RFR: 8269914: Factor out heap printing for G1 young and full gc [v2]

[Thomas Schatzl]

> Hi all,
> 
> can I have reviews for this change that factors out before/after heap related printing into a single scoped object to be used for both young and full gc code?
> 
> There is some minor change in order of printing of unrelated log output (COMMIT/UNCOMMIT region state changes vs. other heap printing), during full gc but since this is very low level debugging I do not see a problem to do that.
> 
> (Sorry for the trouble with open/closing this issue already: have been experimenting with the feature to base PRs on other PRs which kind-of failed a bit; rebased on tip after being able to push all dependencies, so this one should be good)
> 
> To keep JFR event sending in the correct order, this change includes JDK-8270018.
> 
> Thanks,
>   Thomas

Thomas Schatzl has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  Initial implementation of heap printing refactoring

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4705/files
  - new: https://git.openjdk.java.net/jdk/pull/4705/files/bb712baa..b5b57c06

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4705&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4705&range=00-01

  Stats: 191 lines in 5 files changed: 73 ins; 109 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4705.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4705/head:pull/4705

PR: https://git.openjdk.java.net/jdk/pull/4705