update styles and add home page

pkg/graceful/with-interrupt.go

@@ -0,0 +1,127 @@
+package graceful
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"os/signal"
+	"sync"
+	"time"
+
+	"github.com/rs/zerolog/log"
+	"go.uber.org/multierr"
+)
+
+func WithInterupt(ctx context.Context) context.Context {
+	log := log.Ctx(ctx)
+	ctx, cancel := context.WithCancel(ctx)
+
+	// Listen for Interrupt signals
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt)
+
+	go func() {
+		defer signal.Stop(c)
+
+		for {
+			select {
+			case <-c:
+				cancel()
+				log.Warn().Msg("Shutting down! interrupt received")
+				return
+			case <-ctx.Done():
+				log.Warn().Msg("Shutting down! context cancelled")
+				return
+			}
+		}
+	}()
+
+	return ctx
+}
+
+type contextKey struct{ string }
+
+var wgKey = contextKey{"waitgroup"}
+
+type wgContext struct {
+	wg  sync.WaitGroup
+	err error
+	ctx context.Context
+}
+
+func (wg *wgContext) String() string {
+	return fmt.Sprintf("WaitGroup[%v %v]", wg.err, wg.ctx)
+}
+
+type WG interface {
+	Wait(time.Duration) error
+	Go(func() error)
+}
+
+func WithWaitGroup(ctx context.Context) (context.Context, WG) {
+	if wg := WaitGroup(ctx); wg != nil {
+		return ctx, wg
+	}
+	wg := &wgContext{ctx: ctx}
+	return context.WithValue(ctx, wgKey, wg), wg
+}
+
+func WaitGroup(ctx context.Context) *wgContext {
+	if wg, ok := ctx.Value(wgKey).(*wgContext); ok {
+		return wg
+	}
+	return nil
+}
+
+func (wg *wgContext) Go(fn func() error) {
+	if wg == nil {
+		panic("nil wait group")
+	}
+
+	wg.Add(1)
+	go func() {
+		err := fn()
+		wg.err = multierr.Append(wg.err, err)
+		wg.Done()
+	}()
+}
+
+func (wg *wgContext) Add(n int) {
+	wg.wg.Add(n)
+}
+
+func (wg *wgContext) Done() {
+	wg.wg.Done()
+}
+
+func (wg *wgContext) Wait(gracetime time.Duration) error {
+	if wg == nil {
+		return nil
+	}
+
+	log := log.Ctx(wg.ctx)
+
+	ch := make(chan struct{})
+	go func() {
+		wg.wg.Wait()
+		close(ch)
+	}()
+
+	<-wg.ctx.Done()
+	wg.err = multierr.Append(wg.err, wg.ctx.Err())
+
+	log.Debug().Msg("shutdown begin")
+	timer := time.NewTimer(gracetime)
+
+	select {
+	case <-ch:
+	case <-timer.C:
+		wg.err = multierr.Append(wg.err, ErrExpiredGrace)
+	}
+	log.Debug().Msg("shutdown complete")
+
+	return wg.err
+}
+
+var ErrExpiredGrace = errors.New("grace time expired")