On Thu, 23 Feb 2023 08:32:29 GMT, Claes Redestad <redes...@openjdk.org> wrote:
>> `Charset` class is initialized *before* system properties are set up, in >> order to check the JNU encoding (used for file path name) is a supported >> charset or not. In some OS environments, GB18030 is the native encoding so >> we need to avoid checking the system property in such a case. > > `@Stable` semantics are still fuzzy to me but the rule I've adhered to is > that back to back stores to the field - if unavoidable - needs to be > idempotent since the JIT (or AOT) may record any non-null value as a compile > time constant at any time. > > I'd write this to not update the static field if initLevel() < 1. Such calls > should be rare and only happen once on a system that has GB18030 as their > native encoding. Scratch that: as it seems to be important that we don't switch after startup then what this code is really reaching for is `static final` field semantics. Since `StandardCharsets` might be loaded very early a holder class pattern might be necessary: isGB18030_2000() { return GB18030Properties.GB18030_2000; } private static class GB18030Properties { private static final GB18030_2000 = init(); private static boolean init() { if (VM.initLevel() < 1) { // Cannot get the system property yet. Assumes non-2000 return false; } return "2000".equals(GetPropertyAction.privilegedGetProperty("jdk.charset.GB18030")); } } ------------- PR: https://git.openjdk.org/jdk/pull/12518