RFR(S): 8198608: Improvements to command-line flags printing

[David Holmes]

I'll sponsor this.

I don't see Goetz's email to the list but will take it as per your response.

Cheers,
David

On 3/03/2018 1:04 AM, Schmidt, Lutz wrote:
> Hi David,
> 
> it would be great if you could sponsor this change. I was able to successfully test on darwinintel64, linuxs390x, linuxppc64, and linuxx86_64. Our AIX systems are not playing nice with me at the moment (no issues with the change, just general misbehavior).
> 
> I have modified line 551 according to your suggestion (and line 519 as well). Webrev updated in-place.
> 
> So let's hope for a second review over the weekend.
> 
> Regards,
> Lutz
> 
> 
> On 02.03.18, 02:19, "David Holmes" <david.holmes at oracle.com> wrote:
> 
>      On 1/03/2018 11:25 PM, Schmidt, Lutz wrote:
>      > Hi David,
>      > thank you for looking at this. You are right, the comment is a useless leftover -> removed in if and else branch.
>      
>      Looks fine. Just need a second reviewer. Do you need a sponsor to test
>      on additional platforms? Otherwise what platforms have you tested?
>      
>      > With the "\n" handling, I believe we are on the safe side. If a newline character is detected in the parameter string, it is replaced by a st->cr() call. That call does the expected on any platform, I would hope. Flag::print_as_flag() (not in the scope of the change) uses a similar handling.
>      >
>      > The newlines are contained in string literals in C code (e.g. default values for parameters) or stem from ccstrlist concatenations. That is all under VM control. So I do not see a risk here. You can try yourself on any platform with the -XX:DisableIntrinsic=test1 parameter multiple times.
>      >
>      > If a user manages to specify a parameter string with platform (windows) specific line terminators and hopes for correct (\n-like) handling, he or she will be disappointed. I would assume the PrintFlags formatting isn't the only place that's impacted.
>      
>      Sorry I mistakenly thought you had modified the newline handling, when
>      you hadn't. If there is an issue it would be preexisting. I was
>      wondering how you would get a multi-line ccstr value. If you entered it
>      on the command-line e.g:
>      
>      java -XX:OnError="Line 1
>      Line2"
>      
>      then I would expect to find the platform line separator within the
>      string. In testing this with the existing PrintFlagsFinal Linux does:
>      
>      ccstrlist OnError                                  = Line 1
>             OnError                             += Line 2
>                     {product} {command line}
>      
>      but testing on Windows is a problem. The regular cmd shell can't take
>      multi-line arguments. If you use the ^ escape trick it actually strips
>      the newline and passes the arg as one line. So I guess the issue is
>      somewhat moot. :)
>      
>      
>      One further nit:
>      
>        551           st->print("%s", "+=");
>      
>      should just be:
>      
>        551           st->print("+=");
>      
>      Thanks,
>      David
>      
>      > I have updated the webrev in-place with the comments removed.
>      >
>      > Thanks again, Lutz
>      >
>      >
>      > On 28.02.18, 23:26, "David Holmes" <david.holmes at oracle.com> wrote:
>      >
>      >      Hi Lutz,
>      >
>      >      On 24/02/2018 2:48 AM, Schmidt, Lutz wrote:
>      >      > Dear all,
>      >      >
>      >      > may I please request reviews for this small enhancement:
>      >      >
>      >      > Bug:     https://bugs.openjdk.java.net/browse/JDK-8198608
>      >      > Webrev:  http://cr.openjdk.java.net/~lucy/webrevs/8198608.00/
>      >      >
>      >      > The code in Flag::print_on() so far wasn’t very easy to understand. Changing the layout of what was printed required some deep thinking. I hope that, with my changes, future modifications will be easier.
>      >      >
>      >      > The before/after output of -XX:+PrintFlagsFinal is identical, except for those argument names which are longer than expected. In that case, the new version prints one space less, which is by intention.
>      >
>      >      This all seems okay - and easier to modify further if needed.
>      >
>      >      Two minor comments:
>      >
>      >        576     // Flag::print_on(...) redesign (!print_ranges)
>      >
>      >      Isn't this the print_ranges case? But in any case not sure a comment
>      >      with "redesign" in it is that meaningful given you can't see the old design.
>      >
>      >      Does the ccstr newline handling work on all platforms (ie Windows) - I'm
>      >      never sure when it suffices to check for '\n' and when we have to check
>      >      for the platform specific line terminators.
>      >
>      >      Thanks,
>      >      David
>      >
>      >      > Thank you!
>      >      > Lutz
>      >      >
>      >      >
>      >      >
>      >      > Dr. Lutz Schmidt | SAP JVM | PI  SAP CP Core | T: +49 (6227) 7-42834
>      >      >
>      >
>      >
>      
>