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rs-malloc-array
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Avril 4 years ago
commit d8af6e37a2
Signed by: flanchan
GPG Key ID: 284488987C31F630
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3
.gitignore vendored
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/target
Cargo.lock
*~

25
Cargo.toml
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[package]
name = "malloc-array"
description = "libc heap array allocator"
version = "0.1.0"
authors = ["Avril <flanchan@cumallover.me>"]
edition = "2018"
license = "GPL v3"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[features]
default = ["zst_noalloc"]
# Assume Rust will free things allocated with malloc() properly.
assume_libc = []
# Do not allocate for ZSTs
zst_noalloc = []
# Use jemalloc instead of libc malloc
jemalloc = ["jemalloc-sys"]
[dependencies]
libc = "0.2"
jemalloc-sys = { version = "0.3", optional = true }

109
src/alloc.rs
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use std::{
ffi::c_void,
error,
fmt,
};
use crate::{
ptr::{self,VoidPointer,},
};
#[derive(Debug)]
pub struct Error;
impl error::Error for Error{}
impl fmt::Display for Error
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
{
write!(f, "Allocation failed.")
}
}
#[inline]
unsafe fn malloc_internal(sz: libc::size_t) -> *mut c_void
{
#[cfg(feature="jemalloc")]
return jemalloc_sys::malloc(sz);
#[cfg(not(feature="jemalloc"))]
return libc::malloc(sz);
}
#[inline]
unsafe fn calloc_internal(nm: libc::size_t, sz: libc::size_t) -> *mut c_void
{
#[cfg(feature="jemalloc")]
return jemalloc_sys::calloc(nm,sz);
#[cfg(not(feature="jemalloc"))]
return libc::calloc(nm,sz);
}
#[inline]
unsafe fn free_internal(ptr: *mut c_void)
{
#[cfg(feature="jemalloc")]
return jemalloc_sys::free(ptr);
#[cfg(not(feature="jemalloc"))]
return libc::free(ptr);
}
#[inline]
unsafe fn realloc_internal(ptr: *mut c_void, sz: libc::size_t) -> *mut c_void
{
#[cfg(feature="jemalloc")]
return jemalloc_sys::realloc(ptr,sz);
#[cfg(not(feature="jemalloc"))]
return libc::realloc(ptr,sz);
}
const NULL_PTR: *mut c_void = 0 as *mut c_void;
pub unsafe fn malloc(sz: usize) -> Result<VoidPointer,Error>
{
#[cfg(feature="zst_noalloc")]
if sz == 0 {
return Ok(ptr::NULL_PTR);
}
match malloc_internal(sz as libc::size_t)
{
null if null == NULL_PTR => Err(Error),
ptr => Ok(ptr as VoidPointer),
}
}
pub unsafe fn calloc(nm: usize, sz: usize) -> Result<VoidPointer, Error>
{
#[cfg(feature="zst_noalloc")]
if (nm*sz) == 0 {
return Ok(ptr::NULL_PTR);
}
match calloc_internal(nm as libc::size_t, sz as libc::size_t)
{
null if null == NULL_PTR => Err(Error),
ptr => Ok(ptr as VoidPointer),
}
}
pub unsafe fn free(ptr: VoidPointer)
{
if ptr != crate::ptr::NULL_PTR {
free_internal(ptr as *mut c_void);
}
}
pub unsafe fn realloc(ptr: VoidPointer, sz: usize) -> Result<VoidPointer, Error>
{
#[cfg(feature="zst_noalloc")]
if sz == 0 {
free(ptr);
return Ok(crate::ptr::NULL_PTR);
}
if ptr == crate::ptr::NULL_PTR {
return malloc(sz);
}
match realloc_internal(ptr as *mut c_void, sz as libc::size_t)
{
null if null == NULL_PTR => Err(Error),
ptr => Ok(ptr as VoidPointer),
}
}

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src/iter.rs
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use super::*;
use std::{
mem::{
replace,
MaybeUninit,
forget,
},
};
use ptr::{
VoidPointer,
};
pub struct IntoIter<T>
{
start: *mut T,
current: *mut T,
sz: usize,
}
impl<T> IntoIter<T>
{
fn current_offset(&self) -> usize
{
(self.current as usize) - (self.start as usize)
}
fn free_if_needed(&mut self)
{
if self.start != ptr::null() && self.current_offset() >= self.sz {
unsafe {
alloc::free(self.start as VoidPointer);
}
self.start = ptr::null();
}
}
}
impl<T> Iterator for IntoIter<T>
{
type Item = T;
fn next(&mut self) -> Option<Self::Item>
{
let output = if self.current_offset() >= self.sz {
None
} else {
unsafe {
let output = replace(&mut (*self.current), MaybeUninit::zeroed().assume_init());
self.current = self.current.offset(1);
Some(output)
}
};
self.free_if_needed();
output
}
}
impl<T> IntoIterator for HeapArray<T>
{
type Item = T;
type IntoIter = IntoIter<T>;
fn into_iter(self) -> Self::IntoIter
{
let output = Self::IntoIter {
start: self.ptr,
current: self.ptr,
sz: self.len(),
};
forget(self);
output
}
}

