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Diffstat (limited to 'library/std/src/sync/rwlock.rs')
| -rw-r--r-- | library/std/src/sync/rwlock.rs | 799 |
1 files changed, 799 insertions, 0 deletions
diff --git a/library/std/src/sync/rwlock.rs b/library/std/src/sync/rwlock.rs new file mode 100644 index 00000000000..50f54dbf143 --- /dev/null +++ b/library/std/src/sync/rwlock.rs @@ -0,0 +1,799 @@ +use crate::cell::UnsafeCell; +use crate::fmt; +use crate::mem; +use crate::ops::{Deref, DerefMut}; +use crate::ptr; +use crate::sys_common::poison::{self, LockResult, TryLockError, TryLockResult}; +use crate::sys_common::rwlock as sys; + +/// A reader-writer lock +/// +/// This type of lock allows a number of readers or at most one writer at any +/// point in time. The write portion of this lock typically allows modification +/// of the underlying data (exclusive access) and the read portion of this lock +/// typically allows for read-only access (shared access). +/// +/// In comparison, a [`Mutex`] does not distinguish between readers or writers +/// that acquire the lock, therefore blocking any threads waiting for the lock to +/// become available. An `RwLock` will allow any number of readers to acquire the +/// lock as long as a writer is not holding the lock. +/// +/// The priority policy of the lock is dependent on the underlying operating +/// system's implementation, and this type does not guarantee that any +/// particular policy will be used. +/// +/// The type parameter `T` represents the data that this lock protects. It is +/// required that `T` satisfies [`Send`] to be shared across threads and +/// [`Sync`] to allow concurrent access through readers. The RAII guards +/// returned from the locking methods implement [`Deref`] (and [`DerefMut`] +/// for the `write` methods) to allow access to the content of the lock. +/// +/// # Poisoning +/// +/// An `RwLock`, like [`Mutex`], will become poisoned on a panic. Note, however, +/// that an `RwLock` may only be poisoned if a panic occurs while it is locked +/// exclusively (write mode). If a panic occurs in any reader, then the lock +/// will not be poisoned. +/// +/// # Examples +/// +/// ``` +/// use std::sync::RwLock; +/// +/// let lock = RwLock::new(5); +/// +/// // many reader locks can be held at once +/// { +/// let r1 = lock.read().unwrap(); +/// let r2 = lock.read().unwrap(); +/// assert_eq!(*r1, 5); +/// assert_eq!(*r2, 5); +/// } // read locks are dropped at this point +/// +/// // only one write lock may be held, however +/// { +/// let mut w = lock.write().unwrap(); +/// *w += 1; +/// assert_eq!(*w, 6); +/// } // write lock is dropped here +/// ``` +/// +/// [`Deref`]: ../../std/ops/trait.Deref.html +/// [`DerefMut`]: ../../std/ops/trait.DerefMut.html +/// [`Send`]: ../../std/marker/trait.Send.html +/// [`Sync`]: ../../std/marker/trait.Sync.html +/// [`Mutex`]: struct.Mutex.html +#[stable(feature = "rust1", since = "1.0.0")] +pub struct RwLock<T: ?Sized> { + inner: Box<sys::RWLock>, + poison: poison::Flag, + data: UnsafeCell<T>, +} + +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl<T: ?Sized + Send> Send for RwLock<T> {} +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl<T: ?Sized + Send + Sync> Sync for RwLock<T> {} + +/// RAII structure used to release the shared read access of a lock when +/// dropped. +/// +/// This structure is created by the [`read`] and [`try_read`] methods on +/// [`RwLock`]. +/// +/// [`read`]: struct.RwLock.html#method.read +/// [`try_read`]: struct.RwLock.html#method.try_read +/// [`RwLock`]: struct.RwLock.html +#[must_use = "if