[
https://issues.apache.org/jira/browse/BEAM-5427?focusedWorklogId=145837&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-145837
]
ASF GitHub Bot logged work on BEAM-5427:
----------------------------------------
Author: ASF GitHub Bot
Created on: 19/Sep/18 22:16
Start Date: 19/Sep/18 22:16
Worklog Time Spent: 10m
Work Description: HuangLED closed pull request #6432: [BEAM-5427] Fix and
update AverageFn sample code.
URL: https://github.com/apache/beam/pull/6432
This is a PR merged from a forked repository.
As GitHub hides the original diff on merge, it is displayed below for
the sake of provenance:
As this is a foreign pull request (from a fork), the diff is supplied
below (as it won't show otherwise due to GitHub magic):
diff --git
a/sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Combine.java
b/sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Combine.java
index 2c65f94d09a..f9d68adfe95 100644
--- a/sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Combine.java
+++ b/sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Combine.java
@@ -254,10 +254,26 @@ private Combine() {
*
* <pre>{@code
* public class AverageFn extends CombineFn<Integer, AverageFn.Accum,
Double> {
- * public static class Accum {
+ * public static class Accum implements java.io.Serializable {
* int sum = 0;
* int count = 0;
+ *
+ * @Override
+ * public boolean equals(Object other) {
+ * if (other == null) return false;
+ * if (other == this) return true;
+ * if (!(other instanceof Accum))return false;
+ *
+ *
+ * Accum o = (Accum)other;
+ * if (this.sum != o.sum || this.count != o.count) {
+ * return false;
+ * } else {
+ * return true;
+ * }
+ * }
* }
+ *
* public Accum createAccumulator() {
* return new Accum();
* }
@@ -289,6 +305,22 @@ private Combine() {
* arbitrary tree structure. Commutativity is required because any order of
the input values is
* ignored when breaking up input values into groups.
*
+ * <h3>Note on Data Encoding</h3>
+ *
+ * <p>Data encoding is required to make CombineFn work.
+ * The sample code above implements {@code java.io.Serializable} so that
CombineFn in
+ * consequence makes use of SerializableCoder to encode the data.
+ * In many cases though, relying on Serializable could be
+ * less preferred for efficiency considerations. In addition, Serializable
may not be applicable
+ * in all situations. There are two alternatives to make data encoding work
for AverageFn:
+ *
+ * <ul>
+ * <li> Generic Coder class. Implement an encoder class explicitly and use
{@code @DefaultCoder} tag.
+ * <li> {@link CombineFn} Specific way. While extending {@link CombineFn},
overwrite
+ * both {@link #getAccumulatorCoder}
+ * and {@link #getDefaultOutputCoder}.
+ * </ul>
+ *
* @param <InputT> type of input values
* @param <AccumT> type of mutable accumulator values
* @param <OutputT> type of output values
diff --git a/website/src/contribute/index.md b/website/src/contribute/index.md
index eb38ccce7dd..fd8db873d83 100644
--- a/website/src/contribute/index.md
+++ b/website/src/contribute/index.md
@@ -66,7 +66,7 @@ Coding happens at
[https://github.com/apache/beam](https://github.com/apache/beam). To
contribute, follow the usual GitHub process: fork the repo, make your changes,
and open a pull request and @mention a reviewer. If you have more than one
commit
-in your change, you many be asked to rebase and squash the commits.
+in your change, you may be asked to rebase and squash the commits.
If you are unfamiliar with this workflow, GitHub maintains these helpful
guides:
- [Git Handbook](https://guides.github.com/introduction/git-handbook/)
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Issue Time Tracking
-------------------
Worklog Id: (was: 145837)
Time Spent: 10m
Remaining Estimate: 0h
> Fix sample code (AverageFn) in Combine.java
> -------------------------------------------
>
> Key: BEAM-5427
> URL: https://issues.apache.org/jira/browse/BEAM-5427
> Project: Beam
> Issue Type: Improvement
> Components: examples-java
> Reporter: Ruoyun Huang
> Assignee: Reuven Lax
> Priority: Minor
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Sample code missing coder.
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