Github user sureshsubbiah commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/229#discussion_r47986827
--- Diff: core/sql/src/main/java/org/trafodion/sql/HBaseClient.java ---
@@ -1032,11 +1032,58 @@ public float getBlockCacheFraction()
float defCacheFraction = 0.4f;
return config.getFloat("hfile.block.cache.size",defCacheFraction);
}
+
+ // if we make the method below public later, should think about
whether this is the
+ // right class to host this method
+
+ // compares two qualifiers as unsigned, lexicographically ordered byte
strings
+ static private boolean isQualifierLessThanOrEqual(KeyValue nextKv,
+ KeyValue currKv)
+ {
+ int currLength = currKv.getQualifierLength();
+ int currOffset = currKv.getQualifierOffset();
+ byte [] currQual = currKv.getQualifierArray();
+ int nextLength = nextKv.getQualifierLength();
+ int nextOffset = nextKv.getQualifierOffset();
+ byte [] nextQual = nextKv.getQualifierArray();
+
+ // If we later decide we need a performance-critical version of
this method,
+ // we should just use a native method that calls C memcmp.
+
+ int minLength = nextLength;
+ if (currLength < nextLength)
+ minLength = currLength;
+
+ for (int i = 0; i < minLength; i++) {
+ // ugh... have to do some gymnastics to make this an
+ // unsigned comparison
+ int nextQualI = nextQual[i+nextOffset];
+ if (nextQualI < 0)
+ nextQualI = nextQualI + 256;
+ int currQualI = currQual[i+currOffset];
+ if (currQualI < 0)
+ currQualI = currQualI + 256;
+
+ if (nextQualI < currQualI)
+ return true;
+ else if (nextQualI > currQualI)
+ return false;
+ // else equal, move on to next byte
+ }
+
+ // the first minLength bytes are the same; the shorter array
+ // is regarded as less
+
+ boolean rc = (nextLength <= currLength);
+
+ return rc;
+ }
+
--- End diff --
This method looks good me. An alternative may be to use the compareTo
method in ByteBuffer
http://docs.oracle.com/javase/1.5.0/docs/api/java/nio/ByteBuffer.html#compareTo(java.nio.ByteBuffer)
We use ByteBuffer in a few places in
$MY_SQROOT/../sql/src/main/java/org/trafodion/sql and
$MY_SQROOT/../sql/src/main/java/org/trafodion/sql/udr.
In this case we may have to use the wrap method to get a ByteBuffer of just
the relevant parts and then call compareTo on that?
http://docs.oracle.com/javase/1.5.0/docs/api/java/nio/ByteBuffer.html#wrap(byte[],
int, int)
I have been fascinated by the ByteBuffer class and could not pass up an
opportunity to mention them here. Current code is good too.
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