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lz4.rs
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lz4.rs
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//! lz4 de/compression interface
use crate::exceptions::{CompressionError, DecompressionError};
use crate::io::{AsBytes, RustyBuffer};
use crate::BytesType;
use lz4::{block, block::CompressionMode};
use pyo3::prelude::*;
use pyo3::wrap_pyfunction;
use pyo3::PyResult;
use std::io::Cursor;
const DEFAULT_COMPRESSION_LEVEL: u32 = 4;
pub(crate) fn init_py_module(m: &PyModule) -> PyResult<()> {
m.add_function(wrap_pyfunction!(compress, m)?)?;
m.add_function(wrap_pyfunction!(decompress, m)?)?;
m.add_function(wrap_pyfunction!(compress_block, m)?)?;
m.add_function(wrap_pyfunction!(decompress_block, m)?)?;
m.add_function(wrap_pyfunction!(compress_into, m)?)?;
m.add_function(wrap_pyfunction!(decompress_into, m)?)?;
m.add_function(wrap_pyfunction!(compress_block_into, m)?)?;
m.add_function(wrap_pyfunction!(decompress_block_into, m)?)?;
m.add_function(wrap_pyfunction!(compress_block_bound, m)?)?;
m.add_class::<Compressor>()?;
m.add_class::<Decompressor>()?;
Ok(())
}
/// LZ4 compression.
///
/// Python Example
/// --------------
/// ```python
/// >>> # Note, output_len is currently ignored; underlying algorithm does not support reading to slice at this time
/// >>> cramjam.lz4.decompress(compressed_bytes, output_len=Optional[int])
/// ```
#[pyfunction]
pub fn decompress(py: Python, data: BytesType, output_len: Option<usize>) -> PyResult<RustyBuffer> {
crate::generic!(py, internal::decompress[data], output_len = output_len).map_err(DecompressionError::from_err)
}
/// lZ4 compression.
///
/// Python Example
/// --------------
/// ```python
/// >>> # Note, output_len is currently ignored; underlying algorithm does not support reading to slice at this time
/// >>> cramjam.lz4.compress(b'some bytes here', output_len=Optional[int])
/// ```
#[pyfunction]
pub fn compress(py: Python, data: BytesType, level: Option<u32>, output_len: Option<usize>) -> PyResult<RustyBuffer> {
crate::generic!(py, internal::compress[data], output_len = output_len, level = level)
.map_err(CompressionError::from_err)
}
/// Compress directly into an output buffer
#[pyfunction]
pub fn compress_into(py: Python, input: BytesType, mut output: BytesType, level: Option<u32>) -> PyResult<usize> {
crate::generic!(py, internal::compress[input, output], level = level).map_err(CompressionError::from_err)
}
/// Decompress directly into an output buffer
#[pyfunction]
pub fn decompress_into(py: Python, input: BytesType, mut output: BytesType) -> PyResult<usize> {
crate::generic!(py, internal::decompress[input, output]).map_err(DecompressionError::from_err)
}
/// LZ4 _block_ decompression.
///
/// `output_len` is optional, it's the upper bound length of decompressed data; if it's not provided,
/// then it's assumed `store_size=True` was used during compression and length will then be taken
/// from the header.
///
/// Python Example
/// --------------
/// ```python
/// >>> cramjam.lz4.decompress_block(compressed_bytes, output_len=Optional[int])
/// ```
#[pyfunction]
pub fn decompress_block(py: Python, data: BytesType, output_len: Option<usize>) -> PyResult<RustyBuffer> {
let bytes = data.as_bytes();
py.allow_threads(|| block::decompress(bytes, output_len.map(|v| v as i32)))
.map_err(DecompressionError::from_err)
.map(RustyBuffer::from)
}
/// lZ4 _block_ compression.
///
/// The kwargs mostly follow the same definition found in [python-lz4 block.compress](https://python-lz4.readthedocs.io/en/stable/lz4.block.html#module-lz4.block)
///
/// Python Example
/// --------------
/// ```python
/// >>> cramjam.lz4.compress_block(
/// ... b'some bytes here',
/// ... output_len=Optional[int],
/// ... mode=Option[str],
/// ... acceleration=Option[int],
/// ... compression=Option[int],
/// ... store_size=Option[bool]
/// ... )
/// ```
#[pyfunction]
#[allow(unused_variables)]
pub fn compress_block(
py: Python,
data: BytesType,
output_len: Option<usize>,
mode: Option<&str>,
acceleration: Option<i32>,
compression: Option<i32>,
store_size: Option<bool>,
) -> PyResult<RustyBuffer> {
let bytes = data.as_bytes();
py.allow_threads(|| {
let store_size = store_size.unwrap_or(true);
let mode = compression_mode(mode, compression, acceleration)?;
block::compress(bytes, Some(mode), store_size)
})
.map_err(CompressionError::from_err)
.map(RustyBuffer::from)
}
/// LZ4 _block_ decompression into a pre-allocated buffer.
///
/// Python Example
/// --------------
/// ```python
/// >>> cramjam.lz4.decompress_block_into(compressed_bytes, output_buffer)
/// ```
#[pyfunction]
pub fn decompress_block_into(py: Python, input: BytesType, mut output: BytesType) -> PyResult<usize> {
let bytes = input.as_bytes();
let out_bytes = output.as_bytes_mut();
py.allow_threads(|| block::decompress_to_buffer(bytes, None, out_bytes))
.map_err(DecompressionError::from_err)
.map(|v| v as _)
}
/// lZ4 _block_ compression into pre-allocated buffer.
