RFR: 8331291: java.lang.classfile.Attributes class performs a lot of static initializations

[Adam Sotona]

Yes, we can replace currently proposed holder pattern implementation with StableValues when ready, without changes in the proposed Attributes class API.

From: Brian Goetz <brian.goetz at oracle.com>
Date: Tuesday, 30 April 2024 at 14:44
To: Adam Sotona <adam.sotona at oracle.com>, classfile-api-dev at openjdk.org <classfile-api-dev at openjdk.org>
Subject: Re: RFR: 8331291: java.lang.classfile.Attributes class performs a lot of static initializations
StableValue is coming soon, and the attributes is a great candidate for a lazy StableValue map.
On 4/30/2024 7:58 AM, Adam Sotona wrote:
Hi,
During performance optimization work on Class-File API as JDK lambda generator we found some static initialization killers.
One of them is `java.lang.classfile.Attributes` with tens of static fields initialized with individual attribute mappers, and common set of all mappers, and static map from attribute names to the mappers.

I propose to turn all the static fields into lazy-initialized static methods and remove `PREDEFINED_ATTRIBUTES` and `standardAttribute(Utf8Entry name)` static mapping method from the `Attributes` API class.

Please let me know your comments or objections and please review the [PR](https://github.com/openjdk/jdk/pull/19006) and [CSR](https://bugs.openjdk.org/browse/JDK-8331414), so we can make it into 23.

Thank you,
Adam

-------------

Commit messages:
 - added impl comment
 - removed list of predefined attributes
 - move mappers implementations to AbstractAttributeMapper
 - 8331291: java.lang.classfile.Attributes class performs a lot of static initializations

Changes: https://git.openjdk.org/jdk/pull/19006/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19006&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331291
 CSR: https://bugs.openjdk.org/browse/JDK-8331414
  Stats: 2029 lines in 47 files changed: 904 ins; 619 del; 506 mod
  Patch: https://git.openjdk.org/jdk/pull/19006.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19006/head:pull/19006

PR: https://git.openjdk.org/jdk/pull/19006

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