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85 lines
1.6 KiB
Markdown
85 lines
1.6 KiB
Markdown
# async
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async is a module to provide help with asynchronous tasks.
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# Usage
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The following functions and class are exposed in `mod.ts`:
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## deferred
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Create a Promise with the `reject` and `resolve` functions.
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```typescript
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import { deferred } from "https://deno.land/std/async/mod.ts";
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const p = deferred<number>();
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// ...
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p.resolve(42);
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```
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## delay
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Resolve a Promise after a given amount of milliseconds.
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```typescript
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import { delay } from "https://deno.land/std/async/mod.ts";
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// ...
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const delayedPromise = delay(100);
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const result = await delayedPromise;
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// ...
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```
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## MuxAsyncIterator
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The MuxAsyncIterator class multiplexes multiple async iterators into a single
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stream.
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The class makes an assumption that the final result (the value returned and not
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yielded from the iterator) does not matter. If there is any result, it is
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discarded.
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```typescript
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import { MuxAsyncIterator } from "https://deno.land/std/async/mod.ts";
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async function* gen123(): AsyncIterableIterator<number> {
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yield 1;
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yield 2;
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yield 3;
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}
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async function* gen456(): AsyncIterableIterator<number> {
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yield 4;
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yield 5;
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yield 6;
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}
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const mux = new MuxAsyncIterator<number>();
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mux.add(gen123());
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mux.add(gen456());
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for await (const value of mux) {
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// ...
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}
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// ..
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```
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## pooledMap
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Transform values from an (async) iterable into another async iterable. The
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transforms are done concurrently, with a max concurrency defined by the
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poolLimit.
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```typescript
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import { pooledMap } from "https://deno.land/std/async/mod.ts";
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const results = pooledMap(
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2,
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[1, 2, 3],
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(i) => new Promise((r) => setTimeout(() => r(i), 1000)),
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);
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for await (const value of results) {
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// ...
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}
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```
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