RPC: use AbortController and AbortSignal to cancel requests

[paralin]

Related to #665 but not exactly the same.

TypeScript/JavaScript has AbortController now as a general way of canceling things:

https://developer.mozilla.org/en-US/docs/Web/API/AbortController

Here's an example of how it's used in yamux in javascript:

https://github.com/ChainSafe/js-libp2p-yamux/blob/c396f8c1b99f3c68104c894a1ac88a805bff68a3/src/muxer.ts#L49
https://github.com/ChainSafe/js-libp2p-yamux/blob/c396f8c1b99f3c68104c894a1ac88a805bff68a3/src/muxer.ts#L215

I propose adding an optional parameter to the RPC methods: AbortSignal -

const abortController = new AbortController()
const responsePromise = rpcClient.DoSomething(request, abortController.signal)
abortController.abort()
// responsePromise is rejected w/ Aborted

This can be used to stop a request before it completes.

[paralin]

This can also be used with abortable-iterator to abort AsyncIterable objects:

import { abortableSource } from 'abortable-iterator'

const asyncCounter = async function * (start, delay) {
  let i = start
  while (true) {
    yield new Promise(resolve => setTimeout(() => resolve(i++), delay))
  }
}

// Create a counter that'll yield numbers from 0 upwards every second
const everySecond = asyncCounter(0, 1000)

// Make everySecond abortable!
const controller = new AbortController()
const abortableEverySecond = abortableSource(everySecond, controller.signal)

// Abort after 5 seconds
setTimeout(() => controller.abort(), 5000)

try {
  // Start the iteration, which will throw after 5 seconds when it is aborted
  for await (const n of abortableEverySecond) {
    console.log(n)
  }
} catch (err) {
  if (err.code === 'ERR_ABORTED') {
    // Expected - all ok :D
  } else {
    throw err
  }
}

[paralin]

Changes required:

• Add optional AbortSignal parameter to RPC calls
• Add optional AbortSignal parameter to serverStreamingRequest, etc in the Rpc interface.

It would then be up to the client implementation to honor the AbortSignal.

[stephenh]

🎉 This issue has been resolved in version 1.136.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release
• v1.136.0

Your semantic-release bot 📦🚀