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https://issues.apache.org/jira/browse/HBASE-6493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13564531#comment-13564531
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Nick Dimiduk commented on HBASE-6493:
-------------------------------------
Grep on trunk reveals the following:
{noformat}
$ grep -rin 'Hash.*<byte\[\]>' *
hbase-common/src/main/java/org/apache/hadoop/hbase/util/test/RedundantKVGenerator.java:192:
new HashMap<Integer, List<byte[]>>();
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java:3287:
columnFamilies = new HashSet<byte[]>();
hbase-server/src/main/java/org/apache/hadoop/hbase/security/access/AccessController.java:481:
HashMap<byte[], Set<byte[]>> familyMap =
Maps.newHashMapWithExpectedSize(families.size());
hbase-server/src/main/java/org/apache/hadoop/hbase/security/access/AccessController.java:1197:
HashMap<byte[], Set<byte[]>> familyMap =
Maps.newHashMapWithExpectedSize(1);
{noformat}
- The {{RedundantKVGenerator}} hit is a false-positive.
- In {{HRegionServer}}, {{columnFamilies}} is normally the keySet produced by
the store, backed by an instance of {{ConcurrentSkipListMap}} which is
constructed to use {{Bytes.BYTES_RAWCOMPARATOR}}. To preserve identical
semantics, this line should be updated to use, say, a {{TreeSet}} with the same
comparator.
- {{AccessController:481}} eventually passes the {{HashMap}} down to the
{{AuthResult}} constructor, which iterates its content to generate a String. No
comparisons here.
- Likewise with {{AccessController:1197}}.
I'll create a patch to replace {{columnFamilies}} with a {{TreeSet}}.
> HashSet of byte array is being used in couple of places
> -------------------------------------------------------
>
> Key: HBASE-6493
> URL: https://issues.apache.org/jira/browse/HBASE-6493
> Project: HBase
> Issue Type: Bug
> Reporter: Shrijeet Paliwal
> Priority: Minor
>
> While working on a jira I realized I had made a mistake of making a HashSet
> of byte array.
> Then out of curiosity I checked if we do same any where else in code base. I
> came with following files.
> # /src/main/java/org/apache/hadoop/hbase/mapreduce/RowCounter.java:
> Set<byte []> qualifiers = new HashSet<byte[]>();
> # /src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java:
> columnFamilies = new HashSet<byte[]>();
> #
> /src/test/java/org/apache/hadoop/hbase/filter/TestFirstKeyValueMatchingQualifiersFilter.java:
> Set<byte[]> quals = new HashSet<byte[]>();
> #
> /src/test/java/org/apache/hadoop/hbase/regionserver/metrics/TestSchemaMetrics.java:
> Set<byte[]> families = new HashSet<byte[]>();
> (1) and (3) are mine and I will fix them (not yet committed). Quoting the
> exact reference from (2) below :
> {code}
> @Override
>
> public GetStoreFileResponse getStoreFile(final RpcController controller,
>
> final GetStoreFileRequest request) throws ServiceException {
>
> try {
>
> HRegion region = getRegion(request.getRegion());
>
> requestCount.incrementAndGet();
>
> Set<byte[]> columnFamilies = null;
>
> if (request.getFamilyCount() == 0) {
>
> columnFamilies = region.getStores().keySet();
>
> } else {
>
> columnFamilies = new HashSet<byte[]>();
>
> for (ByteString cf: request.getFamilyList()) {
>
> columnFamilies.add(cf.toByteArray());
>
> }
>
> }
> {code}
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