RFR: 8142952: Unified Logging framework does not allow multiple -Xlog: arguments

[David Holmes]

Hi Marcus,

I had assumed from the JEP that multiple -Xlog arguments for different 
tags were already supported - so good to see that is now fixed.

I'm unclear what the semantics are for combining multiple -Xlog 
arguments for the same tag (either directly or via implicit wildcards)? 
Most detailed level wins? Last arg wins?

Thanks,
David

On 27/11/2015 1:17 AM, Marcus Larsson wrote:
> Hi,
>
> New webrev after offline review with Bengt and Staffan:
> http://cr.openjdk.java.net/~mlarsson/8142952/webrev.01/
>
> Incremental:
> http://cr.openjdk.java.net/~mlarsson/8142952/webrev.00-01/
>
> Changes:
> * LogLevel::Unchanged was changed to LogLevel::NotMentioned.
> * Test improvements.
>
> I also looked at FormatBuffers for the string handling in LogOutput, but
> unfortunately they are sized according to template parameters and hence
> don't play well with the dynamic expansion required here.
>
> Thanks
> Marcus
>
> On 2015-11-24 11:46, Marcus Larsson wrote:
>> Hi,
>>
>> Please review the following patch to enable multiple -Xlog arguments
>> to aggregate the log configuration.
>>
>> Summary:
>> Tag sets that are unaffected by a -Xlog argument will now be left
>> untouched, enabling them to keep settings from a previous -Xlog argument.
>>
>> To be able to print the current log configuration, the _config_string
>> on LogOutputs has to be derived from each enabled tag set and its
>> level, instead of the previous copying of the -Xlog argument. This
>> means that -Xlog:all:stdout sets the _config_string for stdout to the
>> explicit list of all tag sets in the VM, with level set to info.
>>
>> Webrev:
>> http://cr.openjdk.java.net/~mlarsson/8142952/webrev.00/
>>
>> Issue:
>> https://bugs.openjdk.java.net/browse/JDK-8142952
>>
>> Testing:
>> Included test through JPRT.
>>
>> Thanks,
>> Marcus
>