rename Subsystem -> Module, add NewLifecycleL

lifecycle.go

@@ -5,10 +5,10 @@ import (
 	"log/slog"
 )
 
-// setupFn is a function that runs setup logic for a sub-system.
+// setupFn is a function that runs setup logic for a module.
 type setupFn func() error
 
-// teardownFn is a function that runs teardown logic for a sub-system.
+// teardownFn is a function that runs teardown logic for a module.
 type teardownFn func()
 
 // LifecycleOpts contains user-exposed options when defining a lifecycle.
@@ -18,38 +18,44 @@ type LifecycleOpts struct {
 }
 
 // Lifecycle represents the core application structure. Lifecycle manages
-// resources providing an orchestrator for setup and teardown of sub-systems.
+// resources providing an orchestrator for setup and teardown of modules.
 type Lifecycle struct {
 	// Logger is the logger for the lifecycle. If not set, it will be initialized
 	// by the lifecycle itself using the default logger.
 	logger *slog.Logger
 
-	subsystems      []*Subsystem
+	modules         []*Module
 	setupTracker    map[string]bool
 	teardownTracker map[string]bool
 	opts            LifecycleOpts
 }
 
 // NewLifecycle creates a new Lifecycle instance with a default logger and the
-// given subsystems. It panics if any subsystem has a duplicate name.
-func NewLifecycle(defaultLogger *slog.Logger, subsystems ...*Subsystem) *Lifecycle {
+// given modules. It panics if any module has a duplicate name.
+func NewLifecycle(modules ...*Module) *Lifecycle {
+	return NewLifecycleL(nil, modules...)
+}
+
+// NewLifecycleL creates a new Lifecycle instance with a specific logger and the
+// given modules. See NewLifecycle for more details.
+func NewLifecycleL(defaultLogger *slog.Logger, modules ...*Module) *Lifecycle {
 	// Use the provided logger or initialize a default one
 	if defaultLogger == nil {
 		defaultLogger = slog.Default()
 	}
 
-	// Ensure subsystems are unique
+	// Ensure modules are unique
 	unique := make(map[string]bool)
-	for _, sub := range subsystems {
+	for _, sub := range modules {
 		if _, exists := unique[sub.name]; exists {
-			panic(fmt.Sprintf("duplicate subsystem name: %s", sub.name))
+			panic(fmt.Sprintf("duplicate module name: %s", sub.name))
 		}
 		unique[sub.name] = true
 	}
 
 	return &Lifecycle{
 		logger:          defaultLogger,
-		subsystems:      subsystems,
+		modules:         modules,
 		setupTracker:    make(map[string]bool),
 		teardownTracker: make(map[string]bool),
 	}
@@ -61,13 +67,21 @@ func (app *Lifecycle) WithOpts(opts LifecycleOpts) *Lifecycle {
 	return app
 }
 
-// Setup initializes all sub-systems in the order they were defined and checks
-// for dependencies. It returns an error if any sub-system fails to initialize or
+// Logger returns the logger for the lifecycle.
+func (app *Lifecycle) Logger() *slog.Logger {
+	if app.logger == nil {
+		panic("lifecycle logger is not initialized")
+	}
+	return app.logger
+}
+
+// Setup initializes all modules in the order they were defined and checks
+// for dependencies. It returns an error if any module fails to initialize or
 // if dependencies are not satisfied. Lifecycle.Teardown should always be run at the end
 // of the application lifecycle to ensure all resources are cleaned up properly.
 func (app *Lifecycle) Setup() error {
 	setupCount := 0
-	for _, sub := range app.subsystems {
+	for _, sub := range app.modules {
 		if ok, err := app.setupSingle(sub, app.logger); err != nil {
 			return err
 		} else if ok {
@@ -75,76 +89,76 @@ func (app *Lifecycle) Setup() error {
 		}
 	}
 
-	app.logger.Info("Lifecycle sub-systems initialized, backend setup complete",
-		"count", setupCount, "subsystems", mapToString(app.setupTracker))
+	app.logger.Info("Lifecycle modules initialized, backend setup complete",
+		"count", setupCount, "modules", mapToString(app.setupTracker))
 
 	return nil
 }
 
-// Teardown runs all sub-system teardown functions in reverse order of setup.
+// Teardown runs all module teardown functions in reverse order of setup.
 // Teardown should always be run at the end of the application lifecycle
 // to ensure all resources are cleaned up properly.
 func (app *Lifecycle) Teardown() error {
 	teardownCount := 0
-	for i := len(app.subsystems) - 1; i >= 0; i-- {
-		if ok, err := app.singleTeardown(app.subsystems[i]); err != nil {
+	for i := len(app.modules) - 1; i >= 0; i-- {
+		if ok, err := app.singleTeardown(app.modules[i]); err != nil {
 			return err
 		} else if ok {
 			teardownCount++
 		}
 	}
 
