abortable-generator
Abortable AsyncGenerators using AbortControllers
Installation
npm i --save node-module-template
Usage
Supports both ESM and CommonJS
import abortable from 'abortable-generator`
// commonjs
const abortable = require('abortable-generator').default
Problem with "stuck" AsyncGenerators
There is a problem with AsyncGenerators where unsettled Promises can prevent them from finishing (and sometimes lead to memory leaks 😱)
async function* getItems() {
try {
yield new Promise((resolve) => {})
} finally {
}
}
const items = getItems()
setTimeout(() => {
items.return()
}, 100)
for await (let item of items) {
}
Abort "stuck" AsyncGenerators w/ return
Here's an example of how to abort "stuck" AsyncGenerators using abortable-generator
import abortable from 'abortable-generators'
const getItems = abortable(async function* (raceAbort) {
yield raceAbort(new Promise((resolve) => {}))
})
const items = getItems()
setTimeout(() => {
items.return()
}, 100)
for await (let item of items) {
}
Abort "stuck" AsyncGenerators w/ return with try...catch...finally
Here's an example of how to abort "stuck" AsyncGenerators using abortable-generator
import abortable from 'abortable-generators'
const getItems = abortable(async function* (raceAbort) {
try {
yield raceAbort(new Promise((resolve) => {}))
} catch (err) {
if (err.name === 'AbortError') {
return
}
throw err
} finally {
}
})
const items = getItems()
setTimeout(() => {
items.return()
}, 100)
for await (let item of items) {
}
Throw an error into a "stuck" AsyncGenerators w/ throw
Here's an example of how to throw an error into a "stuck" AsyncGenerators using abortable-generator
import abortable from 'abortable-generators'
const getItems = abortable(async function* (raceAbort) {
try {
yield raceAbort(new Promise((resolve) => {}))
} catch (err) {
throw err
} finally {
}
})
const items = getItems()
setTimeout(() => {
const err = new Error('boom')
items.throw(err)
}, 100)
for await (let item of items) {
}
Abort "stuck" AsyncGenerators w/ an AbortSignal
Here's an example of how to abort "stuck" AsyncGenerators using abortable-generator
import abortable from 'abortable-generators'
const controller = new AbortController()
const signal = controller.signal
const getItems = abortable(async function* (raceAbort) {
try {
yield raceAbort(new Promise((resolve) => {}))
} catch (err) {
if (err.name === 'AbortError') {
return
}
throw err
} finally {
}
})
const items = getItems(signal)
setTimeout(() => {
controller.abort()
}, 100)
for await (let item of items) {
}
Abort AsyncGenerators containing cancellable Promises
Here's an example of how to abort AsyncGenerators that contain cancellable Promises (supporting AbortSignal)
import abortable from 'abortable-generators'
const getItems = abortable(async function* (raceAbort) {
try {
yield raceAbort((signal) => fetch('https://codeshare.io', { signal }))
} catch (err) {
if (err.name === 'AbortError') {
return
}
throw err
} finally {
}
})
const items = getItems()
setTimeout(() => {
items.return()
}, 100)
for await (let item of items) {
}
Advanced Example: Abort nested AsyncGenerators w/ multiple Promises and external AbortSignal
Here's an example of how to abort AsyncGenerators that contain cancellable Promises (supporting AbortSignal)
import abortable from 'abortable-generators'
const controller = new AbortController()
const signal = controller.signal
const getMoreItems = abortable(async function* (raceAbort) {
try {
await raceAbort(timeoutPromise(100))
yield raceAbort((signal) => fetch('https://codeshare.io', { signal }))
} catch (err) {
if (err.name === 'AbortError') {
return
}
throw err
} finally {
}
})
const getItems = abortable(async function* (raceAbort) {
let moreItems
try {
moreItems = await raceAbort(signal => getMoreItems(signal))
for await (let item in moreItems) {
yield item
}
await raceAbort(timeoutPromise(100))
yield raceAbort((signal) => fetch('https://codeshare.io', { signal }))
} catch (err) {
if (err.name === 'AbortError') {
return
}
throw err
} finally {
await moreItems?.return()
}
})
const items = getItems(signal)
setTimeout(() => {
items.return()
}, 100)
for await (let item of items) {
}
License
MIT