Added chunking to enable batching ssm-run instances (#6)

Author: sendqueery

util/batch/chunk.go

@@ -0,0 +1,27 @@
+package batch
+
+// ChunkFunc is a function when used e.g with chunk, provides a minimum and maximum range
+// to batch the items of a slice.
+type ChunkFunc func(min int, max int) (bool, error)
+
+func Chunk(length, batch int, fn ChunkFunc) error {
+	for i := 0; i < length; i += batch {
+		j := i + batch
+
+		if j > length {
+			j = length
+		}
+
+		cont, err := fn(i, j)
+
+		if err != nil {
+			return err
+		}
+
+		if !cont {
+			return nil
+		}
+	}
+
+	return nil
+}

util/batch/chunk_test.go

@@ -0,0 +1,28 @@
+package batch
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestChunk(t *testing.T) {
+	items := []int{12, 22, 53, 24, 75, 96, 67, 18, 39, 10, 13, 99, 31}
+
+	counter := 0
+	fn := func(min int, max int) (bool, error) {
+		assert.Equal(t, counter, min)
+
+		if max == len(items) {
+			assert.Equal(t, len(items), max)
+		} else {
+			assert.Equal(t, counter+2, max)
+		}
+
+		counter += 2
+		return true, nil
+	}
+
+	err := Chunk(len(items), 2, fn)
+	assert.NoError(t, err)
+}