move wakup mechanism into separate package

daemon/job/active.go

@@ -6,6 +6,7 @@ import (
 	"github.com/problame/go-streamrpc"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/zrepl/zrepl/config"
+	"github.com/zrepl/zrepl/daemon/job/wakeup"
 	"github.com/zrepl/zrepl/daemon/transport/connecter"
 	"github.com/zrepl/zrepl/daemon/filters"
 	"github.com/zrepl/zrepl/daemon/pruner"
@@ -233,7 +234,7 @@ outer:
 			log.WithError(ctx.Err()).Info("context")
 			break outer
 
-		case <-WaitWakeup(ctx):
+		case <-wakeup.Wait(ctx):
 		case <-periodicDone:
 		}
 		invocationCount++

daemon/job/job.go

@@ -3,7 +3,6 @@ package job
 import (
 	"context"
 	"encoding/json"
-	"errors"
 	"fmt"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/zrepl/zrepl/logger"
@@ -15,7 +14,6 @@ type contextKey int
 
 const (
 	contextKeyLog contextKey = iota
-	contextKeyWakeup
 )
 
 func GetLogger(ctx context.Context) Logger {
@@ -29,22 +27,6 @@ func WithLogger(ctx context.Context, l Logger) context.Context {
 	return context.WithValue(ctx, contextKeyLog, l)
 }
 
-type WakeupFunc func() error
-
-var AlreadyWokenUp = errors.New("already woken up")
-
-func WithWakeup(ctx context.Context) (context.Context, WakeupFunc) {
-	wc := make(chan struct{})
-	wuf := func() error {
-		select {
-		case wc <- struct{}{}:
-			return nil
-		default:
-			return AlreadyWokenUp
-		}
-	}
-	return context.WithValue(ctx, contextKeyWakeup, wc), wuf
-}
 
 type Job interface {
 	Name() string
@@ -119,12 +101,3 @@ func (s *Status) UnmarshalJSON(in []byte) (err error) {
 	}
 	return err
 }
-
-func WaitWakeup(ctx context.Context) <-chan struct{} {
-	wc, ok := ctx.Value(contextKeyWakeup).(chan struct{})
-	if !ok {
-		wc = make(chan struct{})
-	}
-	return wc
-}
-

daemon/job/wakeup/wakeup.go

@@ -0,0 +1,35 @@
+package wakeup
+
+import (
+	"context"
+	"errors"
+)
+
+type contextKey int
+
+const contextKeyWakeup contextKey = iota
+
+func Wait(ctx context.Context) <-chan struct{} {
+	wc, ok := ctx.Value(contextKeyWakeup).(chan struct{})
+	if !ok {
+		wc = make(chan struct{})
+	}
+	return wc
+}
+
+type Func func() error
+
+var AlreadyWokenUp = errors.New("already woken up")
+
+func Context(ctx context.Context) (context.Context, Func) {
+	wc := make(chan struct{})
+	wuf := func() error {
+		select {
+		case wc <- struct{}{}:
+			return nil
+		default:
+			return AlreadyWokenUp
+		}
+	}
+	return context.WithValue(ctx, contextKeyWakeup, wc), wuf
+}