Struct Guard

pub struct Guard { /* private fields */ }

An interrupt guard.

Created using disable.

While an instance of this guard is held, interrupts are disabled. When this guard is dropped, interrupts are restored to the state before disabling.

Caveats (Drop Order)

If interrupts are enabled, acquiring a guard will disable them. Dropping this guard will enable interrupts again. Different Guards might be dropped in arbitrary order.

This may result in interrupts being enabled again, even though another Guard is still held. For this to happen, one must explicitly drop guards in the wrong order, though. As long as guards don’t leave their original drop scope, they are dropped automatically in the correct order.

Examples

// interrupts may or may not be enabled
let guard = interrupts::disable();
// interrupts are disabled
drop(guard);
// interrupts are restored to the previous state

Dropping guards in the wrong order (don’t do this):

// Interrupts are enabled
let a = interrupts::disable();
// Interrupts are disabled
let b = interrupts::disable();
drop(a);
// Interrupts are enabled, although we still hold a guard in b
drop(b);

Trait Implementations

impl Drop for Guard

fn drop(&mut self)

Executes the destructor for this type.