Allow wasi-http to return error to the caller instead of fail hard #10784
Description
Feature
Giving the following wasi-http design and implementation:
resource response-outparam {
set: static func(
param: response-outparam,
response: result<outgoing-response, error-code>,
);
}
fn set(
&mut self,
id: Resource<HostResponseOutparam>,
resp: Result<Resource<HostOutgoingResponse>, types::ErrorCode>,
) -> wasmtime::Result<()> {
let val = match resp {
Ok(resp) => Ok(self.table().delete(resp)?.try_into()?),
Err(e) => Err(e),
};
self.table()
.delete(id)?
.result
.send(val) <--- may fail the host call
.map_err(|_| anyhow::anyhow!("failed to initialize response"))
}
The common scenario is a host is waiting for a response from the guest under a given timeout. If the timeout is reached without having anything from the guest, the host will drop the receiver side of the channel, which will fail the hostcall and likely crash the wasi program.
Benefit
The error doesn't seem to be fatal, and the caller should be able to decide what to do next.
Implementation
Maybe allow the set API to return an error to the caller.