RFR: 8262520: Add CLHSDB command to connect to debug server [v3]

[Yasumasa Suenaga]

On Tue, 2 Mar 2021 22:24:17 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> Yasumasa Suenaga has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix comments
>
> src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/HSDB.java line 100:
> 
>> 98:     execPath = null;
>> 99:     coreFilename = null;
>> 100:     remoteMachineName = null;
> 
> In general it's not clear to me why HSDB.java needed to be modified in a way similar to CLHSDB.java. If the goal is really just to add debug server support to the `clshdb attach` command, why is HSDB involved in that? Or is this adding debug server support elsewhere also (in which case it's not clear to me where this exposed to the user)?

As I said in above, CLHSDB.java and HSDB.java are similar, and also I added `attach(String debugServerName)` to `CommandProcessor$DebuggerInterface` which is used in HSDB.java, so I changed HSDB.java even though it does not affect to HSDB.

We can implement `attach(String debugServerName)` as empty method, and it might be reasonable. What do you think?

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PR: https://git.openjdk.java.net/jdk/pull/2773