Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/1001#discussion_r145576718
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/SqlPatternContainsMatcher.java
---
@@ -17,36 +17,133 @@
*/
package org.apache.drill.exec.expr.fn.impl;
-public class SqlPatternContainsMatcher implements SqlPatternMatcher {
+public final class SqlPatternContainsMatcher implements SqlPatternMatcher {
final String patternString;
CharSequence charSequenceWrapper;
final int patternLength;
public SqlPatternContainsMatcher(String patternString, CharSequence
charSequenceWrapper) {
- this.patternString = patternString;
+ this.patternString = patternString;
this.charSequenceWrapper = charSequenceWrapper;
- patternLength = patternString.length();
+ patternLength = patternString.length();
}
@Override
- public int match() {
- final int txtLength = charSequenceWrapper.length();
- int patternIndex = 0;
- int txtIndex = 0;
+ public final int match() {
+ // The idea is to write loops with simple condition checks to allow
the Java Hotspot vectorize
+ // the generate code.
+ if (patternLength == 1) {
+ return match_1();
+ } else if (patternLength == 2) {
+ return match_2();
+ } else if (patternLength == 3) {
+ return match_3();
+ } else {
+ return match_N();
+ }
+ }
+
+ private final int match_1() {
--- End diff --
See note about UTF-8. If we don't care about the match position (that is,
we don't need `strpos()`, and all we care is whether it matches or not, then we
can do the work on the undecoded UTF-8 bytes, saving a large amount of
complexity.
---
