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https://issues.apache.org/jira/browse/HDFS-4712?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13644694#comment-13644694
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Colin Patrick McCabe commented on HDFS-4712:
--------------------------------------------
bq. + dataNodeInfoList = calloc(jNumDataNodeInfos,
sizeof(hdfsDataNodeInfo**));
Should be sizeof(hdfsDataNodeInfo*)... although it doesn't matter, since those
pointers will be the same size :)
bq.+ dataNodeInfos->location =
+ (const char*)((*env)->GetStringUTFChars(env, jVal.l, NULL));
Need to check to make sure this didn't fail. If it failed, an exception will
be raised. I suggest using {{newCStr}}, which handles the exception issues for
you.
bq. + dataNodeInfoList[i] = (hdfsDataNodeInfo*)
malloc(sizeof(hdfsDataNodeInfo));
You need to check if this failed (we check all the other allocation sites.)
{code}
+ if (jExc) {
+ printExceptionAndFree( env,jExc,PRINT_EXC_ALL,
+ "org.apache.hadoop.hdfs.DistributedFileSystem::getDataNodeStats");
+ errno = EPERM;
+ goto done;
+ }
+
+
+ jobjectArray jDatanodeInfos = NULL;
{code}
Please don't use C99-style declarations after the start of the function. They
don't work well with gotos. For example, in this case, if you follow that
goto, jDatanodeInfos has undefined contents (which is likely to cause crashes
when you try to clean up). Put all the declarations at the top, except scoped
declarations.
> New libhdfs method hdfsGetDataNodes
> -----------------------------------
>
> Key: HDFS-4712
> URL: https://issues.apache.org/jira/browse/HDFS-4712
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: libhdfs
> Reporter: andrea manzi
> Attachments: HDFS-4712.patch, hdfs.c.diff, hdfs.h.diff
>
>
> we have implemented a possible extension to libhdfs to retrieve information
> about the available datanodes ( there was a mail on the hadoop-hdsf-dev
> mailing list initially abut this :
> http://mail-archives.apache.org/mod_mbox/hadoop-hdfs-dev/201204.mbox/%3CCANhO-
> s0mvororrxpjnjbql6brkj4c7l+u816xkdc+2r0whj...@mail.gmail.com%3E)
> i would like to know how to proceed to create a patch, cause on the wiki
> http://wiki.apache.org/hadoop/HowToContribute i can see info about JAVA
> patches but nothing related to extensions in C.
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