Struct bitflags::__core::sync::RwLock

pub struct RwLock<T> where T: ?Sized {
    // some fields omitted
}

[−] Expand description

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).

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 contained of the lock.

Poisoning

RwLocks, like Mutexes, will become poisoned on panics. 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