| 1 | use std::ops::{Deref, DerefMut}; |
| 2 | use std::convert::AsRef; |
| 3 | use std::sync::atomic::*; |
| 4 | |
| 5 | struct NABufferData<T> { |
| 6 | data: T, |
| 7 | refs: AtomicUsize, |
| 8 | } |
| 9 | |
| 10 | impl<T> NABufferData<T> { |
| 11 | fn new(data: T) -> Self { |
| 12 | Self { |
| 13 | data, |
| 14 | refs: AtomicUsize::new(1), |
| 15 | } |
| 16 | } |
| 17 | fn inc_refs(obj: &mut Self) { |
| 18 | obj.refs.fetch_add(1, Ordering::SeqCst); |
| 19 | } |
| 20 | fn dec_refs(obj: &mut Self) -> bool { |
| 21 | obj.refs.fetch_sub(1, Ordering::SeqCst) == 0 |
| 22 | } |
| 23 | fn get_num_refs(obj: &Self) -> usize { |
| 24 | obj.refs.load(Ordering::Relaxed) |
| 25 | } |
| 26 | fn get_read_ptr(obj: &Self) -> &T { |
| 27 | &obj.data |
| 28 | } |
| 29 | fn get_write_ptr(obj: &mut Self) -> Option<&mut T> { |
| 30 | Some(&mut obj.data) |
| 31 | } |
| 32 | } |
| 33 | |
| 34 | pub struct NABufferRef<T> { |
| 35 | ptr: *mut NABufferData<T>, |
| 36 | } |
| 37 | |
| 38 | impl<T> NABufferRef<T> { |
| 39 | pub fn new(val: T) -> Self { |
| 40 | let bdata = NABufferData::new(val); |
| 41 | let nbox: Box<_> = Box::new(bdata); |
| 42 | Self { ptr: Box::into_raw(nbox) } |
| 43 | } |
| 44 | pub fn get_num_refs(&self) -> usize { |
| 45 | unsafe { |
| 46 | NABufferData::get_num_refs(self.ptr.as_mut().unwrap()) |
| 47 | } |
| 48 | } |
| 49 | pub fn as_mut(&mut self) -> Option<&mut T> { |
| 50 | unsafe { |
| 51 | NABufferData::get_write_ptr(self.ptr.as_mut().unwrap()) |
| 52 | } |
| 53 | } |
| 54 | } |
| 55 | |
| 56 | impl<T> AsRef<T> for NABufferRef<T> { |
| 57 | fn as_ref(&self) -> &T { |
| 58 | unsafe { |
| 59 | NABufferData::get_read_ptr(self.ptr.as_mut().unwrap()) |
| 60 | } |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | impl<T> Deref for NABufferRef<T> { |
| 65 | type Target = T; |
| 66 | fn deref(&self) -> &T { self.as_ref() } |
| 67 | } |
| 68 | |
| 69 | impl<T> DerefMut for NABufferRef<T> { |
| 70 | fn deref_mut(&mut self) -> &mut T { self.as_mut().unwrap() } |
| 71 | } |
| 72 | |
| 73 | impl<T> Clone for NABufferRef<T> { |
| 74 | fn clone(&self) -> Self { |
| 75 | unsafe { |
| 76 | NABufferData::inc_refs(self.ptr.as_mut().unwrap()); |
| 77 | } |
| 78 | Self { ptr: self.ptr } |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | impl<T> Drop for NABufferRef<T> { |
| 83 | fn drop(&mut self) { |
| 84 | unsafe { |
| 85 | if NABufferData::dec_refs(self.ptr.as_mut().unwrap()) { |
| 86 | std::ptr::drop_in_place(self.ptr); |
| 87 | } |
| 88 | } |
| 89 | } |
| 90 | } |
| 91 | |
| 92 | impl<T:Default> Default for NABufferRef<T> { |
| 93 | fn default() -> Self { |
| 94 | Self::new(T::default()) |
| 95 | } |
| 96 | } |