p-fifo

Promised First-In-First-Out buffer. Await on push to be told when a value is consumed and await on shift for a value to consume when the buffer is empty

Install

1npm i p-fifo

Usage

Await on push

await on push to be told when your pushed value is consumed:

1const Fifo = require('p-fifo')
2const fifo = new Fifo()
3
4// Consume a value from the buffer after 1 second
5setTimeout(() => fifo.shift(), 1000)
6
7console.time('push')
8// Nothing in the buffer, push a value and wait for it to be consumed
9await fifo.push('hello')
10console.log('"hello" was consumed')
11console.timeEnd('push')
12
13// Output:
14// "hello" was consumed
15// push: 1006.723ms

Await on shift

If the buffer is empty, you can await on a value to be pushed:

1const Fifo = require('p-fifo')
2const fifo = new Fifo()
3
4// Push a value into the buffer after 1 second
5setTimeout(() => fifo.push('hello'), 1000)
6
7console.time('shift')
8// Nothing in the buffer, wait for something to arrive
9const value = await fifo.shift()
10console.log(`consumed "${value}" from the buffer`)
11console.timeEnd('shift')
12
13// Output:
14// consumed "hello" from the buffer
15// shift: 1002.652ms

API

1const fifo = new Fifo()

fifo.push(value): Promise

Add a value to the end of the FIFO buffer.

Returns a promise that is resolved when the pushed value is shifted off the start of the buffer.

fifo.shift(): Promise<Any>

Remove the first value from the FIFO buffer and return that removed value in a promise.

Returns a promise that resolves to a value from start of the FIFO buffer. If there are no values in the buffer the promise will resolve when a value is next pushed.

Note that multiple calls to shift when the buffer is empty will not resolve to the same value i.e. a corresponding number of calls to push will need to be made to resolve all the promises returned by calls to shift.

fifo.isEmpty(): Boolean

Returns true if the FIFO buffer is empty and false otherwise.

Contribute

Feel free to dive in! Open an issue or submit PRs.

License

MIT © Alan Shaw