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https://issues.apache.org/jira/browse/HDFS-14799?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ayush Saxena updated HDFS-14799:
--------------------------------
Fix Version/s: 3.3.0
Hadoop Flags: Reviewed
Resolution: Fixed
Status: Resolved (was: Patch Available)
> Do Not Call Map containsKey In Conjunction with get
> ---------------------------------------------------
>
> Key: HDFS-14799
> URL: https://issues.apache.org/jira/browse/HDFS-14799
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 3.2.0
> Reporter: David Mollitor
> Assignee: hemanthboyina
> Priority: Minor
> Labels: newbie, noob
> Fix For: 3.3.0
>
> Attachments: HDFS-14799.001.patch
>
>
> {code:java|title=InvalidateBlocks.java}
> private final Map<DatanodeInfo, LightWeightHashSet<Block>>
> nodeToBlocks = new HashMap<>();
> private final Map<DatanodeInfo, LightWeightHashSet<Block>>
> nodeToECBlocks = new HashMap<>();
> ...
> private LightWeightHashSet<Block> getBlocksSet(final DatanodeInfo dn) {
> if (nodeToBlocks.containsKey(dn)) {
> return nodeToBlocks.get(dn);
> }
> return null;
> }
> private LightWeightHashSet<Block> getECBlocksSet(final DatanodeInfo dn) {
> if (nodeToECBlocks.containsKey(dn)) {
> return nodeToECBlocks.get(dn);
> }
> return null;
> }
> {code}
> There is no need to check for {{containsKey}} here since a call to {{get}}
> will already return 'null' if the key is not there. This just adds overhead
> of having to dive into the Map twice to get the value.
> {code}
> private LightWeightHashSet<Block> getECBlocksSet(final DatanodeInfo dn) {
> return nodeToECBlocks.get(dn);
> }
> {code}
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