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src/lib.rs
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#![allow(dead_code)]
extern crate libc;
#[cfg(feature="jemalloc")]
extern crate jemalloc_sys;
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn as_slice() {
let heap = heap![unsafe 0, 1, 2, 3u8];
assert_eq!(heap.as_slice(), [0,1,2,3u8]);
}
#[test]
fn non_trivial_type() {
let heap = heap!["test one".to_owned(), "test two".to_owned()];
assert_eq!(heap.as_slice(), ["test one", "test two"]);
}
#[test]
fn zero_size() {
let heap: HeapArray<u8> = heap![];
let heap_zst: HeapArray<()> = heap![(); 3];
assert_eq!(&heap.as_slice(), &[]);
assert_eq!(&heap_zst.as_slice(), &[(),(),()]);
}
#[test]
fn into_iter() {
let primitive = heap![1,3,5,7,9u32];
for x in primitive.into_iter()
{
assert_eq!(x % 2, 1);
}
let non = heap!["string one".to_owned(), "string two".to_owned()];
for x in non.into_iter()
{
assert_eq!(&x[..6], "string");
}
}
}
mod ptr;
mod alloc;
mod reinterpret;
use std::{
ops::{
Drop,
Index,IndexMut,
Deref,DerefMut,
},
borrow::{
Borrow,BorrowMut,
},
slice::{
self,
SliceIndex,
},
};
use crate::{
ptr::{
VoidPointer,
},
};
#[macro_export]
/// `vec![]`-like macro for creating `HeapArray<T>` instances.
///
/// Provices methods for creating safly accessable arrays using `malloc()` with a `Vec<T>` like interface.
/// Also provides methods of optimising deallocations.
///
/// # Usage
///
/// Works like array definitions `[type; size]`, and like the `vec![]` macro `[value; size]`. Prepend the statement with `unsafe` (`[unsafe type|value; size]`) to prevent potentially redundant `drop()` calls.
///
/// # Examples
///
/// ```rust
/// use malloc_array::{heap, HeapArray};
/// let ints = heap![unsafe 4u32; 32]; // Creates a 32 element `u32` array with each element set to `4`.
/// let ints = heap![unsafe u32; 32]; // Creates an uninitialised 32 element `u32` array.
/// let ints = heap![u32; 32]; // Same as above, except when `ints` is dropped, each element will be also dropped redundantly.
/// let strings = heap!["string one".to_owned(), "string two".to_owned()]; //Creates a 2 element string array.
/// let strings = heap![unsafe "memory".to_owned(), "leak".to_owned()]; //Same as above, except `drop()` will not be called on the 2 strings, potentially causing a memory leak.
/// let strings: HeapArray<u8> = heap![]; //Creates an empty `u8` array.
/// ```
macro_rules! heap {
() => {
$crate::HeapArray::new_uninit(0)
};
(@) => (0usize);
(@ $x:tt $($xs:tt)* ) => (1usize + $crate::heap!(@ $($xs)*));
(unsafe $($xs:tt)*) => {
{
#[allow(unused_unsafe)]
unsafe {
let mut output = $crate::heap!($($xs)*);
output.drop_check = false;
output
}
}
};
($type:ty; $number:expr) => {
{
$crate::HeapArray::<$type>::new($number)
}
};
($value:expr; $number:expr) => {
{
let num = $number;
let mut ha = $crate::HeapArray::new_uninit(num);
for x in 0..num {
ha[x] = $value;
}
ha
}
};
($($n:expr),*) => {
{
let mut ha = $crate::HeapArray::new_uninit($crate::heap!(@ $($n)*));
{
let fp = 0;
$(
let fp = fp + 1;
ha[fp-1] = $n;
)*
}
ha
}
};
}
pub struct HeapArray<T> {
ptr: *mut T,
size: usize,
/// Call `drop()` on sub-elements when `drop`ping the array. This is not needed for types that implement `Copy`.
pub drop_check: bool,
}
impl<T> HeapArray<T>
{
pub fn len_bytes(&self) -> usize
{
Self::element_size() * self.size
}
pub fn len(&self) -> usize
{
self.size
}
const fn element_size() -> usize
{
std::mem::size_of::<T>()
}
const fn is_single() -> bool
{
std::mem::size_of::<T>() == 1
}
pub fn new(size: usize) -> Self
{
Self {
ptr: unsafe{alloc::calloc(size, Self::element_size()).expect("calloc()")} as *mut T,
size,
drop_check: true,
}
}
pub fn new_uninit(size: usize) -> Self
{
Self {
ptr: unsafe{alloc::malloc(size * Self::element_size()).expect("malloc()")} as *mut T,
size,
drop_check: true,
}
}
pub fn new_repeat(initial: T, size: usize) -> Self
where T: Copy
{
let this = Self::new_uninit(size);
if size > 0 {
if Self::is_single() {
unsafe {
ptr::memset(this.ptr as *mut u8, reinterpret::bytes(initial), this.len_bytes());
}
} else {
unsafe {
for x in 0..size {
*this.ptr.offset(x as isize) = initial;
}
}
}
}
this
}
pub fn new_range<U>(initial: U, size: usize) -> Self
where T: Copy,
U: AsRef<[T]>
{
let initial = initial.as_ref();
if size > 0 {
if initial.len() == 1 {
Self::new_repeat(initial[0], size)
} else {
let this = Self::new_uninit(size);
unsafe {
for x in 0..size {
*this.ptr.offset(x as isize) = initial[x % initial.len()];
}
this
}
}
} else {
Self::new_uninit(size)
}
}
pub fn as_slice(&self) -> &[T]
{
unsafe{slice::from_raw_parts(self.ptr, self.size)}
}
pub fn as_slice_mut(&mut self) -> &mut [T]
{
unsafe{slice::from_raw_parts_mut(self.ptr, self.size)}
}
pub fn as_ptr(&self) -> *const T
{
self.ptr as *const T
}
pub fn as_ptr_mut(&mut self) -> *mut T
{
self.ptr
}
pub fn memory(&self) -> &[u8]
{
unsafe {
slice::from_raw_parts(self.ptr as *const u8, self.len_bytes())
}
}
pub fn memory_mut(&mut self) -> &mut [u8]
{
unsafe {
slice::from_raw_parts_mut(self.ptr as *mut u8, self.len_bytes())
}
}
#[allow(unused_mut)]
pub fn into_boxed_slice(mut self) -> Box<[T]>
{
#[cfg(feature="assume_libc")]
unsafe {
let bx = Box::from_raw(self.as_slice_mut() as *mut [T]);
std::mem::forget(self);
bx
}
#[cfg(not(feature="assume_libc"))]
{
let vec = Vec::from(self);
return vec.into_boxed_slice();
}
}
}
impl<T, I> Index<I> for HeapArray<T>
where I: SliceIndex<[T]>
{
type Output = <I as SliceIndex<[T]>>::Output;
fn index(&self, index: I) -> &Self::Output
{
&self.as_slice()[index]
}
}
impl<T, I> IndexMut<I> for HeapArray<T>
where I: SliceIndex<[T]>
{
fn index_mut(&mut self, index: I) -> &mut <Self as Index<I>>::Output
{
&mut self.as_slice_mut()[index]
}
}
impl<T> Drop for HeapArray<T>
{
fn drop(&mut self)
{
if self.ptr != ptr::null::<T>() {
if self.drop_check {
for i in 0..self.size
{
unsafe {
drop(ptr::take(self.ptr.offset(i as isize)));
}
}
}
unsafe{alloc::free(self.ptr as VoidPointer)};
self.ptr = ptr::null::<T>();
}
}
}
impl<T> AsMut<[T]> for HeapArray<T>
{
fn as_mut(&mut self) -> &mut [T]
{
self.as_slice_mut()
}
}
impl<T> AsRef<[T]> for HeapArray<T>
{
fn as_ref(&self) -> &[T]
{
self.as_slice()
}
}
impl<T> Deref for HeapArray<T>
{
type Target = [T];
fn deref(&self) -> &Self::Target
{
self.as_slice()
}
}
impl<T> DerefMut for HeapArray<T>
{
fn deref_mut(&mut self) -> &mut <Self as Deref>::Target
{
self.as_slice_mut()
}
}
impl<T> Borrow<[T]> for HeapArray<T>
{
fn borrow(&self) -> &[T]
{
self.as_slice()
}
}
impl<T> BorrowMut<[T]> for HeapArray<T>
{
fn borrow_mut(&mut self) -> &mut [T]
{
self.as_slice_mut()
}
}
impl<T> From<HeapArray<T>> for Vec<T>
{
fn from(ha: HeapArray<T>) -> Self
{
let mut output = Vec::with_capacity(ha.len());
for item in ha.into_iter()
{
output.push(item);
}
output
}
}
mod iter;
pub use iter::*;

