nihav-core/src/refs.rs

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