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jemallocator 0.1.0

A Rust allocator backed by jemalloc 
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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![feature(allocator)]
#![allocator]
#![no_std]

extern crate jemalloc_sys as ffi;
extern crate libc;

use libc::{c_int, size_t, c_void};

// The minimum alignment guaranteed by the architecture. This value is used to
// add fast paths for low alignment values. In practice, the alignment is a
// constant at the call site and the branch will be optimized out.
#[cfg(all(any(target_arch = "arm",
              target_arch = "mips",
              target_arch = "mipsel",
              target_arch = "powerpc")))]
const MIN_ALIGN: usize = 8;
#[cfg(all(any(target_arch = "x86",
              target_arch = "x86_64",
              target_arch = "aarch64",
              target_arch = "powerpc64",
              target_arch = "powerpc64le")))]
const MIN_ALIGN: usize = 16;

// MALLOCX_ALIGN(a) macro
fn mallocx_align(a: usize) -> c_int {
    a.trailing_zeros() as c_int
}

fn align_to_flags(align: usize) -> c_int {
    if align <= MIN_ALIGN {
        0
    } else {
        mallocx_align(align)
    }
}

#[no_mangle]
pub extern fn __rust_allocate(size: usize, align: usize) -> *mut u8 {
    let flags = align_to_flags(align);
    unsafe { ffi::mallocx(size as size_t, flags) as *mut u8 }
}

#[no_mangle]
pub extern fn __rust_reallocate(ptr: *mut u8,
                                _old_size: usize,
                                size: usize,
                                align: usize)
                                -> *mut u8 {
    let flags = align_to_flags(align);
    unsafe { ffi::rallocx(ptr as *mut c_void, size as size_t, flags) as *mut u8 }
}

#[no_mangle]
pub extern fn __rust_reallocate_inplace(ptr: *mut u8,
                                        _old_size: usize,
                                        size: usize,
                                        align: usize)
                                        -> usize {
    let flags = align_to_flags(align);
    unsafe { ffi::xallocx(ptr as *mut c_void, size as size_t, 0, flags) as usize }
}

#[no_mangle]
pub extern fn __rust_deallocate(ptr: *mut u8, old_size: usize, align: usize) {
    let flags = align_to_flags(align);
    unsafe { ffi::sdallocx(ptr as *mut c_void, old_size as size_t, flags) }
}

#[no_mangle]
pub extern fn __rust_usable_size(size: usize, align: usize) -> usize {
    let flags = align_to_flags(align);
    unsafe { ffi::nallocx(size as size_t, flags) as usize }
}

// These symbols are used by jemalloc on android but the really old android
// we're building on doesn't have them defined, so just make sure the symbols
// are available.
#[no_mangle]
#[cfg(target_os = "android")]
pub extern fn pthread_atfork(_prefork: *mut u8,
                             _postfork_parent: *mut u8,
                             _postfork_child: *mut u8) -> i32 {
    0
}

#[cfg(test)]
mod tests {
    #[test]
    fn smoke() {
        let ptr = super::__rust_allocate(100, 8);
        assert!(!ptr.is_null());
        super::__rust_deallocate(ptr, 100, 8);
    }
}