move wakeup subcommand into signal subcommand and add reset subcommand

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/reset"
 	"github.com/zrepl/zrepl/daemon/job/wakeup"
 	"github.com/zrepl/zrepl/daemon/transport/connecter"
 	"github.com/zrepl/zrepl/daemon/filters"
@@ -248,6 +249,21 @@ func (j *ActiveSide) do(ctx context.Context) {
 	log := GetLogger(ctx)
 	ctx = logging.WithSubsystemLoggers(ctx, log)
 
+	// allow cancellation of an invocation (this function)
+	ctx, cancelThisRun := context.WithCancel(ctx)
+	defer cancelThisRun()
+	runDone := make(chan struct{})
+	defer close(runDone)
+	go func() {
+		select {
+		case <-runDone:
+		case <-reset.Wait(ctx):
+			log.Info("reset received, cancelling current invocation")
+			cancelThisRun()
+		case <-ctx.Done():
+		}
+	}()
+
 	client, err := j.clientFactory.NewClient()
 	if err != nil {
 		log.WithError(err).Error("factory cannot instantiate streamrpc client")

daemon/job/reset/reset.go

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