RFR: 8048093 - Explicitly setting := vs = in the -XX:+PrintFlagsFinal output

[Vladimir Kozlov]

Nobody will remember the meaning of such marking. You should use normal words.
The output already have flag's type as, for example, "{C2 product}". You can add an other word there to indicate type of 
initialization: default|command|ergo.

Thanks,
Vladimir

On 6/21/16 12:09 PM, Jesper Wilhelmsson wrote:
> Hi,
>
> Please review this change to make -XX:+PrintFlagsFinal distinguish between flags changed on the command line and flags
> changed by the ergonomics.
>
> To enable us to remember if a flag was set on the command line or not after having been changed by the ergonomics I use
> another bit in the Flag struct.
>
> The actual symbols printed by PrintFlagsFinal are chosen somewhat arbitrary and I'm open to suggestions (bike sheding)
> about how to visualize this the best.
>
> The old decorations are:
>
> ' =' - Default value (no decoration)
> ':=' - Value was changed, either by command line or ergonomics or other
>
> The new decorations are:
>
> ' =' - Default value (no decoration)
> ':=' - Set on the command line
> '?=' - Changed by the ergonomics
> '!=' - Set on the command line AND changed by the ergonomics
> '-=' - Any other origin, like changed by management API or taken from a config file
>
> My reasoning behind selecting these characters are that ':=' looks like a solid assignment and will therefore represent
> the command line. You never know what you get from the ergonomics, so '?=' seems appropriate. '!=' because you'd want to
> know that the ergonomics changed a value you had set on the command line.
>
> Another option could be to use a colon ':=' for the command line, and a comma ',=' for the ergonomics. That would
> naturally give us the semi-colon ';=' for something set on the command line and changed by the ergonomics. I didn't go
> with this because the colon and semi-colon can be hard to distinguish from each other.
>
> As mentioned above there are other origins, the enum contains eight values. There is no mention of the other types in
> the bug and there are no is_...() for the other types in globals.cpp, so they didn't seem as important. If the general
> opinion is that these other origins are as important, or we might as well..., I'd suggest that we use letters as
> decorations. Let me know if you have an opinion.
>
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8048093
> Webrev: http://cr.openjdk.java.net/~jwilhelm/8048093/webrev.00/
>
> Thanks,
> /Jesper