nihav-core/src/refs.rs

   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 }