saphyr-serde/bench/tools/README.md

saphyr tools

This directory contains tools that are used to develop the crate. Due to dependency management, only some of them are available as binaries from the saphyr crate.

Tool	Invocation
bench_compare	cargo bench_compare
dump_events	cargo run --bin dump_events -- [...]
gen_large_yaml	cargo gen_large_yaml

bench_compare

See the dedicated README file.

dump_events

This is a debugging helper for the parser. It outputs events emitted by the parser for a given file. This can be paired with the YAMLRUST2_DEBUG environment variable to have an in-depth overview of which steps the scanner and the parser are taking.

Example

Consider the following input.yaml YAML file:

- foo: bar
- baz:
  c: [3, 4, 5]

Running cargo run --bin dump_events -- input.yaml outputs:

      ↳ StreamStart
      ↳ DocumentStart
      ↳ SequenceStart(0, None)
      ↳ MappingStart(0, None)
      ↳ Scalar("foo", Plain, 0, None)
      ↳ Scalar("bar", Plain, 0, None)
      ↳ MappingEnd
      ↳ MappingStart(0, None)
      ↳ Scalar("baz", Plain, 0, None)
      ↳ Scalar("~", Plain, 0, None)
      ↳ Scalar("c", Plain, 0, None)
      ↳ SequenceStart(0, None)
      ↳ Scalar("3", Plain, 0, None)
      ↳ Scalar("4", Plain, 0, None)
      ↳ Scalar("5", Plain, 0, None)
      ↳ SequenceEnd
      ↳ MappingEnd
      ↳ SequenceEnd
      ↳ DocumentEnd
      ↳ StreamEnd

Running YAMLRUST2_DEBUG=1 cargo run --bin dump_events -- input.yaml outputs much more details:

Full output

Parser state: StreamStart
    ↳ StreamStart(Utf8) Marker { index: 0, line: 1, col: 0 }
      ↳ StreamStart

Parser state: ImplicitDocumentStart
  → fetch_next_token after whitespace Marker { index: 0, line: 1, col: 0 } '-'
    ↳ BlockSequenceStart Marker { index: 0, line: 1, col: 0 }
      ↳ DocumentStart

Parser state: BlockNode
      ↳ SequenceStart(0, None)

Parser state: BlockSequenceFirstEntry
    ↳ BlockEntry Marker { index: 2, line: 1, col: 2 }
  → fetch_next_token after whitespace Marker { index: 2, line: 1, col: 2 } 'f'
  → fetch_next_token after whitespace Marker { index: 5, line: 1, col: 5 } ':'
    ↳ BlockMappingStart Marker { index: 5, line: 1, col: 5 }
      ↳ MappingStart(0, None)

Parser state: BlockMappingFirstKey
    ↳ Key Marker { index: 2, line: 1, col: 2 }
    ↳ Scalar(Plain, "foo") Marker { index: 2, line: 1, col: 2 }
      ↳ Scalar("foo", Plain, 0, None)

Parser state: BlockMappingValue
    ↳ Value Marker { index: 5, line: 1, col: 5 }
  → fetch_next_token after whitespace Marker { index: 7, line: 1, col: 7 } 'b'
    ↳ Scalar(Plain, "bar") Marker { index: 7, line: 1, col: 7 }
      ↳ Scalar("bar", Plain, 0, None)

Parser state: BlockMappingKey
  → fetch_next_token after whitespace Marker { index: 11, line: 2, col: 0 } '-'
    ↳ BlockEnd Marker { index: 11, line: 2, col: 0 }
      ↳ MappingEnd

Parser state: BlockSequenceEntry
    ↳ BlockEntry Marker { index: 13, line: 2, col: 2 }
  → fetch_next_token after whitespace Marker { index: 13, line: 2, col: 2 } 'b'
  → fetch_next_token after whitespace Marker { index: 16, line: 2, col: 5 } ':'
    ↳ BlockMappingStart Marker { index: 16, line: 2, col: 5 }
      ↳ MappingStart(0, None)

Parser state: BlockMappingFirstKey
    ↳ Key Marker { index: 13, line: 2, col: 2 }
    ↳ Scalar(Plain, "baz") Marker { index: 13, line: 2, col: 2 }
      ↳ Scalar("baz", Plain, 0, None)

