Trait Factor

pub trait Factor: Any + Sized {
    type RuntimeConfig;
    type AppState: Sync;
    type InstanceBuilder: FactorInstanceBuilder;

    // Required methods
    fn configure_app<T: RuntimeFactors>(
        &self,
        ctx: ConfigureAppContext<'_, T, Self>,
    ) -> Result<Self::AppState>;
    fn prepare<T: RuntimeFactors>(
        &self,
        ctx: PrepareContext<'_, T, Self>,
    ) -> Result<Self::InstanceBuilder>;

    // Provided method
    fn init<T: Send + 'static>(
        &mut self,
        ctx: InitContext<'_, T, Self>,
    ) -> Result<()> { ... }
}

A contained (i.e., “factored”) piece of runtime functionality.

Required Associated Types

type RuntimeConfig

The particular runtime configuration relevant to this factor.

Runtime configuration allows for user-provided customization of the factor’s behavior on a per-app basis.

type AppState: Sync

The application state of this factor.

This state may be cached by the runtime across multiple requests.

type InstanceBuilder: FactorInstanceBuilder

The builder of instance state for this factor.

Required Methods

fn configure_app<T: RuntimeFactors>( &self, ctx: ConfigureAppContext<'_, T, Self>, ) -> Result<Self::AppState>

Performs factor-specific validation and configuration for the given App.

ConfigureAppContext gives access to:

• The spin_app::App
• This factors’s RuntimeConfig
• The AppState for any factors configured before this one

A runtime may - but is not required to - reuse the returned config across multiple instances. Because this method may be called per-instantiation, it should avoid any blocking operations that could unnecessarily delay execution.

This method may be called without any call to init or prepare in cases where only validation is needed (e.g., spin doctor).

fn prepare<T: RuntimeFactors>( &self, ctx: PrepareContext<'_, T, Self>, ) -> Result<Self::InstanceBuilder>

Creates a new FactorInstanceBuilder, which will later build per-instance state for this factor.

This method is given access to the app component being instantiated and to any other factors’ instance builders that have already been prepared. As such, this is the primary place for inter-factor dependencies to be used.

Provided Methods

fn init<T: Send + 'static>( &mut self, ctx: InitContext<'_, T, Self>, ) -> Result<()>

Initializes this Factor for a runtime once at runtime startup.

This will be called at most once, before any call to Factor::prepare. InitContext provides access to a wasmtime Linker, so this is where any bindgen add_to_linker calls go.

The type parameter T here is the same as the wasmtime::Store type parameter T, which will contain the RuntimeFactors::InstanceState.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors