Rollup merge of rust-lang#147328 - EFanZh:lock-with, r=joboet

Implement non-poisoning `Mutex::with_mut`, `RwLock::with` and `RwLock::with_mut`

ACP: rust-lang/libs-team#497.

Author: Zalathar

library/std/src/sync/nonpoison/mutex.rs

@@ -376,6 +376,40 @@ impl<T: ?Sized> Mutex<T> {
     pub const fn data_ptr(&self) -> *mut T {
         self.data.get()
     }
+
+    /// Acquires the mutex and provides mutable access to the underlying data by passing
+    /// a mutable reference to the given closure.
+    ///
+    /// This method acquires the lock, calls the provided closure with a mutable reference
+    /// to the data, and returns the result of the closure. The lock is released after
+    /// the closure completes, even if it panics.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(lock_value_accessors, nonpoison_mutex)]
+    ///
+    /// use std::sync::nonpoison::Mutex;
+    ///
+    /// let mutex = Mutex::new(2);
+    ///
+    /// let result = mutex.with_mut(|data| {
+    ///     *data += 3;
+    ///
+    ///     *data + 5
+    /// });
+    ///
+    /// assert_eq!(*mutex.lock(), 5);
+    /// assert_eq!(result, 10);
+    /// ```
+    #[unstable(feature = "lock_value_accessors", issue = "133407")]
+    // #[unstable(feature = "nonpoison_mutex", issue = "134645")]
+    pub fn with_mut<F, R>(&self, f: F) -> R
+    where
+        F: FnOnce(&mut T) -> R,
+    {
+        f(&mut self.lock())
+    }
 }
 
 #[unstable(feature = "nonpoison_mutex", issue = "134645")]

library/std/src/sync/nonpoison/rwlock.rs

@@ -498,6 +498,68 @@ impl<T: ?Sized> RwLock<T> {
     pub const fn data_ptr(&self) -> *mut T {
         self.data.get()
     }
+
+    /// Locks this `RwLock` with shared read access to the underlying data by passing
+    /// a reference to the given closure.
+    ///
+    /// This method acquires the lock, calls the provided closure with a reference
+    /// to the data, and returns the result of the closure. The lock is released after
+    /// the closure completes, even if it panics.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(lock_value_accessors, nonpoison_rwlock)]
+    ///
+    /// use std::sync::nonpoison::RwLock;
+    ///
+    /// let rwlock = RwLock::new(2);
+    /// let result = rwlock.with(|data| *data + 3);
+    ///
+    /// assert_eq!(result, 5);
+    /// ```
+    #[unstable(feature = "lock_value_accessors", issue = "133407")]
+    // #[unstable(feature = "nonpoison_rwlock", issue = "134645")]
+    pub fn with<F, R>(&self, f: F) -> R
+    where
+        F: FnOnce(&T) -> R,
+    {
+        f(&self.read())
+    }
+
+    /// Locks this `RwLock` with exclusive write access to the underlying data by passing
+    /// a mutable reference to the given closure.
+    ///
+    /// This method acquires the lock, calls the provided closure with a mutable reference
+    /// to the data, and returns the result of the closure. The lock is released after
+    /// the closure completes, even if it panics.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(lock_value_accessors, nonpoison_rwlock)]
+    ///
+    /// use std::sync::nonpoison::RwLock;
+    ///
+    /// let rwlock = RwLock::new(2);
+    ///
+    /// let result = rwlock.with_mut(|data| {
+    ///     *data += 3;
+    ///
+    ///     *data + 5
+    /// });
+    ///
+    /// assert_eq!(*rwlock.read(), 5);
+    /// assert_eq!(result, 10);
+    /// ```
+    #[unstable(feature = "lock_value_accessors", issue = "133407")]
+    // #[unstable(feature = "nonpoison_rwlock", issue = "134645")]
+    pub fn with_mut<F, R>(&self, f: F) -> R
+    where
+        F: FnOnce(&mut T) -> R,
+    {
+        f(&mut self.write())
+    }
 }
 
 #[unstable(feature = "nonpoison_rwlock", issue = "134645")]

library/std/tests/sync/mutex.rs

@@ -549,3 +549,17 @@ fn panic_while_mapping_unlocked_poison() {
 
     drop(lock);
 }
+
+#[test]
+fn test_mutex_with_mut() {
+    let mutex = std::sync::nonpoison::Mutex::new(2);
+
+    let result = mutex.with_mut(|value| {
+        *value += 3;
+
+        *value + 5
+    });
+
+    assert_eq!(*mutex.lock(), 5);
+    assert_eq!(result, 10);
+}

library/std/tests/sync/rwlock.rs

@@ -861,3 +861,25 @@ fn panic_while_mapping_write_unlocked_poison() {
 
     drop(lock);
 }
+
+#[test]
+fn test_rwlock_with() {
+    let rwlock = std::sync::nonpoison::RwLock::new(2);
+    let result = rwlock.with(|value| *value + 3);
+
+    assert_eq!(result, 5);
+}
+
+#[test]
+fn test_rwlock_with_mut() {
+    let rwlock = std::sync::nonpoison::RwLock::new(2);
+
+    let result = rwlock.with_mut(|value| {
+        *value += 3;
+
+        *value + 5
+    });
+
+    assert_eq!(*rwlock.read(), 5);
+    assert_eq!(result, 10);
+}