8283060: RawNativeLibraries should allow multiple clients to load/unload the same library

[mlchung]

A small improvement to RawNativeLibraries. RawNativeLibraries::load returns the same NativeLibrary instance of a given path if it's called multiple times. This means that multiple clients have to coordinate that the last one using the loaded library is the one to close the library by calling RawNativeLibraries::unload; otherwise, an exception may be thrown.

This patch changes RawNativeLibraries::load to delegate to the underlying platform-specific library loading mechanism e.g. dlopen/dlclose that keeps the reference count. So each call to RawNativeLibraries::load and unload is simply a call to dlopen and dlclose respectively. Each client of calling RawNativeLibraries::load is responsible for calling RawNativeLibraries::unload. This will be consistent with the current behavior when you call load and unload with a different RawNativeLibraries instance.

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Progress

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Issue

• JDK-8283060: RawNativeLibraries should allow multiple clients to load/unload the same library

Reviewers

• Athijegannathan Sundararajan (@sundararajana - Reviewer)
• Jorn Vernee (@JornVernee - Reviewer)
• Jaikiran Pai (@jaikiran - Committer)

Reviewing

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[mlbridge]

Webrevs

• 00: Full (23dc9d66)

[sundararajana]

LGTM

[openjdk]

@mlchung 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:

8283060: RawNativeLibraries should allow multiple clients to load/unload the same library

Reviewed-by: sundar, jvernee, jpai

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 103 new commits pushed to the master branch:

• b8dd21b: 8283801: Cleanup confusing String.toString calls
• ce27d9d: 8283494: Factor out calculation of actual number of XMM registers
• e61ccfb: 8283470: Update java.lang.invoke.VarHandle to use sealed classes
• e85fa2f: 8283700: Add final or sealed modifier to appropriate java.awt API classes
• ec9ab55: 8282374: Java_sun_awt_X11_XlibWrapper_XSynchronize is wrong and unused
• a625bfd: 8283903: GetContainerCpuLoad does not return the correct result in share mode
• 97c7298: 8282046: Create a regression test for JDK-8000326
• ae57258: 8283715: Update ObjectStreamClass to be final
• d9d19e9: 8284015: ProblemList containers/docker/TestJcmd.java on linux-x64
• a3223cb: 8283999: Update JMH devkit to 1.35
• ... and 93 more: https://git.openjdk.java.net/jdk/compare/3e73a0b726a97df0a4e92f9cf917429346090f45...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.

[jaikiran]

Hello Mandy,
Apart from the caller being used for checks while constructing a RawNativeLibraries in RawNativeLibraries.newInstance(MethodHandles.Lookup trustedCaller), I don't see this instance member being used anywhere. Do you think we need to store this as an instance member?

[mlchung]

I keep it as a record and for debugging use in case.

[mlchung]

/integrate

[openjdk]

Going to push as commit 1ddab6f.
Since your change was applied there have been 104 commits pushed to the master branch:

• 835c7e8: 8283907: Fix Huawei copyright in various files
• b8dd21b: 8283801: Cleanup confusing String.toString calls
• ce27d9d: 8283494: Factor out calculation of actual number of XMM registers
• e61ccfb: 8283470: Update java.lang.invoke.VarHandle to use sealed classes
• e85fa2f: 8283700: Add final or sealed modifier to appropriate java.awt API classes
• ec9ab55: 8282374: Java_sun_awt_X11_XlibWrapper_XSynchronize is wrong and unused
• a625bfd: 8283903: GetContainerCpuLoad does not return the correct result in share mode
• 97c7298: 8282046: Create a regression test for JDK-8000326
• ae57258: 8283715: Update ObjectStreamClass to be final
• d9d19e9: 8284015: ProblemList containers/docker/TestJcmd.java on linux-x64
• ... and 94 more: https://git.openjdk.java.net/jdk/compare/3e73a0b726a97df0a4e92f9cf917429346090f45...master

Your commit was automatically rebased without conflicts.

[openjdk]

@mlchung Pushed as commit 1ddab6f.

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