archive/jdk
1
0
Fork 0
mirror of https://github.com/openjdk/jdk.git synced 2025-08-27 14:54:52 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

8192943: Optimize atomic accumulators using VarHandle getAndSet

Browse source 
Reviewed-by: martin, psandoz, chegar
This commit is contained in:
Doug Lea 2017-12-08 15:26:56 -08:00
parent 0b3b384a27
commit 00d1900dc9
5 changed files with 113 additions and 117 deletions
Download patch file Download diff file Expand all files Collapse all files

46
src/java.base/share/classes/java/util/concurrent/atomic/DoubleAdder.java
View file

@ -87,15 +87,15 @@ public class DoubleAdder extends Striped64 implements Serializable {
* @param x the value to add
*/
public void add(double x) {
Cell[] as; long b, v; int m; Cell a;
if ((as = cells) != null ||
Cell[] cs; long b, v; int m; Cell c;
if ((cs = cells) != null ||
!casBase(b = base,
Double.doubleToRawLongBits
(Double.longBitsToDouble(b) + x))) {
boolean uncontended = true;
if (as == null || (m = as.length - 1) < 0 ||
(a = as[getProbe() & m]) == null ||
!(uncontended = a.cas(v = a.value,
if (cs == null || (m = cs.length - 1) < 0 ||
(c = cs[getProbe() & m]) == null ||
!(uncontended = c.cas(v = c.value,
Double.doubleToRawLongBits
(Double.longBitsToDouble(v) + x))))
doubleAccumulate(x, null, uncontended);
@ -115,12 +115,12 @@ public class DoubleAdder extends Striped64 implements Serializable {
* @return the sum
*/
public double sum() {
Cell[] as = cells;
Cell[] cs = cells;
double sum = Double.longBitsToDouble(base);
if (as != null) {
for (Cell a : as)
if (a != null)
sum += Double.longBitsToDouble(a.value);
if (cs != null) {
for (Cell c : cs)
if (c != null)
sum += Double.longBitsToDouble(c.value);
}
return sum;
}
@ -133,12 +133,12 @@ public class DoubleAdder extends Striped64 implements Serializable {
* known that no threads are concurrently updating.
*/
public void reset() {
Cell[] as = cells;
Cell[] cs = cells;
base = 0L; // relies on fact that double 0 must have same rep as long
if (as != null) {
for (Cell a : as)
if (a != null)
a.reset();
if (cs != null) {
for (Cell c : cs)
if (c != null)
c.reset();
}
}
@ -153,16 +153,12 @@ public class DoubleAdder extends Striped64 implements Serializable {
* @return the sum
*/
public double sumThenReset() {
Cell[] as = cells;
double sum = Double.longBitsToDouble(base);
base = 0L;
if (as != null) {
for (Cell a : as) {
if (a != null) {
long v = a.value;
a.reset();
sum += Double.longBitsToDouble(v);
}
Cell[] cs = cells;
double sum = Double.longBitsToDouble(getAndSetBase(0L));
if (cs != null) {
for (Cell c : cs) {
if (c != null)
sum += Double.longBitsToDouble(c.getAndSet(0L));
}
}
return sum;