RFR: JDK-8292914: Introduce a system property that enables stable names for lambda classes [v2]
Strahinja Stanojevic
duke at openjdk.org
Wed Sep 7 10:45:47 UTC 2022
> This PR introduces a system property that creates stable names for the lambda classes in the JDK. Instead of using an atomic counter in the lambda name, we can use a 32-bit hash after `$$Lambda$`. Thus, the name becomes `lambdaCapturingClass$$Lambda$hashValue`.
> Parameters used to create a stable part of the name (hash value) are a superset of the parameters used for lambda class archiving when the CDS dumping option is enabled. During the stable name creation process,
> all the common parameters are in the same form as in the low-level implementation (C part of the code) of the archiving process.
> We concatenate all of those parameters in one string `hashData`. We calculate the long hash value for `hashData` in the same manner as the `java.lang.StringUTF16#hashCode` does, and then we hash that value using `Long.toString(longHashValue, Character.MAX_RADIX)`. The desired length for this hash is equal to the length of the `Long.toString(Long.MAX_VALUE, Character.MAX_RADIX)`.
> Sometimes, the calculated hash value is shorter than the desired length, so we pad it with the character `#` to hit it. Appending `#` only affects the hash length, but not its stability.
>
> Link to the related issue: https://bugs.openjdk.org/browse/JDK-8292914
Strahinja Stanojevic has updated the pull request incrementally with one additional commit since the last revision:
Enhance test with lambdas created as method references
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/10024/files
- new: https://git.openjdk.org/jdk/pull/10024/files/1f551d1d..dd268934
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=10024&range=01
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=10024&range=00-01
Stats: 30 lines in 2 files changed: 12 ins; 16 del; 2 mod
Patch: https://git.openjdk.org/jdk/pull/10024.diff
Fetch: git fetch https://git.openjdk.org/jdk pull/10024/head:pull/10024
PR: https://git.openjdk.org/jdk/pull/10024
More information about the core-libs-dev
mailing list