Module xaynet_server::state_machine

The state machine that controls the execution of the PET protocol.

Overview

The StateMachine is responsible for executing the individual tasks of the PET protocol. The main tasks include: building the sum and seed dictionaries, aggregating the masked models, determining the applicable mask and unmasking the global masked model.

Furthermore, the StateMachine publishes protocol events and handles protocol errors.

The StateMachine as well as the PET settings can be configured in the config file. See here for more details.

Phase states

Idle

Publishes PhaseName::Idle, increments the round id by 1, invalidates the SumDict, SeedDict, scalar and mask length, updates the EncryptKeyPair, thresholds as well as the seed and publishes the EncryptKeyPair and the RoundParameters.

Sum

Publishes PhaseName::Sum, builds and publishes the SumDict, ensures that enough sum messages have been submitted and initializes the SeedDict.

Update

Publishes PhaseName::Update, builds and publishes the SeedDict, ensures that enough update messages have been submitted and aggregates the masked model.

Sum2

Publishes PhaseName::Sum2, builds the mask dictionary, ensures that enough sum2 messages have been submitted and determines the applicable mask for unmasking the global masked model.

Unmask

Publishes PhaseName::Unmask, unmasks the global masked model and publishes the global model.

Error

Publishes PhaseName::Error and handles PhaseStateErrors that can occur during the execution of the StateMachine. In most cases, the error is handled by restarting the round. However, if a PhaseStateError::RequestChannel occurs, the StateMachine will shut down.

Shutdown

Publishes PhaseName::Shutdown and shuts down the StateMachine. During the shutdown, the StateMachine performs a clean shutdown of the Request channel by closing it and consuming all remaining messages.

Requests

By initiating a new StateMachine via StateMachineInitializer::init(), a new StateMachineRequest channel is created, the function of which is to send StateMachineRequests to the StateMachine. The sender half of that channel (RequestSender) is returned back to the caller of StateMachineInitializer::init(), whereas the receiver half (RequestReceiver) is used by the StateMachine.

See here for more details.

Events

During the execution of the PET protocol, the StateMachine will publish various events (see Phase states). Everyone who is interested in the events can subscribe to the respective events via the EventSubscriber. An EventSubscriber is automatically created when a new StateMachine is created through StateMachineInitializer::init().

See here for more details.

Re-exports

pub use self::initializer::StateMachineInitializer;

Modules

coordinator	Coordinator state and round parameter types.
events	This module provides the StateMachine, Events, EventSubscriber and EventPublisher types.
initializer	A state machine initializer.
phases	This module provides the PhaseStates of the StateMachine.
requests	This module provides the the StateMachine, Request, RequestSender and RequestReceiver types.

Enums

RequestError	Error returned when the state machine fails to handle a request
StateMachine	The state machine with all its states.

Type Definitions

StateMachineResult