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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:20:29 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:20:29 +0000 |
commit | 631cd5845e8de329d0e227aaa707d7ea228b8f8f (patch) | |
tree | a1b87c8f8cad01cf18f7c5f57a08f102771ed303 /library/std/src/sync/mutex.rs | |
parent | Adding debian version 1.69.0+dfsg1-1. (diff) | |
download | rustc-631cd5845e8de329d0e227aaa707d7ea228b8f8f.tar.xz rustc-631cd5845e8de329d0e227aaa707d7ea228b8f8f.zip |
Merging upstream version 1.70.0+dfsg1.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'library/std/src/sync/mutex.rs')
-rw-r--r-- | library/std/src/sync/mutex.rs | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/library/std/src/sync/mutex.rs b/library/std/src/sync/mutex.rs index 065045f44..b8fec6902 100644 --- a/library/std/src/sync/mutex.rs +++ b/library/std/src/sync/mutex.rs @@ -107,8 +107,8 @@ use crate::sys::locks as sys; /// *guard += 1; /// ``` /// -/// It is sometimes necessary to manually drop the mutex guard to unlock it -/// sooner than the end of the enclosing scope. +/// To unlock a mutex guard sooner than the end of the enclosing scope, +/// either create an inner scope or drop the guard manually. /// /// ``` /// use std::sync::{Arc, Mutex}; @@ -125,11 +125,18 @@ use crate::sys::locks as sys; /// let res_mutex_clone = Arc::clone(&res_mutex); /// /// threads.push(thread::spawn(move || { -/// let mut data = data_mutex_clone.lock().unwrap(); -/// // This is the result of some important and long-ish work. -/// let result = data.iter().fold(0, |acc, x| acc + x * 2); -/// data.push(result); -/// drop(data); +/// // Here we use a block to limit the lifetime of the lock guard. +/// let result = { +/// let mut data = data_mutex_clone.lock().unwrap(); +/// // This is the result of some important and long-ish work. +/// let result = data.iter().fold(0, |acc, x| acc + x * 2); +/// data.push(result); +/// result +/// // The mutex guard gets dropped here, together with any other values +/// // created in the critical section. +/// }; +/// // The guard created here is a temporary dropped at the end of the statement, i.e. +/// // the lock would not remain being held even if the thread did some additional work. /// *res_mutex_clone.lock().unwrap() += result; /// })); /// }); @@ -146,6 +153,8 @@ use crate::sys::locks as sys; /// // It's even more important here than in the threads because we `.join` the /// // threads after that. If we had not dropped the mutex guard, a thread could /// // be waiting forever for it, causing a deadlock. +/// // As in the threads, a block could have been used instead of calling the +/// // `drop` function. /// drop(data); /// // Here the mutex guard is not assigned to a variable and so, even if the /// // scope does not end after this line, the mutex is still released: there is @@ -160,6 +169,7 @@ use crate::sys::locks as sys; /// /// assert_eq!(*res_mutex.lock().unwrap(), 800); /// ``` +/// #[stable(feature = "rust1", since = "1.0.0")] #[cfg_attr(not(test), rustc_diagnostic_item = "Mutex")] pub struct Mutex<T: ?Sized> { |