Plugin Lifecycle

Plugin Lifecycle Overview

Plugins in Pumpkin go through a well-defined lifecycle managed by the PluginManager. Understanding this lifecycle is essential for proper resource management and plugin behavior.

Lifecycle Hooks

The Plugin trait defines two main lifecycle hooks:

on_load

Called when the plugin is loaded and initialized.

fn on_load(&mut self, context: Arc<Context>) -> PluginFuture<'_, Result<(), String>> {
    Box::pin(async move {
        // Initialize plugin resources
        // Register event handlers
        // Register commands
        // Load configuration
        
        Ok(())
    })
}

When it’s called:

After the plugin is discovered in the plugins/ directory
When the loader successfully loads the plugin binary
Before the plugin is marked as active

What to do here:

Initialize plugin state
Register event handlers
Register commands
Load configuration files
Set up database connections
Register services

Return value:

Ok(()) - Plugin initialized successfully
Err(String) - Initialization failed, plugin will be unloaded

on_unload

Called when the plugin is being unloaded or when initialization fails.

fn on_unload(&mut self, context: Arc<Context>) -> PluginFuture<'_, Result<(), String>> {
    Box::pin(async move {
        // Clean up resources
        // Unregister commands
        // Close connections
        
        Ok(())
    })
}

When it’s called:

When the server shuts down
When the plugin is manually unloaded
After on_load fails (cleanup after failed initialization)
Before the plugin is removed from the plugin manager

What to do here:

Unregister commands
Close database connections
Save configuration
Clean up temporary files
Release resources

Note: Event handlers are automatically cleaned up when a plugin is unloaded.

Plugin States

Plugins progress through several states:

pub enum PluginState {
    Loading,           // Plugin is being initialized
    Loaded,           // Plugin is active and running
    Failed(String),   // Plugin failed to load
}

Checking Plugin State

// Check if a plugin is active
let is_active = plugin_manager.is_plugin_active("my_plugin").await;

// Get plugin state
if let Some(state) = plugin_manager.get_plugin_state("my_plugin").await {
    match state {
        PluginState::Loading => println!("Plugin is loading..."),
        PluginState::Loaded => println!("Plugin is active"),
        PluginState::Failed(err) => println!("Plugin failed: {}", err),
    }
}

// Wait for a plugin to finish loading
plugin_manager.wait_for_plugin("my_plugin").await?;

Lifecycle Example

Here’s a complete example showing proper lifecycle management:

use std::sync::Arc;
use pumpkin::plugin::{Plugin, PluginFuture, Context};

pub struct DatabasePlugin {
    connection: Option<DatabaseConnection>,
}

impl DatabasePlugin {
    pub fn new() -> Self {
        Self { connection: None }
    }
}

impl Plugin for DatabasePlugin {
    fn on_load(&mut self, context: Arc<Context>) -> PluginFuture<'_, Result<(), String>> {
        Box::pin(async move {
            context.log("Initializing database plugin...");

            // Load configuration
            let config_path = context.get_data_folder().join("config.toml");
            let config = load_config(&config_path)
                .map_err(|e| format!("Failed to load config: {}", e))?;

            // Connect to database
            let connection = DatabaseConnection::connect(&config.db_url).await
                .map_err(|e| format!("Database connection failed: {}", e))?;
            
            self.connection = Some(connection);

            context.log("Database plugin initialized successfully");
            Ok(())
        })
    }

    fn on_unload(&mut self, context: Arc<Context>) -> PluginFuture<'_, Result<(), String>> {
        Box::pin(async move {
            context.log("Shutting down database plugin...");

            // Close database connection
            if let Some(connection) = self.connection.take() {
                connection.close().await
                    .map_err(|e| format!("Failed to close connection: {}", e))?;
            }

            context.log("Database plugin unloaded");
            Ok(())
        })
    }
}

Async Loading

Plugins are loaded asynchronously to prevent blocking the server:

// Plugins are loaded in parallel
let load_tasks = vec![
    start_loading_plugin("plugin1"),
    start_loading_plugin("plugin2"),
    start_loading_plugin("plugin3"),
];

// All plugins initialize concurrently
join_all(load_tasks).await;

Waiting for All Plugins

You can wait for all plugins to finish loading:

// Wait for all plugins to complete loading
plugin_manager.wait_for_all_plugins().await;

// Check if all plugins finished (succeeded or failed)
let all_done = plugin_manager.all_plugins_loaded().await;

// Get failed plugins
let failed = plugin_manager.get_failed_plugins().await;
for (name, error) in failed {
    println!("Plugin {} failed: {}", name, error);
}

Best Practices

Do’s

Always clean up resources in on_unload
Return descriptive error messages from on_load
Use async operations efficiently
Validate configuration during on_load
Handle errors gracefully

Don’ts

Don’t perform blocking operations in lifecycle hooks
Don’t assume other plugins are loaded during on_load
Don’t ignore errors from async operations
Don’t leak resources if initialization fails

Platform Considerations

Windows

On Windows, plugins cannot be fully unloaded from memory due to OS limitations. They can only be deactivated. The on_unload hook still runs, but the binary remains loaded.

Linux/macOS

Plugins can be completely unloaded and their memory freed.

Next Steps

Event System - Learn about event handling
Explore advanced plugin patterns
Review plugin API reference

Plugin Development

API Reference

Plugin Lifecycle