Rico

Rico provides simple data types persisted to Riak.

Supports Array, List, Set, SortedSet, Map, SortedMap, CappedSortedMap, Value objects.

Installation

Add rico to your Gemfile and bundle install:

gem "rico"

Configuration

By default, Rico uses a generic Riak::Client instance for operations. You can specify your own options for the Riak client (perhaps inside of a rails initializer) like so:

Rico.configure do |c|
  c.options = { http_port: 1234, ... }
end

You can also provide a namespace to be used as a key prefix:

Rico.configure do |c|
  c.namespace = "development"             # => "development:BUCKET:KEY"
  c.namespace = ["my_app", "production"]  # => "my_app:production:BUCKET:KEY"
end

Supported Data Types

Arrays - sequence of values

a = Rico::Array.new "bucket", "key"
a.add [3, 1, 1, 4, 2]   # writes to riak
a.members               # => [3, 1, 1, 4, 2]
a.length                # => 5
a.remove [2, 4]         # writes to riak
a.members               # => [3, 1, 1]
a.raw_data              # => '{"_type":"array","_values":[3,1,1],"_deletes":[2,4]}'

Lists - sorted sequence of values

l = Rico::List.new "bucket", "key"
l.add [3, 1, 1, 4, 2]
l.members               # => [1, 1, 2, 3, 4]

Sets - unique sequence of values

s = Rico::Set.new "bucket", "key"
s.add [3, 1, 1, 4, 2]
s.members               # => [3, 1, 4, 2]

Sorted Sets - unique, sorted sequence of values

s = Rico::SortedSet.new "bucket", "key"
s.add [3, 1, 1, 4, 2]
s.members               # => [1, 2, 3, 4]
s.reduce(&:+)

Maps - key-value mappings

m = Rico::Map.new "bucket", "key"
m.add({"a" => 1})
m.add({"b" => 2, "c" => 3})
m.members               # => {"a"=>1, "b"=>2, "c"=>3}

Sorted Maps - key-value mappings sorted by key

m = Rico::SortedMap.new "bucket", "key"
m.add({"b" => 2, "c" => 3})
m.add({"a" => 1})
m.members               # => {"a"=>1, "b"=>2, "c"=>3}
m.raw_data              # => '{"_type":"smap","_values":{"a":1,"b":2,"c":3}}'

Capped Sorted Maps - key-value mappings sorted by key and bound by size

m = Rico::CappedSortedMap.new "bucket", "key", limit: 2
m.add({"b" => 2, "c" => 3})
m.add({"a" => 1})
m.members               # => {"b"=>2, "c"=>3}
m.length                # => 2

Values - generic serialized values

v = Rico::Value.new "bucket", "key"
v.get                   # => nil
v.set "bob"
v.get                   # => "bob"

Content Types

JSON: Objects are serialized and stored as JSON by default, using a Content-Type header of application/json

JSON+gzip: Objects can be serialized and stored as JSON and then compressed with gzip by specifying a Content-Type header of application/x-json. Note that it is not currently possible non-JSON data with the gzip content header using Rico.

s = Rico::Set.new "bucket", "key"
s.content_type = "application/x-gzip"
s.add [1,2,3]
s.members               # => [1, 2, 3]
s.data                  # => {"_type"=>"set", "_values"=>[1, 2, 3]}
s.raw_data              # => "\u001F\x8B\b\u0000G...."

Under The Hood

Objects are stored in a simple map encoded to JSON.

Array, List, Set and SortedSet types look like this:

{ "_type": "sset", "_values": [1,2,3], "_deletes": [4] }

The _deletes field acts as a temporary tombstone for preserve deletes during conflict resolution. The field will normally contain the deletes processed during the last write, or the cumulative deletes processed during the last sibling merge. The value of _deletes is intentionally forgotten after a successful read and will not taint future operations.

Conflict resolution works by adding the difference between value arrays, removing deleted values and returning the result. This implementation is susceptible to sticky deletes - if different clients delete and add the same value simultenously the delete will ultimately win and the value is left out.

Map, SortedMap and CappedSortedMap types look like this:

{ "_type": "csmap", "_values": {"a": 1, "b": 2, "c": 3}, "_deletes": ["d"] }

The _deletes field for map objects contains only the keys deleted.

Conflict resolution works by merging value hashes, removing deleted keys and returning the result. This implementation is susceptible to sticky deletes - if different clients delete and add the same key simultenously the delete will ultimately win and the value is left out.

Value type looks like this:

{ "_type": "value", "_value": "Hipsters love modern folk rock" }

Conflict resolution is handled by last-write-wins.

Notes

Enumerable

Enumerable-looking types are indeed Enumerable

Persistence

Data is persisted at operation time. For example, List#add(5) will immediately update the record in Riak. It'd generally be wise to compute a list of values to be added or removed and then issue a single operation.

Contributing

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Added some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request

License

MIT License

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 HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 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.