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-rw-r--r--src/rwlock/read_lock.rs76
1 files changed, 76 insertions, 0 deletions
diff --git a/src/rwlock/read_lock.rs b/src/rwlock/read_lock.rs
index d719a50..ae593e2 100644
--- a/src/rwlock/read_lock.rs
+++ b/src/rwlock/read_lock.rs
@@ -87,6 +87,34 @@ impl<'l, T, R> ReadLock<'l, T, R> {
impl<T: ?Sized, R: RawRwLock> ReadLock<'_, T, R> {
/// Locks the underlying [`RwLock`] with shared read access, blocking the
/// current thread until it can be acquired.
+ ///
+ /// The calling thread will be blocked until there are no more writers
+ /// which hold the lock. There may be other readers currently inside the
+ /// lock when this method returns.
+ ///
+ /// Returns an RAII guard which will release this thread's shared access
+ /// once it is dropped.
+ ///
+ /// Because this method takes a [`ThreadKey`], it's not possible for this
+ /// method to cause a deadlock.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::sync::Arc;
+ /// use std::thread;
+ /// use happylock::{RwLock, ThreadKey};
+ /// use happylock::rwlock::ReadLock;
+ ///
+ /// let key = ThreadKey::get().unwrap();
+ /// let lock: &'static mut RwLock<_> = Box::leak(Box::new(RwLock::new(1)));
+ /// let reader = ReadLock::new(&lock);
+ ///
+ /// let n = reader.lock(key);
+ /// assert_eq!(*n, 1);
+ /// ```
+ ///
+ /// [`ThreadKey`]: `crate::ThreadKey`
pub fn lock<'s, 'key: 's, Key: Keyable + 'key>(
&'s self,
key: Key,
@@ -96,6 +124,35 @@ impl<T: ?Sized, R: RawRwLock> ReadLock<'_, T, R> {
/// Attempts to acquire the underlying [`RwLock`] with shared read access
/// without blocking.
+ ///
+ /// If the access could not be granted at this time, then `Err` is
+ /// returned. Otherwise, an RAII guard is returned which will release the
+ /// shared access when it is dropped.
+ ///
+ /// This function does not provide any guarantees with respect to the
+ /// ordering of whether contentious readers or writers will acquire the
+ /// lock first.
+ ///
+ /// # Errors
+ ///
+ /// If the `RwLock` could not be acquired because it was already locked
+ /// exclusively, then an error will be returned containing the given key.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use happylock::{RwLock, ThreadKey};
+ /// use happylock::rwlock::ReadLock;
+ ///
+ /// let key = ThreadKey::get().unwrap();
+ /// let lock = RwLock::new(1);
+ /// let reader = ReadLock::new(&lock);
+ ///
+ /// match reader.try_lock(key) {
+ /// Ok(n) => assert_eq!(*n, 1),
+ /// Err(_) => unreachable!(),
+ /// };
+ /// ```
pub fn try_lock<'s, 'key: 's, Key: Keyable + 'key>(
&'s self,
key: Key,
@@ -111,6 +168,25 @@ impl<T: ?Sized, R: RawRwLock> ReadLock<'_, T, R> {
/// Immediately drops the guard, and consequently releases the shared lock
/// on the underlying [`RwLock`].
+ ///
+ /// This function is equivalent to calling [`drop`] on the guard, except
+ /// that it returns the key that was used to create it. Alternately, the
+ /// guard will be automatically dropped when it goes out of scope.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use happylock::{RwLock, ThreadKey};
+ /// use happylock::rwlock::ReadLock;
+ ///
+ /// let key = ThreadKey::get().unwrap();
+ /// let lock = RwLock::new(0);
+ /// let reader = ReadLock::new(&lock);
+ ///
+ /// let mut guard = reader.lock(key);
+ /// assert_eq!(*guard, 0);
+ /// let key = ReadLock::unlock(guard);
+ /// ```
pub fn unlock<'key, Key: Keyable + 'key>(guard: RwLockReadGuard<'_, 'key, T, Key, R>) -> Key {
RwLock::unlock_read(guard)
}