Added JobsWaitingInQueue in Scheduler

scheduler.go

@@ -44,6 +44,9 @@ type Scheduler interface {
 	// Update replaces the existing Job's JobDefinition with the provided
 	// JobDefinition. The Job's Job.ID() remains the same.
 	Update(uuid.UUID, JobDefinition, Task, ...JobOption) (Job, error)
+	// JobsWaitingInQueue number of jobs waiting in Queue in case of LimitModeWait
+	// In case of LimitModeReschedule or no limit it will be always zero
+	JobsWaitingInQueue() int
 }
 
 // -----------------------------------------------
@@ -678,6 +681,13 @@ func (s *scheduler) Update(id uuid.UUID, jobDefinition JobDefinition, task Task,
 	return s.addOrUpdateJob(id, jobDefinition, task, options)
 }
 
+func (s *scheduler) JobsWaitingInQueue() int {
+	if s.exec.limitMode != nil && s.exec.limitMode.mode == LimitModeWait {
+		return len(s.exec.limitMode.in)
+	}
+	return 0
+}
+
 // -----------------------------------------------
 // -----------------------------------------------
 // ------------- Scheduler Options ---------------

scheduler_test.go

@@ -1392,6 +1392,59 @@ func TestScheduler_RemoveJob(t *testing.T) {
 	}
 }
 
+func TestScheduler_JobsWaitingInQueue(t *testing.T) {
+	goleak.VerifyNone(t)
+	tests := []struct {
+		name            string
+		limit           uint
+		mode            LimitMode
+		startAt         func() OneTimeJobStartAtOption
+		expectedInQueue int
+	}{
+		{
+			"with mode wait limit 1",
+			1,
+			LimitModeWait,
+			func() OneTimeJobStartAtOption {
+				return OneTimeJobStartDateTime(time.Now().Add(10 * time.Millisecond))
+			},
+			4,
+		},
+		{
+			"with mode wait limit 10",
+			10,
+			LimitModeWait,
+			func() OneTimeJobStartAtOption {
+				return OneTimeJobStartDateTime(time.Now().Add(10 * time.Millisecond))
+			},
+			0,
+		},
+		{
+			"with mode Reschedule",
+			1,
+			LimitModeReschedule,
+			func() OneTimeJobStartAtOption {
+				return OneTimeJobStartDateTime(time.Now().Add(10 * time.Millisecond))
+			},
+			0,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s := newTestScheduler(t, WithLimitConcurrentJobs(tt.limit, tt.mode))
+			for i := 0; i <= 4; i++ {
+				_, err := s.NewJob(OneTimeJob(tt.startAt()), NewTask(func() { time.Sleep(10 * time.Second) }))
+				require.NoError(t, err)
+			}
+			s.Start()
+			time.Sleep(100 * time.Millisecond)
+			assert.Equal(t, tt.expectedInQueue, s.JobsWaitingInQueue())
+			_ = s.Shutdown()
+		})
+	}
+}
+
 func TestScheduler_RemoveLotsOfJobs(t *testing.T) {
 	goleak.VerifyNone(t)
 	tests := []struct {