examples/routines: Add routines example

examples/routines/main.go

@@ -0,0 +1,114 @@
+// Example routines demonstrates the use of routines and a routine manager.
+package main
+
+import "log"
+import "time"
+import "context"
+import "math/rand"
+import "git.tebibyte.media/sashakoshka/go-service/daemon"
+import "git.tebibyte.media/sashakoshka/go-service/routines"
+
+func main () {
+	cow := cow { name: "cow" }
+	sheep := sheep { name: "sheep" }
+	horse := horse {
+		name: "horse",
+		sheep: &sheep,
+	}
+	
+	manager := routines.Manager {
+		Routines: []routines.Routine {
+			&cow,
+			&sheep,
+			&horse,
+		},
+	}
+	
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second * 12)
+	daemon.OnSigint(cancel)
+	err := manager.Run(ctx)
+	if err != nil { log.Fatalln(err) }
+}
+
+type cow struct {
+	name string
+}
+
+func (this *cow) Init (ctx context.Context) error {
+	log.Printf("%s: waking up\n", this.name)
+	defer log.Printf("%s: woke up\n", this.name)
+	time.Sleep(time.Duration(float64(time.Second) * 4 * rand.Float64()))
+	return nil
+}
+
+func (this *cow) Run (ctx context.Context) error {
+	log.Printf("%s: running\n", this.name)
+	defer log.Printf("%s: going to sleep\n", this.name)
+
+	ticker := time.NewTicker(time.Duration(float64(time.Second) * 4 * rand.Float64()))
+	defer ticker.Stop()
+	
+	for {
+		select {
+		case <- ctx.Done(): return ctx.Err()
+		case <- ticker.C:   log.Printf("%s: moo\n", this.name)
+		}
+	}
+}
+
+type sheep struct {
+	name string
+	poke chan struct { }
+}
+
+func (this *sheep) Init (ctx context.Context) error {
+	log.Printf("%s: waking up\n", this.name)
+	defer log.Printf("%s: woke up\n", this.name)
+	this.poke = make(chan struct { })
+	time.Sleep(time.Duration(float64(time.Second) * 4 * rand.Float64()))
+	return nil
+}
+
+func (this *sheep) Run (ctx context.Context) error {
+	log.Printf("%s: running\n", this.name)
+	defer log.Printf("%s: going to sleep\n", this.name)
+
+	for {
+		select {
+		case <- ctx.Done(): return ctx.Err()
+		case <- this.poke:  log.Printf("%s: baa\n", this.name)
+		}
+	}
+}
+
+
+type horse struct {
+	name  string
+	sheep *sheep
+}
+
+func (this *horse) Init (ctx context.Context) error {
+	log.Printf("%s: waking up\n", this.name)
+	defer log.Printf("%s: woke up\n", this.name)
+	time.Sleep(time.Duration(float64(time.Second) * 4 * rand.Float64()))
+	return nil
+}
+
+func (this *horse) Run (ctx context.Context) error {
+	log.Printf("%s: running\n", this.name)
+	defer log.Printf("%s: going to sleep\n", this.name)
+
+	ticker := time.NewTicker(time.Duration(float64(time.Second) * 4 * rand.Float64()))
+	defer ticker.Stop()
+	
+	for {
+		select {
+		case <- ctx.Done(): return ctx.Err()
+		case <- ticker.C:
+			if this.sheep != nil {
+				log.Printf("%s: poking %s\n", this.name, this.sheep.name)
+				this.sheep.poke <- struct { } { }
+			}
+		}
+	}
+}