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# RiakFS

RiakFS is an implementation of filesystem in [Riak](http://basho.com/riak/) that emulates node.js `fs` module.
The following methods are implemented:

*  `open`
*  `close`
*  `read`
*  `write`
*  `readdir`
*  `mkdir`
*  `rmdir`
*  `rename`
*  `unlink`
*  `stat`
*  `fstat`
*  `utimes`
*  `futimes`
*  `appendFile`
*  `exists`
*  `createReadStream`
*  `createWriteStream`


It also adds some convenient methods like:

*  `makeTree` - recursively create directory tree
*  `copy` - copy files (within same riakfs)
*  `updateMeta` and `setMeta` - manipulate custom metadata saved with files
*  `share` - share directory with another riakfs

All methods will return a [promise](https://github.com/petkaantonov/bluebird) as well as call a usual callback

## Implementation

Files are stored in two buckets: `fs.files` and `fs.chunks` (you can use your own names with `root` option, see example below). First one is used for storing file metadata such as file size, mtime, ctime, contentType, etc as well as parent directory index (2i). Keys in `fs.files` bucket are full file paths ('/a/b/c/d.txt'). Actual file data is divided into chunks (256kb each) and stored in `fs.chunks` bucket.

RiakFS makes use of Riak 2i (secondary indexes) so it requires [LevelDB](http://docs.basho.com/riak/latest/ops/advanced/backends/leveldb/) backend. 2i is only used for finding directory contents (e.g. `readdir`).

## Siblings resolution

~~RiakFS uses `allow_mult=true` for its files (file meta information) bucket and tries to resolve possible [siblings](http://docs.basho.com/riak/latest/theory/concepts/Vector-Clocks/#Siblings) during read operations.~~
RiakFS will handle tombstones conflicts (for example when doing mkdir immediately after rmdir).

Both buckets use `allow_mult=false`. I'm going to change this as soon as I have better siblings resolution pattern.

## Installation

```
$ npm install riakfs
```

## Example

open/write/close:

```javascript
require('riakfs').create({
    root: 'test-fs' // root is a bucket name prefix, bucket names will be: test-fs.files, test-fs.chunks
})
.then(function(riakfs){
    return riakfs.open('/testFile', 'w').then(function(fd){
        return riakfs.write(fd, 'test', 0, 4, null).then(function() {
            return riakfs.close(fd)
        })
    })
})
```

writeFile (copy file from hard drive):

```javascript
Promise.promisify(fs.readFile)('/someFile.jpg').then(function(data) {
    return riakfs.writeFile('/someFile.jpg', data)
})
```

streams:

```javascript
var readStream = fs.createReadStream('/someFile.jpg')
var writeStream = riakfs.createWriteStream('/someFile.jpg')

readStream.pipe(writeStream)

writeStream.on('close', function() {
    // done!
})
```

You can also save some custom meta information with files by passing an object instead of string path to `open`, `writeFile` or `createWriteStream`:

```javascript
var file = {
    filename: '/testFile',
    meta: {
        someKey: 'someValue',
        otherKey: {
            subKey: 'subValue'
        }
    }
}
return riakfs.open(file, 'w').then(function(fd){
    ...
})
```

or use `updateMeta` and `setMeta` methods

Saved metadata can be retrieved with a `stat` or `open` calls:

```javascript
return riakfs.stat('/testFile').then(function(stats){
    // stats.file.meta
})
```

```javascript
return riakfs.open('/testFile').then(function(fd){
    // fd.file.meta
})
```

See tests for more.

## Events

RiakFS can optionally trigger events on file/dir changes:

```javascript
// pass events: true option to enable events
return riakfs.create({ events: true }).then(function(fs){
    fs.on('change', function(filename, info) { // triggered when file data is changed
    })

    fs.on('new', function(filename, info) { // triggered when new file or directory is created
    })

    fs.on('rename', function(old, _new, info) { // triggered when file or dir is renamed
    })

    fs.on('delete', function(filename, info) { // triggered when file or directory is deleted
    })
})
```

### Shared directories

RiakFS allows sharing directories between different filesystems (those with different `root` option).
Given two filesystems: fs1 and fs2, one can share some directory from fs1 like this:

```javascript
fs1.share('/some/dir', fs2.options.root, 'alias')
```

or readonly:

```javascript
fs1.share('/some/dir', fs2.options.root, 'alias', true)
```

This will create a directory named `/Shared/alias` in fs1.

You can read sharing info by `stat`ing on shared directories from both filesystems:

from fs1:

```javascript
fs1.stat('/some/dir').then(function(stats){
    // read stats.file.share:
    /*
    {
        to: [ { root: 'fs2-root', alias: 'alias', readOnly: false } ],
        owner: { root: 'fs1-root', path: '/some/dir' }
    }
     */
})
```

same result from fs2:

```javascript
fs2.stat('/Shared/alias').then(function(stats){
    // read stats.file.share:
    /*
    {
        to: [ { root: 'fs2-root', alias: 'alias', readOnly: false } ],
        owner: { root: 'fs1-root', path: '/some/dir' }
    }
     */
})
```

#### Cancel sharing:

from fs1:

```javascript
fs1.unshare('/some/dir', fs2.options.root) // this will cancel sharing with fs2
```

from fs2:

```javascript
fs2.unshare('/Shared/alias')
```
#### Initializing filesystems for shared dirs

Your application should provide a function that should return a promise for RiakFS instance for specified root, example:

```javascript
require('riakfs').create({ root: someId, events: true,
    shared: {
        fs: function(_root){
            // return riakfs instance for specified `root` = _root
        }
    }
})
```

### Trash

RiakFs allows to move files to /.Trash upon removal. Just enable trash support when initialising riakfs:

```javascript
require('riakfs').create({ root: someId, trash: true })
```

Files are not removed automatically by RiakFs from /.Trash so your application should take care of this. You can use `mtime` to detect when file was removed.

## Application

The idea is that this module (connected `riakfs` instance) can be used as a drop-in replacement for node `fs` module.

## Status

Not tested in production yet. Under development. Pull requests are welcomed.

## Riak settings
I suggest to increase erlang network buffer size (See: http://www.erlang.org/doc/man/erl.html#%2bzdbbl)
*  In version 1.4.x this parameter is located in vm.args file. The value is in kilobytes (so 32768 - 32MB).
*  In version 2.0 the parameter is called erlang.distribution_buffer_size, should be put in riak.conf and the value is in bytes (33554432 = 32MB).

## Authors

* Oleksiy Krivoshey [https://github.com/oleksiyk](https://github.com/oleksiyk)

# License (MIT)

Copyright (c) 2014
 Oleksiy Krivoshey.

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

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