8347955: TimeZone methods to stream the available timezone IDs by justin-curtis-lu · Pull Request #23251 · openjdk/jdk

justin-curtis-lu · 2025-01-23T02:49:49Z

Please review this PR and CSR which add a pair of methods to java.util.TimeZone that return a stream of the available IDs. See the CSR for the motivation.

A number of existing tests are modified to use the new methods. See test/jdk/java/util/TimeZone/AvailableIDsTest.java which tests the new methods.

Progress

Change must be properly reviewed (1 review required, with at least 1 Reviewer)
Change must not contain extraneous whitespace
Commit message must refer to an issue
Change requires CSR request JDK-8348325 to be approved

Issues

JDK-8347955: TimeZone methods to stream the available timezone IDs (Enhancement - P4)
JDK-8348325: TimeZone methods to stream the available timezone IDs (CSR)

Reviewers

Naoto Sato (@naotoj - Reviewer)
Roger Riggs (@RogerRiggs - Reviewer)

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bridgekeeper · 2025-01-23T02:50:26Z

👋 Welcome back jlu! 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 · 2025-01-23T02:50:53Z

@justin-curtis-lu 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:

8347955: TimeZone methods to stream the available timezone IDs

Reviewed-by: naoto, rriggs

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 67 new commits pushed to the master branch:

21feef3: 8348239: SA does not know about DeoptimizeObjectsALotThread
8cc1304: 8287788: Implement a better allocator for downcalls
039e73f: 8346736: Java Security Standard Algorithm Names spec should include key algorithm names
aba60a9: 8189441: Define algorithm names for keys derived from KeyAgreement
03106eb: 8344119: CUPSPrinter does not respect PostScript printer definition specification in case of reading ImageableArea values from PPD files
ad01dfb: 8346920: Serial: Support allocation in old generation when heap is almost full
1d8ccb8: 8342465: Improve API documentation for java.lang.classfile
7d6055a: 8348429: Update cross-compilation devkits to Fedora 41/gcc 13.2
f1e0797: 8348586: Optionally silence make warnings about non-control variables
ffeb9b5: 8342807: Update links in java.base to use https://
... and 57 more: https://git.openjdk.org/jdk/compare/b720517cb33c2119ec6ed85504bce321de748228...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.

openjdk · 2025-01-23T02:51:37Z

@justin-curtis-lu The following labels will be automatically applied to this pull request:

core-libs
i18n

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

mlbridge · 2025-01-23T02:55:46Z

Webrevs

naotoj

Looks good. Some files need copyright year bump

naotoj · 2025-01-23T17:41:35Z

src/java.base/share/classes/java/util/TimeZone.java

+     * not create a copy of the {@code TimeZone} IDs array.
+     *
+     * @param rawOffset the given time zone GMT offset in milliseconds.
+     * @return an array of IDs, where the time zone for that ID has


array -> stream

Thanks for the catch. Fixed this and bumped those Zone* file copyright years in 48956fd. I double checked that all the test files have 2025 copyright years.

naotoj · 2025-01-23T17:57:35Z

src/java.base/share/classes/sun/util/calendar/ZoneInfoFile.java

        // specify it. Keep the same behavior for better
        // compatibility.
-        String[] list = ids.toArray(new String[ids.size()]);
+        String[] list = ids.toArray(new String[0]);


Why is this change? Since the array has correct size, no extra array allocation is needed?

Regarding the switch from toArray(new T[size]) to toArray(new T[0]), based off https://shipilev.net/blog/2016/arrays-wisdom-ancients/#_conclusion, the JVM performs the latter faster. I believe the article data/results still hold true now.

naotoj · 2025-01-23T18:13:47Z

src/java.base/share/classes/sun/util/calendar/ZoneInfoFile.java

+    public static Stream<String> zoneIds(int rawOffset) {
+        return zoneIds()
+                .filter(id -> getZoneInfo(id).getRawOffset() == rawOffset)
+                .sorted(); // Sort the IDs, see getZoneIds(int)


This is interesting. one with rawOffset is soreted, but the other is not. It is inconsistent but probably we should align as you did here.

