Re: RFR: JDK-8266670: Better modeling of access flags in core reflection [v25]
On Tue, 14 Jun 2022 02:32:54 GMT, Joe Darcy wrote: >> This is an early review of changes to better model JVM access flags, that is >> "modifiers" like public, protected, etc. but explicitly at a VM level. >> >> Language level modifiers and JVM level access flags are closely related, but >> distinct. There are concepts that overlap in the two domains (public, >> private, etc.), others that only have a language-level modifier (sealed), >> and still others that only have an access flag (synthetic). >> >> The existing java.lang.reflect.Modifier class is inadequate to model these >> subtleties. For example, the bit positions used by access flags on different >> kinds of elements overlap (such as "volatile" for fields and "bridge" for >> methods. Just having a raw integer does not provide sufficient context to >> decode the corresponding language-level string. Methods like >> Modifier.methodModifiers() were introduced to cope with this situation. >> >> With additional modifiers and flags on the horizon with projects like >> Valhalla, addressing the existent modeling deficiency now ahead of time is >> reasonable before further strain is introduced. >> >> This PR in its current form is meant to give the overall shape of the API. >> It is missing implementations to map from, say, method modifiers to access >> flags, taking into account overlaps in bit positions. >> >> The CSR https://bugs.openjdk.java.net/browse/JDK-8281660 will be filled in >> once the API is further along. > > Joe Darcy has updated the pull request incrementally with one additional > commit since the last revision: > > Respond to review feedback. src/java.base/share/classes/java/lang/reflect/AccessFlag.java line 64: > 62: * arity (varargs)} method. > 63: * > 64: * The access flag constants are ordered by non-decreasing mask This paragraph seems more like an @implNote, describing the ordering of the source. - PR: https://git.openjdk.org/jdk/pull/7445
Re: RFR: JDK-8266670: Better modeling of access flags in core reflection [v25]
On Tue, 14 Jun 2022 02:32:54 GMT, Joe Darcy wrote:
>> This is an early review of changes to better model JVM access flags, that is
>> "modifiers" like public, protected, etc. but explicitly at a VM level.
>>
>> Language level modifiers and JVM level access flags are closely related, but
>> distinct. There are concepts that overlap in the two domains (public,
>> private, etc.), others that only have a language-level modifier (sealed),
>> and still others that only have an access flag (synthetic).
>>
>> The existing java.lang.reflect.Modifier class is inadequate to model these
>> subtleties. For example, the bit positions used by access flags on different
>> kinds of elements overlap (such as "volatile" for fields and "bridge" for
>> methods. Just having a raw integer does not provide sufficient context to
>> decode the corresponding language-level string. Methods like
>> Modifier.methodModifiers() were introduced to cope with this situation.
>>
>> With additional modifiers and flags on the horizon with projects like
>> Valhalla, addressing the existent modeling deficiency now ahead of time is
>> reasonable before further strain is introduced.
>>
>> This PR in its current form is meant to give the overall shape of the API.
>> It is missing implementations to map from, say, method modifiers to access
>> flags, taking into account overlaps in bit positions.
>>
>> The CSR https://bugs.openjdk.java.net/browse/JDK-8281660 will be filled in
>> once the API is further along.
>
> Joe Darcy has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Respond to review feedback.
src/java.base/share/classes/java/lang/reflect/AccessFlag.java line 104:
> 102: */
> 103: PROTECTED(Modifier.PROTECTED, true,
> 104: Set.of(Location.FIELD, Location.METHOD,
> Location.INNER_CLASS)),
In both space and startup time, creating separate sets for the same set of
Locations is inefficient.
src/java.base/share/classes/java/lang/reflect/AccessFlag.java line 213:
> 211: * {@value "0x%04x" Modifier#STRICT}.
> 212: */
> 213: STRICT(Modifier.STRICT, true, Set.of(Location.METHOD)),
ACC_STRICT is defined for class files and appears in the Class.getModifiers()
before class file version 46.
Also it is included in Modifer.classModifiers(); Modifer.CLASS_MODIFIERS.
it might be worth a note saying it is class file version specific.
-
PR: https://git.openjdk.org/jdk/pull/7445
Re: RFR: JDK-8266670: Better modeling of access flags in core reflection [v25]
> This is an early review of changes to better model JVM access flags, that is > "modifiers" like public, protected, etc. but explicitly at a VM level. > > Language level modifiers and JVM level access flags are closely related, but > distinct. There are concepts that overlap in the two domains (public, > private, etc.), others that only have a language-level modifier (sealed), and > still others that only have an access flag (synthetic). > > The existing java.lang.reflect.Modifier class is inadequate to model these > subtleties. For example, the bit positions used by access flags on different > kinds of elements overlap (such as "volatile" for fields and "bridge" for > methods. Just having a raw integer does not provide sufficient context to > decode the corresponding language-level string. Methods like > Modifier.methodModifiers() were introduced to cope with this situation. > > With additional modifiers and flags on the horizon with projects like > Valhalla, addressing the existent modeling deficiency now ahead of time is > reasonable before further strain is introduced. > > This PR in its current form is meant to give the overall shape of the API. It > is missing implementations to map from, say, method modifiers to access > flags, taking into account overlaps in bit positions. > > The CSR https://bugs.openjdk.java.net/browse/JDK-8281660 will be filled in > once the API is further along. Joe Darcy has updated the pull request incrementally with one additional commit since the last revision: Respond to review feedback. - Changes: - all: https://git.openjdk.org/jdk/pull/7445/files - new: https://git.openjdk.org/jdk/pull/7445/files/75ac9c18..adcbcb71 Webrevs: - full: https://webrevs.openjdk.java.net/?repo=jdk=7445=24 - incr: https://webrevs.openjdk.java.net/?repo=jdk=7445=23-24 Stats: 4 lines in 2 files changed: 1 ins; 0 del; 3 mod Patch: https://git.openjdk.org/jdk/pull/7445.diff Fetch: git fetch https://git.openjdk.org/jdk pull/7445/head:pull/7445 PR: https://git.openjdk.org/jdk/pull/7445