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src/ptr.rs
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use std::{
ffi::c_void,
mem::{
self,
MaybeUninit,
},
};
use libc::{
size_t,
c_int,
};
pub type VoidPointer = *mut ();
pub type ConstVoidPointer = *const ();
pub const NULL_PTR: VoidPointer = 0 as VoidPointer;
pub fn null<T>() -> *mut T
{
NULL_PTR as *mut T
}
pub unsafe fn memset(ptr: *mut u8, value: u8, length: usize)
{
libc::memset(ptr as *mut c_void, value as c_int, length as size_t);
}
pub unsafe fn replace<T>(ptr: *mut T, value: T) -> T
{
mem::replace(&mut *ptr, value)
}
pub unsafe fn take<T>(ptr: *mut T) -> T
{
mem::replace(&mut *ptr, MaybeUninit::zeroed().assume_init())
}

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src/reinterpret.rs
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use std::{
mem::size_of,
};
#[inline]
pub unsafe fn bytes<T,U>(input: T) -> U
where T: Copy,
U: Copy
{
//let _array: [(); size_of::<T>() - size_of::<U>()]; // rust is silly....
if size_of::<U>() < size_of::<T>() {
panic!("reinterpret: Expected at least {} bytes, got {}.", size_of::<T>(), size_of::<U>());
}
return *((&input as *const T) as *const U)
}
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