RFR: JDK-8308300: enhance exceptions in MappedMemoryUtils.c

[Alan Bateman]

On Fri, 19 May 2023 06:58:49 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> MappedMemoryUtils.c can generate exceptions like those :
> java.io.UncheckedIOException: java.io.IOException: Invalid argument
>        at java.base/java.nio.MappedMemoryUtils.force(MappedMemoryUtils.java:105)
>        at java.base/java.nio.Buffer$2.force(Buffer.java:890)
>        at java.base/jdk.internal.misc.ScopedMemoryAccess.forceInternal(ScopedMemoryAccess.java:317)
>        at java.base/jdk.internal.misc.ScopedMemoryAccess.force(ScopedMemoryAccess.java:305)
>        at java.base/jdk.internal.foreign.MappedMemorySegmentImpl.force(MappedMemorySegmentImpl.java:92)
>        at TestByteBuffer.testMappedSegmentAsByteBuffer(TestByteBuffer.java:327)
> 
> (we see this for example on AIX); there is some room for improvement, at least the info should be added that msync failed and caused this exception.

src/java.base/share/native/libjava/jni_util.c line 196:

> 194: {
> 195:     JNU_ThrowByNameWithMessageAndLastError(env, "java/io/IOException", message);
> 196: }

The additional function looks okay but I think the function description would be clearer if it were like this


/*
 * Throw java.io.IOException using a given message and the string
 * returned by getLastErrorString to construct the detail string.
 */


I see JNU_ThrowIOExceptionWithLastError also "Convenience method" but it's a function :-)

src/java.base/unix/native/libnio/MappedMemoryUtils.c line 114:

> 112:     if (result == -1) {
> 113:         JNU_ThrowIOExceptionWithMessageAndLastError(env, "madvise with parameter MADV_WILLNEED failed");
> 114:     }

Maybe change "with parameter" to "with advise" so it's clearer what the value is about?

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PR Review Comment: https://git.openjdk.org/jdk/pull/14054#discussion_r1198727146
PR Review Comment: https://git.openjdk.org/jdk/pull/14054#discussion_r1198728333