install-nix-action/node_modules/throat/README.md
Domen Kožar 70742d22d9
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2019-11-19 17:50:30 +01:00

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# throat
Throttle the parallelism of an asynchronous, promise returning, function / functions. This has special utility when you set the concurrency to `1`. That way you get a mutually exclusive lock.
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## Installation
npm install throat
## API
### throat(concurrency)
This returns a function that acts a bit like a lock (exactly as a lock if concurrency is 1).
Example, only 2 of the following functions will execute at any one time:
```js
const throat = require('throat')(2);
// alternatively provide your own promise implementation
const throat = require('throat')(require('promise'))(2);
const promise = Promise.resolve();
const resA = throat(() => /* async stuff... */ promise);
const resB = throat(() => /* async stuff... */ promise);
const resC = throat(() => /* async stuff... */ promise);
const resD = throat(() => /* async stuff... */ promise);
const resE = throat(() => /* async stuff... */ promise);
```
### throat(concurrency, worker)
This returns a function that is an exact copy of `worker` except that it will only execute up to `concurrency` times in parallel before further requests are queued:
```js
const throat = require('throat');
// alternatively provide your own promise implementation
const throat = require('throat')(require('promise'));
const input = ['fileA.txt', 'fileB.txt', 'fileC.txt', 'fileD.txt'];
const data = Promise.all(input.map(throat(2, fileName => readFile(fileName))));
```
Only 2 files will be read at a time, sometimes limiting parallelism in this way can improve scalability.
## License
MIT