8269223: -Xcheck:jni WARNINGs working with fonts on Linux by mkartashev · Pull Request #4572 · openjdk/jdk

mkartashev · 2021-06-23T09:19:16Z

Added an ExceptionCheck() followed by ExceptionDescribe() and ExceptionClear() immediately after the Java calls made from the callback function ReadTTFontFileFunc() in freetypeScaler.c.

The exception(s) need to be cleared because we're not returning immediately to Java that would've been able to handle them gracefully. And in order not to loose the exception entirely (even though the return value would also indicate an error condition), print out the exception with ExceptionDescribe() to aid in debugging.

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Issue

JDK-8269223: -Xcheck:jni WARNINGs working with fonts on Linux

Reviewers

Phil Race (@prrace - Reviewer) ⚠️ Review applies to 13b0868
Sergey Bylokhov (@mrserb - Reviewer)

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bridgekeeper · 2021-06-23T09:19:25Z

👋 Welcome back mkartashev! 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 · 2021-06-23T09:23:07Z

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

2d

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mlbridge · 2021-06-23T09:28:43Z

Webrevs

mrserb · 2021-06-29T23:16:11Z

test/jdk/java/awt/font/JNICheck/FreeTypeScalerJNICheck.java

+/* @test
+ * @bug 8269223
+ * @summary Verifies that -Xcheck:jni issues no warnings from freetypeScaler.c
+ * @requires os.family == "linux"


Can we run this test on all platforms? Since this bug was not found, means we did not cover this code by the tests, and it will be useful to test it even if the code path will be different on other platforms.

Sure; dropped the @requires clause.

mrserb · 2021-06-29T23:19:43Z

src/java.desktop/share/native/libfontmanager/freetypeScaler.c

                                 FTScalerInfo* scalerInfo) {
    freeNativeResources(env, scalerInfo);
    (*env)->CallVoidMethod(env, scaler, invalidateScalerMID);
+    // NB: Exceptions must not be cleared (and therefore no JNI calls performed) after calling this method


Please split long lines to 80 chars per line

mrserb · 2021-06-29T23:26:46Z

src/java.desktop/share/native/libfontmanager/freetypeScaler.c

                                          sunFontIDs.ttReadBlockMID,
                                          bBuffer, offset, numBytes);
+            // This is a callback, we are not returning immediately to Java and better report exceptions now
+            CHECK_EXCEPTION(env);


Probably we should report it only if "debugFonts" was set?

prrace · 2021-06-30T00:08:22Z

src/java.desktop/share/native/libfontmanager/freetypeScaler.c

+    if ((*(env))->ExceptionCheck(env)) { \
+        (*(env))->ExceptionDescribe(env);\
+        (*(env))->ExceptionClear(env);   \
+    }


https://docs.oracle.com/en/java/javase/11/docs/specs/jni/functions.html#exceptiondescribe

"The pending exception is cleared as a side-effect of calling this function"

So you certainly don't need both of these and I would prefer that Describe only be used if really debugging where we think there's a REAL chance of an exception rather than just to keep JNI happy.

And the upcall that is likely (readBlock) itself will log any IOException (and catch it) in the event of an I/O error so I really think this is unlikely to be useful here.

Yes, makes sense. I made CHECK_EXCEPTION() call either Clear... or Describe... based on the value of debugFonts.
Please, take a look.

prrace · 2021-06-30T00:09:05Z

src/java.desktop/share/native/libfontmanager/freetypeScaler.c

                                          scalerInfo->font2D,
                                          sunFontIDs.ttReadBlockMID,
                                          bBuffer, offset, numBytes);
+            // This is a callback, we are not returning immediately to Java and better report exceptions now


I think the comment is un-needed .. since the only reason to call CHECK_EXCEPTION() is because of this.
Same for the other case.

OK, comments removed.

1. Allowed test to run on any platform. 2. Trimmed comments to fit in with 80 columns. 3. Removed unnecessayr comments. 4. Made the ExceptionDescribe() calls conditional on the value of FontUtilities.debugFonts()

mrserb · 2021-07-02T04:02:45Z

Looks fine to me, I'll run the tests.

mkartashev · 2021-07-07T09:56:27Z

Looks fine to me, I'll run the tests.

@mrserb Any news on that front?

mrserb · 2021-07-09T16:42:38Z

@mrserb Any news on that front?

