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https://issues.apache.org/jira/browse/HADOOP-18215?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17689411#comment-17689411
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ASF GitHub Bot commented on HADOOP-18215:
-----------------------------------------
omalley commented on code in PR #4215:
URL: https://github.com/apache/hadoop/pull/4215#discussion_r1107882426
##########
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/WritableName.java:
##########
@@ -79,20 +79,42 @@ public static synchronized String getName(Class<?>
writableClass) {
return writableClass.getName();
}
+ /**
+ * Return the class for a name. Requires the class for name to extend
Writable.
+ * See {@link #getClass(String, Configuration, boolean)} if class doesn't
extend Writable.
+ * Default is {@link Class#forName(String)}.
+ *
+ * @param name input name.
+ * @param conf input configuration.
+ * @return class for a name.
+ * @throws IOException raised on errors performing I/O.
+ */
+ public static synchronized Class<?> getClass(String name, Configuration conf)
+ throws IOException {
+ return getClass(name, conf, true);
+ }
+
/**
* Return the class for a name.
* Default is {@link Class#forName(String)}.
*
* @param name input name.
* @param conf input configuration.
+ * @param requireWritable if true, require the class for name to extend
Writable
* @return class for a name.
* @throws IOException raised on errors performing I/O.
*/
- public static synchronized Class<?> getClass(String name, Configuration conf
- ) throws IOException {
+ public static synchronized Class<?> getClass(String name, Configuration conf,
+ boolean requireWritable) throws IOException {
Review Comment:
I'd propose that we unconditionally remove the check for Writable in
getClass. My thought is:
* Users can always enforce the constraint later if they want to.
* All uses of the method with Hadoop's code base don't want to limit the
output.
* The check isn't consistent. (It is only applied for aliases, not natural
class names.)
* Removing the check won't break any callers since they couldn't get
non-Writables before.
> Enhance WritableName to be able to return aliases for classes that use
> serializers
> ----------------------------------------------------------------------------------
>
> Key: HADOOP-18215
> URL: https://issues.apache.org/jira/browse/HADOOP-18215
> Project: Hadoop Common
> Issue Type: Improvement
> Reporter: Bryan Beaudreault
> Assignee: Bryan Beaudreault
> Priority: Minor
> Labels: pull-request-available
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> WritableName allows users shim in aliases for writables, in the case where a
> SequenceFile was written with a Writable class that has since been renamed or
> moved to another package. However, this requires that the aliased class
> extend Writable.
> Separately it's possible to configure jobs with keys and values which don't
> actually extend Writable. Instead they are meant to be
> serialized/deserialized using the serialization classes defined in
> {{io.serializations}} config.
> Unfortunately, the current implementation does not support these key/value
> classes. All we need to do to support this is remove the
> {{.asSubclass(Writable.class)}} as is already the case for the default.
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