60 lines
2 KiB
Rust
60 lines
2 KiB
Rust
|
use swactor::actor::{ActorInterface, Ctx};
|
||
|
|
use wasmtime::{Memory, Store, TypedFunc};
|
||
|
|
|
||
|
|
use crate::ByteMessage;
|
||
|
|
|
||
|
|
/// State accessible to host functions during guest execution.
|
||
|
|
#[derive(Default)]
|
||
|
|
pub(crate) struct HostState {
|
||
|
|
pub outbox: Vec<(swactor::actor::ActorAddress, Vec<u8>)>,
|
||
|
|
}
|
||
|
|
|
||
|
|
/// An actor whose logic is defined by a WebAssembly guest module.
|
||
|
|
///
|
||
|
|
/// Messages arrive as [`ByteMessage`], are copied into Wasm linear memory,
|
||
|
|
/// and processed by the guest's `handle` export. The guest can send messages
|
||
|
|
/// back via the `swactor.send` host import.
|
||
|
|
pub struct WasmActor {
|
||
|
|
pub(crate) store: Store<HostState>,
|
||
|
|
pub(crate) memory: Memory,
|
||
|
|
pub(crate) alloc: TypedFunc<i32, i32>,
|
||
|
|
pub(crate) handle: TypedFunc<(i32, i32), ()>,
|
||
|
|
}
|
||
|
|
|
||
|
|
impl ActorInterface for WasmActor {
|
||
|
|
type Incoming = ByteMessage;
|
||
|
|
type Response = ();
|
||
|
|
|
||
|
|
fn handle(&mut self, ctx: &Ctx, msg: ByteMessage) {
|
||
|
|
let bytes = &msg.0;
|
||
|
|
let len: i32 = match i32::try_from(bytes.len()) {
|
||
|
|
Ok(n) => n,
|
||
|
|
Err(_) => return, // message too large for i32 ABI
|
||
|
|
};
|
||
|
|
|
||
|
|
// 1. Allocate space in guest memory
|
||
|
|
let ptr = match self.alloc.call(&mut self.store, len) {
|
||
|
|
Ok(ptr) if ptr < 0 => return, // invalid pointer
|
||
|
|
Ok(0) if len > 0 => return, // OOM — drop message
|
||
|
|
Ok(ptr) => ptr,
|
||
|
|
Err(_) => return, // alloc trapped — drop message
|
||
|
|
};
|
||
|
|
|
||
|
|
// 2. Write message bytes into guest memory
|
||
|
|
self.memory.data_mut(&mut self.store)
|
||
|
|
[ptr as usize..(ptr as usize + bytes.len())]
|
||
|
|
.copy_from_slice(bytes);
|
||
|
|
|
||
|
|
// 3. Call guest handle
|
||
|
|
if self.handle.call(&mut self.store, (ptr, len)).is_err() {
|
||
|
|
return; // handle trapped — drop message, keep actor alive
|
||
|
|
}
|
||
|
|
|
||
|
|
// 4. Drain outbox → send via ctx
|
||
|
|
let outbox: Vec<_> = self.store.data_mut().outbox.drain(..).collect();
|
||
|
|
for (dest, payload) in outbox {
|
||
|
|
let _ = ctx.send(dest, ByteMessage(payload));
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|