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use std::mem::transmute;
use std::ops::{Deref, DerefMut};
use std::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard, TryLockError};
use crate::type_name::TypeName;
#[derive(Debug, Default)]
pub struct Lock<Value>
where
Value: TypeName,
{
inner: RwLock<Value>,
}
impl<Value> Lock<Value>
where
Value: TypeName,
{
pub fn new(value: Value) -> Self
{
Self { inner: RwLock::new(value) }
}
/// Tries to a acquire a handle to the resource with read access.
///
/// # Errors
/// Returns `Err` if unavailable (A mutable handle is hold).
pub fn read_nonblock(&self) -> Result<ReadGuard<Value>, Error>
{
let guard = self.inner.try_read().or_else(|err| match err {
TryLockError::WouldBlock => Err(Error::Unavailable),
TryLockError::Poisoned(poison_err) => Ok(poison_err.into_inner()),
})?;
#[cfg(feature = "debug")]
tracing::trace!("Acquired lock to value of type {}", guard.type_name());
Ok(ReadGuard { inner: guard })
}
/// Tries to a acquire a handle to the resource with mutable access.
///
/// # Errors
/// Returns `Err` if unavailable (A mutable or immutable handle is hold).
pub fn write_nonblock(&self) -> Result<WriteGuard<Value>, Error>
{
let guard = self.inner.try_write().or_else(|err| match err {
TryLockError::WouldBlock => Err(Error::Unavailable),
TryLockError::Poisoned(poison_err) => Ok(poison_err.into_inner()),
})?;
#[cfg(feature = "debug")]
tracing::trace!(
"Acquired mutable lock to value of type {}",
guard.type_name()
);
Ok(WriteGuard { inner: guard })
}
pub fn into_inner(self) -> Value
{
self.inner
.into_inner()
.unwrap_or_else(|err| err.into_inner())
}
}
#[derive(Debug, thiserror::Error)]
pub enum Error
{
#[error("Lock is unavailable")]
Unavailable,
}
#[derive(Debug)]
pub struct ReadGuard<'guard, Value>
where
Value: TypeName,
{
inner: RwLockReadGuard<'guard, Value>,
}
impl<'guard, Value> ReadGuard<'guard, Value>
where
Value: TypeName,
{
/// Converts the `ReadGuard` to a `ReadGuard` with a possibly longer lifetime.
///
/// # Safety
/// The returned `ReadGuard` must **NOT** be used for longer than the original
/// lifetime.
pub unsafe fn upgrade_lifetime<'new>(self) -> ReadGuard<'new, Value>
{
unsafe { transmute(self) }
}
}
impl<'guard, Value> Deref for ReadGuard<'guard, Value>
where
Value: TypeName,
{
type Target = Value;
fn deref(&self) -> &Self::Target
{
&self.inner
}
}
impl<'guard, Value> Drop for ReadGuard<'guard, Value>
where
Value: TypeName,
{
fn drop(&mut self)
{
#[cfg(feature = "debug")]
tracing::trace!("Dropped lock to value of type {}", self.type_name());
}
}
#[derive(Debug)]
pub struct WriteGuard<'guard, Value>
where
Value: TypeName,
{
inner: RwLockWriteGuard<'guard, Value>,
}
impl<'guard, Value> Deref for WriteGuard<'guard, Value>
where
Value: TypeName,
{
type Target = Value;
fn deref(&self) -> &Self::Target
{
&self.inner
}
}
impl<'guard, Value> DerefMut for WriteGuard<'guard, Value>
where
Value: TypeName,
{
fn deref_mut(&mut self) -> &mut Self::Target
{
&mut self.inner
}
}
impl<'guard, Value> Drop for WriteGuard<'guard, Value>
where
Value: TypeName,
{
fn drop(&mut self)
{
#[cfg(feature = "debug")]
tracing::trace!("Dropped mutable lock to value of type {}", self.type_name());
}
}
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