https://github.com/jd1378/deno-semaphore

https://deno.land/x/[email protected]
https://github.com/jd1378/deno-semaphore

Last synced: 13 days ago
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https://deno.land/x/[email protected]

• Host: GitHub
• URL: https://github.com/jd1378/deno-semaphore
• Owner: jd1378
• License: mit
• Created: 2021-01-25T04:23:13.000Z (almost 4 years ago)
• Default Branch: main
• Last Pushed: 2022-10-20T15:28:29.000Z (about 2 years ago)
• Last Synced: 2024-09-17T16:10:50.579Z (about 2 months ago)
• Language: TypeScript
• Homepage:
• Size: 12.7 KB
• Stars: 6
• Watchers: 1
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# deno-semaphore

This is a quick port of [await-semaphore](https://www.npmjs.com/package/await-semaphore)

The use case should be identical.

I'll include It's readme here for ease of access:

## await-semaphore

Awaitable semaphore/mutex

A semaphore implementation using ES6 promises and supporting 3 styles:

* async/await style (needs typescript)

* thunk style (automatic acquire/release)

* promise style

Also includes `Mutex` as a convenience for `new Semaphore(1)`.

## API

### new Semaphore(count: number)

Create a new semaphore with the given count.

```javascript

import {Semaphore} from '...';

var semaphore = new Semaphore(10);

```

### semaphore.acquire(): Promise<() => void>

Acquire the semaphore and returns a promise for the release function. Be sure to handle release for exception case.

```javascript

semaphore.acquire()

.then(release => {

    //critical section...

    doSomething()

    .then(res => {

        //...

        release();

    })

    .catch(err => {

        //...

        release();

    });

});

```

### semaphore.use(thunk: () => Promise): Promise

Alternate method for using the semaphore by providing a thunk. This automatically handles acquire/release.

```javascript

semaphore.use(() => {

    //critical section...

});

```

### new Mutex()

An alias for `new Semaphore(1)`. Mutex has the same methods as Semaphore.

```javascript

import {Mutex} from 'await-semaphore';

var mutex = new Mutex();

```

## Examples

Create a version of `fetch()` with concurrency limited to 10.

### async/await style (typescript)

```typescript

var semaphore = new Semaphore(10);

async function niceFetch(url) {

    var release = await semaphore.acquire();

    var result = await fetch(url);

    release();

    return result;

}

```

### thunk style (javascript)

```javascript

var semaphore = new Semaphore(10);

function niceFetch(url) {

    return semaphore.use(() => fetch(url));

}

```

### promise style (javascript)

```javascript

var semaphore = new Semaphore(10);

function niceFetch(url) {

    return semaphore.acquire()

    .then(release => {

        return fetch(url)

        .then(result => {

            release();

            return result;

        });

    });

}

```