level-stream

level-stream

Persist streams in LevelDB.

Usage

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

var stream = require('level-stream');
var levelup = require('levelup');
var fs = require('fs');

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

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

Resuming

When reading fails you might not want to start over again completely but rather resume at the last point that worked. When passing ts : true as an option you don't only get the stored chunks but also when they were written:

stream(db, '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 }:

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

API

stream(db, key[, options])

Returns a Duplex Stream.

If you start reading from it it replays the stream stored at key. If you write to it it persists written data 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.

stream(db)

Extend db with the db#stream so you can do

db.stream('file')

TODO

• live streams: stream.live(...) should stay open and emit new data.
• more node-core style API, like stream(db).createReadStream(key[, opts])

Installation

With npm do

$ npm install level-stream

License

(MIT)