unused the RwLock will immediately unlock"] +#[stable(feature = "rust1", since = "1.0.0")] +pub struct RwLockReadGuard<'a, T: ?Sized + 'a> { + lock: &'a RwLock<T>, +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T: ?Sized> !Send for RwLockReadGuard<'_, T> {} + +#[stable(feature = "rwlock_guard_sync", since = "1.23.0")] +unsafe impl<T: ?Sized + Sync> Sync for RwLockReadGuard<'_, T> {} + +/// RAII structure used to release the exclusive write access of a lock when +/// dropped. +/// +/// This structure is created by the [`write`] and [`try_write`] methods +/// on [`RwLock`]. +/// +/// [`write`]: struct.RwLock.html#method.write +/// [`try_write`]: struct.RwLock.html#method.try_write +/// [`RwLock`]: struct.RwLock.html +#[must_use = "if unused the RwLock will immediately unlock"] +#[stable(feature = "rust1", since = "1.0.0")] +pub struct RwLockWriteGuard<'a, T: ?Sized + 'a> { + lock: &'a RwLock<T>, + poison: poison::Guard, +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T: ?Sized> !Send for RwLockWriteGuard<'_, T> {} + +#[stable(feature = "rwlock_guard_sync", since = "1.23.0")] +unsafe impl<T: ?Sized + Sync> Sync for RwLockWriteGuard<'_, T> {} + +impl<T> RwLock<T> { + /// Creates a new instance of an `RwLock<T>` which is unlocked. + /// + /// # Examples + /// + /// ``` + /// use std::sync::RwLock; + /// + /// let lock = RwLock::new(5); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn new(t: T) -> RwLock<T> { + RwLock { + inner: box sys::RWLock::new(), + poison: poison::Flag::new(), + data: UnsafeCell::new(t), + } + } +} + +impl<T: ?Sized> RwLock<T> { + /// Locks this 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. This method does not provide any guarantees with + /// respect to the ordering of whether contentious readers or writers will + /// acquire the lock first. + /// + /// Returns an RAII guard which will release this thread's shared access + /// once it is dropped. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. + /// The failure will occur immediately after the lock has been acquired. + /// + /// # Panics + /// + /// This function might panic when called if the lock is already held by the current thread. + /// + /// # Examples + /// + /// ``` + /// use std::sync::{Arc, RwLock}; + /// use std::thread; + /// + /// let lock = Arc::new(RwLock::new(1)); + /// let c_lock = lock.clone(); + /// + /// let n = lock.read().unwrap(); + /// assert_eq!(*n, 1); + /// + /// thread::spawn(move || { + /// let r = c_lock.read(); + /// assert!(r.is_ok()); + /// }).join().unwrap(); + /// ``` + #[inline] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn read(&self) -> LockResult<RwLockReadGuard<'_, T>> { + unsafe { + self.inner.read(); + RwLockReadGuard::new(self) + } + } + + /// Attempts to acquire this rwlock with shared read access. + /// + /// 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 block. + /// + /// This function does not provide any guarantees with respect to the ordering + /// of whether contentious readers or writers will acquire the lock first. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. An + /// error will only be returned if the lock would have otherwise been + /// acquired. + /// + /// # Examples + /// + /// ``` + /// use std::sync::RwLock; + /// + /// let lock = RwLock::new(1); + /// + /// match lock.try_read() { + /// Ok(n) => assert_eq!(*n, 1), + /// Err(_) => unreachable!