Trait Once

Source

pub unsafe trait Once:
    Default
    + Send
    + Sync
    + 'static {
    // Required methods
    fn once(&self, f: impl FnOnce());
    fn is_completed(&self) -> bool;
}

Expand description

A synchronization primitive which can be used to run a one-time initialization.

§Safety

Implementations must guarantee that:

Once::once executes the provided closure at most once across all concurrent callers, and blocks all concurrent callers until that single execution completes, establishing an acquire/release synchronization edge from the completion of the closure to the return of Once::once.
Once::is_completed returns true if and only if an invocation of Once::once has completed without panicking, establishing an acquire synchronization edge with the completion of that closure.
Default::default returns an uncompleted instance for which Once::is_completed returns false.

Required Methods§

Source

fn once(&self, f: impl FnOnce())

Performs a one-time initialization routine.

The given closure f will be executed if and only if this Once has not already been completed. Concurrent calls to once block until initialization finishes.

§Panics

If f panics, the implementation is expected to panic on further attempts to initialize. Note that Netstack3 is usually used in panic=abort compilations, so we don’t need anything stronger than that.

Source