Auto State Machine Crate Documentation

Overview

The Auto State Machine crate provides a flexible and intuitive way to create an automated actor with customizable behavior. It is built around the concept of states and callbacks, allowing users to define specific actions and transitions depending on the client's current state. This approach makes it ideal for creating complex workflows, automations, or state-driven applications.

Features

State Management: Define states and their associated callbacks to manage the flow of your application.
Control Flow: Dynamically control the execution flow with pause, resume, and stop functionalities.
Tick Rate Control: Specify the rate at which the client checks and updates states, allowing for fine-tuned control over execution speed.
User Context: Pass a user-defined context through states, enabling stateful operations and data persistence across state transitions.
Async and Blocking: An async implementation is provided by default. The most common imagined use-case for this crate is working with IO tasks, so an async implementation is exposed by default. However, blocking tasks are expected to be fairly frequent, so a blocking implementation is also provided in the blocking module.

Quick Start

Here's a basic example to get you started:

use autostatemachine::{StateMachineBuilder, StateMachineContext, extractor::State};
use std::time::Duration;

fn sample_callback(context: StateMachineContext, State(user_context): State<()>) -> String {
    println!("Current state: {}", context.current_state);
    "init".to_string()
}

let mut client = StateMachineBuilder::new(())
    .add_state("init".to_string(), sample_callback)
    .initial_state("init".to_string())
    .tick_rate(Duration::from_secs(1))
    .build();

client.run();
// The client is now running, transitioning from "init" to "next_state"
// according to the logic you've defined.
std::thread::sleep(Duration::from_millis(50));
client.stop();

Getting Started

To use StateMachine, include it in your Cargo.toml file:

[dependencies] autostatemachine = "0.1.0"

Make sure to replace "0.1.0" with the latest version of the crate.

StateMachineBuilder

The StateMachineBuilder struct is the entry point for creating an StateMachine. It allows you to configure the client by adding states, setting a tick rate, specifying an initial state, and providing a user context.

Creating a New Builder

To start building your StateMachine, create a new instance of StateMachineBuilder:

use autostatemachine::StateMachineBuilder;
let builder = StateMachineBuilder::new(user_context);

The user_context parameter is a user-defined data structure that will be passed to each callback. It can be used to maintain state or share information between callbacks.

Adding States

You can add states to your client using the add_state method. Each state requires a name and a callback function that defines the state's behavior:

builder.add_state("state_name".to_string(), callback_function);

The callback function can be any function that implements the Callback trait, allowing for flexible state behavior definition.

Setting the Tick Rate

The tick rate determines how often the client's state is updated. You can set the tick rate using the tick_rate method:

builder.tick_rate(Duration::from_millis(100));

Specifying the Initial State

Before building your client, you must specify the initial state using the initial_state method:

builder.initial_state("initial_state_name".to_string());

Building the StateMachine

Once all configurations are set, you can build your StateMachine:

let client = builder.build();

This method finalizes the builder and returns an instance of StateMachine.

Example

Here's a complete example that demonstrates how to create an StateMachine with two states:

use autostatemachine::{StateMachineBuilder, StateMachineContext, extractor::TickRate}; 
use std::time::Duration;  
fn main() {     
    fn test1(_: StateMachineContext) -> String {         
        println!("State: test1");         
        "test2".to_string()     
    }      
    fn test2(_: StateMachineContext, TickRate(r): TickRate) -> String {         
        println!("State: test2, TickRate: {:?}", r);
        "test1".to_string()     
    }      
    let client = StateMachineBuilder::new(())         
        .add_state("test1".to_string(), test1)         
        .add_state("test2".to_string(), test2)         
        .initial_state("test1".to_string())         
        .tick_rate(Duration::from_millis(100))         
        .build();      
    // Use the client... 
}

This example creates an StateMachine with two states (test1 and test2) and a tick rate of 100 milliseconds. The client starts in the test1 state and prints a message before transitioning to the test2 state, which also prints a message and transitions back to test1.

Advanced Usage

For advanced scenarios, such as modifying the user context within your handlers, consider using thread-safe wrappers like Arc<Mutex<T>> or Arc<RwLock<T>>. This approach allows for safe concurrent access and modification of the shared context from multiple callbacks.

StateMachine

The StateMachine struct is the core of your automated client, managing states, transitions, and the execution cycle based on predefined states and associated callbacks.

Example Usage

To use StateMachine, you typically start by defining state callbacks, configuring an StateMachineBuilder instance, and then building your StateMachine. Once built, you can control the client's execution flow with its methods.

Creating and Running an StateMachine

use autostatemachine::{StateMachineBuilder, StateMachineContext};
use std::sync::{Arc, Mutex};
use std::time::Duration;

fn main() {
    let mut client = StateMachineBuilder::new(Arc::new(Mutex::new(MyContext::new())))
        .add_state("state1".to_string(), state1_handler)
        .add_state("state2".to_string(), state2_handler)
        .initial_state("state1".to_string())
        .tick_rate(Duration::from_millis(100))
        .build();

    client.run();

    // The client will now automatically transition between states based on the logic
    // defined in `state1_handler` and `state2_handler`.
}

Controlling Execution With Lifecycle Methods

// Assuming `client` has been initialized and started as above

// Pause execution
client.pause();

// Resume execution
client.resume();

// Stop execution
client.stop();

Implementation Notes

The run method spawns a new thread where the client's execution cycle is managed. This allows the main program to continue running independently of the client's state transitions.
Pausing or stopping the client affects its internal lifecycle status, which is checked at each tick interval to determine whether to proceed with state transitions or to perform lifecycle management actions like halting execution.

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