Parser state: BlockMappingValue
    ↳ Value Marker { index: 16, line: 2, col: 5 }
  → fetch_next_token after whitespace Marker { index: 20, line: 3, col: 2 } 'c'
  → fetch_next_token after whitespace Marker { index: 21, line: 3, col: 3 } ':'
    ↳ Key Marker { index: 20, line: 3, col: 2 }
      ↳ Scalar("~", Plain, 0, None)

Parser state: BlockMappingKey
    ↳ Scalar(Plain, "c") Marker { index: 20, line: 3, col: 2 }
      ↳ Scalar("c", Plain, 0, None)

Parser state: BlockMappingValue
    ↳ Value Marker { index: 21, line: 3, col: 3 }
  → fetch_next_token after whitespace Marker { index: 23, line: 3, col: 5 } '['
    ↳ FlowSequenceStart Marker { index: 23, line: 3, col: 5 }
      ↳ SequenceStart(0, None)

Parser state: FlowSequenceFirstEntry
  → fetch_next_token after whitespace Marker { index: 24, line: 3, col: 6 } '3'
  → fetch_next_token after whitespace Marker { index: 25, line: 3, col: 7 } ','
    ↳ Scalar(Plain, "3") Marker { index: 24, line: 3, col: 6 }
      ↳ Scalar("3", Plain, 0, None)

Parser state: FlowSequenceEntry
    ↳ FlowEntry Marker { index: 25, line: 3, col: 7 }
  → fetch_next_token after whitespace Marker { index: 27, line: 3, col: 9 } '4'
  → fetch_next_token after whitespace Marker { index: 28, line: 3, col: 10 } ','
    ↳ Scalar(Plain, "4") Marker { index: 27, line: 3, col: 9 }
      ↳ Scalar("4", Plain, 0, None)

Parser state: FlowSequenceEntry
    ↳ FlowEntry Marker { index: 28, line: 3, col: 10 }
  → fetch_next_token after whitespace Marker { index: 30, line: 3, col: 12 } '5'
  → fetch_next_token after whitespace Marker { index: 31, line: 3, col: 13 } ']'
    ↳ Scalar(Plain, "5") Marker { index: 30, line: 3, col: 12 }
      ↳ Scalar("5", Plain, 0, None)

Parser state: FlowSequenceEntry
    ↳ FlowSequenceEnd Marker { index: 31, line: 3, col: 13 }
      ↳ SequenceEnd

Parser state: BlockMappingKey
  → fetch_next_token after whitespace Marker { index: 33, line: 4, col: 0 } '\0'
    ↳ BlockEnd Marker { index: 33, line: 4, col: 0 }
      ↳ MappingEnd

Parser state: BlockSequenceEntry
    ↳ BlockEnd Marker { index: 33, line: 4, col: 0 }
      ↳ SequenceEnd

Parser state: DocumentEnd
    ↳ StreamEnd Marker { index: 33, line: 4, col: 0 }
      ↳ DocumentEnd

Parser state: DocumentStart
      ↳ StreamEnd

While this cannot be shown in Markdown, the output is colored so that it is a bit easier to read.

gen_large_yaml

It is hard to find large (100+MiB) real-world YAML files that could be used to benchmark a parser. This utility generates multiple large files that are meant to stress the parser with different layouts of YAML files. The resulting files do not look like anything that would be encountered in production, but can serve as a base to test several features of a YAML parser.

The generated files are the following:

• big.yaml: A large array of records with few fields. One of the fields is a description, a large text block scalar spanning multiple lines. Most of the scanning happens in block scalars.
• nested.yaml: Very short key-value pairs that nest deeply.
• small_objects.yaml: A large array of 2 key-value mappings.
• strings_array.yaml: A large array of lipsum one-liners (~150-175 characters in length).

All generated files are meant to be between 200 and 250 MiB in size.

This tool depends on external dependencies that are not part of yaml-rust2's dependencies or dev-dependencies and as such can't be called through cargo run directly. A dedicated cargo gen_large_yaml alias can be used to generate the benchmark files.