[
https://issues.apache.org/jira/browse/BEAM-3304?focusedWorklogId=648943&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-648943
]
ASF GitHub Bot logged work on BEAM-3304:
----------------------------------------
Author: ASF GitHub Bot
Created on: 10/Sep/21 00:10
Start Date: 10/Sep/21 00:10
Worklog Time Spent: 10m
Work Description: lostluck commented on a change in pull request #15409:
URL: https://github.com/apache/beam/pull/15409#discussion_r705803299
##########
File path: sdks/go/examples/snippets/09triggers.go
##########
@@ -0,0 +1,88 @@
+// 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.
+
+// Package snippets contains code used in the Beam Programming Guide
+// as examples for the Apache Beam Go SDK. These snippets are compiled
+// and their tests run to ensure correctness. However, due to their
+// piecemeal pedagogical use, they may not be the best example of
+// production code.
+//
+// The Beam Programming Guide can be found at
https://beam.apache.org/documentation/programming-guide/.
+package snippets
+
+import (
+ "time"
+
+ "github.com/apache/beam/sdks/v2/go/pkg/beam"
+ "github.com/apache/beam/sdks/v2/go/pkg/beam/core/graph/window"
+ "github.com/apache/beam/sdks/v2/go/pkg/beam/testing/teststream"
+ "github.com/apache/beam/sdks/v2/go/pkg/beam/transforms/stats"
+)
+
+// TriggerElementCount tests the ElementCount Trigger, it waits for atleast N
elements to be ready
+// to fire an output pane
+func TriggerElementCount(s beam.Scope) beam.PCollection {
+ con := teststream.NewConfig()
+ con.AddElements(1000, 1.0, 2.0, 3.0)
+ con.AdvanceWatermark(2000)
+ con.AddElements(6000, 4.0, 5.0)
+ con.AdvanceWatermark(10000)
+ con.AddElements(52000, 10.0)
+ con.AdvanceWatermark(53000)
+
+ col := teststream.Create(s, con)
+
+ // waits only for two elements to arrive and fires output after that
and never fires that.
+ // For the trigger to fire every 2 elements, combine it with Repeat
Trigger
+ tr := window.Trigger{Kind: window.ElementCountTrigger, ElementCount: 2}
+ windowed := beam.WindowInto(s, window.NewGlobalWindows(), col,
beam.WindowTrigger{Name: tr}, beam.AccumulationMode{Mode: window.Discarding})
+ sums := stats.Sum(s, windowed)
+ return sums
+}
+
+// TriggerAfterProcessingTime tests the AfterProcessingTime Trigger, it fires
output panes once 't' processing time has passed
+// Not yet supported by the flink runner:
+// java.lang.UnsupportedOperationException: Advancing Processing time is not
supported by the Flink Runner.
+func TriggerAfterProcessingTime(s beam.Scope) beam.PCollection {
+ con := teststream.NewConfig()
+ con.AdvanceProcessingTime(100)
+ con.AddElements(1000, 1.0, 2.0, 3.0)
+ con.AdvanceProcessingTime(2000)
+ con.AddElements(22000, 4.0)
+
+ col := teststream.Create(s, con)
Review comment:
Note: unless you'reusing these with the [START foo] [END foo] comments,
there's no reason to duplicate all this code to this file. It's not even
necessary to have a proper test stream input or a fully executable test
pipeline. Either use the code for snippets or delete it.
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Issue Time Tracking
-------------------
Worklog Id: (was: 648943)
Time Spent: 10.5h (was: 10h 20m)
> Go triggering support
> ---------------------
>
> Key: BEAM-3304
> URL: https://issues.apache.org/jira/browse/BEAM-3304
> Project: Beam
> Issue Type: Improvement
> Components: sdk-go
> Reporter: Henning Rohde
> Assignee: Ritesh Ghorse
> Priority: P3
> Time Spent: 10.5h
> Remaining Estimate: 0h
>
> `Add support for triggers.
> [https://beam.apache.org/documentation/programming-guide/#triggers]
> Triggers are special runner side behavior indicating how to handle data WRT
> the watermark and window. Commonly configuring the processing for “late data”
> and similar.
> These are not currently implemented for user use in the Go SDK. Reshuffle
> configures triggers, but it’s not accessible. A correct trigger
> implementation can at least re-implement Reshuffle in a user pipeline, rather
> than handled specially within the framework.
> * Requires extending the window package to be able to configure the various
> triggers.
> * Specifically being able to compose triggers as also permitted by the proto.
> **
> [https://github.com/apache/beam/blob/6e7b1c44bc7275ee047afc059fd610cd3f4e5bee/model/pipeline/src/main/proto/beam_runner_api.proto#L1111]
>
> * Requires updating the graphx package translate.go to marshal (and
> unmarshal?) the triggers to and from Beam PipelineProto Windowing strategies.
> * Requires supporting triggers with the beam.WindowInto transform for user
> pipeline use as well as complete documentation on its use from the user side.
> **
> [https://github.com/apache/beam/blob/6e7b1c44bc7275ee047afc059fd610cd3f4e5bee/sdks/go/pkg/beam/windowing.go]
>
> * Panes need to be decoded, otherwise triggering will cause runtime errors:
> [https://lists.apache.org/thread.html/r94c42d2d116f6464cd6b689543e5e578edf8310bf7c6e48a0958a56c%40%3Cdev.beam.apache.org%3E]
>
> * Handle pane propagation and observation in the exec package, and in user
> dofns.
> ** Panes indicate whether data was on time or not, and similar facets which
> may be relevant for processing.
> ** Might simply extend the existing window interface.
>
> Similar to windowing, many of the same places as
> https://issues.apache.org/jira/browse/BEAM-11100 need to be modified.
> At simplest though, it's mostly a runner side construction, with less concern
> on the exec side, and generally much simpler.
> Appropriate integration tests against portable runners must be implemented:
> [https://github.com/apache/beam/tree/master/sdks/go/test/integration/primitives]
>
> And optionally add support for the configurable triggers to the the Go Direct
> Runner. However, the results must be compared and validated against a
> semantically correct runner like the python portable runner first. At
> minimum, the Go Direct Runner should be made aware of triggers and produce a
> coherent error whenever there's a trigger it can't deal with.
>
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