thetumbled commented on code in PR #21107:
URL: https://github.com/apache/pulsar/pull/21107#discussion_r1312980829
##########
pulsar-common/src/main/java/org/apache/pulsar/common/util/collections/ConcurrentLongLongPairHashMap.java:
##########
@@ -322,15 +324,15 @@ private static final class Section extends StampedLock {
LongPair get(long key1, long key2, int keyHash) {
long stamp = tryOptimisticRead();
boolean acquiredLock = false;
- int bucket = signSafeMod(keyHash, capacity);
+ int bucketIndex = signSafeMod(keyHash, capacity) * ITEM_SIZE;
Review Comment:
We have ensured that the index returned by method `signSafeMod` is a
multiple of `ITEM_SIZE`, why do we need to multiply by 4 again? I don't get it.
##########
pulsar-common/src/main/java/org/apache/pulsar/common/util/collections/ConcurrentLongHashMap.java:
##########
@@ -632,8 +632,14 @@ static final long hash(long key) {
return hash;
}
- static final int signSafeMod(long n, int max) {
- return (int) n & (max - 1);
+ static final int signSafeMod(long dividend, int divisor) {
+ int mod = (int) (dividend % divisor);
+
+ if (mod < 0) {
+ mod += divisor;
+ }
Review Comment:
As `max-1 > 0`, we won't get a negative result with `(int) n & (max - 1)`
even if `n` is negative. This is unnecessary.
##########
pulsar-common/src/main/java/org/apache/pulsar/common/util/collections/ConcurrentLongHashMap.java:
##########
@@ -632,8 +632,14 @@ static final long hash(long key) {
return hash;
}
- static final int signSafeMod(long n, int max) {
- return (int) n & (max - 1);
+ static final int signSafeMod(long dividend, int divisor) {
+ int mod = (int) (dividend % divisor);
Review Comment:
Using `&` is faster than the `%`, which is a trick to speed up.
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