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use anyhow::{Context, Error};
use flate2::{read::GzDecoder, write::GzEncoder};
use rayon::prelude::*;
use std::{convert::TryFrom, fmt, io::Read, io::Write, path::Path, str::FromStr};
use xz2::{read::XzDecoder, write::XzEncoder};
#[derive(Debug, Copy, Clone)]
pub enum CompressionFormat {
Gz,
Xz,
}
impl CompressionFormat {
pub(crate) fn detect_from_path(path: impl AsRef<Path>) -> Option<Self> {
match path.as_ref().extension().and_then(|e| e.to_str()) {
Some("gz") => Some(CompressionFormat::Gz),
Some("xz") => Some(CompressionFormat::Xz),
_ => None,
}
}
pub(crate) fn extension(&self) -> &'static str {
match self {
CompressionFormat::Gz => "gz",
CompressionFormat::Xz => "xz",
}
}
pub(crate) fn encode(&self, path: impl AsRef<Path>) -> Result<Box<dyn Encoder>, Error> {
let mut os = path.as_ref().as_os_str().to_os_string();
os.push(format!(".{}", self.extension()));
let path = Path::new(&os);
if path.exists() {
crate::util::remove_file(path)?;
}
let file = crate::util::create_new_file(path)?;
Ok(match self {
CompressionFormat::Gz => Box::new(GzEncoder::new(file, flate2::Compression::best())),
CompressionFormat::Xz => {
let mut filters = xz2::stream::Filters::new();
// the preset is overridden by the other options so it doesn't matter
let mut lzma_ops = xz2::stream::LzmaOptions::new_preset(9).unwrap();
// This sets the overall dictionary size, which is also how much memory (baseline)
// is needed for decompression.
lzma_ops.dict_size(64 * 1024 * 1024);
// Use the best match finder for compression ratio.
lzma_ops.match_finder(xz2::stream::MatchFinder::BinaryTree4);
lzma_ops.mode(xz2::stream::Mode::Normal);
// Set nice len to the maximum for best compression ratio
lzma_ops.nice_len(273);
// Set depth to a reasonable value, 0 means auto, 1000 is somwhat high but gives
// good results.
lzma_ops.depth(1000);
// 2 is the default and does well for most files
lzma_ops.position_bits(2);
// 0 is the default and does well for most files
lzma_ops.literal_position_bits(0);
// 3 is the default and does well for most files
lzma_ops.literal_context_bits(3);
filters.lzma2(&lzma_ops);
let compressor = XzEncoder::new_stream(
std::io::BufWriter::new(file),
xz2::stream::MtStreamBuilder::new()
.threads(1)
.filters(filters)
.encoder()
.unwrap(),
);
Box::new(compressor)
}
})
}
pub(crate) fn decode(&self, path: impl AsRef<Path>) -> Result<Box<dyn Read>, Error> {
let file = crate::util::open_file(path.as_ref())?;
Ok(match self {
CompressionFormat::Gz => Box::new(GzDecoder::new(file)),
CompressionFormat::Xz => Box::new(XzDecoder::new(file)),
})
}
}
/// This struct wraps Vec<CompressionFormat> in order to parse the value from the command line.
#[derive(Debug, Clone)]
pub struct CompressionFormats(Vec<CompressionFormat>);
impl TryFrom<&'_ str> for CompressionFormats {
type Error = Error;
fn try_from(value: &str) -> Result<Self, Self::Error> {
let mut parsed = Vec::new();
for format in value.split(',') {
match format.trim() {
"gz" => parsed.push(CompressionFormat::Gz),
"xz" => parsed.push(CompressionFormat::Xz),
other => anyhow::bail!("unknown compression format: {}", other),
}
}
Ok(CompressionFormats(parsed))
}
}
impl FromStr for CompressionFormats {
type Err = Error;
fn from_str(value: &str) -> Result<Self, Self::Err> {
Self::try_from(value)
}
}
impl fmt::Display for CompressionFormats {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
for (i, format) in self.iter().enumerate() {
if i != 0 {
write!(f, ",")?;
}
fmt::Display::fmt(
match format {
CompressionFormat::Xz => "xz",
CompressionFormat::Gz => "gz",
},
f,
)?;
}
Ok(())
}
}
impl Default for CompressionFormats {
fn default() -> Self {
Self(vec![CompressionFormat::Gz, CompressionFormat::Xz])
}
}
impl CompressionFormats {
pub(crate) fn iter(&self) -> impl Iterator<Item = CompressionFormat> + '_ {
self.0.iter().map(|i| *i)
}
}
pub(crate) trait Encoder: Send + Write {
fn finish(self: Box<Self>) -> Result<(), Error>;
}
impl<W: Send + Write> Encoder for GzEncoder<W> {
fn finish(self: Box<Self>) -> Result<(), Error> {
GzEncoder::finish(*self).context("failed to finish .gz file")?;
Ok(())
}
}
impl<W: Send + Write> Encoder for XzEncoder<W> {
fn finish(self: Box<Self>) -> Result<(), Error> {
XzEncoder::finish(*self).context("failed to finish .xz file")?;
Ok(())
}
}
pub(crate) struct CombinedEncoder {
encoders: Vec<Box<dyn Encoder>>,
}
impl CombinedEncoder {
pub(crate) fn new(encoders: Vec<Box<dyn Encoder>>) -> Box<dyn Encoder> {
Box::new(Self { encoders })
}
}
impl Write for CombinedEncoder {
fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
self.write_all(buf)?;
Ok(buf.len())
}
fn write_all(&mut self, buf: &[u8]) -> std::io::Result<()> {
self.encoders
.par_iter_mut()
.map(|w| w.write_all(buf))
.collect::<std::io::Result<Vec<()>>>()?;
Ok(())
}
fn flush(&mut self) -> std::io::Result<()> {
self.encoders
.par_iter_mut()
.map(|w| w.flush())
.collect::<std::io::Result<Vec<()>>>()?;
Ok(())
}
}
impl Encoder for CombinedEncoder {
fn finish(self: Box<Self>) -> Result<(), Error> {
self.encoders
.into_par_iter()
.map(|e| e.finish())
.collect::<Result<Vec<()>, Error>>()?;
Ok(())
}
}
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