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https://issues.apache.org/jira/browse/BEAM-9650?focusedWorklogId=417952&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-417952
]
ASF GitHub Bot logged work on BEAM-9650:
----------------------------------------
Author: ASF GitHub Bot
Created on: 07/Apr/20 20:27
Start Date: 07/Apr/20 20:27
Worklog Time Spent: 10m
Work Description: pabloem commented on pull request #11182: [BEAM-9650]
Add PeriodicImpulse Transform and slowly changing side input documentation
URL: https://github.com/apache/beam/pull/11182#discussion_r405088559
##########
File path: sdks/python/apache_beam/transforms/periodicsequence.py
##########
@@ -0,0 +1,165 @@
+#
+# 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.
+#
+
+from __future__ import absolute_import
+
+import time
+
+import apache_beam as beam
+import apache_beam.runners.sdf_utils as sdf_utils
+from apache_beam.io.restriction_trackers import OffsetRange
+from apache_beam.io.restriction_trackers import OffsetRestrictionTracker
+from apache_beam.transforms import core
+from apache_beam.transforms import window
+from apache_beam.transforms.ptransform import PTransform
+from apache_beam.transforms.window import TimestampedValue
+from apache_beam.utils import timestamp
+from apache_beam.utils.timestamp import MAX_TIMESTAMP
+from apache_beam.utils.timestamp import Timestamp
+
+
+class ImpulseSeqGenRestrictionProvider(core.RestrictionProvider):
+ def initial_restriction(self, element):
+ start, end, interval = element
+ return OffsetRange(start - interval, end)
+
+ def create_tracker(self, restriction):
+ return ImpulseSeqGenRestrictionTracker(restriction)
+
+ def restriction_size(self, unused_element, restriction):
+ return restriction.size()
+
+
+class ImpulseSeqGenRestrictionTracker(OffsetRestrictionTracker):
+ def try_split(self, fraction_of_remainder):
+ if not self._checkpointed:
+ if fraction_of_remainder != 0:
+ return None
+
+ if self._current_position is None:
+ cur = self._range.start
+ else:
+ cur = self._current_position
+ split_point = cur
+
+ if split_point < self._range.stop:
+ self._checkpointed = True
+ self._range, residual_range = self._range.split_at(split_point)
+ return self._range, residual_range
+
+ def cur_pos(self):
+ return self._current_position
+
+ def try_claim(self, pos):
+ if ((self._last_claim_attempt is None) or
+ (pos > self._last_claim_attempt and pos == self._range.stop)):
+ self._last_claim_attempt = pos
+ return True
+ else:
+ return super(ImpulseSeqGenRestrictionTracker, self).try_claim(pos)
+
+
+class ImpulseSeqGenDoFn(beam.DoFn):
+ def process(
+ self,
+ element,
+ restriction_tracker=beam.DoFn.RestrictionParam(
+ ImpulseSeqGenRestrictionProvider())):
+ '''
+ PeriodicSequence transform receives tuple elements with three parts:
+
+ * first_timestamp = first timestamp to output element for.
+ * last_timestamp = last timestamp/time to output element for.
+ * fire_interval = how often to fire an element.
+
+ For each input element received, PeriodicSequence transform will start
+ generating output elements in following pattern:
+
+ * if element timestamp is less than current runtime then output element.
+ * if element timestamp is greater than current runtime, wait until next
+ element timestamp.
+
+ PeriodicSequence can't guarantee that each element is output at exact time.
+ PeriodicSequence guarantees that elements would not be output prior to
given
+ runtime timestamp.
+
+ :param element: (start_timestamp, end_timestamp, interval)
+ :param restriction_tracker:
+ :return: yields elements at processing real-time intervals with value of
+ target output timestamp for the element.
+ '''
+ _, _, interval = element
+
+ assert isinstance(restriction_tracker, sdf_utils.RestrictionTrackerView)
+
+ t = time.time()
+ cr = restriction_tracker.current_restriction()
+ current_timestamp = cr.start
+
+ restriction_tracker.try_claim(current_timestamp)
+ if current_timestamp <= t:
+ if restriction_tracker.try_claim(current_timestamp + interval):
+ current_timestamp += interval
+ yield current_timestamp
+
+ if current_timestamp + interval >= cr.stop:
+ restriction_tracker.try_claim(cr.stop)
+ else:
+ restriction_tracker.defer_remainder(
+ timestamp.Timestamp(current_timestamp))
+
+
+class PeriodicSequence(PTransform):
+ """
+ See ImpulseSeqGenDoFn.
+ """
+ def __init_(self):
+ pass
+
+ def expand(self, pbegin):
+ return (
+ pbegin
Review comment:
Renaming to pcoll, as the input is an actual Pcollection, right?
```suggestion
def expand(self, pcoll):
return (
pcoll
```
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Issue Time Tracking
-------------------
Worklog Id: (was: 417952)
Time Spent: 1.5h (was: 1h 20m)
> Add consistent slowly changing side inputs support
> --------------------------------------------------
>
> Key: BEAM-9650
> URL: https://issues.apache.org/jira/browse/BEAM-9650
> Project: Beam
> Issue Type: Bug
> Components: io-ideas
> Reporter: Mikhail Gryzykhin
> Assignee: Mikhail Gryzykhin
> Priority: Major
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> Add implementation for slowly changing dimentions based on [design
> doc](https://docs.google.com/document/d/1LDY_CtsOJ8Y_zNv1QtkP6AGFrtzkj1q5EW_gSChOIvg/edit]
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