feat: Add more events for starting and stopping of worker

* When worker is started, then it sends event "started"
* It also sends event "stopped", when it is terminated and
  proces cannot handle message anymore
* Small refactoring of code (do not use numeric constant)
* Updated doc strings
* Extended documentation in com.redhat.Yggdrasil1.Worker1.xml
  according changes in code

internal/work/dispatcher.go

@@ -111,6 +111,7 @@ func (d *Dispatcher) Connect() error {
 	go func() {
 		for s := range signals {
 			log.Tracef("received signal: %#v", s)
+
 			dest, err := d.senderName(dbus.Sender(s.Sender))
 			if err != nil {
 				log.Errorf("cannot find sender: %v", err)

ipc/com.redhat.Yggdrasil1.Worker1.xml

@@ -74,6 +74,16 @@
             3 = WORKING
             Emitted when the worker wishes to continue to announce it is
             working.
+
+            4 = STARTED
+            Emitted when the worker is started, and it is ready
+            to handle received messages. The message_id and response_id are
+            empty.
+
+            5 = STOPPED
+            Emitted when the worker is stopped, and it is not able
+            to handle received messages anymore. The message_id and
+            response_id are also empty.
         -->
         <signal name="Event">
             <arg type="u" name="name" />

ipc/interfaces.go

@@ -2,6 +2,7 @@ package ipc
 
 import (
 	_ "embed"
+	"fmt"
 )
 
 //go:embed com.redhat.Yggdrasil1.Dispatcher1.xml
@@ -12,13 +13,16 @@ var InterfaceDispatcher string
 type DispatcherEvent uint
 
 const (
-	// Emitted when the dispatcher receives the "disconnect" command.
+	// DispatcherEventReceivedDisconnect is emitted when the dispatcher receives
+	// the "disconnect" command.
 	DispatcherEventReceivedDisconnect DispatcherEvent = 1
 
-	// Emitted when the transport unexpected disconnects from the network.
+	// DispatcherEventUnexpectedDisconnect is emitted when the transport unexpected
+	// disconnects from the network.
 	DispatcherEventUnexpectedDisconnect DispatcherEvent = 2
 
-	// Emitted when the transport reconnects to the network.
+	// DispatcherEventConnectionRestored is emitted when the transport reconnects
+	// to the network.
 	DispatcherEventConnectionRestored DispatcherEvent = 3
 )
 
@@ -29,28 +33,40 @@ type WorkerEventName uint
 
 const (
 
-	// Emitted when the worker "accepts" a dispatched message and begins
-	// "working".
+	// WorkerEventNameBegin is emitted when the worker "accepts"
+	// a dispatched message and begins "working".
 	WorkerEventNameBegin WorkerEventName = 1
 
-	// Emitted when the worker finishes "working".
+	// WorkerEventNameEnd is emitted when the worker finishes "working".
 	WorkerEventNameEnd WorkerEventName = 2
 
-	// Emitted when the worker wishes to continue to announce it is
-	// working.
+	// WorkerEventNameWorking is emitted when the worker wishes
+	// to continue to announce it is working.
 	WorkerEventNameWorking WorkerEventName = 3
+
+	// WorkerEventNameStarted is emitted when finished starting
+	// process and it can
+	WorkerEventNameStarted WorkerEventName = 4
+
+	// WorkerEventNameStopped is emitted when worker is stopped,
+	// and it cannot process any message
+	WorkerEventNameStopped WorkerEventName = 5
 )
 
 func (e WorkerEventName) String() string {
 	switch e {
-	case 1:
+	case WorkerEventNameBegin:
 		return "BEGIN"
-	case 2:
+	case WorkerEventNameEnd:
 		return "END"
-	case 3:
+	case WorkerEventNameWorking:
 		return "WORKING"
+	case WorkerEventNameStarted:
+		return "STARTED"
+	case WorkerEventNameStopped:
+		return "STOPPED"
 	}
-	return ""
+	return fmt.Sprintf("UNKNOWN (value: %d)", e)
 }
 
 type WorkerEvent struct {

worker/worker.go

@@ -125,6 +125,17 @@ func (w *Worker) Connect(quit <-chan os.Signal) error {
 		return fmt.Errorf("request name failed")
 	}
 
+	// Emit a started event
+	err = w.EmitEvent(
+		ipc.WorkerEventNameStarted,
+		"",
+		"",
+		map[string]string{},
+	)
+	if err != nil {
+		return fmt.Errorf("cannot emit event: %w", err)
+	}
+
 	signals := make(chan *dbus.Signal)
 	w.conn.Signal(signals)
 	go func() {
@@ -142,6 +153,17 @@ func (w *Worker) Connect(quit <-chan os.Signal) error {
 
 	<-quit
 
+	// Emit a stopped event
+	err = w.EmitEvent(
+		ipc.WorkerEventNameStopped,
+		"",
+		"",
+		map[string]string{},
+	)
+	if err != nil {
+		return fmt.Errorf("cannot emit event: %w", err)
+	}
+
 	return nil
 }