Crate wasmtime_wasi_keyvalue

Wasmtime’s wasi-keyvalue Implementation

This crate provides a Wasmtime host implementation of the wasi-keyvalue API. With this crate, the runtime can run components that call APIs in wasi-keyvalue and provide components with access to key-value storages.

Currently supported storage backends:

• In-Memory (empty identifier)

Examples

The usage of this crate is very similar to other WASI API implementations such as wasi:cli and wasi:http.

A common scenario is accessing KV store in a wasi:cli component. A standalone example of doing all this looks like:

use wasmtime::{
    component::{Linker, ResourceTable},
    Config, Engine, Result, Store,
};
use wasmtime_wasi::{IoView, WasiCtx, WasiCtxBuilder, WasiView};
use wasmtime_wasi_keyvalue::{WasiKeyValue, WasiKeyValueCtx, WasiKeyValueCtxBuilder};

#[tokio::main]
async fn main() -> Result<()> {
    let mut config = Config::new();
    config.async_support(true);
    let engine = Engine::new(&config)?;

    let mut store = Store::new(&engine, Ctx {
        table: ResourceTable::new(),
        wasi_ctx: WasiCtxBuilder::new().build(),
        wasi_keyvalue_ctx: WasiKeyValueCtxBuilder::new().build(),
    });

    let mut linker = Linker::<Ctx>::new(&engine);
    wasmtime_wasi::add_to_linker_async(&mut linker)?;
    // add `wasi-keyvalue` world's interfaces to the linker
    wasmtime_wasi_keyvalue::add_to_linker(&mut linker, |h: &mut Ctx| {
        WasiKeyValue::new(&h.wasi_keyvalue_ctx, &mut h.table)
    })?;

    // ... use `linker` to instantiate within `store` ...

    Ok(())
}

struct Ctx {
    table: ResourceTable,
    wasi_ctx: WasiCtx,
    wasi_keyvalue_ctx: WasiKeyValueCtx,
}

impl IoView for Ctx {
    fn table(&mut self) -> &mut ResourceTable { &mut self.table }
}
impl WasiView for Ctx {
    fn ctx(&mut self) -> &mut WasiCtx { &mut self.wasi_ctx }
}

Structs

WasiKeyValue

A wrapper capturing the needed internal wasi-keyvalue state.

WasiKeyValueCtx

Capture the state necessary for use in the wasi-keyvalue API implementation.

WasiKeyValueCtxBuilder

Builder-style structure used to create a WasiKeyValueCtx.

Functions

add_to_linker

Add all the wasi-keyvalue world’s interfaces to a [wasmtime::component::Linker].