Implement f64 method polyfills with intrinsics support (#21)

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "caches"
-version = "0.2.8"
+version = "0.2.9"
 authors = ["Al Liu <[email protected]>"]
 description = "This is a Rust implementation for popular caches (support no_std)."
 homepage = "https://github.com/al8n/caches-rs"
@@ -42,7 +42,9 @@ nightly = ["rand/nightly"]
 
 [dependencies]
 bitvec = { version = "1", default-features = false }
+cfg-if = "1.0.0"
 hashbrown = { version = "0.14", optional = true }
+libm = {version = "0.2.8", optional = true}
 rand = {version = "0.8", optional = true}
 
 [dev-dependencies]

benches/wtinylfu_cache.rs

@@ -1,4 +1,4 @@
-use caches::{Cache, WTinyLFUCache, WTinyLFUCacheBuilder};
+use caches::{lfu::DefaultKeyHasher, Cache, WTinyLFUCache, WTinyLFUCacheBuilder};
 use criterion::{black_box, criterion_group, criterion_main, BatchSize, Criterion};
 use fnv::FnvBuildHasher;
 use rand::{thread_rng, Rng};
@@ -59,10 +59,11 @@ fn bench_wtinylfu_cache_fx_hasher(c: &mut Criterion) {
                         .collect(),
                 );
 
-                let builder = WTinyLFUCacheBuilder::new(82, 6488, 1622, 8192)
+                let builder = WTinyLFUCacheBuilder::<u64, DefaultKeyHasher<u64>, BuildHasherDefault<FxHasher>, BuildHasherDefault<FxHasher>, BuildHasherDefault<FxHasher>>::new(82, 6488, 1622, 8192)
                     .set_window_hasher(BuildHasherDefault::<FxHasher>::default())
                     .set_protected_hasher(BuildHasherDefault::<FxHasher>::default())
-                    .set_probationary_hasher(BuildHasherDefault::<FxHasher>::default());
+                    .set_probationary_hasher(BuildHasherDefault::<FxHasher>::default())
+                    .set_key_hasher(DefaultKeyHasher::default());
                 let l = WTinyLFUCache::from_builder(builder).unwrap();
                 (l, nums)
             },
@@ -99,7 +100,8 @@ fn bench_wtinylfu_cache_fnv_hasher(c: &mut Criterion) {
                         })
                         .collect(),
                 );
-                let builder = WTinyLFUCacheBuilder::new(82, 6488, 1622, 8192)
+                let builder = WTinyLFUCacheBuilder::<u64, DefaultKeyHasher<u64>, BuildHasherDefault<fnv::FnvHasher>, BuildHasherDefault<fnv::FnvHasher>, BuildHasherDefault<fnv::FnvHasher>>::new(82, 6488, 1622, 8192)
+                    .set_key_hasher(DefaultKeyHasher::default())
                     .set_window_hasher(FnvBuildHasher::default())
                     .set_protected_hasher(FnvBuildHasher::default())
                     .set_probationary_hasher(FnvBuildHasher::default());

src/lfu/tinylfu/bloom.rs

@@ -7,7 +7,10 @@
 // use bitvec::vec::BitVec;
 use alloc::{vec, vec::Vec};
 
+use crate::polyfill::{ceil, ln};
+
 const LN_2: f64 = core::f64::consts::LN_2;
+const LN_2_2: f64 = LN_2 * LN_2;
 
 fn get_size(ui64: u64) -> (u64, u64) {
     let ui64 = if ui64 < 512 { 512 } else { ui64 };
@@ -21,8 +24,8 @@ fn get_size(ui64: u64) -> (u64, u64) {
 }
 
 fn calc_size_by_wrong_positives(num_entries: f64, wrongs: f64) -> (u64, u64) {
-    let size = (-num_entries * wrongs.ln() / LN_2.powi(2)).ceil() as u64;
-    let locs = (LN_2 * size as f64 / num_entries).ceil() as u64;
+    let size = ceil(-num_entries * ln(wrongs) / LN_2_2) as u64;
+    let locs = ceil(LN_2 * size as f64 / num_entries) as u64;
     (size, locs)
 }
 

src/lib.rs

@@ -89,10 +89,17 @@
 #![cfg_attr(docsrs, feature(doc_cfg))]
 #![cfg_attr(docsrs, allow(unused_attributes))]
 #![deny(missing_docs)]
-#![allow(clippy::blocks_in_if_conditions, clippy::enum_variant_names)]
+#![allow(unused_doc_comments)]
+#![allow(clippy::blocks_in_conditions, clippy::enum_variant_names)]
 
 extern crate alloc;
 
+#[macro_use]
+extern crate cfg_if;
+
+#[doc(hidden)]
+pub(crate) mod polyfill;
+
 #[cfg(not(feature = "std"))]
 extern crate hashbrown;
 

src/lru/two_queue.rs

@@ -9,6 +9,9 @@ use alloc::fmt;
 use core::borrow::Borrow;
 use core::hash::{BuildHasher, Hash};
 
+// f64 function polyfill to support no_std contexts
+use crate::polyfill::floor;
+
 /// `DEFAULT_2Q_RECENT_RATIO` is the ratio of the [`TwoQueueCache`] dedicated
 /// to recently added entries that have only been accessed once.
 ///
@@ -191,8 +194,8 @@ impl<RH: BuildHasher, FH: BuildHasher, GH: BuildHasher> TwoQueueCacheBuilder<RH,
         }
 
         // Determine the sub-sizes
-        let rs = ((size as f64) * rr).floor() as usize;
-        let es = ((size as f64) * gr).floor() as usize;
+        let rs = floor((size as f64) * rr) as usize;
+        let es = floor((size as f64) * gr) as usize;
 
         // allocate the lrus
 
@@ -361,8 +364,8 @@ impl<K: Hash + Eq, V> TwoQueueCache<K, V> {
         }
 
         // Determine the sub-sizes
-        let rs = ((size as f64) * rr).floor() as usize;
-        let es = ((size as f64) * gr).floor() as usize;
+        let rs = floor((size as f64) * rr) as usize;
+        let es = floor((size as f64) * gr) as usize;
 
         // allocate the lrus
         let recent = RawLRU::new(size).unwrap();

src/polyfill.rs

@@ -0,0 +1,37 @@
+/// Three level poliyfill dor the f64 `ceil`, `ln`, and `floor` functions.
+/// Using these functions in a no_std context falls back to libm's manual
+/// implementation from musl's libc.
+/// Using the nightly feature allows the upgrade to using LLVM hints, and
+/// allowing LLVM to provide a software fallback for target platforms
+/// witout hardware f64 instructions.
+
+cfg_if! {
+    if #[cfg(feature = "std")] {
+        #[inline(always)]
+        pub(crate) fn ceil(val: f64) -> f64 {
+            val.ceil()
+        }
+        #[inline(always)]
+        pub(crate) fn ln(val: f64) -> f64 {
+            val.ln()
+        }
+        #[inline(always)]
+        pub(crate) fn floor(val: f64) -> f64 {
+            val.floor()
+        }
+    } else {
+        use libm;
+        #[inline(always)]
+        pub(crate) fn ceil(val: f64) -> f64 {
+            libm::ceil(val)
+        }
+        #[inline(always)]
+        pub(crate) fn ln(val: f64) -> f64 {
+            libm::log(val)
+        }
+        #[inline(always)]
+        pub(crate) fn floor(val: f64) -> f64 {
+            libm::floor(val)
+        }
+    }
+}