feat(params): move context-free getters into Rust

Compression-parameter table selection and adjustment were already implemented
as Rust leaves, but the internal and public ZSTD_getCParams/ZSTD_getParams
helpers still assembled those results in the C translation unit. That left
source-size and dictionary-mode policy duplicated at the C/Rust boundary.

Add Rust implementations for the internal and public getter policies. The
internal helpers preserve a zero source size as a known empty input, while the
public helpers retain the API rule that zero means unknown. The C side keeps
only the build-specific exclusion-mask construction and thin ABI adapters, so
reduced builds continue to select the same available strategy cascade.

Test Plan:
- `cargo test --manifest-path rust/Cargo.toml --lib -- --test-threads=1`
  -- passed (411 tests).
- `cargo clippy --manifest-path rust/Cargo.toml --lib -- -D warnings`
  -- passed.
- `cargo +nightly fmt --manifest-path rust/Cargo.toml -- --check` -- passed.
- `make -B -C lib -j2 lib` -- passed.
- Focused tests cover public zero-to-unknown translation, internal zero
  semantics, default frame parameters, and dictionary attachment modes.
This commit is contained in:
2026-07-18 18:43:00 +02:00
parent 4f55ce323f
commit 7867f64413
2 changed files with 229 additions and 25 deletions
+24 -12
View File
@@ -148,6 +148,18 @@ ZSTD_compressionParameters
ZSTD_rust_params_adjustCParams(ZSTD_compressionParameters cParams, U64 srcSize,
size_t dictSize, int mode,
int useRowMatchFinder);
ZSTD_compressionParameters ZSTD_rust_params_getCParamsInternal(
int compressionLevel, U64 srcSizeHint, size_t dictSize, int mode,
U32 exclusionMask);
ZSTD_parameters ZSTD_rust_params_getParamsInternal(
int compressionLevel, U64 srcSizeHint, size_t dictSize, int mode,
U32 exclusionMask);
ZSTD_compressionParameters ZSTD_rust_params_getCParams(
int compressionLevel, U64 srcSizeHint, size_t dictSize,
U32 exclusionMask);
ZSTD_parameters ZSTD_rust_params_getParams(
int compressionLevel, U64 srcSizeHint, size_t dictSize,
U32 exclusionMask);
ZSTD_compressionParameters ZSTD_rust_params_applyStrategyExclusions(
ZSTD_compressionParameters cParams, U32 exclusionMask);
ZSTD_compressionParameters ZSTD_rust_params_getCParamsFromCCtxParams(
@@ -5697,12 +5709,9 @@ static void ZSTD_dedicatedDictSearch_revertCParams(
* Note: `mode` controls how we treat the `dictSize`. See docs for `ZSTD_CParamMode_e`. */
static ZSTD_compressionParameters ZSTD_getCParams_internal(int compressionLevel, unsigned long long srcSizeHint, size_t dictSize, ZSTD_CParamMode_e mode)
{
/* Table selection is context-free and lives in Rust; the adjustment step
* stays behind ZSTD_adjustCParams_internal() so this build's strategy
* cascade applies. */
ZSTD_compressionParameters const cp = ZSTD_rust_params_selectCParams(
compressionLevel, srcSizeHint, dictSize, (int)mode);
return ZSTD_adjustCParams_internal(cp, srcSizeHint, dictSize, mode, ZSTD_ps_auto);
return ZSTD_rust_params_getCParamsInternal(
compressionLevel, srcSizeHint, dictSize, (int)mode,
ZSTD_getCParamsExclusionMask());
}
/*! ZSTD_getCParams() :
@@ -5710,8 +5719,9 @@ static ZSTD_compressionParameters ZSTD_getCParams_internal(int compressionLevel,
* Size values are optional, provide 0 if not known or unused */
ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long long srcSizeHint, size_t dictSize)
{
if (srcSizeHint == 0) srcSizeHint = ZSTD_CONTENTSIZE_UNKNOWN;
return ZSTD_getCParams_internal(compressionLevel, srcSizeHint, dictSize, ZSTD_cpm_unknown);
return ZSTD_rust_params_getCParams(
compressionLevel, srcSizeHint, dictSize,
ZSTD_getCParamsExclusionMask());
}
/*! ZSTD_getParams() :
@@ -5721,9 +5731,10 @@ ZSTD_compressionParameters ZSTD_getCParams(int compressionLevel, unsigned long l
static ZSTD_parameters
ZSTD_getParams_internal(int compressionLevel, unsigned long long srcSizeHint, size_t dictSize, ZSTD_CParamMode_e mode)
{
ZSTD_compressionParameters const cParams = ZSTD_getCParams_internal(compressionLevel, srcSizeHint, dictSize, mode);
DEBUGLOG(5, "ZSTD_getParams (cLevel=%i)", compressionLevel);
return ZSTD_rust_params_makeParams(cParams);
return ZSTD_rust_params_getParamsInternal(
compressionLevel, srcSizeHint, dictSize, (int)mode,
ZSTD_getCParamsExclusionMask());
}
/*! ZSTD_getParams() :
@@ -5732,8 +5743,9 @@ ZSTD_getParams_internal(int compressionLevel, unsigned long long srcSizeHint, si
* Fields of `ZSTD_frameParameters` are set to default values */
ZSTD_parameters ZSTD_getParams(int compressionLevel, unsigned long long srcSizeHint, size_t dictSize)
{
if (srcSizeHint == 0) srcSizeHint = ZSTD_CONTENTSIZE_UNKNOWN;
return ZSTD_getParams_internal(compressionLevel, srcSizeHint, dictSize, ZSTD_cpm_unknown);
return ZSTD_rust_params_getParams(
compressionLevel, srcSizeHint, dictSize,
ZSTD_getCParamsExclusionMask());
}
void ZSTD_registerSequenceProducer(
+205 -13
View File
@@ -5,13 +5,14 @@
//! Context-free compression-parameter selection and sizing leaves.
