npm package: @jamify/redis-streams
Description: Stream data to Redis with TypeScript
Author: styxlab
Latest version: 1.3.0

# redis-streams

Extends the redis client [ioredis](https://github.com/luin/ioredis) with streaming functions.
This library allows to read and write data into redis via node streams. The implementation is
inspired by redis-rstream and redis-wstream by [@jeffbski](https://github.com/jeffbski) and
has been simplified, made type safe with TypeScript and includes additional features.
This library can be conveniently used with async/await promise syntax.

The write stream has ben enhanced to include automatic generation of cryptographic hashes
such as _sha1_ and others. Furthermore the redis key can be automatically set to the
self-generated hash to allow for integrity checks and easy lookups.

If the maxBytes option is set on the write stream, an exception is thrown if the stream
exceeds that upper limit. You can also set the TTL option, in order to automatically remove
the data from the cache once the key is expired.

The main benefit of streaming is more efficient memory usage and safe-guards against buffer overflows.
Performance gains vary based on your hardware and depend on both data and chunk sizes. The default
chunk size has been set to 1 MB and can be changed through the options. Performance gains in my tests
were approximately 20% for writing into the redis cache and insignificant during reading from the cache.

## Installation

```
yarn add @jamify/redis-streams
```

## Quick start

```
import { StreamIORedis } from '@jamify/redis-streams'

const redisClient = new StreamIORedis()

redisClient.readStream(key)
  .pipe(createWriteStream('image.jpg'))
  .on('finish', done)

createReadStream('image.jpg')
  .pipe(redisClient.writeStream(key))
  .on('finish', done)

// promise version of writeStream
await writeStreamPromise(createReadStream('image.jpg'), key)

// Save to auto generated sha1 key
await writeStreamPromise(createReadStream('image.jpg'), null, { algorithm: 'sha1' })

// Throw exception, if maxBytes is exceeded
await writeStreamPromise(createReadStream('image.jpg'), null, { algorithm: 'sha1', maxBytes: 10240 })

```

This will extend the `IORedis client` class with two additional functions:

`readStream(key, options?): RedisRStream` - Get a [Readable stream](https://nodejs.org/api/stream.html#stream_class_stream_readable) from redis.

`writeStream(key, options?): RedisWStream` - Get a [Writable stream](https://nodejs.org/api/stream.html#stream_class_stream_writable) from redis.

`writeStreamPromise(rstream, key, options?): Promise<RedisWStream>` - Promise version of `writeStream(key)`

### Options for RedisRStream:

```
{ 
  highWaterMark, // maximum internal buffer size
}
```

### Options for RedisWStream:

```
{ 
 highWaterMark, // maximum internal buffer size
 clientMulti,   // attach redis.multi in order to defer key rename
 algorithm,     // crypto algorithm for hashing
 maxBytes,      // maximum allowed bytes for writing
 ttl            // key expire time in seconds
}
```

## Unit testing

```
yarn test
```

## Credits

- https://github.com/jeffbski/redis-rstream
- https://github.com/jeffbski/redis-wstream
- https://github.com/4front/redis-streams

# Copyright & License

Copyright (c) 2020 Jamify - Released under the [MIT license](LICENSE).