Async tail call

[molvqingtai]

This is an experimental idea, if asynchronous tail calls are supported, then getter/setter and chained call batching can be supported.

Current Version:

call method immediately sends a remote request

const valuePromise:Promise<value> = api.getValue() // send call

const value = await valuePromise:Promise<value> 

Tail Call Version：

Only when accessing promise.then() does the remote request get initiated.

const callPromise:RpcPromise<call> = api.getValue() // Mark path

const value = await callPromise // send call

const value = await api.getValue() // send call

const valuePromise:RpcPromise<value> = api.value  // Mark path

const value = await valuePromise // send call

In the tail call version, RpcPromise is directly returned in all call chains, which is a wrapped promise. The actual RPC call is only sent when accessing then, so we can collect the call path and implement batch processing before calling then, and we can directly use getters and setters without depending on asynchronous methods.

1. getter/setter

const value = await api.foo.value

await api.foo.value = 'bar'

2. pipe

// Send two call request calls
const foo await = api.foo()
const bar await = api.bar(foo)

// Just one call request is needed.
const bar = await api.bar(api.foo())
// or
const bar = await pipe(api.foo,api.bar)

3. RpcPromise getter

const fooPromise:RpcPromise<foo> = api.foo

const valuePromise:RpcPromise<foo.value> = fooPromise.value

const value = await valuePromise // send call


const bar = await api.bar(value) // send call

const bar = await api.bar(valuePromise) // send call

Challenges to be addressed::

1. No matter what the server defines, it is always inferred as an asynchronous method on the client, and the parameters can receive arg | RpcPromise | Promise

2. If you need to support callback on the server side, you must use a long connection, such as websocket.

3. Unserializable values should be prohibited from calling then

const value = await (await foo.bar()).getValue()

const bar = await foo.bar() // error?

// work
const value = await foo.bar().getValue()

Reference:

https://github.com/cloudflare/capnweb#http-batch-client

[mediaput]

什么时候开整？？期待👀