Request for review (M): 7178363 G1: Remove the serial code for PrintGCDetails and make it a special case of the parallel code

[Bengt Rutisson]

Hi everyone,

I would like some reviews of this change:
http://cr.openjdk.java.net/~brutisso/7178363/webrev.00/

This removes the special treatment for ParallelGCThreads=0 from the G1 
logging. I did keep the log output unchanged for that case. Basically it 
just has one indentation level less and skips some output. I am not sure 
this is really necessary since it is really a special case. I'm open to 
change that special treatment too and just have the same output as for 
ParallelGCThreads=1.

The PrintGCDetails log output should be the same as before with three 
minor adjustments:

- The "Sum" is now not printed for the start and end values for GC 
workers. This sum does not really make sense to me.

- The "(ms)" unit was removed from output that aren't in milliseconds 
(termination attempts for example).

- The average value is now printed as a double for all types.

I tried to clean up the code a bit and introduced a separate class, 
Snippet WorkerDataArray, to keep track of the per thread logging. I also 
introduced getters and setters to avoid having to make G1CollectorPolicy 
and TraceGen0TimeData friend classes to G1GCPhaseTimes.

Thanks,
Bengt