Add Size method

Author: alldroll

cdb.go

@@ -44,6 +44,8 @@ type Reader interface {
 	Iterator() (Iterator, error)
 	// IteratorAt returns new Iterator object that points on first record associated with given key.
 	IteratorAt(key []byte) (Iterator, error)
+	// Size returns the size of the dataset
+	Size() int
 }
 
 // Iterator provides API for walking through database's records. Do not share object between multiple goroutines.

cdb_test.go

@@ -50,6 +50,10 @@ func TestShouldReturnAllValues(t *testing.T) {
 			t.Errorf("Expected value %s, got %s", c.value, value)
 		}
 	}
+
+	if reader.Size() != 7 {
+		t.Errorf("Expected size %d, got %d", 7, reader.Size())
+	}
 }
 
 func TestShouldReturnNilOnNonExistingKeys(t *testing.T) {

reader.go

@@ -20,6 +20,7 @@ type readerImpl struct {
 	reader io.ReaderAt
 	hasher Hasher
 	endPos uint32
+	size   int
 }
 
 // newReader return new readerImpl object on success, otherwise return nil and error
@@ -48,6 +49,7 @@ func (r *readerImpl) initialize() error {
 	for i := range &r.refs {
 		j := i * 8
 		r.refs[i].position, r.refs[i].length = binary.LittleEndian.Uint32(buf[j:j+4]), binary.LittleEndian.Uint32(buf[j+4:j+8])
+		r.size += int(r.refs[i].length >> 1)
 	}
 
 	for _, ref := range &r.refs {
@@ -165,6 +167,11 @@ func (r *readerImpl) IteratorAt(key []byte) (Iterator, error) {
 	), nil
 }
 
+// Size returns the size of the dataset
+func (r *readerImpl) Size() int {
+	return r.size
+}
+
 // calcHash returns hash value of given key
 func (r *readerImpl) calcHash(key []byte) uint32 {
 	hashFunc := r.hasher()
@@ -176,7 +183,7 @@ func (r *readerImpl) calcHash(key []byte) uint32 {
 func (r *readerImpl) checkEntry(entry slot, key []byte) (*sectionReaderFactory, uint32, error) {
 	var (
 		keySize, valSize uint32
-		givenKeySize     uint32 = uint32(len(key))
+		givenKeySize     = uint32(len(key))
 	)
 
 	err := r.readPair(entry.position, &keySize, &valSize)

writer.go

@@ -109,7 +109,7 @@ func (w *writerImpl) Close() error {
 		for _, slot := range table {
 			k := (slot.hash >> 8) % n
 
-			// linear ...
+			// Linear probing
 			for slots[k].position != 0 {
 				k = (k + 1) % n
 			}