JDK-8266536: Provide a variant of os::iso8601_time which works with arbitrary timestamps #3869

tstuefe · 2021-05-05T04:31:57Z

We have os::iso8601_time(), which gives an ISO8601 timestamp of the current time. It would be very useful to have a second variant which can be fed an arbitrary numerical timestamp.

This is useful in the context of making asynchronous UL logging cheaper (see JDK-8229517)

This patch provides an additional API:
char* os::iso8601_time(jlong milliseconds_since_19700101, char* buffer, size_t buffer_length, bool utc);
alongside the existing
char* os::iso8601_time(char* buffer, size_t buffer_length, bool utc);
and implements the latter using the former. Not much code added.

In addition, it adds a regression gtest for these APIs.

Please ignore the harfbuzz change, its a build fix needed for older gcc, will be removed before final push.

Testing: GHA, manual gtests, SAP nightlies on all our platforms.

Thanks, Thomas

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Issue

JDK-8266536: Provide a variant of os::iso8601_time which works with arbitrary timestamps

Reviewers

Xin Liu (@navyxliu - no project role) ⚠️ Review applies to bfa41f1
Volker Simonis (@simonis - Reviewer) ⚠️ Review applies to 40f23a2
Yasumasa Suenaga (@YaSuenag - Reviewer)

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Update a local copy of the PR:
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$ git pull https://git.openjdk.java.net/jdk pull/3869/head

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bridgekeeper · 2021-05-05T04:32:03Z

👋 Welcome back stuefe! 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 · 2021-05-05T04:33:56Z

@tstuefe 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.

navyxliu

The API change looks good to me. I understand that this is prerequisite of your logdecoration change. make sense.

I don't understand your change in harfbuzz header.

navyxliu · 2021-05-05T18:54:42Z

src/java.desktop/share/native/libharfbuzz/hb-ot-shape-complex-use-machine.hh

@@ -375,7 +375,7 @@ hb_iter_with_fallback_t<machine_index_t<Iter>,
 typename Iter::item_t>
 {
        machine_index_t (const Iter& it) : it (it) {}
-        machine_index_t (const machine_index_t& o) : it (o.it) {}
+        machine_index_t (const machine_index_t& o) : hb_iter_with_fallback_t<machine_index_t<Iter>, typename Iter::item_t>(o), it (o.it) {}


is it relevant?
I feel it belongs to a separated issue.

Sorry, forgot to mention. Unrelated harfbuzz build fix for gcc 8 and earlier. Will remove before the final push.

The API change looks good to me. I understand that this is prerequisite of your logdecoration change. make sense.

I don't understand your change in harfbuzz header.

Thanks for your review, Xin.

mlbridge · 2021-05-06T04:43:11Z

Webrevs

simonis

Change looks good. I have just two minor questions (see inline).

Thanks for adding the gtest!

simonis · 2021-05-06T09:02:49Z

test/hotspot/gtest/runtime/test_os.cpp

+static bool very_simple_string_matcher(const char* pattern, const char* s) {
+  const size_t lp = strlen(pattern);
+  const size_t ls = strlen(s);
+  if (ls < lp) {


Shouldn't this be !=?

I wanted to be able to give prefix pattern which do not cover the whole string.

simonis · 2021-05-06T09:04:22Z

test/hotspot/gtest/runtime/test_os.cpp

+  result = os::iso8601_time(buffer, sizeof(buffer), false);
+  tty->print_cr("%s", result);
+  EXPECT_EQ(result, buffer);
+  EXPECT_TRUE(very_simple_string_matcher(pattern, result));


Do you intentionally repeat this same test for a second time? Does it provide any benefit?

Oops, no, this is an oversight. I'll remove the second test, thanks for catching this.

tstuefe · 2021-05-06T09:52:01Z

Change looks good. I have just two minor questions (see inline).

Thanks for adding the gtest!

Thanks Volker!

simonis

Looks good, thanks.

openjdk · 2021-05-06T13:45:35Z

@tstuefe 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:

8266536: Provide a variant of os::iso8601_time which works with arbitrary timestamps

Reviewed-by: xliu, simonis, ysuenaga

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 20 new commits pushed to the master branch:

ebb68d2: 8049700: Deprecate obsolete classes and methods in javax/swing/plaf/basic
3a474d9: 8265612: revise the help info for jmap histo command
c97f56c: 8266172: -Wstringop-overflow happens in vmError.cpp
43ad24f: 8265465: jcmd VM.cds should keep already dumped archive when exception happens
66191ff: 8266193: BasicJMapTest does not include testHistoParallel methods
36e5ad6: 8263236: runtime/os/TestTracePageSizes.java fails on old kernels
0ca86da: 8266002: vmTestbase/nsk/jvmti/ClassPrepare/classprep001 should skip events for unexpected classes
52f1db6: 8262002: java/lang/instrument/VerifyLocalVariableTableOnRetransformTest.sh failed with "TestCaseScaffoldException: DummyClassWithLVT did not match .class file"
04f7112: 8266293: Key protection using PBEWithMD5AndDES fails with "java.security.InvalidAlgorithmParameterException: Salt must be 8 bytes long"
a90b33a: 8266573: Make sure blackholes are tagged for all JVMCI paths
... and 10 more: https://git.openjdk.java.net/jdk/compare/a86ee9b3f370b59caea2ae78169d13498560cd8e...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.

tstuefe · 2021-05-06T16:10:23Z

Looks good, thanks.

