RFR: 8354362: Use automatic indentation in CollectedHeap printing

[Joel Sikström]

Hello,

> This PR only focuses on fixing indentation and re-arranging some callsites. It does *not* change the contents of any output, apart from some (IMO relevant) indentation/whitespace additions.

Currently, the CollectedHeap printing code (print_on and print_on_error, with calls "below") prepends spaces in messages in a way that only makes sense if you write the code and then check the output to see if you've done everything correctly. To make writing and maintaining printing code easy, I propose we move to a system where each printing method, starting at callers of print_on and print_on_error, uses the indentation API in outputStream and does not rely on prepending spaces like is done right now.

What I propose is that any (GC) printing method should not make any assumptions of the indentation level of its caller(s). This means that each function shall:
1. Not prepend any spaces to its printing, and instead expect that the caller(s) should handle any indentation before calling this function.
2. Enforce its own indentation, by enabling auto indentation in its own context and for its "lower level" calls (which is often the desired outcome).

Combining these two rules means that *any* (GC) printing method can be called from anywhere and give sensible output, without (seemingly random) indentation of expectations elsewhere.

I have aggregated calls that print on the same indentation level to the same callsite. This makes it clear where to look in the code and also makes it easier to add/enforce indendation. To this end, I have re-arranged print_on_error so that it never includes print_on. The new system I propose is that print_on and print_on_error can be called separately for different information, which aligns well with having the same callsite for the same indentation. See changes in vmError.cpp for how this is implemented.

Instead of prepending spaces, I use StreamAutoIndentor, defined in ostream.hpp. To make using automatic indentation easier, I've made some changes to StreamAutoIndentor so that it inherits from streamIndentor and also add an *optional* argument to StreamAutoIndentor to apply an indentation. My reasoning for this is that most places that use streamIndentor also want to use StreamAutoIndentor (either immediately or some time before) so that it is automatically applied. A downside of this change is that any previous uses of StreamAutoIndentor now also needs to store an extra int worth of memory. To me, this is a trade-off worth making, considering that memory for buffers of strings usually outweigh this extra memory cost. Additionally, when factoring in the improved code understandability and maintainability, I feel like it's a change worth making.

Some new changes in the way the printing looks are:
* Epsilon has received indentation in its print_on, which was not there before, in an effort to look similar to other GCs and also improve readability.
* Shenandoah has also received indentation to behave similar to other GCs.
* "the space" in Serial's output was indented by two spaces, now it's one.
* With the removal of print_on from print_on_error, I've also removed Epsilon's barrier set printing, making it's print_on_error empty. Before this, Serial printed two spaces between the sections in the hs_err file.

Code re-structure:
* PSOldGen::print_on had an inlined version of virtual_space()->print_space_boundaries_on(st), which is now called instead.
* PSYoungGen::print_on had its name inlined. Now, name() is called instead, which is how PSOldGen::print_on does it.
* I've added a common print_space_boundaries_on for the virtual space used in Serial's DefNewGeneration and TenuredGeneration, like how Parallel does it.
* I've opted to use fill_to() in Metaspace printing so that it works well with ZGC printing. This does not really affect other GCs since only ZGC aligns with the same column as Metaspace.

Testing:
* GHA, Oracle's tier 1-3
* Manual inspection of printed content 
  * Exit printing `-Xlog:gc+heap+exit=info`
  * Periodic printing `-Xlog:gc+heap=debug`
  * jcmd `jcmd <pid> GC.heap_info`
  * jcmd `jcmd <pid> VM.info`
  * hs_err file, both "Heap:" and "Heap before/after invocations=" printing, `-XX:ErrorHandlerTest=14`

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Commit messages:
 - 8354362: Use automatic indentation in CollectedHeap printing

Changes: https://git.openjdk.org/jdk/pull/24593/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24593&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354362
  Stats: 239 lines in 26 files changed: 88 ins; 88 del; 63 mod
  Patch: https://git.openjdk.org/jdk/pull/24593.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24593/head:pull/24593

PR: https://git.openjdk.org/jdk/pull/24593