RFR (L) 8151711: Move G1 number sequences out of the G1 collector policy

[Mikael Gerdin]

Hi all,

Currently a large part of the G1 collector policy consists of counters 
and number sequences for different measurements performed by the collector.
In order to reduce the overall API surface of the G1CollectorPolicy 
class and possibly allow for different collector policy implementations 
the measurements and simple predictions based on the number sequences 
should be factored out of the policy code. The policy will then become 
more of a decision maker and not a combined data store and decision maker.

My current working name for the new class is G1Measurements but I'm not 
overly attached to the name.

I've made the new files "hg copies" of the g1CollectorPolicy files since 
a lot of methods and members are simply moved as-is to the new class.
One thing I did modify was to move decisions based on the 
collector_state() out of the prediction methods and instead based the 
selection on a boolean parameter.

I suggest that in order to review the changes you open up your favorite 
3-way diff tool and view a 3-way side-by-side diff of
g1CollectorPolicy.cpp (from my webrev),
g1CollectorPolicy.cpp (from before my suggested changes),
g1Measurements.cpp (from my webrev).

In diffuse this would be done as:
diffuse \
src/share/vm/gc/g1/g1CollectorPolicy.cpp \
-r qparent src/share/vm/gc/g1/g1CollectorPolicy.cpp \
src/share/vm/gc/g1/g1Measurements.cpp

This allows you to (hopefully) verify the moved contents.
I've tried pretty hard to keep the code in the same order as in the 
original location.

For g1Measurements.hpp I've been a bit more lax to let the header be 
nice and tidy.

Bug: https://bugs.openjdk.java.net/browse/JDK-8151711
Webrev: http://cr.openjdk.java.net/~mgerdin/8151711/webrev.0/
Testing: RBT gc testing, JPRT, Perf testing on aurora.

Thanks
/Mikael