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Diffstat (limited to 'src/rwlock/read_lock.rs')
-rw-r--r--src/rwlock/read_lock.rs40
1 files changed, 38 insertions, 2 deletions
diff --git a/src/rwlock/read_lock.rs b/src/rwlock/read_lock.rs
index dbab8de..176fc01 100644
--- a/src/rwlock/read_lock.rs
+++ b/src/rwlock/read_lock.rs
@@ -6,9 +6,25 @@ use crate::key::Keyable;
use super::{ReadLock, RwLock, RwLockReadGuard, RwLockReadRef};
-impl<'a, T: ?Sized, R> Debug for ReadLock<'a, T, R> {
+impl<'a, T: ?Sized + Debug, R: RawRwLock> Debug for ReadLock<'a, T, R> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
- f.write_str(&format!("ReadLock<{}>", std::any::type_name::<T>()))
+ // safety: this is just a try lock, and the value is dropped
+ // immediately after, so there's no risk of blocking ourselves
+ // or any other threads
+ if let Some(value) = unsafe { self.try_lock_no_key() } {
+ f.debug_struct("ReadLock").field("data", &&*value).finish()
+ } else {
+ struct LockedPlaceholder;
+ impl Debug for LockedPlaceholder {
+ fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+ f.write_str("<locked>")
+ }
+ }
+
+ f.debug_struct("ReadLock")
+ .field("data", &LockedPlaceholder)
+ .finish()
+ }
}
}
@@ -25,6 +41,16 @@ impl<'a, T: ?Sized, R> AsRef<RwLock<T, R>> for ReadLock<'a, T, R> {
}
impl<'a, T: ?Sized, R> ReadLock<'a, T, R> {
+ /// Creates a new `ReadLock` which accesses the given [`RwLock`]
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use happylock::{rwlock::ReadLock, RwLock};
+ ///
+ /// let lock = RwLock::new(5);
+ /// let read_lock = ReadLock::new(&lock);
+ /// ```
#[must_use]
pub const fn new(rwlock: &'a RwLock<T, R>) -> Self {
Self(rwlock)
@@ -32,6 +58,8 @@ impl<'a, T: ?Sized, R> ReadLock<'a, T, R> {
}
impl<'a, T: ?Sized, R: RawRwLock> ReadLock<'a, T, R> {
+ /// Locks the underlying [`RwLock`] with shared read access, blocking the
+ /// current thread until it can be acquired.
pub fn lock<'s, 'key: 's, Key: Keyable + 'key>(
&'s self,
key: Key,
@@ -39,10 +67,14 @@ impl<'a, T: ?Sized, R: RawRwLock> ReadLock<'a, T, R> {
self.0.read(key)
}
+ /// Creates a shared lock without a key. Locking this without exclusive
+ /// access to the key is undefined behavior.
pub(crate) unsafe fn lock_no_key(&self) -> RwLockReadRef<'_, T, R> {
self.0.read_no_key()
}
+ /// Attempts to acquire the underlying [`RwLock`] with shared read access
+ /// without blocking.
pub fn try_lock<'s, 'key: 's, Key: Keyable + 'key>(
&'s self,
key: Key,
@@ -50,10 +82,14 @@ impl<'a, T: ?Sized, R: RawRwLock> ReadLock<'a, T, R> {
self.0.try_read(key)
}
+ /// Attempts to create an exclusive lock without a key. Locking this
+ /// without exclusive access to the key is undefined behavior.
pub(crate) unsafe fn try_lock_no_key(&self) -> Option<RwLockReadRef<'_, T, R>> {
self.0.try_read_no_key()
}
+ /// Immediately drops the guard, and consequentlyreleases the shared lock
+ /// on the underlying [`RwLock`].
pub fn unlock<'key, Key: Keyable + 'key>(guard: RwLockReadGuard<'_, 'key, T, Key, R>) -> Key {
RwLock::unlock_read(guard)
}