1 #![no_std] 2 #![feature(core_intrinsics)] 3 #![allow(internal_features)] 4 #![allow(clippy::needless_return)] 5 6 #[cfg(test)] 7 #[macro_use] 8 extern crate std; 9 10 use core::cmp::min; 11 use core::intrinsics::unlikely; 12 use core::marker::PhantomData; 13 use core::ops::Deref; 14 15 struct EmptyIdaItemRef<'a> { 16 _marker: PhantomData<&'a EmptyIdaItem>, 17 } 18 19 impl<'a> Deref for EmptyIdaItemRef<'a> { 20 type Target = EmptyIdaItem; 21 22 fn deref(&self) -> &Self::Target { 23 &EmptyIdaItem 24 } 25 } 26 27 struct EmptyIdaItem; 28 29 unsafe impl kdepends::xarray::ItemEntry for EmptyIdaItem { 30 type Ref<'a> = EmptyIdaItemRef<'a> where Self: 'a; 31 32 fn into_raw(self) -> *const () { 33 core::ptr::null() 34 } 35 36 unsafe fn from_raw(_raw: *const ()) -> Self { 37 EmptyIdaItem 38 } 39 40 unsafe fn raw_as_ref<'a>(_raw: *const ()) -> Self::Ref<'a> { 41 EmptyIdaItemRef { 42 _marker: PhantomData, 43 } 44 } 45 } 46 /// id分配器 47 pub struct IdAllocator { 48 current_id: usize, 49 min_id: usize, 50 max_id: usize, 51 used: usize, 52 xarray: kdepends::xarray::XArray<EmptyIdaItem>, 53 } 54 55 impl IdAllocator { 56 /// 创建一个新的id分配器 57 pub const fn new(initial_id: usize, max_id: usize) -> Option<Self> { 58 if initial_id >= max_id { 59 return None; 60 } 61 Some(Self { 62 current_id: initial_id, 63 min_id: initial_id, 64 max_id, 65 used: 0, 66 xarray: kdepends::xarray::XArray::new(), 67 }) 68 } 69 70 /// 可用的id数量 71 #[inline] 72 pub fn available(&self) -> usize { 73 self.max_id - self.min_id - self.used 74 } 75 76 /// 分配一个新的id 77 /// 78 /// ## 返回 79 /// 80 /// 如果分配成功，返回Some(id)，否则返回None 81 pub fn alloc(&mut self) -> Option<usize> { 82 if unlikely(self.available() == 0) { 83 return None; 84 } 85 86 if let Some(try1) = self.do_find_first_free_index(self.current_id, self.max_id) { 87 self.current_id = try1; 88 self.xarray.store(try1 as u64, EmptyIdaItem); 89 self.used += 1; 90 return Some(try1); 91 } 92 93 // 从头开始找 94 if let Some(try2) = 95 self.do_find_first_free_index(self.min_id, min(self.current_id, self.max_id)) 96 { 97 self.current_id = try2; 98 self.xarray.store(try2 as u64, EmptyIdaItem); 99 self.used += 1; 100 return Some(try2); 101 } 102 return None; 103 } 104 105 /// 检查id是否存在 106 /// 107 /// ## 参数 108 /// 109 /// - `id`：要检查的id 110 /// 111 /// ## 返回 112 /// 113 /// 如果id存在，返回true，否则返回false 114 pub fn exists(&self, id: usize) -> bool { 115 if id < self.min_id || id >= self.max_id { 116 return false; 117 } 118 self.xarray.load(id as u64).is_some() 119 } 120 121 fn do_find_first_free_index(&self, start_id: usize, end: usize) -> Option<usize> { 122 (start_id..end).find(|&i| !self.exists(i)) 123 } 124 125 /// 释放一个id 126 /// 127 /// ## 参数 128 /// 129 /// - `id`：要释放的id 130 pub fn free(&mut self, id: usize) { 131 if id < self.min_id || id >= self.max_id { 132 return; 133 } 134 if self.xarray.remove(id as u64).is_some() { 135 self.used -= 1; 136 } 137 } 138 139 /// 返回已经使用的id数量 140 pub fn used(&self) -> usize { 141 self.used 142 } 143 144 /// 返回最大id数 145 pub fn get_max_id(&self) -> usize { 146 self.max_id 147 } 148 } 149 150 impl core::fmt::Debug for IdAllocator { 151 fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result { 152 f.debug_struct("IdAllocator") 153 .field("current_id", &self.current_id) 154 .field("min_id", &self.min_id) 155 .field("max_id", &self.max_id) 156 .field("used", &self.used) 157 .field("xarray", &"xarray<()>") 158 .finish() 159 } 160 } 161 162 #[cfg(test)] 163 mod tests { 164 use super::*; 165 #[test] 166 fn test_new_fail() { 167 assert_eq!(IdAllocator::new(10, 10).is_none(), true); 168 assert_eq!(IdAllocator::new(11, 10).is_none(), true); 169 } 170 #[test] 171 fn test_new_success() { 172 assert_eq!(IdAllocator::new(9, 10).is_some(), true); 173 assert_eq!(IdAllocator::new(0, 10).is_some(), true); 174 } 175 176 #[test] 177 fn test_id_allocator() { 178 let mut ida = IdAllocator::new(0, 10).unwrap(); 179 assert_eq!(ida.alloc(), Some(0)); 180 assert_eq!(ida.alloc(), Some(1)); 181 assert_eq!(ida.alloc(), Some(2)); 182 assert_eq!(ida.alloc(), Some(3)); 183 assert_eq!(ida.alloc(), Some(4)); 184 assert_eq!(ida.alloc(), Some(5)); 185 assert_eq!(ida.alloc(), Some(6)); 186 assert_eq!(ida.alloc(), Some(7)); 187 assert_eq!(ida.alloc(), Some(8)); 188 assert_eq!(ida.alloc(), Some(9)); 189 assert_eq!(ida.alloc(), None); 190 191 for i in 0..10 { 192 assert_eq!(ida.exists(i), true); 193 } 194 195 ida.free(5); 196 197 for i in 0..10 { 198 if i == 5 { 199 assert_eq!(ida.exists(i), false); 200 } else { 201 assert_eq!(ida.exists(i), true); 202 } 203 } 204 assert_eq!(ida.used(), 9); 205 assert_eq!(ida.alloc(), Some(5)); 206 assert_eq!(ida.alloc(), None); 207 208 assert_eq!(ida.used(), 10); 209 for i in 0..10 { 210 ida.free(i); 211 } 212 213 assert_eq!(ida.used(), 0); 214 } 215 } 216