once

import std::sync::once; · source

Once#

type struct Once {
    inner: OnceInner*;

    static new() -> Once;
    call_once(&this, init: () -> void) -> void;
}

Run an initializer exactly once across all threads. The first caller runs it; every other caller blocks until it finishes, and thereafter call_once returns immediately.

import std::sync::once;

mut init: Once = Once::new();
init.call_once(() -> void { setup_tables(); });

The initializer is a () -> void function pointer, and a non-capturing lambda is one.

The backing pthread_once_t starts all-zero, which is PTHREAD_ONCE_INIT, so no separate init call is needed.

Trait implementations#

implement trait Drop for struct Once