Apache9 commented on code in PR #7782:
URL: https://github.com/apache/hbase/pull/7782#discussion_r3036942185
##########
hbase-server/src/main/java/org/apache/hadoop/hbase/util/BloomFilterUtil.java:
##########
@@ -278,4 +279,31 @@ public static byte[] getBloomFilterParam(BloomType
bloomFilterType, Configuratio
}
return bloomParam;
}
+
+ /**
+ * Generate the two hash values needed for Bloom filter index generation.
Bloom filters require a
+ * (hash1, hash2) pair to derive multiple probe locations.
+ * <ul>
+ * <li>If the hash implementation provides a 64-bit hash, we split the
64-bit value into two
+ * 32-bit hashes to avoid extra hashing cost.</li>
+ * <li>Otherwise, fall back to classic double hashing by rehashing with
hash1 as the seed.</li>
+ * </ul>
+ * @param hash the hash function
+ * @param key the hash key
+ * @return a pair of hash values (hash1, hash2)
+ */
+ public static Pair<Integer, Integer> getHashPair(Hash hash, HashKey<?> key) {
Review Comment:
Let's just return long here, and let upper layer do some shift magic to get
the two ints? I believe hashing is compute sensitive, so let's try to avoid
unnecessary boxing/unboxing operations.
##########
hbase-server/src/main/java/org/apache/hadoop/hbase/util/BloomFilterUtil.java:
##########
@@ -278,4 +279,31 @@ public static byte[] getBloomFilterParam(BloomType
bloomFilterType, Configuratio
}
return bloomParam;
}
+
+ /**
+ * Generate the two hash values needed for Bloom filter index generation.
Bloom filters require a
+ * (hash1, hash2) pair to derive multiple probe locations.
+ * <ul>
+ * <li>If the hash implementation provides a 64-bit hash, we split the
64-bit value into two
+ * 32-bit hashes to avoid extra hashing cost.</li>
+ * <li>Otherwise, fall back to classic double hashing by rehashing with
hash1 as the seed.</li>
+ * </ul>
+ * @param hash the hash function
+ * @param key the hash key
+ * @return a pair of hash values (hash1, hash2)
+ */
+ public static Pair<Integer, Integer> getHashPair(Hash hash, HashKey<?> key) {
+ if (hash instanceof Hash64) {
Review Comment:
Is it possible to avoid instanceof here? Let Hash instance returns if it
supports 64 bits hash result?
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