split into separate files
This commit is contained in:
Elijah Duffy
222
app.go
222
app.go
@@ -3,225 +3,3 @@
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// and the logger. app should never be imported except by a main package.
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// Examples of suitable main packages are cmd and test.
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package app
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import (
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"fmt"
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"log/slog"
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)
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// setupFn is a function that runs setup logic for a sub-system.
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type setupFn func() error
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// teardownFn is a function that runs teardown logic for a sub-system.
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type teardownFn func()
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// LifecycleOpts contains user-exposed options when defining a lifecycle.
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type LifecycleOpts struct {
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// DisableAutoload disables dependency autoloading (enabled by default).
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DisableAutoload bool
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}
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// Lifecycle represents the core application structure. Lifecycle manages
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// resources providing an orchestrator for setup and teardown of sub-systems.
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type Lifecycle struct {
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subsystems []*Subsystem
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setupTracker map[string]bool
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teardownTracker map[string]bool
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opts LifecycleOpts
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}
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// NewLifecycle creates a new Lifecycle instance with the given subsystems.
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func NewLifecycle(subsystems ...*Subsystem) *Lifecycle {
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// Ensure subsystems are unique
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unique := make(map[string]bool)
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for _, sub := range subsystems {
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if _, exists := unique[sub.name]; exists {
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panic(fmt.Sprintf("duplicate subsystem name: %s", sub.name))
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}
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unique[sub.name] = true
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}
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return &Lifecycle{
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subsystems: subsystems,
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setupTracker: make(map[string]bool),
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teardownTracker: make(map[string]bool),
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}
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}
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// WithOpts sets the options for the lifecycle.
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func (app *Lifecycle) WithOpts(opts LifecycleOpts) *Lifecycle {
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app.opts = opts
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return app
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}
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// Setup initializes all sub-systems in the order they were defined and checks
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// for dependencies. It returns an error if any sub-system fails to initialize or
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// if dependencies are not satisfied. Lifecycle.Teardown should always be run at the end
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// of the application lifecycle to ensure all resources are cleaned up properly.
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func (app *Lifecycle) Setup() error {
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setupCount := 0
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for _, sub := range app.subsystems {
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if ok, err := app.setupSingle(sub); err != nil {
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return err
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} else if ok {
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setupCount++
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}
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}
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slog.Info("Lifecycle sub-systems initialized, backend setup complete",
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"count", setupCount, "subsystems", mapToString(app.setupTracker))
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return nil
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}
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// Teardown runs all sub-system teardown functions in reverse order of setup.
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// Teardown should always be run at the end of the application lifecycle
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// to ensure all resources are cleaned up properly.
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func (app *Lifecycle) Teardown() error {
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teardownCount := 0
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for i := len(app.subsystems) - 1; i >= 0; i-- {
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if ok, err := app.singleTeardown(app.subsystems[i]); err != nil {
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return err
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} else if ok {
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teardownCount++
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}
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}
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slog.Info("All sub-systems torn down, backend teardown complete",
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"count", teardownCount, "subsystems", mapToString(app.teardownTracker))
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return nil
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}
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// Require adds sub-system(s) to the lifecycle and immediately runs any setup
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// function. Relevant when a sub-system is not part of the main application
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// but may still be conditionally necessary. Any sub-systems that are already
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// set up are ignored.
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func (app *Lifecycle) Require(subsystems ...*Subsystem) error {
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for _, sub := range subsystems {
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if sub == nil {
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return fmt.Errorf("sub-system is nil")
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}
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// Check if the sub-system is already set up
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if _, ok := app.setupTracker[sub.name]; ok {
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slog.Warn("sub-system already set up, ignoring", "subsystem", sub.name)
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continue
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}
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// Add the sub-system to the lifecycle
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app.subsystems = append(app.subsystems, sub)
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// Run the setup function for the sub-system
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if _, err := app.setupSingle(sub); err != nil {
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return fmt.Errorf("error setting up required subsystem '%s': %w", sub.name, err)
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}
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}
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slog.Info("New sub-systems initialized", "all", mapToString(app.setupTracker))
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return nil
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}
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// setupSingle is a helper function to set up a single sub-system.
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func (app *Lifecycle) setupSingle(sub *Subsystem) (bool, error) {
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if sub == nil {
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return false, fmt.Errorf("sub-system is nil")
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}
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// Check if all dependencies are satisfied
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for _, dep := range sub.depends {
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if _, ok := app.setupTracker[dep.name]; !ok {
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if app.opts.DisableAutoload {
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return false, fmt.Errorf("dependency '%s' not satisfied for '%s'", dep.name, sub.name)
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} else {
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// Attempt to set up the dependency
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if _, err := app.setupSingle(dep); err != nil {
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return false, fmt.Errorf("error setting up dependency '%s' for '%s': %w", dep.name, sub.name, err)
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}
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}
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}
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}
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if sub.setup != nil {
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// Run the setup function for the sub-system
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if err := sub.setup(); err != nil {
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return false, fmt.Errorf("error initializing '%s': %w", sub.name, err)
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}
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// Mark this subsystem as setup
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app.setupTracker[sub.name] = true
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return true, nil
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}
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return false, nil
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}
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// singleTeardown is a helper function to tear down a single sub-system.
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func (app *Lifecycle) singleTeardown(sub *Subsystem) (bool, error) {
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if sub == nil {
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return false, fmt.Errorf("sub-system is nil")
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}
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// Check if the sub-system was set up
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if _, ok := app.setupTracker[sub.name]; !ok {
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return false, nil
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}
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// Run the teardown function for the sub-system
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if sub.teardown != nil {
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sub.teardown()
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// Mark this subsystem as torn down
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app.teardownTracker[sub.name] = true
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return true, nil
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}
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return false, nil
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}
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// Subsystem represents a sub-system of the application, with its setup and
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// teardown functions and dependencies.
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type Subsystem struct {
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name string
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setup setupFn
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teardown teardownFn
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depends []*Subsystem
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}
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// SubsystemOpts contains user-exposed options when defining a subsystem.
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type SubsystemOpts struct {
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// Setup is the setup function for the subsystem.
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Setup setupFn
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// Teardown is the teardown function for the subsystem.
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Teardown teardownFn
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// Depends is a list of subsystems that this subsystem depends on.
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Depends []*Subsystem
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}
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// NewSubsystem creates a new Subsystem instance with the given name and options.
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func NewSubsystem(name string, opts SubsystemOpts) *Subsystem {
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return &Subsystem{
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name: name,
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setup: opts.Setup,
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teardown: opts.Teardown,
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depends: opts.Depends,
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}
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}
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// mapToString converts a map to an opinionated string representation.
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func mapToString(m map[string]bool) string {
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if len(m) == 0 {
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return "[]"
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}
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result := "["
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for k, v := range m {
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if v {
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result += fmt.Sprintf("'%s' ", k)
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}
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}
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result = result[:len(result)-1] + "]"
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return result
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}
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