Noticed that too. There is also the argument that since these stream methods are new, we can leave it un-sorted but we would have to specify the deviation. Although I agree it is best to align for consistency.

Actually I'm wondering if we should specify these rawOffset methods with an @implNote that states they are sorted.

I'd rather not. If we did, users would wonder why no-arg return is not sorted, which might be a mere overlook (and if we sort it, it would be costly (num of tzids are not small))

Fair enough.

liach · 2025-01-23T20:04:04Z

src/java.base/share/classes/java/util/TimeZone.java

+     * @see #getAvailableIDs(int)
+     * @since 25
+     */
+    public static synchronized Stream<String> availableIDs(int rawOffset) {


Why are these new methods synchronized? I think the streams and the spliterators are late-binding, so the synchronization does not synchronize the access to the underlying arrays. synchronized modifier also does not appear in Javadoc and is not part of the API surface, so it can be safely removed.

Right, it can be removed. Actually, I think getAvailableIDs() and getAvailableIDs(int) also do not need to be synchronized. The internal IDs are eagerly initialized in the static block of ZoneInfoFile.java and are effectively final and not modified.

Yep; their synchronized are incorrect. The object monitor lock should have been on ZoneInfoFile.class to be effective.

Related PR waiting for review - #17441

naotoj

LGTM

RogerRiggs

Looks good

justin-curtis-lu · 2025-01-28T21:30:16Z

Thanks for the reviews.
/integrate

openjdk · 2025-01-28T21:31:49Z

Going to push as commit 3a564ed.
Since your change was applied there have been 84 commits pushed to the master branch:

1efae9a: 8348888: tier1 closed build failure on Windows after JDK-8348348
c018a60: 8344637: Fix Page8 of manual test java/awt/print/PrinterJob/PrintTextTest.java on Linux and Windows
c3c3888: 8336760: [JVMCI] -XX:+PrintCompilation should also print "hosted" JVMCI compilations
9f4d3de: 8347718: Unexpected NullPointerException in C2 compiled code due to ReduceAllocationMerges
a224f12: 8348205: Improve cutover time selection when building available currencies set
8103256: 8348348: Remove unnecessary #ifdef STATIC_BUILD around DEF_STATIC_JNI_OnLoad from zip_util.c
fb066ca: 8347272: [ubsan] JvmLauncher.cpp:262:52: runtime error: applying non-zero offset 40 to null pointer
5fec999: 8339668: Parallel: Adopt PartialArrayState to consolidate marking stack in Full GC
2bef5b4: 8348323: Corrupted timezone string in JVM crash log
3a8680e: 8347058: When automatically translating the page to pt-br, all CSS styling disappears
... and 74 more: https://git.openjdk.org/jdk/compare/b720517cb33c2119ec6ed85504bce321de748228...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-01-28T21:31:58Z

@justin-curtis-lu Pushed as commit 3a564ed.

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

justin-curtis-lu added 3 commits January 22, 2025 18:23

src

d253cc9

test

5aa2d3d

space at EOF

4df9016

openjdk bot changed the title ~~JDK-8347955: TimeZone methods to stream the available timezone IDs~~ 8347955: TimeZone methods to stream the available timezone IDs Jan 23, 2025

openjdk bot added csr Pull request needs approved CSR before integration rfr Pull request is ready for review labels Jan 23, 2025

openjdk bot added core-libs core-libs-dev@openjdk.org i18n i18n-dev@openjdk.org labels Jan 23, 2025

naotoj reviewed Jan 23, 2025

View reviewed changes

justin-curtis-lu added 2 commits January 23, 2025 10:48

reflect Naoto's review

48956fd

include copyright bump for missed file in JDK-834836501

db90722

liach reviewed Jan 23, 2025

View reviewed changes

new methods do not need to be synchronized

ef3e275

openjdk bot removed the csr Pull request needs approved CSR before integration label Jan 24, 2025

naotoj approved these changes Jan 24, 2025

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openjdk bot added the ready Pull request is ready to be integrated label Jan 24, 2025

RogerRiggs approved these changes Jan 27, 2025

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openjdk bot added the integrated Pull request has been integrated label Jan 28, 2025

openjdk bot closed this Jan 28, 2025

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Jan 28, 2025

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