RFR: 8256308: Send arguments to javac server in a config file [v6]

[Jonathan Gibbons]

On Mon, 16 Nov 2020 12:44:08 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

>> Currently, to use the javac server, a horrendously long command line option is created, looking like this: `--server:portfile=<path to portfile>:sjavac=<command to launch server>`, where the sjavac command has had all spaces replaced by %20. Since Project Jigsaw, the set of module arguments needed is huge to begin with, making this command line incomprehensible after mangling.
>> 
>> Apart from making java command lines hard to read (and copy/paste!) by developers, it also makes it hard for scripts to parse. The upcoming winenv rewrite is dependent on being able to differentiate between path names and other arguments, which is not possible in this mess.
>> 
>> So, instead, let's write it to a file, without any escaping, and just pass the configuration file name to the server.
>> 
>> Note that this will change the behavior of the javac server, but as the source code states this is not a documented or externally supported API no CSR is needed. 
>> 
>> I also cleaned up some code in SjavacClient, in particular code relating to the passing of arguments. (We never change poolsize or keepalive when we call it.)
>
> Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix whitespace issues

There seems to be much more here than there needs to be.

If the issue is just long command lines, then the obvious/conventional solution would be to use @files, which would be a tiny change to the sjavac source code, to insert a single call to `CommandLine.parse` to expand any @file arguments on the command line.

So, before reading all the various details in this proposed change, is there any reason why the simple @file solution cannot be used?

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PR: https://git.openjdk.java.net/jdk/pull/1195