keep ref ids in RefIndex sorted

cache/diff.go

@@ -3,6 +3,7 @@ package cache
 import (
 	"code.google.com/p/goprotobuf/proto"
 	bin "encoding/binary"
+	"sort"
 	"sync"
 )
 
@@ -39,8 +40,7 @@ func (index *RefIndex) Add(id, ref int64) error {
 		refs.Ids = make([]int64, 0, 1)
 	}
 	// TODO change to delta encoding
-	// TODO check for duplicates
-	refs.Ids = append(refs.Ids, ref)
+	refs.insertId(ref)
 
 	data, err = proto.Marshal(refs)
 	if err != nil {
@@ -50,6 +50,19 @@ func (index *RefIndex) Add(id, ref int64) error {
 	return err
 }
 
+func (r *Refs) insertId(ref int64) {
+	i := sort.Search(len(r.Ids), func(i int) bool {
+		return r.Ids[i] >= ref
+	})
+	if i < len(r.Ids) && r.Ids[i] >= ref {
+		r.Ids = append(r.Ids, 0)
+		copy(r.Ids[i+1:], r.Ids[i:])
+		r.Ids[i] = ref
+	} else {
+		r.Ids = append(r.Ids, ref)
+	}
+}
+
 func (index *RefIndex) Get(id int64) []int64 {
 	keyBuf := make([]byte, 8)
 	bin.PutVarint(keyBuf, id)

cache/diff_test.go

@@ -0,0 +1,46 @@
+package cache
+
+import (
+	"testing"
+)
+
+func TestInsertId(t *testing.T) {
+
+	refs := Refs{}
+	refs.Ids = make([]int64, 0, 1)
+
+	refs.insertId(1)
+	if refs.Ids[0] != 1 {
+		t.Fatal(refs)
+	}
+
+	refs.insertId(10)
+	if refs.Ids[0] != 1 && refs.Ids[1] != 10 {
+		t.Fatal(refs)
+	}
+
+	// insert twice
+	refs.insertId(10)
+	if refs.Ids[0] != 1 && refs.Ids[1] != 10 {
+		t.Fatal(refs)
+	}
+
+	// insert before
+	refs.insertId(0)
+	if refs.Ids[0] != 0 && refs.Ids[1] != 1 && refs.Ids[2] != 10 {
+		t.Fatal(refs)
+	}
+
+	// insert after
+	refs.insertId(12)
+	if refs.Ids[0] != 0 && refs.Ids[1] != 1 && refs.Ids[2] != 10 && refs.Ids[3] != 12 {
+		t.Fatal(refs)
+	}
+
+	// insert between
+	refs.insertId(11)
+	if refs.Ids[0] != 0 && refs.Ids[1] != 1 && refs.Ids[2] != 10 && refs.Ids[3] != 11 && refs.Ids[4] != 12 {
+		t.Fatal(refs)
+	}
+
+}