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use rustix::fd::BorrowedFd;
use rustix::fs::{flock, FlockOperation};
use std::io::{self, Error, ErrorKind};
use std::os::unix::io::AsRawFd;
use super::{RwLockReadGuard, RwLockWriteGuard};
#[derive(Debug)]
pub struct RwLock<T: AsRawFd> {
pub(crate) inner: T,
}
impl<T: AsRawFd> RwLock<T> {
#[inline]
pub fn new(inner: T) -> Self {
RwLock { inner }
}
#[inline]
pub fn write(&mut self) -> io::Result<RwLockWriteGuard<'_, T>> {
flock(&self.as_fd(), FlockOperation::LockExclusive)?;
Ok(RwLockWriteGuard::new(self))
}
#[inline]
pub fn try_write(&mut self) -> Result<RwLockWriteGuard<'_, T>, Error> {
flock(&self.as_fd(), FlockOperation::NonBlockingLockExclusive).map_err(|err| match err
.kind()
{
ErrorKind::AlreadyExists => ErrorKind::WouldBlock.into(),
_ => Error::from(err),
})?;
Ok(RwLockWriteGuard::new(self))
}
#[inline]
pub fn read(&self) -> io::Result<RwLockReadGuard<'_, T>> {
flock(&self.as_fd(), FlockOperation::LockShared)?;
Ok(RwLockReadGuard::new(self))
}
#[inline]
pub fn try_read(&self) -> Result<RwLockReadGuard<'_, T>, Error> {
flock(&self.as_fd(), FlockOperation::NonBlockingLockShared).map_err(|err| {
match err.kind() {
ErrorKind::AlreadyExists => ErrorKind::WouldBlock.into(),
_ => Error::from(err),
}
})?;
Ok(RwLockReadGuard::new(self))
}
#[inline]
pub fn into_inner(self) -> T
where
T: Sized,
{
self.inner
}
#[inline]
pub(crate) fn as_fd(&self) -> BorrowedFd<'_> {
// Safety: We assume that `self.inner`'s file descriptor is valid for
// at least the lifetime of `self`.
//
// Once I/O safety is stablized in std, we can switch the public API to
// use `AsFd` instead of `AsRawFd` and eliminate this `unsafe` block.
unsafe { BorrowedFd::borrow_raw(self.inner.as_raw_fd()) }
}
}
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