Key/Value Store

A key value store with case insensitive string keys mapping to versioned objects supporting optimistic concurrency. There are 3 operations:

  • Set(string key, object value, int? expectedVersion = null)
  • Node Get(string key)
  • Remove(string key, int? expectedVersion = null)

Each time a specific key is set the version is incremented, starting with 1. Passing an expected version to Set or Remove requires that the stored version equals the expected version. Pass zero to Set to ensure key is new. If no expected version is passed Set will always succeed while Remove will succeed if the key exists.

Get will throw unless the key exists. The Node return type has two fields, Version and Item. The item is the stored value.

Example

var store = Db.For<KeyValueStore>();
store.Set("mykey",  "myvalue", 0); //expect key doesn't exist
var node = store.Get("mykey");
Assert.AreEqual(node.Version, 1);
Assert.AreEqual(node.Item, "myvalue");

store.Set("mykey", "newvalue"); //no version constraint, increments version from 1 to 2
store.Set("mykey", "fail", 1); //wrong version, expected 1 but was 2
store.Set("mykey", "succeed", 2);

store.Remove("mykey", 2); //FAIL wrong version
store.Remove("mykey");
store.Remove("mykey"); //FAIL, doesn't exist

## KeyValueStoreClient This class wraps a KeyValueStore and serializes/deserializes objects to byte array eliminating the need to deploy assemblies with custom types on the remote server.

Example

var store = Db.For<KeyValueStore>("mode=remote");
var client = new KeyValueStoreClient(store, new BinaryFormatter());

//object (graph) to store, must be serializable
var player = new Player("Coder Bob");
client.Set(player.Id, player);

//retrieve object and modify
var node = client.Get(player.Id);
player.AddScore(42);

//write back using optimistic concurrency
client.Set(player.Id, player, node.Version);