TWEAK: add discard max retry middleware (#48)

Author: taylorchu

middleware/discard/max_retry.go

@@ -0,0 +1,18 @@
+package discard
+
+import (
+	"github.com/taylorchu/work"
+)
+
+// MaxRetry discards a job if its retry count is over limit.
+func MaxRetry(n int64) work.HandleMiddleware {
+	return func(f work.HandleFunc) work.HandleFunc {
+		return func(job *work.Job, opt *work.DequeueOptions) error {
+			err := f(job, opt)
+			if job.Retries >= n {
+				return work.ErrUnrecoverable
+			}
+			return err
+		}
+	}
+}

middleware/discard/max_retry_test.go

@@ -0,0 +1,29 @@
+package discard
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/taylorchu/work"
+)
+
+func TestMaxRetry(t *testing.T) {
+	job := work.NewJob()
+	opt := &work.DequeueOptions{
+		Namespace: "n1",
+		QueueID:   "q1",
+	}
+	d := MaxRetry(1)
+	h := d(func(*work.Job, *work.DequeueOptions) error {
+		return errors.New("no reason")
+	})
+
+	err := h(job, opt)
+	require.Error(t, err)
+	require.NotEqual(t, work.ErrUnrecoverable, err)
+
+	job.Retries = 1
+	err = h(job, opt)
+	require.Equal(t, work.ErrUnrecoverable, err)
+}