The new test fails on all platforms:

Linux/MacOS: The test should be marked as headful, otherwise it may run on headless systems where "No X11 DISPLAY variable was set"
WIndows: The jni warnings are generated in the log.

system. 2. Added exception checks to Windows-specific code.

mrserb · 2021-07-17T03:03:41Z

src/java.desktop/windows/native/libawt/java2d/d3d/D3DRenderQueue.cpp

        J2dTraceLn(J2D_TRACE_VERBOSE, "  executing runnable");
-        JNU_CallMethodByName(env, NULL, pFlush->runnable, "run", "()V");
+        jboolean ignoreException;
+        JNU_CallMethodByName(env, &ignoreException, pFlush->runnable, "run", "()V");


What is the purpose of this change? the only difference is that in the second case the ExceptionCheck will be called, does it affect something?

Yes, the ExceptionCheck() call will silence the warnings from -Xcheck:jni.

Does it actually suppress the "Xcheck:jni" or it clears a raised exception? If an exception is still "raised" after this call we should do some additional steps to log/clean it.

Yes, the exception will still be "raised" after this call. Since there are no JNI calls (at least those that are forbidden to make with an exception pending) between here and return back to Java, I believe no additional steps are necessary.

Then I suggest logging them via some of the trace macros.

Sure, added some logging.

mrserb · 2021-07-17T03:05:35Z

src/java.desktop/windows/native/libawt/windows/awt_Component.cpp

+    jboolean ignoreException;
+    jintArray obj = (jintArray)JNU_CallStaticMethodByName(env, &ignoreException,
+                                                          "java/awt/event/InputEvent",
+                                                          "getButtonDownMasks", "()[I").l;


obj might be null? Can not we just add CHECK_NULL(obj) here?

obj indeed might be null, especially since all kinds of things could go wrong during class/method resolution. Added CHECK_NULL(obj) here.

1. Added CHECK_NULL() to awt_Component.cpp

mkartashev · 2021-08-04T08:19:45Z

Ping.

prrace · 2021-08-12T21:13:04Z

I'm going to see if the test passes on the internal systems we use which I think will be mostly variout RH/OL systems for this headless test for Linux - and it also will get run on Windows Server of some kind .. I don't think macOS will hit this code path at all for this test.

prrace · 2021-08-12T21:57:37Z

test/jdk/java/awt/font/JNICheck/FreeTypeScalerJNICheck.java

+import java.awt.*;
+import java.awt.geom.Rectangle2D;
+import java.awt.image.*;
+import java.io.*;


Can we get rid of all these wild card imports ?

Sure, replaced with single-class imports.

prrace · 2021-08-12T21:58:07Z

test/jdk/java/awt/font/JNICheck/FreeTypeScalerJNICheck.java

+ * @bug 8269223
+ * @summary Verifies that -Xcheck:jni issues no warnings from freetypeScaler.c
+ * @library /test/lib
+ * @key headful


What about this test is headful ?

oh you are getting metrics for a JFrame ? That's not going to exercise any new font code so is pointless except to make it so the test has to be headful.

But getFontMetrics() is the primary "entry point" that generated all the JNI warnings in the first place. And I'm also not sure that we could've gotten all the warnings on Windows without JFrame.

So what's wrong with
g2d.setFont(font);
FontMetrics metrics = g2d.getFontMetrics(font);

?

No frame needed.

Indeed. Changed the test per your suggestions.

prrace · 2021-08-12T21:59:12Z

test/jdk/java/awt/font/JNICheck/FreeTypeScalerJNICheck.java

+
+        for (String ff : families)
+        {
+            Font font = Font.decode(ff);


Gosh, does anyone still use decode() ? I keep forgetting it exists.
You have all the family names, why not just new Font(ff, Font.PLAIN, 12) ?

OK, changed to new Font(...).

1. Optimized imports in the test. 2. Got rid of Font.decode().

prrace · 2021-08-13T19:39:45Z

passes

Looks good. I tried the test as headless and headful which happens to then exercise a broader set of distros than only one or the other the way our systems are set up.

openjdk · 2021-08-13T19:42:56Z

@mkartashev 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:

8269223: -Xcheck:jni WARNINGs working with fonts on Linux

Reviewed-by: prr, serb

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 739 new commits pushed to the master branch:

f77a1a1: 8272472: StackGuardPages test doesn't build with glibc 2.34
04a806e: 8270344: Session resumption errors
d85560e: 8267161: Write automated test case for JDK-4479161
1ea437a: 8272720: Fix the implementation of loop unrolling heuristic with LoopPercentProfileLimit
86add21: 8223923: C2: Missing interference with mismatched unsafe accesses
c701f6e: 8272739: Misformatted error message in EventHandlerCreator
fb1dfc6: 8267185: Add string deduplication support to ParallelGC
d874e96: 8271579: G1: Move copy before CAS in do_copy_to_survivor_space
92bde67: 8271946: Cleanup leftovers in Space and subclasses
db9834f: 8258951: java/net/httpclient/HandshakeFailureTest.java failed with "RuntimeException: Not found expected SSLHandshakeException in java.io.IOException"
... and 729 more: https://git.openjdk.java.net/jdk/compare/1a818154cfe852a680070c5c07f2df33109e5b54...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.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@prrace, @mrserb) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

