Dmitry Konstantinov created CASSANDRA-21075:
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Summary: Optimize UTF8Validator.validate for ASCII prefixed Strings
Key: CASSANDRA-21075
URL: https://issues.apache.org/jira/browse/CASSANDRA-21075
Project: Apache Cassandra
Issue Type: Improvement
Components: CQL/Interpreter
Reporter: Dmitry Konstantinov
Assignee: Dmitry Konstantinov
In UTF8Validator.validate we can apply the same optimization as Guava and JDK
does: they use a plain loop to check if it is ASCII symbol before going into
more complicated UTF8 parsing:
*
[https://github.com/google/guava/blob/master/guava/src/com/google/common/base/Utf8.java#L123]
{code:java}
for (int i = off; i < end; i++) {
if (bytes[i] < 0) {
return isWellFormedSlowPath(bytes, i, end);
}
} {code}
* java.lang.StringCoding#decodeUTF8
{code:java}
// ascii-bais, which has a relative impact to the non-ascii-only bytes
if (COMPACT_STRINGS && !hasNegatives(src, sp, len))
return resultCached().with(Arrays.copyOfRange(src, sp, sp + len),
LATIN1);
return decodeUTF8_0(src, sp, len, doReplace);
where:
public static boolean hasNegatives(byte[] ba, int off, int len) {
for (int i = off; i < off + len; i++) {
if (ba[i] < 0) {
return true;
}
}
return false;
} {code}
See also: https://lemire.me/blog/2018/10/16/validating-utf-8-bytes-java-edition/
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