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//! This module contains zstd-specific types for async-compression.
use libzstd::stream::raw::CParameter::*;
use libzstd::stream::raw::DParameter::*;
/// A compression parameter for zstd. This is a stable wrapper around zstd's own `CParameter`
/// type, to abstract over different versions of the zstd library.
///
/// See the [zstd documentation](https://facebook.github.io/zstd/zstd_manual.html) for more
/// information on these parameters.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub struct CParameter(libzstd::stream::raw::CParameter);
impl CParameter {
/// Window size in bytes (as a power of two)
pub fn window_log(value: u32) -> Self {
Self(WindowLog(value))
}
/// Size of the initial probe table in 4-byte entries (as a power of two)
pub fn hash_log(value: u32) -> Self {
Self(HashLog(value))
}
/// Size of the multi-probe table in 4-byte entries (as a power of two)
pub fn chain_log(value: u32) -> Self {
Self(ChainLog(value))
}
/// Number of search attempts (as a power of two)
pub fn search_log(value: u32) -> Self {
Self(SearchLog(value))
}
/// Minimum size of matches searched for
pub fn min_match(value: u32) -> Self {
Self(MinMatch(value))
}
/// Strategy-dependent length modifier
pub fn target_length(value: u32) -> Self {
Self(TargetLength(value))
}
/// Enable long-distance matching mode to look for and emit long-distance references.
///
/// This increases the default window size.
pub fn enable_long_distance_matching(value: bool) -> Self {
Self(EnableLongDistanceMatching(value))
}
/// Size of the long-distance matching table (as a power of two)
pub fn ldm_hash_log(value: u32) -> Self {
Self(LdmHashLog(value))
}
/// Minimum size of long-distance matches searched for
pub fn ldm_min_match(value: u32) -> Self {
Self(LdmMinMatch(value))
}
/// Size of each bucket in the LDM hash table for collision resolution (as a power of two)
pub fn ldm_bucket_size_log(value: u32) -> Self {
Self(LdmBucketSizeLog(value))
}
/// Frequency of using the LDM hash table (as a power of two)
pub fn ldm_hash_rate_log(value: u32) -> Self {
Self(LdmHashRateLog(value))
}
/// Emit the size of the content (default: true).
pub fn content_size_flag(value: bool) -> Self {
Self(ContentSizeFlag(value))
}
/// Emit a checksum (default: false).
pub fn checksum_flag(value: bool) -> Self {
Self(ChecksumFlag(value))
}
/// Emit a dictionary ID when using a custom dictionary (default: true).
pub fn dict_id_flag(value: bool) -> Self {
Self(DictIdFlag(value))
}
/// Number of threads to spawn.
///
/// If set to 0, compression functions will block; if set to 1 or more, compression will
/// run in background threads and `flush` pushes bytes through the compressor.
///
/// # Panics
///
/// This parameter requires feature `zstdmt` to be enabled, otherwise it will cause a panic
/// when used in `ZstdEncoder::with_quality_and_params()` calls.
//
// TODO: make this a normal feature guarded fn on next breaking release
#[cfg_attr(docsrs, doc(cfg(feature = "zstdmt")))]
pub fn nb_workers(value: u32) -> Self {
Self(NbWorkers(value))
}
/// Number of bytes given to each worker.
///
/// If set to 0, zstd selects a job size based on compression parameters.
pub fn job_size(value: u32) -> Self {
Self(JobSize(value))
}
pub(crate) fn as_zstd(&self) -> libzstd::stream::raw::CParameter {
self.0
}
}
/// A decompression parameter for zstd. This is a stable wrapper around zstd's own `DParameter`
/// type, to abstract over different versions of the zstd library.
///
/// See the [zstd documentation](https://facebook.github.io/zstd/zstd_manual.html) for more
/// information on these parameters.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub struct DParameter(libzstd::stream::raw::DParameter);
impl DParameter {
/// Maximum window size in bytes (as a power of two)
pub fn window_log_max(value: u32) -> Self {
Self(WindowLogMax(value))
}
pub(crate) fn as_zstd(&self) -> libzstd::stream::raw::DParameter {
self.0
}
}