with_read

fn with_read<A, B>(RwLock lock, A -> B f) -> Result<B, ThreadError>

use thread::{with_read};

Runs f on a snapshot of the lock’s value and returns what f returns.

The read lock is released before f runs, so another thread may change the value meanwhile. Waits while a writer holds the lock (blocking every task of the thread, also inside a task::scope).

Parameters#

Returns#

Result<B, ThreadError>

Examples#

use thread::{rwlock, with_read};
use tests::assert;
let lock = match rwlock([1, 2, 3]) {
    Result::Ok(l) => l,
    Result::Err(_) => panic "rwlock failed",
};
let first = match with_read(lock, fn ([int; 3] xs) => xs[0]) {
    Result::Ok(v) => v,
    Result::Err(_) => -1,
};
assert!(first == 1);

See also#

• task::scope
• spawn: Runs f(arg) on another OS thread and returns a handle to it.
• join: Waits for the thread to finish and returns the value its function returned.
• detach: Lets the thread run to completion without being joined.
• channel: Creates an unbounded channel and returns its (Sender, Receiver) ends.
• send: Sends a copy of value on the channel.
• recv: Takes the next value from the channel, waiting until one arrives.
• try_send: Sends value without waiting.