Struct LifetimeState 

pub struct LifetimeState { /* private fields */ }

Cloneable strong handle to the counters behind a Lifetime.

Mostly an implementation detail of this module. Keeping one alive keeps the counters alive, but it does not itself claim a borrow or an access.

Implementations

impl LifetimeState

pub fn can_read(&self) -> bool

Returns true when no mutable borrow is out.

pub fn can_write(&self, id: usize) -> bool

Returns true when there are no readers and id is the current writer depth.

Pass 0 to ask for a top level mutable borrow, or the depth of an existing LifetimeRefMut to ask for a nested reborrow.

pub fn readers_count(&self) -> usize

Returns how many LifetimeRef handles are out.

pub fn writer_depth(&self) -> usize

Returns how deeply mutable borrows are nested, 0 when none is out.

pub fn is_read_accessible(&self) -> bool

Returns true when no write access guard is live.

pub fn is_write_accessible(&self) -> bool

Returns true when no access guard of any kind is live.

pub fn is_in_use(&self) -> bool

Returns true while any access guard is live.

pub fn is_locked(&self) -> bool

Returns true while another thread holds the internal spin lock.

pub fn try_lock(&self) -> Option<LifetimeStateAccess<'_>>

Takes the internal spin lock, or returns None when it is taken.

pub fn lock(&self) -> LifetimeStateAccess<'_>

Takes the internal spin lock, spinning until it is free.

pub unsafe fn lock_unchecked(&self) -> LifetimeStateAccess<'_>

Builds a lock guard without taking the lock.

Safety

No other thread must update the counters while this guard lives. If one does, the read-modify-write pairs in LifetimeStateAccess can lose an update.

pub unsafe fn update_tag(&self, tag: &Lifetime)

Stamps the address of the owning Lifetime as the current tag.

Safety

tag must be the Lifetime that owns this state. Passing another one makes stale handles look valid again.

pub unsafe fn invalidate_tag(&self)

Clears the tag, so every handle taken so far stops upgrading.

Safety

Callers holding handles will see them go dead. Use through Lifetime::invalidate rather than directly.

pub fn tag(&self) -> usize

Returns the current tag, or 0 when the state was invalidated.

pub fn downgrade(&self) -> LifetimeWeakState

Takes a weak handle that remembers the current tag.

Trait Implementations

impl Clone for LifetimeState

fn clone(&self) -> LifetimeState

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for LifetimeState

fn default() -> LifetimeState

Returns the “default value” for a type.