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drinkcat merged 2 commits into from
Aug 9, 2025
Merged

Improve tr performances (Closes: #8439) #8442

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54959f3
tr: improve performances (Closes: #8439)
sylvestre Aug 6, 2025
e7fdeb3
tr: document how to bench its perf
sylvestre Aug 6, 2025
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66 changes: 66 additions & 0 deletions src/uu/tr/BENCHMARKING.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,66 @@
# Benchmarking `tr`

<!-- spell-checker:ignore aeiou -->

`tr` performance is critical for large data processing pipelines. The implementation uses lookup tables for O(1) character operations.

## Building

```shell
cargo build --release --package uu_tr
```

## Basic Benchmarks

### Character Translation

```shell
# Create test data
dd if=/dev/zero bs=1M count=10 | tr '\0' 'x' > 10mb_input

# Benchmark translation
hyperfine --warmup 3 \
'tr a b < 10mb_input > /dev/null' \
'./target/release/tr a b < 10mb_input > /dev/null'
```

### Character Deletion

```shell
# Create mixed input
yes "abcdefghijklmnopqrstuvwxyz" | head -n 1000000 > mixed_input

# Benchmark deletion
hyperfine --warmup 3 \
'tr -d aeiou < mixed_input > /dev/null' \
'./target/release/tr -d aeiou < mixed_input > /dev/null'
```

### Character Classes

```shell
# Benchmark character classes
hyperfine --warmup 3 \
'tr "[:lower:]" "[:upper:]" < mixed_input > /dev/null' \
'./target/release/tr "[:lower:]" "[:upper:]" < mixed_input > /dev/null'
```

## Quick Regression Test

```shell
#!/bin/bash
cargo build --release --package uu_tr

echo "=== Translation ==="
hyperfine 'tr a b < 10mb_input > /dev/null' './target/release/tr a b < 10mb_input > /dev/null'

echo "=== Deletion ==="
hyperfine 'tr -d aeiou < mixed_input > /dev/null' './target/release/tr -d aeiou < mixed_input > /dev/null'
```

## Performance Notes

- Uses lookup tables instead of hash maps for O(1) operations
- 32KB I/O buffers for improved throughput
- Should be competitive with GNU `tr` for most operations

88 changes: 51 additions & 37 deletions src/uu/tr/src/operation.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,11 +17,9 @@ use nom::{
};
use std::{
char,
collections::{HashMap, HashSet},
error::Error,
fmt::{Debug, Display},
io::{BufRead, Write},
ops::Not,
};
use uucore::error::{FromIo, UError, UResult};
use uucore::translate;
Expand Down Expand Up @@ -583,42 +581,58 @@ impl<A: SymbolTranslator, B: SymbolTranslator> SymbolTranslator for ChainedSymbo
}
}

/// Convert a set of bytes to a 256-element bitmap for O(1) lookup
fn set_to_bitmap(set: &[u8]) -> [bool; 256] {
let mut bitmap = [false; 256];
for &byte in set {
bitmap[byte as usize] = true;
}
bitmap
}

#[derive(Debug)]
pub struct DeleteOperation {
set: Vec<u8>,
delete_table: [bool; 256],
}

impl DeleteOperation {
pub fn new(set: Vec<u8>) -> Self {
Self { set }
Self {
delete_table: set_to_bitmap(&set),
}
}
}

impl SymbolTranslator for DeleteOperation {
fn translate(&mut self, current: u8) -> Option<u8> {
// keep if not present in the set
self.set.contains(&current).not().then_some(current)
// keep if not present in the delete set
(!self.delete_table[current as usize]).then_some(current)
}
}

#[derive(Debug)]
pub struct TranslateOperation {
translation_map: HashMap<u8, u8>,
translation_table: [u8; 256],
}

impl TranslateOperation {
pub fn new(set1: Vec<u8>, set2: Vec<u8>) -> Result<Self, BadSequence> {
// Initialize translation table with identity mapping
let mut translation_table = std::array::from_fn(|i| i as u8);

if let Some(fallback) = set2.last().copied() {
Ok(Self {
translation_map: set1
.into_iter()
.zip(set2.into_iter().chain(std::iter::repeat(fallback)))
.collect::<HashMap<_, _>>(),
})
// Apply translations from set1 to set2
for (from, to) in set1
.into_iter()
.zip(set2.into_iter().chain(std::iter::repeat(fallback)))
{
translation_table[from as usize] = to;
}

Ok(Self { translation_table })
} else if set1.is_empty() && set2.is_empty() {
Ok(Self {
translation_map: HashMap::new(),
})
// Identity mapping for empty sets
Ok(Self { translation_table })
} else {
Err(BadSequence::EmptySet2WhenNotTruncatingSet1)
}
Expand All @@ -627,33 +641,28 @@ impl TranslateOperation {

impl SymbolTranslator for TranslateOperation {
fn translate(&mut self, current: u8) -> Option<u8> {
Some(
self.translation_map
.get(&current)
.copied()
.unwrap_or(current),
)
Some(self.translation_table[current as usize])
}
}

#[derive(Debug, Clone)]
pub struct SqueezeOperation {
set1: HashSet<u8>,
squeeze_table: [bool; 256],
previous: Option<u8>,
}

impl SqueezeOperation {
pub fn new(set1: Vec<u8>) -> Self {
Self {
set1: set1.into_iter().collect(),
squeeze_table: set_to_bitmap(&set1),
previous: None,
}
}
}

impl SymbolTranslator for SqueezeOperation {
fn translate(&mut self, current: u8) -> Option<u8> {
let next = if self.set1.contains(&current) {
let next = if self.squeeze_table[current as usize] {
match self.previous {
Some(v) if v == current => None,
_ => Some(current),
Expand All @@ -672,19 +681,26 @@ where
R: BufRead,
W: Write,
{
let mut buf = [0; 8192];
let mut output_buf = Vec::new();
const BUFFER_SIZE: usize = 32768; // Large buffer for better throughput
let mut buf = [0; BUFFER_SIZE];
let mut output_buf = Vec::with_capacity(buf.len());

loop {
let length = match input.read(&mut buf[..]) {
Ok(0) => break, // EOF reached
Ok(len) => len,
Err(e) if e.kind() == std::io::ErrorKind::Interrupted => continue,
Err(e) => return Err(e.map_err_context(|| translate!("tr-error-read-error"))),
};

while let Ok(length) = input.read(&mut buf[..]) {
if length == 0 {
break; // EOF reached
// Process the buffer and collect translated chars to output
output_buf.clear();
for &byte in &buf[..length] {
if let Some(translated) = translator.translate(byte) {
output_buf.push(translated);
}
}

let filtered = buf[..length]
.iter()
.filter_map(|&c| translator.translate(c));
output_buf.extend(filtered);

#[cfg(not(target_os = "windows"))]
output
.write_all(&output_buf)
Expand All @@ -699,8 +715,6 @@ where
return Err(err.map_err_context(|| translate!("tr-error-write-error")));
}
}

output_buf.clear();
}

Ok(())
Expand Down
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