115 lines
2.9 KiB
Go
115 lines
2.9 KiB
Go
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package application
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import (
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"context"
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"errors"
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"fmt"
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"log/slog"
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"os"
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"os/signal"
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"sync"
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"syscall"
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)
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var (
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// ErrApplication indicates that error appeared somewhere in application's lifecycle controller.
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ErrApplication = errors.New("application")
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// Version is application's version.
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Version string
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// Branch is a branch name from which application was built.
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Branch string
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// Commit is a commit hash from which application was built.
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Commit string
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// Build is a build number.
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Build string
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// BuildDate is a date on which application was built.
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BuildDate string
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)
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// Application is an application's lifecycle controlling structure.
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type Application struct {
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ctx context.Context
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shutdownDone chan struct{}
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cancelFunc context.CancelFunc
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services map[string]Service
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dataPath string
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servicesMutex sync.RWMutex
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}
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// New creates new application's lifecycle controlling structure.
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func New() *Application {
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appl := &Application{}
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appl.initialize()
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return appl
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}
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// GetContext returns application's global context.
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func (a *Application) GetContext() context.Context {
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return a.ctx
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}
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// GetShutdownDoneChannel returns channel on which lifecycle controller will tell about shutdown completion.
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// Should be used only in main()!
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func (a *Application) GetShutdownDoneChannel() chan struct{} {
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slog.Debug("Returning shutdown completion channel.")
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return a.shutdownDone
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}
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func (a *Application) initialize() {
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a.ctx, a.cancelFunc = context.WithCancel(context.Background())
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a.ctx, a.cancelFunc = signal.NotifyContext(a.ctx, os.Interrupt, syscall.SIGTERM)
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a.services = make(map[string]Service)
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a.shutdownDone = make(chan struct{}, 1)
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}
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// Shutdown stops application and all registered services.
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func (a *Application) Shutdown() error {
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a.cancelFunc()
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a.servicesMutex.RLock()
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defer a.servicesMutex.RUnlock()
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for _, service := range a.services {
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if err := service.Shutdown(); err != nil {
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slog.Error("Error appeared when trying to shut down service", "service", service.GetName(), "error", err.Error())
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}
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}
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a.shutdownDone <- struct{}{}
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return nil
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}
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// Start starts application and all registered services.
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func (a *Application) Start() error {
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go a.signalsListener()
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a.servicesMutex.RLock()
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defer a.servicesMutex.RUnlock()
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// First pass - connecting dependencies.
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for _, service := range a.services {
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if err := service.ConnectDependencies(); err != nil {
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return fmt.Errorf("%w: connecting dependencies for service '%s': %w", ErrApplication, service.GetName(), err)
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}
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}
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// Second pass - launching startup tasks.
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for name, service := range a.services {
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slog.Debug("Launching startup tasks for service", "service", name)
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if err := service.LaunchStartupTasks(); err != nil {
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return fmt.Errorf("%w: launching startup tasks for '%s': %w", ErrApplication, service.GetName(), err)
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}
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}
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slog.Debug("Application started.")
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return nil
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}
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