//!
//! This module deliberately does **not** own the public `ZSTD_*` symbols yet.
//! `zstd_compress.c` still owns configuration-sensitive policy: private
//! `ZSTD_CCtx_params` layouts, the C-preprocessor construction of excluded
//! block-compressor bits, LDM workspace sizing, and ASAN workspace policy.
//! The Rust policy leaves receive those build values as explicit scalar inputs,
//! retaining byte-for-byte C behavior for reduced builds without exposing
//! private C state across the ABI.
//! The public `ZSTD_*` symbols remain C-owned thin adapters. Rust owns the
//! context-free getter policy behind scalar ABI functions. `zstd_compress.c`
//! still owns configuration-sensitive policy: private `ZSTD_CCtx_params`
//! layouts, the C-preprocessor construction of excluded block-compressor
//! bits, LDM workspace sizing, and ASAN workspace policy. The Rust policy
//! leaves receive those build values as explicit scalar inputs, retaining
//! byte-for-byte C behavior for reduced builds without exposing private C
//! state across the ABI.
use crate::errors::{ZstdErrorCode, ERROR};
use std::mem::size_of;
@@ -855,6 +856,77 @@ fn select_cparams(
cparams
}
fn get_cparams_internal(
compression_level: c_int,
src_size_hint: u64,
dict_size: usize,
mode: c_int,
exclusion_mask: u32,
) -> ZSTD_compressionParameters {
/* ZSTD_getCParams_internal() preserves srcSizeHint == 0 as a known empty
* input. Only the public getter translates zero to UNKNOWN. */
let cparams = select_cparams(compression_level, src_size_hint, dict_size, mode);
adjust_cparams(
apply_strategy_exclusions(cparams, exclusion_mask),
src_size_hint,
dict_size,
mode,
ZSTD_RUST_PS_AUTO,
)
}
#[inline]
fn get_params_internal(
compression_level: c_int,
src_size_hint: u64,
dict_size: usize,
mode: c_int,
exclusion_mask: u32,
) -> ZSTD_parameters {
make_params(get_cparams_internal(
compression_level,
src_size_hint,
dict_size,
mode,
exclusion_mask,
))
}
fn get_cparams_public(
compression_level: c_int,
src_size_hint: u64,
dict_size: usize,
exclusion_mask: u32,
) -> ZSTD_compressionParameters {
let src_size_hint = if src_size_hint == 0 {
ZSTD_CONTENTSIZE_UNKNOWN
} else {
src_size_hint
};
get_cparams_internal(
compression_level,
src_size_hint,
dict_size,
ZSTD_RUST_CPM_UNKNOWN,
exclusion_mask,
)
}
#[inline]
fn get_params_public(
compression_level: c_int,
src_size_hint: u64,
dict_size: usize,
exclusion_mask: u32,
) -> ZSTD_parameters {
make_params(get_cparams_public(
compression_level,
src_size_hint,
dict_size,
exclusion_mask,
))
}
fn get_cparams_from_cctx_params(
compression_level: c_int,
cctx_src_size_hint: c_int,
@@ -873,15 +945,12 @@ fn get_cparams_from_cctx_params(
}
/* ZSTD_getCParams_internal() selects and performs the first adjustment. */
let mut cparams = adjust_cparams(
apply_strategy_exclusions(
select_cparams(compression_level, src_size_hint, dict_size, mode),
exclusion_mask,
),
let mut cparams = get_cparams_internal(
compression_level,
src_size_hint,
dict_size,
mode,
ZSTD_RUST_PS_AUTO,
exclusion_mask,
);
if enable_ldm == ZSTD_RUST_PS_ENABLE {
@@ -1043,6 +1112,57 @@ pub extern "C" fn ZSTD_rust_params_adjustCParams(
adjust_cparams(cparams, srcSize, dictSize, mode, useRowMatchFinder)
}
/// Reproduces `ZSTD_getCParams_internal()` without translating a zero source
/// size to `ZSTD_CONTENTSIZE_UNKNOWN`.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_getCParamsInternal(
compressionLevel: c_int,
srcSizeHint: u64,
dictSize: usize,
mode: c_int,
exclusionMask: u32,
) -> ZSTD_compressionParameters {
get_cparams_internal(compressionLevel, srcSizeHint, dictSize, mode, exclusionMask)
}
/// Reproduces `ZSTD_getParams_internal()` without translating a zero source
/// size to `ZSTD_CONTENTSIZE_UNKNOWN`.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_getParamsInternal(
compressionLevel: c_int,
srcSizeHint: u64,
dictSize: usize,
mode: c_int,
exclusionMask: u32,
) -> ZSTD_parameters {
get_params_internal(compressionLevel, srcSizeHint, dictSize, mode, exclusionMask)
}
/// Reproduces the public `ZSTD_getCParams()` source-size policy: zero means
/// an unknown size, while the internal helper keeps zero as a known empty
/// input.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_getCParams(
compressionLevel: c_int,
srcSizeHint: u64,
dictSize: usize,
exclusionMask: u32,
) -> ZSTD_compressionParameters {
get_cparams_public(compressionLevel, srcSizeHint, dictSize, exclusionMask)
}
/// Reproduces the public `ZSTD_getParams()` source-size policy and default
/// frame-parameter construction.
