8288628: Unnecessary Hashtable usage in ConditionalSpecialCasing

[turbanoff]

If a thread-safe implementation is not needed, it is recommended to use HashMap in place of Hashtable.
ConditionalSpecialCasing.entryTable is read-only Map which is modified only in static block. It means we can safely replace it with HashMap.

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Issue

• JDK-8288628: Unnecessary Hashtable usage in ConditionalSpecialCasing

Reviewers

• Naoto Sato (@naotoj - Reviewer)
• Jaikiran Pai (@jaikiran - Reviewer)

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[mlbridge]

Webrevs

• 00: Full (75dc0c44)

[naotoj]

Looks good.
I would have refactored the initialization of the static map itself, but it would be for another day.

[openjdk]

@turbanoff 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:

8288628: Unnecessary Hashtable usage in ConditionalSpecialCasing

Reviewed-by: naoto, jpai

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At the time when this comment was updated there had been 34 new commits pushed to the master branch:

• 47b8669: 8288573: Make Executable.getParameterCount() actually abstract
• af64d31: Merge
• 53bf1bf: 8286176: Add JNI_VERSION_19 to jni.h and JNI spec
• c254c9d: 8287401: jpackage tests failing on Windows due to powershell issue
• ff3db52: 8288534: Out of bound errors for memory segment access mentions wrong values
• cc44592: 8287904: Reduce runtime of java.net microbenchmarks
• 523d553: 8282777: Create a Regression test for JDK-4515031
• f3da7ff: 8288421: IGV: warn user about all unreachable nodes
• 9d4b25e: 8288281: compiler/vectorapi/VectorFPtoIntCastTest.java failed with "IRViolationException: There were one or multiple IR rule failures."
• e833c1d: 8285519: Change usages of TimeUnit.convert to TimeUnit.toXXX
• ... and 24 more: https://git.openjdk.org/jdk/compare/3475e12fa6c50dbaf53b6b03f3b8032017394c1f...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]

Changing this to HashMap now means that usages of this might have to check for null values returned by the Map APIs. Looking at the usage of entryTable, it appears that there are relevant null checks already in place, plus I don't see any code in this class which directly returns the values from the entryTable to callers of this class.

So the change looks fine to me.

[turbanoff]

/integrate

[openjdk]

Going to push as commit 0f801fe.
Since your change was applied there have been 61 commits pushed to the master branch:

• 701ea3b: 8288556: VM crashes if it gets sent SIGUSR2 from outside
• 5e680d0: 8288724: Prevent NullPointerException in serviceability/tmtools/jstack/DaemonThreadTest.java if jstack process fails
• ad89146: 8288601: Consolidate static/dynamic archive tables
• 7e211d7: 8287672: jtreg test com/sun/jndi/ldap/LdapPoolTimeoutTest.java fails intermittently in nightly run
• 7039c66: Merge
• 453e8be: 8288527: broken link in java.base/java/util/zip/package-summary.html
• 33d0363: 8288741: JFR: Change package name of snippet files
• 0408f9c: 8288663: JFR: Disabling the JfrThreadSampler commits only a partially disabled state
• 1cf83a4: 8287800: JFR: Incorrect error message when starting recording with missing .jfc file
• 09da87c: 8288485: jni/nullCaller/NullCallerTest.java failing (ppc64)
• ... and 51 more: https://git.openjdk.org/jdk/compare/3475e12fa6c50dbaf53b6b03f3b8032017394c1f...master

Your commit was automatically rebased without conflicts.

[openjdk]

@turbanoff Pushed as commit 0f801fe.

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