Line data    Source code

       1              : //! A wrapper around `ArcSwap` that ensures there is only one writer at a time and writes
       2              : //! don't block reads.
       3              : 
       4              : use arc_swap::ArcSwap;
       5              : use std::sync::Arc;
       6              : use tokio::sync::TryLockError;
       7              : 
       8              : pub struct GuardArcSwap<T> {
       9              :     inner: ArcSwap<T>,
      10              :     guard: tokio::sync::Mutex<()>,
      11              : }
      12              : 
      13              : pub struct Guard<'a, T> {
      14              :     _guard: tokio::sync::MutexGuard<'a, ()>,
      15              :     inner: &'a ArcSwap<T>,
      16              : }
      17              : 
      18              : impl<T> GuardArcSwap<T> {
      19          892 :     pub fn new(inner: T) -> Self {
      20          892 :         Self {
      21          892 :             inner: ArcSwap::new(Arc::new(inner)),
      22          892 :             guard: tokio::sync::Mutex::new(()),
      23          892 :         }
      24          892 :     }
      25              : 
      26            0 :     pub fn read(&self) -> Arc<T> {
      27            0 :         self.inner.load_full()
      28            0 :     }
      29              : 
      30            0 :     pub async fn write_guard(&self) -> Guard<'_, T> {
      31            0 :         Guard {
      32            0 :             _guard: self.guard.lock().await,
      33            0 :             inner: &self.inner,
      34            0 :         }
      35            0 :     }
      36              : 
      37         1136 :     pub fn try_write_guard(&self) -> Result<Guard<'_, T>, TryLockError> {
      38         1136 :         let guard = self.guard.try_lock()?;
      39         1136 :         Ok(Guard {
      40         1136 :             _guard: guard,
      41         1136 :             inner: &self.inner,
      42         1136 :         })
      43         1136 :     }
      44              : }
      45              : 
      46              : impl<T> Guard<'_, T> {
      47         1136 :     pub fn read(&self) -> Arc<T> {
      48         1136 :         self.inner.load_full()
      49         1136 :     }
      50              : 
      51          640 :     pub fn write(&mut self, value: T) {
      52          640 :         self.inner.store(Arc::new(value));
      53          640 :     }
      54              : }