Refactor StorageMap to BlobList

bloblist.go

@@ -0,0 +1,99 @@
+package khepri
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"sort"
+	"sync"
+)
+
+type BlobList struct {
+	list []Blob
+	m    sync.Mutex
+}
+
+var ErrBlobNotFound = errors.New("Blob not found")
+
+func NewBlobList() *BlobList {
+	return &BlobList{
+		list: []Blob{},
+	}
+}
+
+func (bl *BlobList) find(blob Blob) (int, Blob, error) {
+	pos := sort.Search(len(bl.list), func(i int) bool {
+		return blob.ID.Compare(bl.list[i].ID) >= 0
+	})
+
+	if pos < len(bl.list) && blob.ID.Compare(bl.list[pos].ID) == 0 {
+		return pos, bl.list[pos], nil
+	}
+
+	return pos, Blob{}, ErrBlobNotFound
+}
+
+func (bl *BlobList) Find(blob Blob) (Blob, error) {
+	bl.m.Lock()
+	defer bl.m.Unlock()
+
+	_, blob, err := bl.find(blob)
+	return blob, err
+}
+
+func (bl *BlobList) Merge(other *BlobList) {
+	bl.m.Lock()
+	defer bl.m.Unlock()
+	other.m.Lock()
+	defer other.m.Unlock()
+
+	for _, blob := range other.list {
+		bl.insert(blob)
+	}
+}
+
+func (bl *BlobList) insert(blob Blob) {
+	pos, _, err := bl.find(blob)
+	if err == nil {
+		// already present
+		return
+	}
+
+	// insert blob
+	// https://code.google.com/p/go-wiki/wiki/bliceTricks
+	bl.list = append(bl.list, Blob{})
+	copy(bl.list[pos+1:], bl.list[pos:])
+	bl.list[pos] = blob
+}
+
+func (bl *BlobList) Insert(blob Blob) {
+	bl.m.Lock()
+	defer bl.m.Unlock()
+
+	bl.insert(blob)
+}
+
+func (bl BlobList) MarshalJSON() ([]byte, error) {
+	return json.Marshal(bl.list)
+}
+
+func (bl *BlobList) UnmarshalJSON(data []byte) error {
+	return json.Unmarshal(data, &bl.list)
+}
+
+// Compare compares two blobs by comparing the ID and the size. It returns -1,
+// 0, or 1.
+func (blob Blob) Compare(other Blob) int {
+	if res := bytes.Compare(other.ID, blob.ID); res != 0 {
+		return res
+	}
+
+	if blob.Size < other.Size {
+		return -1
+	}
+	if blob.Size > other.Size {
+		return 1
+	}
+
+	return 0
+}