Add task metrics to prometheus example

examples/prometheus/prometheus.go

@@ -13,12 +13,14 @@ import (
 func main() {
 
 	// Create a worker pool
-	pool := pond.New(10, 0)
+	pool := pond.New(10, 100)
 
 	// Register pool metrics collectors
+
+	// Worker pool metrics
 	prometheus.MustRegister(prometheus.NewGaugeFunc(
 		prometheus.GaugeOpts{
-			Name: "pond_running_workers",
+			Name: "pool_workers_running",
 			Help: "Number of running worker goroutines",
 		},
 		func() float64 {
@@ -26,13 +28,55 @@ func main() {
 		}))
 	prometheus.MustRegister(prometheus.NewGaugeFunc(
 		prometheus.GaugeOpts{
-			Name: "pond_idle_workers",
+			Name: "pool_workers_idle",
 			Help: "Number of idle worker goroutines",
 		},
 		func() float64 {
 			return float64(pool.IdleWorkers())
 		}))
 
+	// Task metrics
+	prometheus.MustRegister(prometheus.NewCounterFunc(
+		prometheus.CounterOpts{
+			Name: "pool_tasks_submitted_total",
+			Help: "Number of tasks submitted",
+		},
+		func() float64 {
+			return float64(pool.SubmittedTasks())
+		}))
+	prometheus.MustRegister(prometheus.NewGaugeFunc(
+		prometheus.GaugeOpts{
+			Name: "pool_tasks_waiting_total",
+			Help: "Number of tasks waiting in the queue",
+		},
+		func() float64 {
+			return float64(pool.WaitingTasks())
+		}))
+	prometheus.MustRegister(prometheus.NewCounterFunc(
+		prometheus.CounterOpts{
+			Name: "pool_tasks_successful_total",
+			Help: "Number of tasks that completed successfully",
+		},
+		func() float64 {
+			return float64(pool.SuccessfulTasks())
+		}))
+	prometheus.MustRegister(prometheus.NewCounterFunc(
+		prometheus.CounterOpts{
+			Name: "pool_tasks_failed_total",
+			Help: "Number of tasks that completed with panic",
+		},
+		func() float64 {
+			return float64(pool.FailedTasks())
+		}))
+	prometheus.MustRegister(prometheus.NewCounterFunc(
+		prometheus.CounterOpts{
+			Name: "pool_tasks_completed_total",
+			Help: "Number of tasks that completed either successfully or with panic",
+		},
+		func() float64 {
+			return float64(pool.CompletedTasks())
+		}))
+
 	// Expose the registered metrics via HTTP
 	http.Handle("/metrics", promhttp.Handler())
 
@@ -50,7 +94,7 @@ func submitTasks(pool *pond.WorkerPool) {
 		n := i
 		pool.Submit(func() {
 			fmt.Printf("Running task #%d\n", n)
-			time.Sleep(3 * time.Second)
+			time.Sleep(500 * time.Millisecond)
 		})
 	}
 }