//! 当前slab分配器暂时不使用,等待后续完善后合并主线 #![allow(dead_code)] use core::alloc::Layout; // 定义Slab,用来存放空闲块 pub struct Slab { block_size: usize, free_block_list: FreeBlockList, } impl Slab { /// @brief: 初始化一个slab /// @param {usize} start_addr /// @param {usize} slab_size /// @param {usize} block_size pub unsafe fn new(start_addr: usize, slab_size: usize, block_size: usize) -> Slab { let blocks_num = slab_size / block_size; return Slab { block_size, free_block_list: FreeBlockList::new(start_addr, block_size, blocks_num), }; } /// @brief: 获取slab中可用的block数 pub fn used_blocks(&self) -> usize { return self.free_block_list.len(); } /// @brief: 扩大free_block_list /// @param {*} mut /// @param {usize} start_addr /// @param {usize} slab_size pub fn grow(&mut self, start_addr: usize, slab_size: usize) { let num_of_blocks = slab_size / self.block_size; let mut block_list = unsafe { FreeBlockList::new(start_addr, self.block_size, num_of_blocks) }; // 将新链表接到原链表的后面 while let Some(block) = block_list.pop() { self.free_block_list.push(block); } } /// @brief: 从slab中分配一个block /// @return 分配的内存地址 pub fn allocate(&mut self, _layout: Layout) -> Option<*mut u8> { match self.free_block_list.pop() { Some(block) => return Some(block.addr() as *mut u8), None => return None, } } /// @brief: 将block归还给slab pub fn free(&mut self, ptr: *mut u8) { let ptr = ptr as *mut FreeBlock; unsafe { self.free_block_list.push(&mut *ptr); } } } /// slab中的空闲块 struct FreeBlockList { len: usize, head: Option<&'static mut FreeBlock>, } impl FreeBlockList { unsafe fn new(start_addr: usize, block_size: usize, num_of_blocks: usize) -> FreeBlockList { let mut new_list = FreeBlockList::new_empty(); for i in (0..num_of_blocks).rev() { // 从后往前分配,避免内存碎片 let new_block = (start_addr + i * block_size) as *mut FreeBlock; new_list.push(&mut *new_block); } return new_list; } fn new_empty() -> FreeBlockList { return FreeBlockList { len: 0, head: None }; } fn len(&self) -> usize { return self.len; } /// @brief: 将空闲块从链表中弹出 fn pop(&mut self) -> Option<&'static mut FreeBlock> { // 从链表中弹出一个空闲块 let block = self.head.take().map(|node| { self.head = node.next.take(); self.len -= 1; node }); return block; } /// @brief: 将空闲块压入链表 fn push(&mut self, free_block: &'static mut FreeBlock) { free_block.next = self.head.take(); self.len += 1; self.head = Some(free_block); } fn is_empty(&self) -> bool { return self.head.is_none(); } } impl Drop for FreeBlockList { fn drop(&mut self) { while self.pop().is_some() {} } } struct FreeBlock { next: Option<&'static mut FreeBlock>, } impl FreeBlock { /// @brief: 获取FreeBlock的地址 /// @return {*} fn addr(&self) -> usize { return self as *const _ as usize; } }