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) == 1
  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 unsafe impl<T> Sync for NABufferRef<T> {}
  39 unsafe impl<T> Send for NABufferRef<T> {}
  40
  41 impl<T> NABufferRef<T> {
  42     pub fn new(val: T) -> Self {
  43         let bdata = NABufferData::new(val);
  44         let nbox: Box<_> = Box::new(bdata);
  45         Self { ptr: Box::into_raw(nbox) }
  46     }
  47     pub fn get_num_refs(&self) -> usize {
  48         unsafe {
  49             NABufferData::get_num_refs(self.ptr.as_mut().unwrap())
  50         }
  51     }
  52     pub fn as_mut(&mut self) -> Option<&mut T> {
  53         unsafe {
  54             NABufferData::get_write_ptr(self.ptr.as_mut().unwrap())
  55         }
  56     }
  57 }
  58
  59 impl<T> AsRef<T> for NABufferRef<T> {
  60     fn as_ref(&self) -> &T {
  61         unsafe {
  62             NABufferData::get_read_ptr(self.ptr.as_mut().unwrap())
  63         }
  64     }
  65 }
  66
  67 impl<T> Deref for NABufferRef<T> {
  68     type Target = T;
  69     fn deref(&self) -> &T { self.as_ref() }
  70 }
  71
  72 impl<T> DerefMut for NABufferRef<T> {
  73     fn deref_mut(&mut self) -> &mut T { self.as_mut().unwrap() }
  74 }
  75
  76 impl<T> Clone for NABufferRef<T> {
  77     fn clone(&self) -> Self {
  78         unsafe {
  79             NABufferData::inc_refs(self.ptr.as_mut().unwrap());
  80         }
  81         Self { ptr: self.ptr }
  82     }
  83 }
  84
  85 impl<T> Drop for NABufferRef<T> {
  86     fn drop(&mut self) {
  87         unsafe {
  88             if NABufferData::dec_refs(self.ptr.as_mut().unwrap()) {
  89                 let data = Box::from_raw(self.ptr);
  90                 std::mem::drop(data);
  91             }
  92         }
  93     }
  94 }
  95
  96 impl<T:Default> Default for NABufferRef<T> {
  97     fn default() -> Self {
  98         Self::new(T::default())
  99     }
 100 }