5h 10m (was: 5h)
> Provide WatermarkEstimatorProvider for different types of WatermarkEstimator
> ----------------------------------------------------------------------------
>
> Key: BEAM-8537
> URL: https://issues.apache.org/jira/browse/BEAM-8537
> Project: Beam
> Issue Type: Improvement
> Components: sdk-py-core, sdk-py-harness
> Reporter: Boyuan Zhang
> Assignee: Boyuan Zhang
> Priority: Major
> Time Spent: 5h 10m
> Remaining Estimate: 0h
>
> This is a follow up for in-progress PR:
> https://github.com/apache/beam/pull/9794.
> Current implementation in PR9794 provides a default implementation of
> WatermarkEstimator. For further work, we want to let WatermarkEstimator to be
> a pure Interface. We'll provide a WatermarkEstimatorProvider to be able to
> create a custom WatermarkEstimator per windowed value. It should be similar
> to how we track restriction for SDF:
> WatermarkEstimator <---> RestrictionTracker
> WatermarkEstimatorProvider <---> RestrictionTrackerProvider
> WatermarkEstimatorParam <---> RestrictionDoFnParam
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