RFR: 8149383: Convert TraceBiasedLocking to Unified Logging

[Rachel Protacio]

Thanks, David, for reiterating my earlier comment. If it's okay with 
everyone, I think this falls again into the category of "works now, can 
be enhanced with a future RFE". Especially since John's suggestion of 
using LogMessage seems the most likely fix if any (and perhaps an 
equivalent way to accomplish what Kim's code was getting at?). But 
LogMessage framework has not yet been committed, so it would make sense 
to upgrade this implementation, should we deem it necessary, after the 
framework is added and after the primary task of creating a working 
"-Xlog:biasedlocking" option has been accomplished.

To reduce the confusion that some have had regarding the fact that the 
two conditionals differ just in level and not message (for now), I've 
added the comment

    // Log at "info" level if not bulk, else "trace" level

before each of the four instances. See 
http://cr.openjdk.java.net/~rprotacio/8149383.02/

I have Dan and David as reviewers. If Kim or John is okay with this 
proposal of enhancing later, should it be necessary, are we all okay 
with moving forward with this latest version?

Many thanks,
Rachel


On 2/16/2016 8:25 PM, David Holmes wrote:
> Folks,
>
> Rachel already covered this in her original email:
>
>> A comment on the code: in order to maintain the existing functionality
>> of the "(TraceBiasedLocking && (Verbose || !is_bulk))" portions of code,
>> it was necessary to create two separate cases in the conversion, one
>> each for the info (regular) and trace (verbose) levels. It has been
>> asked that the functionality be maintained. The logging statements in
>> these chunks do not necessarily have to stay equal to each other in the
>> future, which this would facilitate.
>
> As she says the logging statements for the two cases need not stay the 
> same, so jumping through hoops to try and print the same message under 
> two different conditions seems like a waste of cycles to me.
>
> Cheers,
> David
>
> On 17/02/2016 8:12 AM, John Rose wrote:
>> On Feb 16, 2016, at 1:16 PM, Daniel D. Daugherty
>> <daniel.daugherty at oracle.com <mailto:daniel.daugherty at oracle.com>> 
>> wrote:
>>>
>>>        I really don't like the duplication, but if I remember correctly
>>>        these are macros so we really can't do something like function
>>>        pointers or some other trick here. Ouch! This duplication 
>>> pattern
>>>        is repeated in several places where the old logging was 
>>> conditional
>>>        on two different option variables and a biased locking 
>>> operational
>>>        state variable (is_bulk).
>>>
>>>        I suppose the logging framework doesn't have an API that says
>>>        to log at different levels based on a parameter. Something like:
>>
>> I agree with Dan.  There's got to be a way to factor this code.
>>
>> Perhaps this is a job for LogMessage:  You compose the message,
>> and then conditionally commit it to two places.
>>
>> — John