@prrace

1. Added code to log the exception if it occurred when running a flushBuffer's runnable. The logging is minimal in order to avoid replacing the exception with another one before it reaches Java. 2. Made the test not dependent on headful code as per @prrace suggestions.

mrserb · 2021-08-16T18:52:26Z

Will the updated test case cover the same code paths where the bugs were found and fixed by this change?

mkartashev · 2021-08-17T18:49:35Z

Will the updated test case cover the same code paths where the bugs were found and fixed by this change?

I believe so - on Linux. Windows-specific changes are mostly covered (I verified Java_java_awt_Component_initIDs() (from awt_Component.cpp) and D3DRQ_FlushBuffer() (from D3DRenderQueue.cpp). Not all the AwtDesktopProperties::Set...Property() (from awt_DesktopProperties.cpp ) are touched by the test. I originally applied the changes to all the similar code there without verifying that each piece is invoked by the test.

mkartashev · 2021-08-22T08:04:08Z

/integrate

openjdk · 2021-08-22T08:05:32Z

@mkartashev
Your change (at version 4b2febe) is now ready to be sponsored by a Committer.

mrserb · 2021-08-23T20:26:41Z

/sponsor

openjdk · 2021-08-23T20:28:28Z

Going to push as commit 9bc0232.
Since your change was applied there have been 749 commits pushed to the master branch:

2ff4c01: 8271600: C2: CheckCastPP which should closely follow Allocate is sunk of a loop
ad92033: 8272736: [JVMCI] Add API for reading and writing JVMCI thread locals
709b591: 8272553: several hotspot runtime/CommandLine tests don't check exit code
1884072: 8265253: javac -Xdoclint:all gives "no comment" warning for code that can't be commented
594e516: 8272778: Consolidate is_instance and is_instance_inlined in java_lang_String
d542745: 8267894: Skip work for empty regions in G1 Full GC
741f58c: 8272417: ZGC: fastdebug build crashes when printing ClassLoaderData
b7f75c0: 8271142: package help is not displayed for missing X11/extensions/Xrandr.h
e8a289e: 8272609: Add string deduplication support to SerialGC
b690f29: 8269687: pauth_aarch64.hpp include name is incorrect
... and 739 more: https://git.openjdk.java.net/jdk/compare/1a818154cfe852a680070c5c07f2df33109e5b54...master

Your commit was automatically rebased without conflicts.

openjdk · 2021-08-23T20:28:46Z

@mrserb @mkartashev Pushed as commit 9bc0232.

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

8269223: -Xcheck:jni WARNINGs working with fonts on Linux

1622a16

openjdk bot added the rfr Pull request is ready for review label Jun 23, 2021

openjdk bot added the 2d client-libs-dev@openjdk.org label Jun 23, 2021

mrserb reviewed Jun 29, 2021

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prrace reviewed Jun 30, 2021

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Addressed PR comments

d1bc82e

1. Allowed test to run on any platform. 2. Trimmed comments to fit in with 80 columns. 3. Removed unnecessayr comments. 4. Made the ExceptionDescribe() calls conditional on the value of FontUtilities.debugFonts()

1. Marked the test as headful so that it doesn't fail on a headless

9cc7c8e

system. 2. Added exception checks to Windows-specific code.

mrserb reviewed Jul 17, 2021

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Addressed PR comments

050c2e9

1. Added CHECK_NULL() to awt_Component.cpp

prrace reviewed Aug 12, 2021

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Addressed PR comments

13b0868

1. Optimized imports in the test. 2. Got rid of Font.decode().

prrace approved these changes Aug 13, 2021

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openjdk bot added the ready Pull request is ready to be integrated label Aug 13, 2021

mrserb approved these changes Aug 17, 2021

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openjdk bot added the sponsor Pull request is ready to be sponsored label Aug 22, 2021

openjdk bot closed this Aug 23, 2021

openjdk bot added integrated Pull request has been integrated and removed ready Pull request is ready to be integrated rfr Pull request is ready for review sponsor Pull request is ready to be sponsored labels Aug 23, 2021

mkartashev deleted the JDK-8269223 branch February 10, 2022 12:16

openjdk bot added the client client-libs-dev@openjdk.org label Feb 10, 2022

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mkartashev commented Jun 23, 2021 •

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