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

[Yasumasa Suenaga]

On Tue, 2 Mar 2021 21:48:30 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/doc/clhsdb.html line 39:
> 
>> 37: Available commands:
>> 38:   assert true | false <font color="red">turn on/off asserts in SA code</font>
>> 39:   attach pid | exec core | remote_server  <font color="red">attach SA to a process, core, or remote debug server</font>
> 
> The `jhsdb` help says `jhsdb jstack --connect debugserver`, so maybe `debug_server` would be better than `remote_server`. I think "remote debug server" in the help text is fine.

Fixed it in new commit.

> src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/CLHSDB.java line 53:
> 
>> 51:         // and coreFilename is the pathname of a core file we are
>> 52:         // supposed to attach to.
>> 53:         // Finally, if remoteMachineName != null, we are supposed to connect to remote debug server.
> 
> Split this line so its length is more consistent with the previous lines.

Fixed it in new commit.

> src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/CLHSDB.java line 125:
> 
>> 123:     private String execPath;
>> 124:     private String coreFilename;
>> 125:     private String remoteMachineName;
> 
> I think `debugServerName` or `remoteDebugServerName` would be better.

Rename to `debugServerName` in new commit.

> src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/CLHSDB.java line 230:
> 
>> 228:             System.out.println("Connecting to debug server, please wait...");
>> 229:             agent.attach(remoteMachineName);
>> 230:             this.remoteMachineName = remoteMachineName;
> 
> I'm a little surprised to see that there is already some support for connecting to a debug server in CLHSDB.java. Was it previously used from anywhere?

I cannot find out caller of `CLHSDB::connect`. I guess CLHSDB.java is copied from HSDB.java because they are similar - HSDB uses `connect()` to connect to debug server.

> src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/HSDB.java line 84:
> 
>> 82:   private String execPath;
>> 83:   private String coreFilename;
>> 84:   private String remoteMachineName;
> 
> `debugServerName` or `remoteDebugServerName`

Rename to `debugServerName` in new commit.

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