RFR: 8238684: Override getOrDefault in immutable Map implementations

Claes Redestad claes.redestad at oracle.com
Fri Feb 7 12:17:40 UTC 2020


in our immutable map implementations, it's unnecessary for getOrDefault
to check containsKey(key) in case get(key) returns null. This follows
since null values are disallowed.

Overriding the method with an implementation is a reasonable
optimization, for example a 50% improvement on the added
microbenchmark. I found this opportunity when looking at startup
profiles, so yes, there's a tiny startup improvement, too. :-)

Webrev: http://cr.openjdk.java.net/~redestad/8238684/open.00/
Bug:    https://bugs.openjdk.java.net/browse/JDK-8238684

Testing: tier1+2 (ongoing)



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