(), + /// }; + /// ``` + #[inline] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn try_read(&self) -> TryLockResult<RwLockReadGuard<'_, T>> { + unsafe { + if self.inner.try_read() { + Ok(RwLockReadGuard::new(self)?) + } else { + Err(TryLockError::WouldBlock) + } + } + } + + /// Locks this rwlock with exclusive write access, blocking the current + /// thread until it can be acquired. + /// + /// This function will not return while other writers or other readers + /// currently have access to the lock. + /// + /// Returns an RAII guard which will drop the write access of this rwlock + /// when dropped. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. + /// An error will be returned when the lock is acquired. + /// + /// # Panics + /// + /// This function might panic when called if the lock is already held by the current thread. + /// + /// # Examples + /// + /// ``` + /// use std::sync::RwLock; + /// + /// let lock = RwLock::new(1); + /// + /// let mut n = lock.write().unwrap(); + /// *n = 2; + /// + /// assert!(lock.try_read().is_err()); + /// ``` + #[inline] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn write(&self) -> LockResult<RwLockWriteGuard<'_, T>> { + unsafe { + self.inner.write(); + RwLockWriteGuard::new(self) + } + } + + /// Attempts to lock this rwlock with exclusive write access. + /// + /// If the lock could not be acquired at this time, then `Err` is returned. + /// Otherwise, an RAII guard is returned which will release the lock when + /// it is dropped. + /// + /// This function does not block. + /// + /// This function does not provide any guarantees with respect to the ordering + /// of whether contentious readers or writers will acquire the lock first. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. An + /// error will only be returned if the lock would have otherwise been + /// acquired. + /// + /// # Examples + /// + /// ``` + /// use std::sync::RwLock; + /// + /// let lock = RwLock::new(1); + /// + /// let n = lock.read().unwrap(); + /// assert_eq!(*n, 1); + /// + /// assert!(lock.try_write().is_err()); + /// ``` + #[inline] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn try_write(&self) -> TryLockResult<RwLockWriteGuard<'_, T>> { + unsafe { + if self.inner.try_write() { + Ok(RwLockWriteGuard::new(self)?) + } else { + Err(TryLockError::WouldBlock) + } + } + } + + /// Determines whether the lock is poisoned. + /// + /// If another thread is active, the lock can still become poisoned at any + /// time. You should not trust a `false` value for program correctness + /// without additional synchronization. + /// + /// # Examples + /// + /// ``` + /// use std::sync::{Arc, RwLock}; + /// use std::thread; + /// + /// let lock = Arc::new(RwLock::new(0)); + /// let c_lock = lock.clone(); + /// + /// let _ = thread::spawn(move || { + /// let _lock = c_lock.write().unwrap(); + /// panic!(); // the lock gets poisoned + /// }).join(); + /// assert_eq!(lock.is_poisoned(), true); + /// ``` + #[inline] + #[stable(feature = "sync_poison", since = "1.2.0")] + pub fn is_poisoned(&self) -> bool { + self.poison.get() + } + + /// Consumes this `RwLock`, returning the underlying data. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. An + /// error will only be returned if the lock would have otherwise been + /// acquired. + /// + /// # Examples + /// + /// ``` + /// use std::sync::RwLock; + /// + /// let lock = RwLock::new(String::new()); + /// { + /// let mut s = lock.write().unwrap(); + /// *s = "modified".to_owned(); + /// } + /// assert_eq!