Struct StopGuard

pub struct StopGuard { /* private fields */ }

Guard allowing to stop blocking operations when dropped.

Usage

1. Instantiate a guard and the paired StopToken via Self::new() in a future.
2. Leave the guard as-is inside the future.
3. Send the token to a blocking Tokio task (i.e., a tokio::task::spawn_blocking() closure).
4. Check the token state periodically via StopToken::should_stop() in the blocking task; stop the task if it is true.

Why this works

If a future is dropped (e.g., by timing it out, selecting between it and another future, etc.), blocking task(s) spawned inside the future will continue executing indefinitely because Rust / Tokio don’t provide means to stop threads (which means do exist in some OSes, but are notoriously unsafe to use). StopGuard provides an app-level solution to this concern. It is a thin non-cloneable wrapper around an Arc, and StopToken is a (cloneable) Weak reference to it. StopToken::should_stop() checks whether the strong count for the Arc is zero.

Implementations

impl StopGuard

pub fn new() -> (Self, StopToken)

Trait Implementations

impl Debug for StopGuard

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.