Struct RestoreOnDrop 

pub struct RestoreOnDrop<T: 'static> { /* private fields */ }

A drop guard that restores a ContextCell to a previously-saved value when dropped.

WideLogGuard owns one of these instead of a raw *mut T. When the guard is dropped, the cell is restored to its prior state. If the user calls std::mem::forget on the guard, the restoration is silently skipped — this is a known limitation, documented on the WideLogGuard rustdoc. A future release may use a leak-detection fallback (e.g. a thread-local “current owner” pointer) to recover safety even on forget.

Safety contract

cell must be a thread-local or task-local ContextCell<T> with a 'static lifetime (i.e. defined in a thread_local! or task_local! block). The previous pointer prev is treated as an opaque value to be restored verbatim; it is never dereferenced.

This type is Send + Sync unconditionally because the only state is a &'static ContextCell<T> (which is Send + Sync) and a raw pointer that is never dereferenced by this type.

Implementations

impl<T: 'static> RestoreOnDrop<T>

pub const unsafe fn new(cell: &'static ContextCell<T>, prev: *mut T) -> Self

Build a restore guard for cell. The cell will be restored to prev when this value is dropped.

Safety

cell must be a thread-local or task-local ContextCell<T> with 'static lifetime. prev is the value previously returned by ContextCell::replace (or null for the initial state).

pub fn disarm(self) -> *mut T

Disable the restore-on-drop behavior. The cell is NOT restored. Returns the saved prev pointer so the caller can restore manually or discard it.

Trait Implementations

impl<T: 'static> Drop for RestoreOnDrop<T>

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.

impl<T: 'static> Send for RestoreOnDrop<T>

impl<T: 'static> Sync for RestoreOnDrop<T>