Treestore

An implementation of the key-value store similar to git's internal mechanism. Uses redis as the actual store, but other backends could be developed.

Essentially, there are two objects: trees and blobs. Blobs contain raw data. Trees contain only references to other trees and/or blobs. In this manner, trees can reference each other.

No versioning as been implemented yet.

Install

gem install treestore

API

class TreeStore

initialize(backend=RedisBackend.new)

Return a new instance of a treestore

add(item)

Create a new blob with data in item, return its key.

retrieve(key)

Retrieve the blob or tree stored at key, and return the data (if key was a blob) or the list of keys of the children (if key was a tree)

make_tree(keys)

Pass of list of keys, which can be either trees or blobs, and create a new tree with those keys as children. Return the key of the newly-created tree.

ref(name)

Return the key referenced by name.

make_ref(name, key)

Create a new reference name, that, if retrieve (see above), will fetch the value stored at key

delete(key)

Delete key. Be careful to clean up all references and trees that point to this key too!

type(key)

Returns :tree if key stores a tree, :blob otherwise

exists?(key)

Does key exist in the store? Returns true or false

Example

irb> require 'treestore'
=> true

irb> t = TreeStore.new
=> #<TreeStore:0x007f8d2a980a58 @backend=#<RedisBackend:0x007f8d2a980a30 @redis=#<Redis client v3.1.0 for redis://127.0.0.1:6379/0>>, @namespace="tree-store">

irb> t.add("foo")
=> "0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33"

irb> a = _
=> "0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33"

irb> items = [a]
=> ["0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33"]

irb> items << t.add("bar")
=> ["0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33", "62cdb7020ff920e5aa642c3d4066950dd1f01f4d"]

irb> tree = t.make_tree(items)
=> "3eb4e0e693987b4bcb871a44e943b7223b5dd2e5"

irb> t.retrieve(tree)
=> ["62cdb7020ff920e5aa642c3d4066950dd1f01f4d", "0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33"]

irb> t.retrieve(t.retrieve(tree).first)
=> "bar"

irb> t.retrieve(t.retrieve(tree)[1])
=> "foo"

irb> t.type(tree)
=> :tree

irb> t.type(t.retrieve(tree)[1])
=> :blob

irb> t.retrieve(tree)[1]
=> "0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33"

irb> t.retrieve(t.retrieve(tree)[1])
=> "foo"

irb> t.make_ref("foo's name", t.retrieve(tree)[1])
=> "foo's name"

irb> t.retrieve("foo's name")
=> "foo"

irb> t.ref("foo's name")
=> "0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33"

irb> t.type("foo's name")
=> :blob