Eric Hanson created HADOOP-10097:
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Summary: Extend JenkinsHash package interface to allow increased
code sharing
Key: HADOOP-10097
URL: https://issues.apache.org/jira/browse/HADOOP-10097
Project: Hadoop Common
Issue Type: Improvement
Reporter: Eric Hanson
Assignee: Eric Hanson
Priority: Minor
I copied some code from org.apache.hadoop.util.hash.JenkinsHash and added it to
org.apache.hadoop.hive.ql.exec.vector.expressions.CuckooSetBytes and modified
it slightly because the interface was not quite right for use CuckooSetBytes.
I propose modifying org.apache.hadoop.util.hash.JenkinsHash to provide an
additional interface function:
public int hash(byte[] key, int start, int nbytes, int initval)
This would return a hash value for the sequence of bytes beginning at start and
ending at start + nbytes (exclusive).
The existing interface function in org.apache.hadoop.util.hash.JenkinsHash
public int hash(byte[] key, int nbytes, int initval)
would then be modified to call this new function. The original hash() function
does not take a start parameter, and always assumes the key in byte[] key
starts at position 0. This will expand the use cases for the JenkinsHash
package. At that point, the Hive CuckooSetBytes class can be modified so that
it can reference the JenkinsHash package of Hadoop and use it directly, rather
than using a copied and modified version of the code locally.
Existing users of hash(byte[] key, int nbytes, int initval) will then have to
pay an extra function call. If the performance ramifications of this worry
anyone, please comment. Alternatives would be to copy the new version of hash()
in entirety into JenkinsHash, or simply not do this JIRA.
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