Struct wasmtime_wasi::preview2::ResourceTable

pub struct ResourceTable { /* private fields */ }

The ResourceTable type maps a Resource<T> to its T.

Implementations

impl ResourceTable

pub fn new() -> ResourceTable

Create an empty table

pub fn with_capacity(capacity: usize) -> ResourceTable

Create an empty table with at least the specified capacity.

pub fn push<T>(&mut self, entry: T) -> Result<Resource<T>, ResourceTableError>

where T: Send + 'static,

Inserts a new value T into this table, returning a corresponding Resource<T> which can be used to refer to it after it was inserted.

pub fn push_child<T, U>( &mut self, entry: T, parent: &Resource<U> ) -> Result<Resource<T>, ResourceTableError>

where T: Send + 'static, U: 'static,

Insert a resource at the next available index, and track that it has a parent resource.

The parent must exist to create a child. All children resources must be destroyed before a parent can be destroyed - otherwise ResourceTable::delete will fail with ResourceTableError::HasChildren.

Parent-child relationships are tracked inside the table to ensure that a parent resource is not deleted while it has live children. This allows child resources to hold “references” to a parent by table index, to avoid needing e.g. an Arc<Mutex<parent>> and the associated locking overhead and design issues, such as child existence extending lifetime of parent referent even after parent resource is destroyed, possibility for deadlocks.

Parent-child relationships may not be modified once created. There is no way to observe these relationships through the ResourceTable methods except for erroring on deletion, or the std::fmt::Debug impl.

pub fn get<T>(&self, key: &Resource<T>) -> Result<&T, ResourceTableError>

where T: Any,

Get an immutable reference to a resource of a given type at a given index.

Multiple shared references can be borrowed at any given time.

pub fn get_mut<T>( &mut self, key: &Resource<T> ) -> Result<&mut T, ResourceTableError>

where T: Any,

Get an mutable reference to a resource of a given type at a given index.

pub fn get_any_mut( &mut self, key: u32 ) -> Result<&mut (dyn Any + 'static), ResourceTableError>

Returns the raw Any at the key index provided.

pub fn delete<T>( &mut self, resource: Resource<T> ) -> Result<T, ResourceTableError>

where T: Any,

Same as delete, but typed

pub fn iter_entries<'a, T>( &'a mut self, map: HashMap<u32, T> ) -> impl Iterator<Item = (Result<&'a mut (dyn Any + 'static), ResourceTableError>, T)>

Zip the values of the map with mutable references to table entries corresponding to each key. As the keys in the HashMap are unique, this iterator can give mutable references with the same lifetime as the mutable reference to the ResourceTable.

pub fn iter_children<T>( &self, parent: &Resource<T> ) -> Result<impl Iterator<Item = &(dyn Any + Send + 'static)>, ResourceTableError>

where T: 'static,

Iterate over all children belonging to the provided parent

Trait Implementations

impl Debug for ResourceTable

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

Formats the value using the given formatter.

impl Default for ResourceTable

fn default() -> ResourceTable

Returns the “default value” for a type.