(lock.into_inner().unwrap(), "modified"); + /// ``` + #[stable(feature = "rwlock_into_inner", since = "1.6.0")] + pub fn into_inner(self) -> LockResult<T> + where + T: Sized, + { + // We know statically that there are no outstanding references to + // `self` so there's no need to lock the inner lock. + // + // To get the inner value, we'd like to call `data.into_inner()`, + // but because `RwLock` impl-s `Drop`, we can't move out of it, so + // we'll have to destructure it manually instead. + unsafe { + // Like `let RwLock { inner, poison, data } = self`. + let (inner, poison, data) = { + let RwLock { ref inner, ref poison, ref data } = self; + (ptr::read(inner), ptr::read(poison), ptr::read(data)) + }; + mem::forget(self); + inner.destroy(); // Keep in sync with the `Drop` impl. + drop(inner); + + poison::map_result(poison.borrow(), |_| data.into_inner()) + } + } + + /// Returns a mutable reference to the underlying data. + /// + /// Since this call borrows the `RwLock` mutably, no actual locking needs to + /// take place -- the mutable borrow statically guarantees no locks exist. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. An + /// error will only be returned if the lock would have otherwise been + /// acquired. + /// + /// # Examples + /// + /// ``` + /// use std::sync::RwLock; + /// + /// let mut lock = RwLock::new(0); + /// *lock.get_mut().unwrap() = 10; + /// assert_eq!(*lock.read().unwrap(), 10); + /// ``` + #[stable(feature = "rwlock_get_mut", since = "1.6.0")] + pub fn get_mut(&mut self) -> LockResult<&mut T> { + // We know statically that there are no other references to `self`, so + // there's no need to lock the inner lock. + let data = unsafe { &mut *self.data.get() }; + poison::map_result(self.poison.borrow(), |_| data) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl<#[may_dangle] T: ?Sized> Drop for RwLock<T> { + fn drop(&mut self) { + // IMPORTANT: This code needs to be kept in sync with `RwLock::into_inner`. + unsafe { self.inner.destroy() } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T: ?Sized + fmt::Debug> fmt::Debug for RwLock<T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self.try_read() { + Ok(guard) => f.debug_struct("RwLock").field("data", &&*guard).finish(), + Err(TryLockError::Poisoned(err)) => { + f.debug_struct("RwLock").field("data", &&**err.get_ref()).finish() + } + Err(TryLockError::WouldBlock) => { + struct LockedPlaceholder; + impl fmt::Debug for LockedPlaceholder { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.write_str("<locked>") + } + } + + f.debug_struct("RwLock").field("data", &LockedPlaceholder).finish() + } + } + } +} + +#[stable(feature = "rw_lock_default", since = "1.10.0")] +impl<T: Default> Default for RwLock<T> { + /// Creates a new `RwLock<T>`, with the `Default` value for T. + fn default() -> RwLock<T> { + RwLock::new(Default::default()) + } +} + +#[stable(feature = "rw_lock_from", since = "1.24.0")] +impl<T> From<T> for RwLock<T> { + /// Creates a new instance of an `RwLock<T>` which is unlocked. + /// This is equivalent to [`RwLock::new`]. + /// + /// [`RwLock::new`]: ../../std/sync/struct.RwLock.html#method.new + fn from(t: T) -> Self { + RwLock::new(t) + } +} + +impl<'rwlock, T: ?Sized> RwLockReadGuard<'rwlock, T> { + unsafe fn new(lock: &'rwlock RwLock<T>) -> LockResult<RwLockReadGuard<'rwlock, T>> { + poison::map_result(lock.poison.borrow(), |_| RwLockReadGuard { lock }) + } +} + +impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> { + unsafe fn new(lock: &'rwlock RwLock<T>) -> LockResult<RwLockWriteGuard<'rwlock, T>> { + poison::map_result(lock.poison.borrow(), |guard| RwLockWriteGuard { lock, poison: guard }) + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl<T: fmt::Debug> fmt::Debug for RwLockReadGuard<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("RwLockReadGuard").field("lock", &self.lock).finish() + } +} + +#[stable(feature = "std_guard_impls", since = "1.20.0")] +impl<T: ?Sized + fmt::Display> fmt::Display for RwLockReadGuard<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + (**self).fmt(f) + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl<T: fmt::Debug> fmt::Debug for RwLockWriteGuard<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("RwLockWriteGuard").field("lock", &self.lock).finish() + } +} + +#[stable(feature = "std_guard_impls", since = "1.20.0")] +impl<T: ?Sized + fmt::Display> fmt::Display for RwLockWriteGuard<'_, T> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + (**self).fmt(f) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T: ?Sized> Deref for RwLockReadGuard<'_, T> { + type Target = T; + + fn deref(&self) -> &T { + unsafe { &*self.lock.data.get() } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T: ?Sized> Deref for RwLockWriteGuard<'_, T> { + type Target = T; + + fn deref(&self) -> &T { + unsafe { &*self.lock.data.get() } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T: ?Sized> DerefMut for RwLockWriteGuard<'_, T> { + fn deref_mut(&mut self) -> &mut T { + unsafe { &mut *self.lock.data.get() } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T: ?Sized> Drop for RwLockReadGuard<'_, T> { + fn drop(&mut self) { + unsafe { + self.lock.inner.read_unlock(); + } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T: ?Sized> Drop for RwLockWriteGuard<'_, T> { + fn drop(&mut self) { + self.lock.poison.done(&self.poison); + unsafe { + self.lock.inner.write_unlock(); + } + } +} + +#[cfg(all(test, not(target_os = "emscripten")))] +mod tests { + use crate::sync::atomic::{AtomicUsize, Ordering}; + use crate::sync::mpsc::channel; + use crate::sync::{Arc, RwLock, TryLockError}; + use crate::thread; + use rand::{self, Rng}; + + #[derive(Eq, PartialEq, Debug)] + struct NonCopy(i32); + + #[test] + fn smoke() { + let l = RwLock::new(()); + drop(l.read().unwrap()); + drop(l.write().unwrap()); + drop((l.read().unwrap(), l.read().unwrap())); + drop(l.write().unwrap()); + } + + #[test] + fn frob() { + const N: u32 = 10; + const M: usize = 1000; + + let r = Arc::new(RwLock::new(())); + + let (tx, rx) = channel::<()>(); + for _ in 0..N { + let tx = tx.clone(); + let r = r.clone(); + thread::spawn(move || { + let mut rng = rand::thread_rng(); + for _ in 0..M { + if rng.gen_bool(1.0 / (N as f64)) { + drop(r.write().unwrap()); + } else { + drop(r.read().unwrap()); + } + } + drop(tx); + }); + } + drop(tx); + let _ = rx.recv(); + } + + #[test] + fn test_rw_arc_poison_wr() { + let arc = Arc::new(RwLock::new(1)); + let arc2 = arc.clone(); + let _: Result<(), _> = thread::spawn(move || { + let _lock = arc2.write().unwrap(); + panic!(); + }) + .join(); + assert!(arc.read().is_err()); + } + + #[test] + fn test_rw_arc_poison_ww() { + let arc = Arc::new(RwLock::new(1)); + assert!(!arc.is_poisoned()); + let arc2 = arc.clone(); + let _: Result<(), _> = thread::spawn(move || { + let _lock = arc2.write().unwrap(); + panic!(); + }) + .join(); + assert!(arc.write().is_err()); + assert!(arc.is_poisoned()); + } + + #[test] + fn test_rw_arc_no_poison_rr() { + let arc = Arc::new(RwLock::new(1)); + let arc2 = arc.clone(); + let _: Result<(), _> = thread::spawn(move || { + let _lock = arc2.read().unwrap(); + panic!(); + }) + .join(); + let lock = arc.read().unwrap(); + assert_eq!(*lock, 1); + } + #[test] + fn test_rw_arc_no_poison_rw() { + let arc = Arc::new(RwLock::new(1)); + let arc2 = arc.clone(); + let _: Result<(), _> = thread::spawn(move || { + let _lock = arc2.read().unwrap(); + panic!