-	app.logger.Info("All sub-systems torn down, backend teardown complete",
-		"count", teardownCount, "subsystems", mapToString(app.teardownTracker))
+	app.logger.Info("All modules torn down, backend teardown complete",
+		"count", teardownCount, "modules", mapToString(app.teardownTracker))
 
 	return nil
 }
 
-// Require adds sub-system(s) to the lifecycle and immediately runs any setup
-// functions. Relevant when a sub-system is not part of the main application
-// but may still be conditionally necessary. Any sub-systems that are already
+// Require adds module(s) to the lifecycle and immediately runs any setup
+// functions. Relevant when a module is not part of the main application
+// but may still be conditionally necessary. Any modules that are already
 // set up are ignored.
-func (app *Lifecycle) Require(subsystems ...*Subsystem) error {
-	return app.RequireL(app.logger, subsystems...)
+func (app *Lifecycle) Require(modules ...*Module) error {
+	return app.RequireL(app.logger, modules...)
 }
 
-// RequireL adds sub-system(s) to the lifecycle with a specific logger and
+// RequireL adds module(s) to the lifecycle with a specific logger and
 // immediately runs any setup functions. See Require for more details.
-// This variation is useful when you need to set up sub-systems with a non-
+// This variation is useful when you need to set up modules with a non-
 // default logger.
-func (app *Lifecycle) RequireL(logger *slog.Logger, subsystems ...*Subsystem) error {
-	for _, sub := range subsystems {
+func (app *Lifecycle) RequireL(logger *slog.Logger, modules ...*Module) error {
+	for _, sub := range modules {
 		if sub == nil {
-			return fmt.Errorf("sub-system is nil")
+			return fmt.Errorf("module is nil")
 		}
 
-		// Check if the sub-system is already set up
+		// Check if the module is already set up
 		if _, ok := app.setupTracker[sub.name]; ok {
-			app.logger.Warn("sub-system already set up, ignoring", "subsystem", sub.name)
+			app.logger.Warn("module already set up, ignoring", "module", sub.name)
 			continue
 		}
 
-		// Add the sub-system to the lifecycle
-		app.subsystems = append(app.subsystems, sub)
+		// Add the module to the lifecycle
+		app.modules = append(app.modules, sub)
 
-		// Run the setup function for the sub-system
+		// Run the setup function for the module
 		if _, err := app.setupSingle(sub, logger); err != nil {
-			return fmt.Errorf("error setting up required subsystem '%s': %w", sub.name, err)
+			return fmt.Errorf("error setting up required module '%s': %w", sub.name, err)
 		}
 	}
 
-	app.logger.Info("New sub-systems initialized", "all", mapToString(app.setupTracker))
+	app.logger.Info("New modules initialized", "all", mapToString(app.setupTracker))
 
 	return nil
 }
 
-// setupSingle is a helper function to set up a single sub-system.
-func (app *Lifecycle) setupSingle(sub *Subsystem, logger *slog.Logger) (bool, error) {
+// setupSingle is a helper function to set up a single module.
+func (app *Lifecycle) setupSingle(sub *Module, logger *slog.Logger) (bool, error) {
 	if sub == nil {
-		return false, fmt.Errorf("sub-system is nil")
+		return false, fmt.Errorf("module is nil")
 	}
 
-	// Set the logger for the sub-system
+	// Set the logger for the module
 	sub.logger = logger
 
 	// Check if all dependencies are satisfied
@@ -163,12 +177,12 @@ func (app *Lifecycle) setupSingle(sub *Subsystem, logger *slog.Logger) (bool, er
 	}
 
 	if sub.setup != nil {
-		// Run the setup function for the sub-system
+		// Run the setup function for the module
 		if err := sub.setup(); err != nil {
 			return false, fmt.Errorf("error initializing '%s': %w", sub.name, err)
 		}
 
-		// Mark this subsystem as setup
+		// Mark this module as setup
 		app.setupTracker[sub.name] = true
 		return true, nil
 	}
@@ -176,22 +190,22 @@ func (app *Lifecycle) setupSingle(sub *Subsystem, logger *slog.Logger) (bool, er
 	return false, nil
 }
 
-// singleTeardown is a helper function to tear down a single sub-system.
-func (app *Lifecycle) singleTeardown(sub *Subsystem) (bool, error) {
+// singleTeardown is a helper function to tear down a single module.
+func (app *Lifecycle) singleTeardown(sub *Module) (bool, error) {
 	if sub == nil {
-		return false, fmt.Errorf("sub-system is nil")
+		return false, fmt.Errorf("module is nil")
 	}
 
-	// Check if the sub-system was set up
+	// Check if the module was set up
 	if _, ok := app.setupTracker[sub.name]; !ok {
 		return false, nil
 	}
 
-	// Run the teardown function for the sub-system
+	// Run the teardown function for the module
 	if sub.teardown != nil {
 		sub.teardown()
 
-		// Mark this subsystem as torn down
+		// Mark this module as torn down
 		app.teardownTracker[sub.name] = true
 		return true, nil
 	}