Skip to content

Instantly share code, notes, and snippets.

@jfet97
Last active November 9, 2022 11:19
Show Gist options
  • Star 3 You must be signed in to star a gist
  • Fork 0 You must be signed in to fork a gist
  • Save jfet97/ff4ecce9daac654c6cde3f83c6fa67c9 to your computer and use it in GitHub Desktop.
Save jfet97/ff4ecce9daac654c6cde3f83c6fa67c9 to your computer and use it in GitHub Desktop.
A simple implementation of a promise queue that is temporal independent
class asyncAwaiterQueue {
constructor(...values) {
this.promise = new Promise(resolve => {
this.resolve = resolve;
});
values.forEach(v => this.put(v));
}
put(value) {
// advance the tail
let resolveNext = null;
const nextPromise = new Promise(resolve => {
resolveNext = resolve;
});
this.resolve({
value: Promise.resolve(value), // normalize the value
nextPromise,
});
this.resolve = resolveNext;
}
get() {
// advance the head
const resultingPromise = this.promise.then(({ value }) => value);
const actualPromise = this.promise;
// defer next node resolution until the current is solved
// because the resultingPromise's value could be a long time running promise
this.promise = resultingPromise.then(() => actualPromise).then(({ nextPromise }) => nextPromise);
return resultingPromise;
}
}
class asyncDoubleAwaiterQueue {
constructor(...values) {
this.get_promise = new Promise((resolve) => {
this.get_resolve = resolve;
});
this.put_promise = new Promise((resolve) => {
this.put_resolve = resolve;
});
values.forEach((v) => this.put(v));
}
put(value) {
const v = Promise.resolve(value); // normalize the value
let get_resolve_next = null;
const get_promise_next = new Promise((resolve) => {
get_resolve_next = resolve;
});
this.get_resolve({
value: v,
get_promise_next,
});
this.get_resolve = get_resolve_next;
const current_put_promise = this.put_promise;
this.put_promise = this.put_promise.then(
({ put_promise_next }) => put_promise_next
);
return current_put_promise;
}
get() {
const resulting_get_promise = this.get_promise
.then(({ value }) => value)
.then((v) => {
let put_resolve_next = null;
const put_promise_next = new Promise((resolve) => {
put_resolve_next = resolve;
});
this.put_resolve({
put_promise_next,
});
this.put_resolve = put_resolve_next;
return v;
});
const current_get_promise = this.get_promise;
this.get_promise = resulting_get_promise
.then(() => current_get_promise)
.then(({ get_promise_next }) => get_promise_next);
return resulting_get_promise;
}
}
const queue = new asyncDoubleAwaiterQueue();
queue.get().then((v) => console.log(`Get 1 of ${v}`));
queue.get().then((v) => console.log(`Get 2 of ${v}`));
queue
.put(new Promise((res) => setTimeout(res, 10000, 1)))
.then((v) => console.log(`Put 1`));
queue
.put(new Promise((res) => setTimeout(res, 5000, 2)))
.then((v) => console.log(`Put 2`));
class AsyncQueue {
constructor(...values) {
this.promise = new Promise(resolve => {
this.resolve = resolve;
});
values.forEach(v => this.put(v));
}
put(value) {
// advance the tail
let resolveNext = null;
const nextPromise = new Promise(resolve => {
resolveNext = resolve;
});
this.resolve({
value,
nextPromise,
});
this.resolve = resolveNext;
}
get() {
// advance the head
const resultingPromise = this.promise.then(({ value }) => value);
this.promise = this.promise.then(({ nextPromise }) => nextPromise);
return resultingPromise;
}
}
@gangsthub
Copy link

I see! Thank you very much. I was clearer with the aww sample. And thanks for the gtor reference. I'll check it out 🙌

@jfet97
Copy link
Author

jfet97 commented Dec 31, 2019

I see! Thank you very much. I was clearer with the aww sample. And thanks for the gtor reference. I'll check it out 🙌

You're welcome 😃

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment