RFR: 8271419: Refactor test code for modifying CDS archive contents [v2]

[Yumin Qi]

On Mon, 2 Aug 2021 06:46:00 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Yumin Qi has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Move more function to CDSArchiveUtils, fixed review comments
>
> test/hotspot/jtreg/runtime/cds/appcds/SharedArchiveConsistency.java line 66:
> 
>> 64:         "Unable to use shared archive",
>> 65:         "The shared archive file has a bad magic number",
>> 66:         "Unable to map shared spaces",
> 
> Why are these new errors needed? Did you change any behavior of the tests?

Thanks for mentioning this. There is an issue to use FileChannel:
            outputChannel.transferFrom(inputChannel, 0, offset);
         + outputChannel.position(offset);    // <---- need explicitly positioned or the following write to overwrite from offset 0.
            outputChannel.write(ByteBuffer.wrap(bytes));
            outputChannel.transferFrom(inputChannel, offset + bytes.length, orgSize - bytes.length);

The added lines should be removed.

> test/lib/jdk/test/lib/cds/CDSArchiveUtils.java line 73:
> 
>> 71: 
>> 72:     public static void initialize() throws Exception {
>> 73:         WhiteBox wb = WhiteBox.getWhiteBox();
> 
> This method can be changed to a `static { ....}` block, so that you don't need to explicitly call `CDSArchiveUtils.initialize()`.

Will move to static block.

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PR: https://git.openjdk.java.net/jdk/pull/4945