Hello everybody!
HashTable needs to calculate the power of two that is not less that the
given number.
This calculation used to be implemented as a relatively inefficient loop
(that's why the issue 7192942 was created).
The implementation was improved with
http://hg.openjdk.java.net/jdk8/jdk8/jdk/rev/2e3cc7f599ca
However it can be improved even more. I reused 7192942 number for this
propose.
Would you please help with reviewing?
Here's the webrev:
http://cr.openjdk.java.net/~igerasim/7192942/0/webrev/
<http://cr.openjdk.java.net/%7Eigerasim/7192942/0/webrev/>
I also created a benchmark test to make sure the improvement is observable.
Here's the jmh benchmark I used:
http://cr.openjdk.java.net/~igerasim/bench/powoftwo/src/main/java/org/benches/PowerOfTwoBench.java
<http://cr.openjdk.java.net/%7Eigerasim/bench/powoftwo/src/main/java/org/benches/PowerOfTwoBench.java>
Benchmark Mode Thr Cnt Sec
Mean Mean error Units
o.b.PowerOfTwoBench.benchPowerOfTwoA avgt 1 20 5
60.697 0.850 msec/op
o.b.PowerOfTwoBench.benchPowerOfTwoB avgt 1 20 5
53.013 0.940 msec/op
The first line is for the current implementation and the second one is
for the proposed change.
Thus, the time gets reduced by 12%.
Sincerely yours,
Ivan
