pi_apm 0.2.1

//! # 提供了全局内存分配器
//!

use std::alloc::{System, GlobalAlloc, Layout};
use std::sync::atomic::{AtomicBool, AtomicIsize, AtomicUsize, Ordering};
use std::time::Instant;
use std::f32::MAX;

///
/// 是否允许分配内存
///
pub static ENABLE_ALLOC: AtomicBool = AtomicBool::new(true);

///
/// 当前虚拟机已分配内存
///
pub static VM_ALLOCATED: AtomicIsize = AtomicIsize::new(0);

/*
* 当前最大已分配内存限制，默认8GB
*/
static MAX_ALLOCATED_LIMIT: AtomicUsize = AtomicUsize::new(8589934590);

/*
* 当前已分配内存
*/
static ALLOCATED: AtomicUsize = AtomicUsize::new(0);

///
/// 计数的系统内存分配器
///
pub struct CounterSystemAllocator;

unsafe impl GlobalAlloc for CounterSystemAllocator {
    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
        let ret = System.alloc(layout);
        if !ret.is_null() {
            ALLOCATED.fetch_add(layout.size(), Ordering::SeqCst);
        }
        return ret;
    }

    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
        System.dealloc(ptr, layout);
        ALLOCATED.fetch_sub(layout.size(), Ordering::SeqCst);
    }
}

///
/// 获取当前最大已分配内存限制
///
#[inline]
pub fn get_max_alloced_limit() -> usize {
    MAX_ALLOCATED_LIMIT.load(Ordering::Relaxed)
}

///
/// 设置当前最大已分配内存限制，必须大于当前所有已分配内存，成功返回上次设置的最大已分配内存限制
///
#[inline]
pub fn set_max_alloced_limit(limit: usize) -> Result<usize, ()> {
    if limit <= all_alloced_size() {
        return Err(());
    }

    Ok(MAX_ALLOCATED_LIMIT.swap(limit, Ordering::SeqCst))
}

///
/// 检查当前所有已分配内存是否已达当前最大已分配内存限制
///
#[inline]
pub fn is_alloced_limit() -> bool {
    let max_alloced_limit = get_max_alloced_limit();

    (max_alloced_limit > 0) && all_alloced_size() >= max_alloced_limit
}

///
/// 获取当前已分配内存数量，单位B
///
#[inline]
pub fn alloced_size() -> usize {
    ALLOCATED.load(Ordering::SeqCst)
}

///
/// 获取虚拟机已分配内存数量，单位B
///
#[inline]
pub fn vm_alloced_size() -> isize {
    VM_ALLOCATED.load(Ordering::SeqCst)
}

///
/// 获取当前已分配和虚拟机已分配内存数量，单位B
///
#[inline]
pub fn all_alloced_size() -> usize {
    let vm_size = vm_alloced_size();
    if vm_size < 0 {
        alloced_size()
    } else {
        alloced_size() + vm_size as usize
    }
}