* Use buffered stdout to reduce write sys calls.
This simple change yielded the biggest performace gain.
* Use `for_byte_record_with_terminator` from the `bstr` crate.
This is to minimize the per line copying needed by
`BufReader::read_until`. The `cut_fields` and `cut_fields_delimiter`
functions used `read_until` to iterate over lines. That required copying
each input line to the line buffer. With
`for_byte_record_with_terminator` copying is minimized as it calls our
closure with a reference to BufReader's buffer most of the time. It
needs to copy (internally) only to process any incomplete lines at the
end of the buffer.
* Re-write `Searcher` to use `memchr`.
Switch from the naive implementation to one that uses `memchr`.
* Rewrite `cut_bytes` almost entirely.
This was already well optimized. The performance gain in this case is
not from avoiding copying. In fact, it needed zero copying whereas new
implementation introduces some copying similar to `cut_fields` described
above. But the occassional copying cost is more than offset by the use
of the very fast `memchr` inside `for_byte_record_with_terminator`.
This change also simplifies the code significantly. Removed the `buffer`
module.
- All assert_eq in tests/common/util.rs now print a pretty diff on test
failures.
- {stdout, stderr}_is_fixture now compare the expected output and the
fixture as Strings, which leads to more usable diffs.
This adds a --debug flag, which, when activated, will draw lines below
the characters that are actually used for comparisons.
This is not a complete implementation of --debug. It should, quoting the man page
for GNU sort: "annotate the part of the line used to sort, and warn
about questionable usage to stderr". Warning about "questionable usage"
is not part of this patch.
This change required some adjustments to be able to get the range that
is actually used for comparisons. Most notably, general numeric comparisons
were rewritten, fixing some bugs along the lines.
Testing is mostly done by adding fixtures for the expected debug output of
existing tests.
- conv=sparse option requires knowledge of File/Stdout to change
behaviour.
- Unclear how best to impl this.
- Possible option: develop 4 versions of dd<X,Y> for each valid pair of { File, Stdin,
Stdout }.
