status: infra for reporting jobs instead of just replication.Report

daemon/job/job.go

@@ -2,7 +2,9 @@ package job
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
+	"fmt"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/zrepl/zrepl/logger"
 )
@@ -47,10 +49,73 @@ func WithWakeup(ctx context.Context) (context.Context, WakeupFunc) {
 type Job interface {
 	Name() string
 	Run(ctx context.Context)
-	Status() interface{}
+	Status() *Status
 	RegisterMetrics(registerer prometheus.Registerer)
 }
 
+type Type string
+
+const (
+	TypeInternal Type = "internal"
+	TypePush Type = "push"
+	TypeSink Type = "sink"
+)
+
+type Status struct {
+	Type Type
+	JobSpecific interface{}
+}
+
+func (s *Status) MarshalJSON() ([]byte, error) {
+	typeJson, err := json.Marshal(s.Type)
+	if err != nil {
+		return nil, err
+	}
+	jobJSON, err := json.Marshal(s.JobSpecific)
+	if err != nil {
+		return nil, err
+	}
+	m := map[string]json.RawMessage {
+		"type": typeJson,
+		string(s.Type): jobJSON,
+	}
+	return json.Marshal(m)
+}
+
+func (s *Status) UnmarshalJSON(in []byte) (err error) {
+	var m map[string]json.RawMessage
+	if err := json.Unmarshal(in, &m); err != nil {
+		return err
+	}
+	tJSON, ok := m["type"]
+	if !ok {
+		return fmt.Errorf("field 'type' not found")
+	}
+	if err := json.Unmarshal(tJSON, &s.Type); err != nil {
+		return err
+	}
+	key := string(s.Type)
+	jobJSON, ok := m[key]
+	if !ok {
+		return fmt.Errorf("field '%s', not found", key)
+	}
+	switch s.Type {
+	case TypePush:
+		var st PushStatus
+		err = json.Unmarshal(jobJSON, &st)
+		s.JobSpecific = &st
+	case TypeSink:
+		var st SinkStatus
+		err = json.Unmarshal(jobJSON, &st)
+		s.JobSpecific = &st
+	case TypeInternal:
+		// internal jobs do not report specifics
+	default:
+		err = fmt.Errorf("unknown job type '%s'", key)
+	}
+	return err
+}
+
 func WaitWakeup(ctx context.Context) <-chan struct{} {
 	wc, ok := ctx.Value(contextKeyWakeup).(chan struct{})
 	if !ok {

daemon/job/push.go

@@ -89,7 +89,11 @@ func (j *Push) RegisterMetrics(registerer prometheus.Registerer) {
 
 func (j *Push) Name() string { return j.name }
 
-func (j *Push) Status() interface{} {
+type PushStatus struct {
+	Replication *replication.Report
+}
+
+func (j *Push) Status() *Status {
 	rep := func() *replication.Replication {
 		j.mtx.Lock()
 		defer j.mtx.Unlock()
@@ -98,10 +102,12 @@ func (j *Push) Status() interface{} {
 		}
 		return j.replication
 	}()
+	s := &PushStatus{}
 	if rep == nil {
-		return nil
+		return &Status{Type: TypePush, JobSpecific: s}
 	}
-	return rep.Report()
+	s.Replication = rep.Report()
+	return &Status{Type: TypePush, JobSpecific: s}
 }
 
 func (j *Push) Run(ctx context.Context) {

daemon/job/sink.go

@@ -41,9 +41,10 @@ func SinkFromConfig(g *config.Global, in *config.SinkJob) (s *Sink, err error) {
 
 func (j *Sink) Name() string { return j.name }
 
-func (*Sink) Status() interface{} {
-	// FIXME
-	return nil
+type SinkStatus struct {}
+
+func (*Sink) Status() *Status {
+	return &Status{Type: TypeSink} // FIXME SinkStatus
 }
 
 func (*Sink) RegisterMetrics(registerer prometheus.Registerer) {}