#[no_mangle]
pub extern "C" fn ZSTD_rust_params_getParams(
compressionLevel: c_int,
srcSizeHint: u64,
dictSize: usize,
exclusionMask: u32,
) -> ZSTD_parameters {
get_params_public(compressionLevel, srcSizeHint, dictSize, exclusionMask)
}
/// Reproduces `ZSTD_getCParamsFromCCtxParams()` from scalar snapshots.
///
/// The C shim supplies the private build policy as an exclusion mask and the
@@ -2075,6 +2195,78 @@ mod tests {
);
}
#[test]
fn public_getters_translate_zero_to_unknown_but_internal_getters_do_not() {
let public_zero = ZSTD_rust_params_getCParams(3, 0, 1, 0);
let public_unknown = ZSTD_rust_params_getCParams(3, ZSTD_CONTENTSIZE_UNKNOWN, 1, 0);
assert_eq!(public_zero, public_unknown);
let internal_zero = ZSTD_rust_params_getCParamsInternal(3, 0, 1, ZSTD_RUST_CPM_UNKNOWN, 0);
assert_eq!(internal_zero.windowLog, 10);
assert_eq!(public_unknown.windowLog, 14);
assert_ne!(internal_zero, public_unknown);
let public_params_zero = ZSTD_rust_params_getParams(3, 0, 1, 0);
let public_params_unknown = ZSTD_rust_params_getParams(3, ZSTD_CONTENTSIZE_UNKNOWN, 1, 0);
assert_eq!(public_params_zero, public_params_unknown);
assert_eq!(public_params_zero.cParams, public_zero);
assert_eq!(
ZSTD_rust_params_getParamsInternal(3, 0, 1, ZSTD_RUST_CPM_UNKNOWN, 0).cParams,
internal_zero
);
}
#[test]
fn getter_modes_preserve_dictionary_attachment_boundaries() {
let attached_with_dict = ZSTD_rust_params_getCParamsInternal(
3,
ZSTD_CONTENTSIZE_UNKNOWN,
1,
ZSTD_RUST_CPM_ATTACH_DICT,
0,
);
let attached_without_dict = ZSTD_rust_params_getCParamsInternal(
3,
ZSTD_CONTENTSIZE_UNKNOWN,
0,
ZSTD_RUST_CPM_ATTACH_DICT,
0,
);
assert_eq!(attached_with_dict, attached_without_dict);
let no_attach = ZSTD_rust_params_getCParamsInternal(
3,
ZSTD_CONTENTSIZE_UNKNOWN,
1,
ZSTD_RUST_CPM_NO_ATTACH_DICT,
0,
);
let create_cdict = ZSTD_rust_params_getCParamsInternal(
3,
ZSTD_CONTENTSIZE_UNKNOWN,
1,
ZSTD_RUST_CPM_CREATE_CDICT,
0,
);
assert_eq!(attached_with_dict.windowLog, 21);
assert_eq!(no_attach.windowLog, 14);
assert_eq!(create_cdict.windowLog, 10);
assert!(attached_with_dict.windowLog > no_attach.windowLog);
assert!(no_attach.windowLog > create_cdict.windowLog);
assert_eq!(
ZSTD_rust_params_getCParamsInternal(
3,
ZSTD_CONTENTSIZE_UNKNOWN,
1,
ZSTD_RUST_CPM_UNKNOWN,
0,
)
.windowLog,
no_attach.windowLog
);
}
fn cctx_policy_params(
cctx_src_size_hint: c_int,
src_size_hint: u64,