Github user davies commented on a diff in the pull request:
https://github.com/apache/spark/pull/6804#discussion_r32376747
--- Diff:
unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java ---
@@ -131,24 +131,31 @@ public boolean contains(final UTF8String substring) {
}
for (int i = 0; i <= bytes.length - b.length; i++) {
- // TODO: Avoid copying.
- if (bytes[i] == b[0] && Arrays.equals(Arrays.copyOfRange(bytes, i, i
+ b.length), b)) {
+ if (bytes[i] == b[0] && startsWith(substring, i)) {
return true;
}
}
return false;
}
+ private boolean startsWith(final UTF8String prefix, int offset) {
+ byte[] b = prefix.getBytes();
+ if (b.length + offset > bytes.length || offset < 0) {
+ return false;
+ }
+ int i = 0;
+ while (i < b.length && b[i] == bytes[i + offset]) {
--- End diff --
As @rxin suggested, we could use unsafe API to compare 8 bytes at once. But
I think in most cases the suffix will be short and this while loop will
terminate very fast, it may not worth that complication.
The while loop is good to me.
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