State & Storage

State

In protokit, every state you define inside your runtime or protocol modules follows the same pattern and is tightly coupled with the concept of state transitions.

Protokit state is built as a Key-Value-Storage, where every key is a single Field element and the values can be an arbitrary-length Field[].

We abstract over this concept by offering the @state() APIs, which do all necessary conversions in the background.

Paths

In protokit, we call our keys “paths”, as they are derived from the business logic.

For State, the path is calculated using the runtime module name, and the state’s property name. $hash(modulename \space || \space propertyname)$

For StateMap, the process is similar with addition of the key used in the map access, $hash(modulename \space || \space propertyname \space || \space hash(key.toFields()))$

As an example, assume you call:

class Balances extends RuntimeModule {
  @state() ledger = StateMap.from(PublicKey, UInt64);
 
  public async mint(sender, amount) {
    await this.ledger.set(sender, amount)
  }
}

For the call on line 5, the computed path would (roughly) be

$Poseidon.hash(["Balances", "ledger", Poseidon.hash([sender])]){:ts}$

State Tree

Protokit operates on a single global sparse merkle tree that holds all the state of the runtime and protocol. We call this the “state tree” and through having height 256, the domain size equals $2^{256}$ .

This domain size allows us to have a 1:1 mapping of any Field to a unique leaf in the state tree. We leverage this to the fact that every protokit state path is at the same time the index of the leaf in the state tree where it’s value is stored.

Sparse Merkle Trees Tutorials