Struct wgpu_core::LifeGuard

pub struct LifeGuard {
    pub(crate) ref_count: Option<RefCount>,
    pub(crate) submission_index: AtomicUsize,
    pub(crate) label: String,
}

Information needed to decide when it’s safe to free some wgpu-core resource.

Each type representing a wgpu-core resource, like Device, Buffer, etc., contains a LifeGuard which indicates whether it is safe to free.

A resource may need to be retained for any of several reasons:

• The user may hold a reference to it (via a wgpu::Buffer, say).

• Other resources may depend on it (a texture view’s backing texture, for example).

• It may be used by commands sent to the GPU that have not yet finished execution.

Fields

ref_count: Option<RefCount>

RefCount for the user’s reference to this resource.

When the user first creates a wgpu-core resource, this RefCount is created along with the resource’s LifeGuard. When the user drops the resource, we swap this out for None. Note that the resource may still be held alive by other resources.

Any Stored<T> value holds a clone of this RefCount along with the id of a T resource.

submission_index: AtomicUsize

The index of the last queue submission in which the resource was used.

Each queue submission is fenced and assigned an index number sequentially. Thus, when a queue submission completes, we know any resources used in that submission and any lower-numbered submissions are no longer in use by the GPU.

label: String

The label from the descriptor used to create the resource.

Implementations

impl LifeGuard

pub(crate) fn new(label: &str) -> Self

pub(crate) fn add_ref(&self) -> RefCount

pub(crate) fn use_at(&self, submit_index: FenceValue) -> bool

Record that this resource will be used by the queue submission with the given index.

Returns true if the resource is still held by the user.

pub(crate) fn life_count(&self) -> FenceValue

Trait Implementations

impl Debug for LifeGuard

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

Formats the value using the given formatter.