///
/// The kwargs mostly follow the same definition found in [python-lz4 block.compress](https://python-lz4.readthedocs.io/en/stable/lz4.block.html#module-lz4.block)
///
/// Python Example
/// --------------
/// ```python
/// >>> cramjam.lz4.compress_block_into(
/// ... b'some bytes here',
/// ... output=output_buffer,
/// ... mode=Option[str],
/// ... acceleration=Option[int],
/// ... compression=Option[int],
/// ... store_size=Option[bool]
/// ... )
/// ```
#[pyfunction]
#[allow(unused_variables)]
pub fn compress_block_into(
py: Python,
data: BytesType,
mut output: BytesType,
mode: Option<&str>,
acceleration: Option<i32>,
compression: Option<i32>,
store_size: Option<bool>,
) -> PyResult<usize> {
let bytes = data.as_bytes();
let out_bytes = output.as_bytes_mut();
py.allow_threads(|| {
let store_size = store_size.unwrap_or(true);
let mode = compression_mode(mode, compression, acceleration)?;
block::compress_to_buffer(bytes, Some(mode), store_size, out_bytes)
})
.map_err(CompressionError::from_err)
.map(|v| v as _)
}
#[inline]
fn compression_mode(
mode: Option<&str>,
compression: Option<i32>,
acceleration: Option<i32>,
) -> PyResult<CompressionMode> {
let m = match mode {
Some(m) => match m {
"default" => CompressionMode::DEFAULT,
"fast" => CompressionMode::FAST(acceleration.unwrap_or(1)),
"high_compression" => CompressionMode::HIGHCOMPRESSION(compression.unwrap_or(9)),
_ => return Err(DecompressionError::new_err(format!("Unrecognized mode '{}'", m))),
},
None => CompressionMode::DEFAULT,
};
Ok(m)
}
///
/// Determine the size of a buffer which is guaranteed to hold the result of block compression, will error if
/// data is too long to be compressed by lz4.
///
/// Python Example
/// --------------
/// ```python
/// >>> cramjam.lz4.compress_block_into(
/// ... b'some bytes here',
/// ... output=output_buffer,
/// ... mode=Option[str],
/// ... acceleration=Option[int],
/// ... compression=Option[int],
/// ... store_size=Option[bool]
/// ... )
/// ```
#[pyfunction]
pub fn compress_block_bound(src: BytesType) -> PyResult<usize> {
block::compress_bound(src.len()).map_err(|e| pyo3::exceptions::PyValueError::new_err(e.to_string()))
}
/// lz4 Compressor object for streaming compression
#[pyclass]
pub struct Compressor {
inner: Option<lz4::Encoder<Cursor<Vec<u8>>>>,
}
#[pymethods]
impl Compressor {
/// Initialize a new `Compressor` instance.
#[new]
pub fn __init__(level: Option<u32>) -> PyResult<Self> {
let inner = lz4::EncoderBuilder::new()
.auto_flush(true)
.level(level.unwrap_or_else(|| DEFAULT_COMPRESSION_LEVEL))
.build(Cursor::new(vec![]))?;
Ok(Self { inner: Some(inner) })
}
/// Compress input into the current compressor's stream.
pub fn compress(&mut self, input: &[u8]) -> PyResult<usize> {
crate::io::stream_compress(&mut self.inner, input)
}
/// Flush and return current compressed stream
#[allow(mutable_transmutes)] // TODO: feature req to lz4 to get mut ref to writer
pub fn flush(&mut self) -> PyResult<RustyBuffer> {
crate::io::stream_flush(&mut self.inner, |e| {
let writer = e.writer();
// no other mutations to buf b/c it'll be truncated and return immediately after this
unsafe { std::mem::transmute::<&Cursor<Vec<u8>>, &mut Cursor<Vec<u8>>>(writer) }
})
}
/// Consume the current compressor state and return the compressed stream
/// **NB** The compressor will not be usable after this method is called.
pub fn finish(&mut self) -> PyResult<RustyBuffer> {
crate::io::stream_finish(&mut self.inner, |inner| {
let (cursor, result) = inner.finish();
result.map(|_| cursor.into_inner())
})
}
}
crate::make_decompressor!();
pub(crate) mod internal {
use crate::lz4::DEFAULT_COMPRESSION_LEVEL;
use lz4::{Decoder, EncoderBuilder};
use std::io::{BufReader, Error, Read, Seek, SeekFrom, Write};
/// Decompress lz4 data
#[inline(always)]
pub fn decompress<W: Write + ?Sized, R: Read>(input: R, output: &mut W) -> Result<usize, Error> {
let mut decoder = Decoder::new(input)?;
let n_bytes = std::io::copy(&mut decoder, output)?;
decoder.finish().1?;
Ok(n_bytes as usize)
}
/// Compress lz4 data
#[inline(always)]
pub fn compress<W: Write + ?Sized + Seek, R: Read>(
input: R,
output: &mut W,
level: Option<u32>,
) -> Result<usize, Error> {
let start_pos = output.seek(SeekFrom::Current(0))?;
let mut encoder = EncoderBuilder::new()
.auto_flush(true)
.level(level.unwrap_or_else(|| DEFAULT_COMPRESSION_LEVEL))
.build(output)?;
// this returns, bytes read from uncompressed, input; we want bytes written
// but lz4 only implements Read for Encoder
let mut buf = BufReader::new(input);
std::io::copy(&mut buf, &mut encoder)?;
let (w, r) = encoder.finish();
r?;
let ending_pos = w.seek(SeekFrom::Current(0))?;
Ok((ending_pos - start_pos) as usize)
}
}