level-stream

level-stream

Persist streams in LevelDB.

Usage

Store a file in LevelDB under the key file and read it out again:

var levelup = require('levelup');
var fs = require('fs');

var db = levelup('/tmp/level-stream');
var streams = require('level-stream')(db);

fs.createReadStream(__dirname + '/file.txt')
  .pipe(streams.createWriteStream('file'))
  .on('end', function () {
    // file.txt is stored in leveldb now
    streams.createReadStream('file').pipe(process.stdout);
  });

Resuming

When reading fails you might not want to start over again completely but rather resume after the last chunk you received. First, pass ts : true as an option so you don't only get the stored chunks but also when they were written:

streams.createReadStream('file', { ts : true }).on('data', console.log);
// => { ts : 1363783762087, data : <Buffer aa aa> }

Now you only need store the timestamp of the last read chunk in a variable and you can resume reading after an error, passing { since : ts }:

streams.createReadStream('file', { since : 1363783762087 }).on('data', console.log);
// => { ts : 1363783876109, data : <Buffer bb bb> }

API

stream(db)

Returns a level-stream instance.

stream#createReadStream(key[, opts])

A readable stream that replays the stream stored at key.

Possible options are:

• ts (Boolean): If true, don't emit raw chunks but rather objects having ts and data fields.
• since (Number): When reading, only read data that has been stored after that date. Automatically sets ts to true.
• live (Boolen): If true, the stream will stay open, emitting new data as it comes in.

stream#createWriteStream(key[, opts])

A writable stream that persists data written to it under key. If something exists under key already it will be deleted.

Possible options are:

• append (Boolean): If true, possibly already existing data stored under key will be appended rather than replaced.

TODO

• option to replace data instead of only appending

Installation

With npm do

$ npm install level-stream

License

(MIT)