Thank you Volker!

navyxliu · 2021-05-06T19:17:29Z

src/hotspot/share/runtime/os.hpp

+  // Fill in buffer with an ISO-8601 string corresponding to the given javaTimeMillis value
+  // E.g., YYYY-MM-DDThh:mm:ss.mmm+zzzz.
+  // Returns buffer, or NULL if it failed.
+  static char* iso8601_time(jlong milliseconds_since_19700101, char buffer[29],


You are supposed to get a compiler warning on this char buffer[29]. ISO C/C++ can't pass in array type as a function argument. As a result, the type buffer automatically casts to char* here.

Further, the function signature is different from its implementation, which use char* buffer instead.
I see that you do enforce length checking in implementation.

Oh, good catch, this is a stray edit I thought I reverted. See below.

ISO C/C++ can't pass in array type as a function argument. As a result, the type buffer automatically casts to char* here.

No, it can, that's totally fine. It gets automatically translated to pointer type, but its a valid expression nonetheless.

It is usually done to indicate that a function expects an output array of a particular length instead of letting the caller guess the right length - and letting him to deal with truncation if he guesses wrong.

I originally planned to define the function as

iso8601_time(jlong milliseconds_since_19700101, char buffer[29]);

to indicate that the only output value length which makes sense is 29, but then I refrained because I wanted to keep the patch simple.

C/C++ allow you to write code like that, but they won't check the length of argument <=29 for you.
I think you sanity check inside of iso8601_time() is good enough.

tstuefe · 2021-05-07T06:07:31Z

Thanks @navyxliu and @simonis and @YaSuenag for your reviews.

Last change:

fixes the stray edit in the prototype Xin noted
adds an explicit constant for the output buffer size of iso timestamps

@YaSuenag could you please officially approve this PR? Unfortunately, Xin is no committer yet, so I need a second reviewer.

Thanks, Thomas

YaSuenag

Looks good!
I think needed_buffer in os::iso8601_time() is no longer needed, but it's ok if it is left.

tstuefe · 2021-05-07T07:02:20Z

Looks good!
I think needed_buffer in os::iso8601_time() is no longer needed, but it's ok if it is left.

Thanks Yasumasa! I changed the code a bit and removed needed_buffer.

YaSuenag

Thank you for fixing it! It still looks good.

tstuefe · 2021-05-07T09:46:14Z

/integrate

openjdk · 2021-05-07T09:48:10Z

@tstuefe Since your change was applied there have been 21 commits pushed to the master branch:

71b8ad4: 8266609: AArch64: include FP/LR space in LIR_Assembler::initial_frame_size_in_bytes()
ebb68d2: 8049700: Deprecate obsolete classes and methods in javax/swing/plaf/basic
3a474d9: 8265612: revise the help info for jmap histo command
c97f56c: 8266172: -Wstringop-overflow happens in vmError.cpp
43ad24f: 8265465: jcmd VM.cds should keep already dumped archive when exception happens
66191ff: 8266193: BasicJMapTest does not include testHistoParallel methods
36e5ad6: 8263236: runtime/os/TestTracePageSizes.java fails on old kernels
0ca86da: 8266002: vmTestbase/nsk/jvmti/ClassPrepare/classprep001 should skip events for unexpected classes
52f1db6: 8262002: java/lang/instrument/VerifyLocalVariableTableOnRetransformTest.sh failed with "TestCaseScaffoldException: DummyClassWithLVT did not match .class file"
04f7112: 8266293: Key protection using PBEWithMD5AndDES fails with "java.security.InvalidAlgorithmParameterException: Salt must be 8 bytes long"
... and 11 more: https://git.openjdk.java.net/jdk/compare/a86ee9b3f370b59caea2ae78169d13498560cd8e...master

Your commit was automatically rebased without conflicts.

Pushed as commit 94c6177.

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

start

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openjdk bot added the hotspot-runtime hotspot-runtime-dev@openjdk.org label May 5, 2021

tstuefe added 3 commits May 5, 2021 09:23

Merge

4b06d9d

Build fix for Harfbuzz

855c52d

gtest for os.iso8601_time should use utc

bfa41f1

tstuefe mentioned this pull request May 5, 2021

JDK-8266503: [UL] Make Decorations safely copy-able and reduce their size #3874

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tstuefe marked this pull request as ready for review May 6, 2021 04:38

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Remove duplicate coding in gtest

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remove harfbuzz fix

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feedback yasumasa and xin

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remove stray edit

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tstuefe deleted the JDK-8266536-os-iso6801-for-arbitrary-timestamps branch June 29, 2021 05:34

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JDK-8266536: Provide a variant of os::iso8601_time which works with arbitrary timestamps #3869

JDK-8266536: Provide a variant of os::iso8601_time which works with arbitrary timestamps #3869

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JDK-8266536: Provide a variant of os::iso8601_time which works with arbitrary timestamps #3869

JDK-8266536: Provide a variant of os::iso8601_time which works with arbitrary timestamps #3869

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