ResourceLimiterAsync in wasmtime - Rust (original) (raw)

Trait ResourceLimiterAsync

Source

pub trait ResourceLimiterAsync {
    // Required methods
    fn memory_growing<'life0, 'async_trait>(
        &'life0 mut self,
        current: usize,
        desired: usize,
        maximum: Option<usize>,
    ) -> Pin<Box<dyn Future<Output = Result<bool>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;
    fn table_growing<'life0, 'async_trait>(
        &'life0 mut self,
        current: usize,
        desired: usize,
        maximum: Option<usize>,
    ) -> Pin<Box<dyn Future<Output = Result<bool>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;

    // Provided methods
    fn memory_grow_failed(&mut self, error: Error) -> Result<()> { ... }
    fn table_grow_failed(&mut self, error: Error) -> Result<()> { ... }
    fn instances(&self) -> usize { ... }
    fn tables(&self) -> usize { ... }
    fn memories(&self) -> usize { ... }
}

Available on crate feature runtime only.

Expand description

Used by hosts to limit resource consumption of instances, blocking asynchronously if necessary.

This trait is identical to ResourceLimiter, except that thememory_growing and table_growing functions are async. Must be used with an async Store configured viaConfig::async_support.

This trait is used withStore::limiter_async: see those docs for restrictions on using other Wasmtime interfaces with an async resource limiter. Additionally see [ResourceLimiter`] for more information about limiting resources from WebAssembly.

The async here enables embedders that are already using asynchronous execution of WebAssembly to block the WebAssembly, but no the OS thread, to answer the question whether growing a memory or table is allowed.