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-rw-r--r--src/libstd/sys_common/remutex.rs224
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diff --git a/src/libstd/sys_common/remutex.rs b/src/libstd/sys_common/remutex.rs
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index 4f19bbc467f..00000000000
--- a/src/libstd/sys_common/remutex.rs
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@@ -1,224 +0,0 @@
-use crate::fmt;
-use crate::marker;
-use crate::ops::Deref;
-use crate::panic::{RefUnwindSafe, UnwindSafe};
-use crate::sys::mutex as sys;
-
-/// A re-entrant mutual exclusion
-///
-/// This mutex will block *other* threads waiting for the lock to become
-/// available. The thread which has already locked the mutex can lock it
-/// multiple times without blocking, preventing a common source of deadlocks.
-pub struct ReentrantMutex<T> {
- inner: sys::ReentrantMutex,
- data: T,
-}
-
-unsafe impl<T: Send> Send for ReentrantMutex<T> {}
-unsafe impl<T: Send> Sync for ReentrantMutex<T> {}
-
-impl<T> UnwindSafe for ReentrantMutex<T> {}
-impl<T> RefUnwindSafe for ReentrantMutex<T> {}
-
-/// An RAII implementation of a "scoped lock" of a mutex. When this structure is
-/// dropped (falls out of scope), the lock will be unlocked.
-///
-/// The data protected by the mutex can be accessed through this guard via its
-/// Deref implementation.
-///
-/// # Mutability
-///
-/// Unlike `MutexGuard`, `ReentrantMutexGuard` does not implement `DerefMut`,
-/// because implementation of the trait would violate Rust’s reference aliasing
-/// rules. Use interior mutability (usually `RefCell`) in order to mutate the
-/// guarded data.
-#[must_use = "if unused the ReentrantMutex will immediately unlock"]
-pub struct ReentrantMutexGuard<'a, T: 'a> {
- // funny underscores due to how Deref currently works (it disregards field
- // privacy).
- __lock: &'a ReentrantMutex<T>,
-}
-
-impl<T> !marker::Send for ReentrantMutexGuard<'_, T> {}
-
-impl<T> ReentrantMutex<T> {
- /// Creates a new reentrant mutex in an unlocked state.
- ///
- /// # Unsafety
- ///
- /// This function is unsafe because it is required that `init` is called
- /// once this mutex is in its final resting place, and only then are the
- /// lock/unlock methods safe.
- pub const unsafe fn new(t: T) -> ReentrantMutex<T> {
- ReentrantMutex { inner: sys::ReentrantMutex::uninitialized(), data: t }
- }
-
- /// Initializes this mutex so it's ready for use.
- ///
- /// # Unsafety
- ///
- /// Unsafe to call more than once, and must be called after this will no
- /// longer move in memory.
- pub unsafe fn init(&self) {
- self.inner.init();
- }
-
- /// Acquires a mutex, blocking the current thread until it is able to do so.
- ///
- /// This function will block the caller until it is available to acquire the mutex.
- /// Upon returning, the thread is the only thread with the mutex held. When the thread
- /// calling this method already holds the lock, the call shall succeed without
- /// blocking.
- ///
- /// # Errors
- ///
- /// If another user of this mutex panicked while holding the mutex, then
- /// this call will return failure if the mutex would otherwise be
- /// acquired.
- pub fn lock(&self) -> ReentrantMutexGuard<'_, T> {
- unsafe { self.inner.lock() }
- ReentrantMutexGuard::new(&self)
- }
-
- /// Attempts to acquire this lock.
- ///
- /// If the lock could not be acquired at this time, then `Err` is returned.
- /// Otherwise, an RAII guard is returned.
- ///
- /// This function does not block.
- ///
- /// # Errors
- ///
- /// If another user of this mutex panicked while holding the mutex, then
- /// this call will return failure if the mutex would otherwise be
- /// acquired.
- pub fn try_lock(&self) -> Option<ReentrantMutexGuard<'_, T>> {
- if unsafe { self.inner.try_lock() } { Some(ReentrantMutexGuard::new(&self)) } else { None }
- }
-}
-
-impl<T> Drop for ReentrantMutex<T> {
- fn drop(&mut self) {
- // This is actually safe b/c we know that there is no further usage of
- // this mutex (it's up to the user to arrange for a mutex to get
- // dropped, that's not our job)
- unsafe { self.inner.destroy() }
- }
-}
-
-impl<T: fmt::Debug + 'static> fmt::Debug for ReentrantMutex<T> {
- fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
- match self.try_lock() {
- Some(guard) => f.debug_struct("ReentrantMutex").field("data", &*guard).finish(),
- None => {
- struct LockedPlaceholder;
- impl fmt::Debug for LockedPlaceholder {
- fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
- f.write_str("<locked>")
- }
- }
-
- f.debug_struct("ReentrantMutex").field("data", &LockedPlaceholder).finish()
- }
- }
- }
-}
-
-impl<'mutex, T> ReentrantMutexGuard<'mutex, T> {
- fn new(lock: &'mutex ReentrantMutex<T>) -> ReentrantMutexGuard<'mutex, T> {
- ReentrantMutexGuard { __lock: lock }
- }
-}
-
-impl<T> Deref for ReentrantMutexGuard<'_, T> {
- type Target = T;
-
- fn deref(&self) -> &T {
- &self.__lock.data
- }
-}
-
-impl<T> Drop for ReentrantMutexGuard<'_, T> {
- #[inline]
- fn drop(&mut self) {
- unsafe {
- self.__lock.inner.unlock();
- }
- }
-}
-
-#[cfg(all(test, not(target_os = "emscripten")))]
-mod tests {
- use crate::cell::RefCell;
- use crate::sync::Arc;
- use crate::sys_common::remutex::{ReentrantMutex, ReentrantMutexGuard};
- use crate::thread;
-
- #[test]
- fn smoke() {
- let m = unsafe {
- let m = ReentrantMutex::new(());
- m.init();
- m
- };
- {
- let a = m.lock();
- {
- let b = m.lock();
- {
- let c = m.lock();
- assert_eq!(*c, ());
- }
- assert_eq!(*b, ());
- }
- assert_eq!(*a, ());
- }
- }
-
- #[test]
- fn is_mutex() {
- let m = unsafe {
- let m = Arc::new(ReentrantMutex::new(RefCell::new(0)));
- m.init();
- m
- };
- let m2 = m.clone();
- let lock = m.lock();
- let child = thread::spawn(move || {
- let lock = m2.lock();
- assert_eq!(*lock.borrow(), 4950);
- });
- for i in 0..100 {
- let lock = m.lock();
- *lock.borrow_mut() += i;
- }
- drop(lock);
- child.join().unwrap();
- }
-
- #[test]
- fn trylock_works() {
- let m = unsafe {
- let m = Arc::new(ReentrantMutex::new(()));
- m.init();
- m
- };
- let m2 = m.clone();
- let _lock = m.try_lock();
- let _lock2 = m.try_lock();
- thread::spawn(move || {
- let lock = m2.try_lock();
- assert!(lock.is_none());
- })
- .join()
- .unwrap();
- let _lock3 = m.try_lock();
- }
-
- pub struct Answer<'a>(pub ReentrantMutexGuard<'a, RefCell<u32>>);
- impl Drop for Answer<'_> {
- fn drop(&mut self) {
- *self.0.borrow_mut() = 42;
- }
- }
-}