lnd/fn/req.go
Keagan McClelland 2c6d229a69
fn: harden and refine the Req[I,O] API.
In this commit we opt to make the internal response channel fully
private and instead expose methods for doing resolution. This
prevents internal implementation details from leaking a little bit
better than the previous iteration.
2024-07-31 12:59:10 -07:00

53 lines
1.8 KiB
Go

package fn
// Req is a type to encapsulate RPC-like calls wherein we send some data
// structure as a request, as well as a channel to receive the response on where
// the remote goroutine will send the result.
//
// NOTE: This construct should only be used for request/response patterns for
// which there is only a single response for the request.
type Req[Input any, Output any] struct {
// Request is the data we are sending to the remote goroutine for
// processing.
Request Input
// response is the channel on which we will receive the result of the
// remote computation.
response chan<- Output
}
// Dispatch is a convenience method that lifts a function that transforms the
// Input to the Output type into a full request handling cycle.
func (r *Req[Input, Output]) Dispatch(handler func(Input) Output) {
r.Resolve(handler(r.Request))
}
// Resolve is a function that is used to send a value of the Output type back
// to the requesting thread.
func (r *Req[Input, Output]) Resolve(output Output) {
select {
case r.response <- output:
default:
// We do nothing here because the only situation in which this
// case will fire is if the request handler attempts to resolve
// a request more than once which is explicitly forbidden.
}
}
// NewReq is the base constructor of the Req type. It returns both the packaged
// Req object as well as the receive side of the response channel that we will
// listen on for the response.
func NewReq[Input, Output any](input Input) (
Req[Input, Output], <-chan Output) {
// Always buffer the response channel so that the goroutine doing the
// processing job does not block if the original requesting routine
// takes an unreasonably long time to read the response.
responseChan := make(chan Output, 1)
return Req[Input, Output]{
Request: input,
response: responseChan,
}, responseChan
}