8314684: Add overview docs to loaderConstraints.cpp #15372

iklam · 2023-08-21T21:15:19Z

I added some documentation to make it easier to understand loaderConstraints.cpp. Please review and check if my description is actually correct. Thanks!

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JDK-8314684: Add overview docs to loaderConstraints.cpp (Enhancement - P4)

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Calvin Cheung (@calvinccheung - Reviewer)
David Holmes (@dholmes-ora - Reviewer)

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$ git pull https://git.openjdk.org/jdk.git pull/15372/head

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bridgekeeper · 2023-08-21T21:16:43Z

👋 Welcome back iklam! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2023-08-21T21:17:27Z

@iklam The following label will be automatically applied to this pull request:

hotspot-runtime

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

mlbridge · 2023-08-21T21:21:37Z

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calvinccheung

Looks good. Just noticed some typos.

calvinccheung · 2023-08-21T22:05:18Z

src/hotspot/share/classfile/loaderConstraints.cpp

+//
+// Management of LoaderConstraints
+//
+// When the SyswtemDictionary decides that loader_x and loader_y must resolve the name N to the same class:


Typo: SyswtemDictionary should be SystemDictionary

calvinccheung · 2023-08-21T22:07:12Z

src/hotspot/share/classfile/loaderConstraints.cpp

+// we assign _klass_<m> = K;
+//
+// if _klass_<m> is non-null, when a loader loader_<m><n> tries to resolve the name N to a class K,
+// where _klass_<m> != K, a LinkageError is thrown, and the resolution fails;


Suggestion: '.' instead of ';'

calvinccheung · 2023-08-21T22:11:18Z

src/hotspot/share/classfile/loaderConstraints.cpp

+// both loader_x and loader_y;
+//
+// Otherwise if LoaderConstraint_x exists but LoaderConstraint_y doesn't exist, add loader_y to LoaderConstraint_x;
+// (and vice versa);


Suggestion: s/and/or
Also, I think the parentheses could be removed.

openjdk · 2023-08-21T22:13:13Z

@iklam This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8314684: Add overview docs to loaderConstraints.cpp

Reviewed-by: ccheung, dholmes

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 17 new commits pushed to the master branch:

7e843c2: 8284772: GHA: Use GCC Major Version Dependencies Only
ba6cdbe: 8309214: sun/security/pkcs11/KeyStore/CertChainRemoval.java fails after 8301154
9f4a9fe: 8312434: SPECjvm2008/xml.transform with CDS fails with "can't seal package nu.xom"
7c169a4: 8312232: Remove sun.jvm.hotspot.runtime.VM.buildLongFromIntsPD()
2eae13c: 8214248: (fs) Files:mismatch spec clarifications
ce1ded1: 8314749: Remove unimplemented _Copy_conjoint_oops_atomic
32bf468: 8314274: G1: Fix -Wconversion warnings around G1CardSetArray::_data
eb06572: 8313408: Use SVG for BoxLayout example
20e9478: 8314426: runtime/os/TestTrimNative.java is failing on slow machines
69d900d: 8314730: GHA: Drop libfreetype6-dev transitional package in favor of libfreetype-dev
... and 7 more: https://git.openjdk.org/jdk/compare/78f74bc8ff1e673991d91a55ef70880d9fb3f6b5...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

dholmes-ora

Well it reads really well and is informative, but is it correct? Hard to evaluate. It would be clearer if the commentary tied into the code more so that I knew where to see each of the things mentioned, and also understand how the different types (LoaderConstraint, ConstraintSet) fit in that description.

Thanks.

iklam · 2023-08-22T21:46:23Z

Well it reads really well and is informative, but is it correct? Hard to evaluate. It would be clearer if the commentary tied into the code more so that I knew where to see each of the things mentioned, and also understand how the different types (LoaderConstraint, ConstraintSet) fit in that description.

Thanks.

I added ConstraintSet to the comments. I also added references to the add_entry and check_or_update functions which are the main entry points.

I have skipped some details to avoid being verbose. For example, add_entry won't add anything to the table if the two loaders have already resolved different classes for the same name.

dholmes-ora · 2023-08-23T02:31:48Z

src/hotspot/share/classfile/loaderConstraints.cpp

+//
+// Otherwise if both LoaderConstraints have different values for _klass, a LinkageError is thrown.
+//
+// Otherwise the two LoaderConstraints are merged into one.


So I looked in LoaderConstraintTable::add_entry to see how this algorithm applied and I could not figure out what condition is actually left (regarding pp1 and pp2) when we get to the merge case at L396 ???

Never mind I see it now: pp1 != pp2 and neither is null.

dholmes-ora

Thanks for the update.

Looks good - very useful.

iklam · 2023-08-27T03:44:09Z

Thanks for the review @calvinccheung and @dholmes-ora
/integrate

openjdk · 2023-08-27T03:44:40Z

Going to push as commit 752a438.
Since your change was applied there have been 61 commits pushed to the master branch:

acd9310: 8313430: [JVMCI] fatal error: Never compilable: in JVMCI shutdown
8a5db6b: 8237542: JMapHeapConfigTest.java doesn't work with negative jlong values
d0cc043: 8314550: [macosx-aarch64] serviceability/sa/TestJmapCore.java fails with "sun.jvm.hotspot.debugger.UnmappedAddressException: 801000800"
837d2e1: 8314483: Optionally override copyright header in generated source
3201623: 8310454: Introduce static-libs-graal bundle
e9ba8d5: 8314960: Add Certigna Root CA - 2
837cf85: 8312547: Max/Min nodes Value implementation could be improved
7342f5a: 8314333: Update com/sun/jdi/ProcessAttachTest.java to use ProcessTools.createTestJvm(..)
f139f30: 8315033: Problemlist java/lang/template/StringTemplateTest.java
f2383b3: 8314063: The socket is not closed in Connection::createSocket when the handshake failed for LDAP connection
... and 51 more: https://git.openjdk.org/jdk/compare/78f74bc8ff1e673991d91a55ef70880d9fb3f6b5...master

Your commit was automatically rebased without conflicts.

openjdk · 2023-08-27T03:44:51Z

@iklam Pushed as commit 752a438.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

8314684: Add overview docs to loaderConstraints.cpp

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openjdk bot added the rfr Pull request is ready for review label Aug 21, 2023

openjdk bot added the hotspot-runtime hotspot-runtime-dev@openjdk.org label Aug 21, 2023

calvinccheung approved these changes Aug 21, 2023

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openjdk bot added the ready Pull request is ready to be integrated label Aug 21, 2023

@calvinccheung comments

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dholmes-ora reviewed Aug 22, 2023

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iklam added 2 commits August 22, 2023 14:38

added info about ConstraintSet

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added references to source code

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dholmes-ora reviewed Aug 23, 2023

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dholmes-ora approved these changes Aug 23, 2023

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calvinccheung approved these changes Aug 23, 2023

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openjdk bot added the integrated Pull request has been integrated label Aug 27, 2023

openjdk bot closed this Aug 27, 2023

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Aug 27, 2023

8314684: Add overview docs to loaderConstraints.cpp #15372

8314684: Add overview docs to loaderConstraints.cpp #15372

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