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Reduce conditionals in AbstractReferenceCounted

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Motivation:
AbstractReferenceCounted as independent conditional statements to check the bounds of the retain IllegalReferenceCountException condition. One of the exceptions also uses the incorrect increment.

Modifications:
- Combined independent conditional checks into 1 where possible
- Correct IllegalReferenceCountException with incorrect increment
- Remove the subtract to check for overflow and re-use the addition and check for overflow to remove 1 arithmetic operation (see http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.18.2)

Result:
AbstractReferenceCounted has less independent branch statements and more correct IllegalReferenceCountException. Compilation size of AbstractReferenceCounted.retain() is reduced from 58 bytes to 47 bytes.
This commit is contained in:
Scott Mitchell 2016-07-20 18:58:02 -04:00
parent d315f1b3ba
commit 01523e7835
1 changed files with 5 additions and 10 deletions
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15
common/src/main/java/io/netty/util/AbstractReferenceCounted.java
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@ -53,11 +53,8 @@ public abstract class AbstractReferenceCounted implements ReferenceCounted {
public ReferenceCounted retain() { public ReferenceCounted retain() {
for (;;) { for (;;) {
int refCnt = this.refCnt; int refCnt = this.refCnt;
if (refCnt == 0) { if (refCnt == 0 || refCnt == Integer.MAX_VALUE) {
throw new IllegalReferenceCountException(0, 1); throw new IllegalReferenceCountException(refCnt, 1);
}
if (refCnt == Integer.MAX_VALUE) {
throw new IllegalReferenceCountException(Integer.MAX_VALUE, 1);
} }
if (refCntUpdater.compareAndSet(this, refCnt, refCnt + 1)) { if (refCntUpdater.compareAndSet(this, refCnt, refCnt + 1)) {
break; break;
@ -73,14 +70,12 @@ public abstract class AbstractReferenceCounted implements ReferenceCounted {
} }
for (;;) { for (;;) {
final int nextCnt;
int refCnt = this.refCnt; int refCnt = this.refCnt;
if (refCnt == 0) { if (refCnt == 0 || (nextCnt = refCnt + increment) < 0) {
throw new IllegalReferenceCountException(0, 1);
}
if (refCnt > Integer.MAX_VALUE - increment) {
throw new IllegalReferenceCountException(refCnt, increment); throw new IllegalReferenceCountException(refCnt, increment);
} }
if (refCntUpdater.compareAndSet(this, refCnt, refCnt + increment)) { if (refCntUpdater.compareAndSet(this, refCnt, nextCnt)) {
break; break;
} }
} }