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https://issues.apache.org/jira/browse/HDFS-6156?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13949723#comment-13949723
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Haohui Mai commented on HDFS-6156:
----------------------------------
{code}
+ SnapshottableDirectoryStatus[] stats = getSnapshottableDirListing(null);
+ if (stats == null) {
+ return null;
+ }
+ List<SnapshotInfo.Bean> beans = new ArrayList<SnapshotInfo.Bean>();
+ for (SnapshottableDirectoryStatus d : stats) {
+ try {
+ for (Snapshot s : getSnapshottableRoot(
+ d.getFullPath().toString()).getSnapshotList()) {
+ beans.add(toBean(s));
}
+ } catch (IOException e) {
+ continue;
{code}
It's more appropriate to refactor / inline {{getSnapshottableDirListing}} here
to generate the list.
{code}
+ private static SnapshottableDirectoryStatus.Bean toBean(
+ SnapshottableDirectoryStatus d) {
+ return new SnapshottableDirectoryStatus.Bean(d);
+ }
+
+ private static SnapshotInfo.Bean toBean(Snapshot s) {
+ return new SnapshotInfo.Bean(s);
}
{code}
Beans are abstractions between two different layers, thus they usually have no
dependency of the application logic (e.g., they don't take an application-level
object in the constructor). A better approach is:
{code}
// in the bean
public Bean(String path, int snapshotNumber, int snapshotQuota,
long modificationTime, short permission, String owner,
String group) {
this.path = path;
this.snapshotNumber = snapshotNumber;
this.snapshotQuota = snapshotQuota;
this.modificationTime = modificationTime;
this.permission = permission;
this.owner = owner;
this.group = group;
}
// in snapshotmanager
public Bean(SnapshottableDirectoryStatus s) {
return new Bean(s.getFoo(), ...);
}
{code}
bq. I think that we do not need to convert List into Arrays.
I think it has no differences in the final results, but it looks to me that
it's also a convention in beans. :-)
> Simplify the JMX API that provides snapshot information
> -------------------------------------------------------
>
> Key: HDFS-6156
> URL: https://issues.apache.org/jira/browse/HDFS-6156
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Haohui Mai
> Assignee: Shinichi Yamashita
> Attachments: HDFS-6156.patch
>
>
> HDFS-5196 introduces a set of new APIs that provide snapshot information
> through JMX. Currently. The API nests {{SnapshotDirectoryMXBean}} into
> {{SnapshotStatsMXBean}}, creating another layer of composition.
> This jira proposes to inline {{SnapshotDirectoryMXBean}} into
> {{SnapshotStatsMXBean}} and to simplify the API.
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