() + }) + .join(); + let lock = arc.write().unwrap(); + assert_eq!(*lock, 1); + } + + #[test] + fn test_rw_arc() { + let arc = Arc::new(RwLock::new(0)); + let arc2 = arc.clone(); + let (tx, rx) = channel(); + + thread::spawn(move || { + let mut lock = arc2.write().unwrap(); + for _ in 0..10 { + let tmp = *lock; + *lock = -1; + thread::yield_now(); + *lock = tmp + 1; + } + tx.send(()).unwrap(); + }); + + // Readers try to catch the writer in the act + let mut children = Vec::new(); + for _ in 0..5 { + let arc3 = arc.clone(); + children.push(thread::spawn(move || { + let lock = arc3.read().unwrap(); + assert!(*lock >= 0); + })); + } + + // Wait for children to pass their asserts + for r in children { + assert!(r.join().is_ok()); + } + + // Wait for writer to finish + rx.recv().unwrap(); + let lock = arc.read().unwrap(); + assert_eq!(*lock, 10); + } + + #[test] + fn test_rw_arc_access_in_unwind() { + let arc = Arc::new(RwLock::new(1)); + let arc2 = arc.clone(); + let _ = thread::spawn(move || -> () { + struct Unwinder { + i: Arc<RwLock<isize>>, + } + impl Drop for Unwinder { + fn drop(&mut self) { + let mut lock = self.i.write().unwrap(); + *lock += 1; + } + } + let _u = Unwinder { i: arc2 }; + panic!(); + }) + .join(); + let lock = arc.read().unwrap(); + assert_eq!(*lock, 2); + } + + #[test] + fn test_rwlock_unsized() { + let rw: &RwLock<[i32]> = &RwLock::new([1, 2, 3]); + { + let b = &mut *rw.write().unwrap(); + b[0] = 4; + b[2] = 5; + } + let comp: &[i32] = &[4, 2, 5]; + assert_eq!(&*rw.read().unwrap(), comp); + } + + #[test] + fn test_rwlock_try_write() { + let lock = RwLock::new(0isize); + let read_guard = lock.read().unwrap(); + + let write_result = lock.try_write(); + match write_result { + Err(TryLockError::WouldBlock) => (), + Ok(_) => assert!(false, "try_write should not succeed while read_guard is in scope"), + Err(_) => assert!(false, "unexpected error"), + } + + drop(read_guard); + } + + #[test] + fn test_into_inner() { + let m = RwLock::new(NonCopy(10)); + assert_eq!(m.into_inner().unwrap(), NonCopy(10)); + } + + #[test] + fn test_into_inner_drop() { + struct Foo(Arc<AtomicUsize>); + impl Drop for Foo { + fn drop(&mut self) { + self.0.fetch_add(1, Ordering::SeqCst); + } + } + let num_drops = Arc::new(AtomicUsize::new(0)); + let m = RwLock::new(Foo(num_drops.clone())); + assert_eq!(num_drops.load(Ordering::SeqCst), 0); + { + let _inner = m.into_inner().unwrap(); + assert_eq!(num_drops.load(Ordering::SeqCst), 0); + } + assert_eq!(num_drops.load(Ordering::SeqCst), 1); + } + + #[test] + fn test_into_inner_poison() { + let m = Arc::new(RwLock::new(NonCopy(10))); + let m2 = m.clone(); + let _ = thread::spawn(move || { + let _lock = m2.write().unwrap(); + panic!("test panic in inner thread to poison RwLock"); + }) + .join(); + + assert!(m.is_poisoned()); + match Arc::try_unwrap(m).unwrap().into_inner() { + Err(e) => assert_eq!(e.into_inner(), NonCopy(10)), + Ok(x) => panic!("into_inner of poisoned RwLock is Ok: {:?}", x), + } + } + + #[test] + fn test_get_mut() { + let mut m = RwLock::new(NonCopy(10)); + *m.get_mut().unwrap() = NonCopy(20); + assert_eq!(m.into_inner().unwrap(), NonCopy(20)); + } + + #[test] + fn test_get_mut_poison() { + let m = Arc::new(RwLock::new(NonCopy(10))); + let m2 = m.clone(); + let _ = thread::spawn(move || { + let _lock = m2.write().unwrap(); + panic!("test panic in inner thread to poison RwLock"); + }) + .join(); + + assert!(m.is_poisoned()); + match Arc::try_unwrap(m).unwrap().get_mut() { + Err(e) => assert_eq!(*e.into_inner(), NonCopy(10)), + Ok(x) => panic!("get_mut of poisoned RwLock is Ok: {:?}", x), + } + } +} |