Merge pull request #10 from letterbeezps/dev

Dev

Author: letterbeezps

internal/merge_iterator.go

@@ -0,0 +1,86 @@
+package keytype
+
+import (
+	"github.com/letterbeezps/miniKV/internal/iface"
+	"github.com/pkg/errors"
+)
+
+type TwoMergeIterator struct {
+	First       iface.Iterator
+	Second      iface.Iterator
+	ChooseFirst bool
+	Less        func(f, s string) bool
+	Equal       func(f, s string) bool
+}
+
+func NewTwoMergeIterstor(f, s iface.Iterator, less, equal func(f, s string) bool) (*TwoMergeIterator, error) {
+	ret := &TwoMergeIterator{
+		First:  f,
+		Second: s,
+		Less:   less,
+		Equal:  equal,
+	}
+	if err := ret.skipSecond(); err != nil {
+		return nil, errors.Wrap(err, "skipSecond")
+	}
+	ret.ChooseFirst = ret.chooseFirst()
+	return ret, nil
+}
+
+func (iter *TwoMergeIterator) chooseFirst() bool {
+	if !iter.First.IsValid() {
+		return false
+	}
+	if !iter.Second.IsValid() {
+		return true
+	}
+	return iter.Less(iter.First.Key(), iter.Second.Key())
+}
+
+func (iter *TwoMergeIterator) skipSecond() error {
+	if iter.First.IsValid() && iter.Second.IsValid() && iter.Equal(iter.First.Key(), iter.Second.Key()) {
+		return iter.Second.Next()
+	}
+	return nil
+}
+
+func (iter *TwoMergeIterator) Value() []byte {
+	if iter.chooseFirst() {
+		return iter.First.Value()
+	} else {
+		return iter.Second.Value()
+	}
+}
+
+func (iter *TwoMergeIterator) Key() string {
+	if iter.chooseFirst() {
+		return iter.First.Key()
+	} else {
+		return iter.Second.Key()
+	}
+}
+
+func (iter *TwoMergeIterator) IsValid() bool {
+	if iter.chooseFirst() {
+		return iter.First.IsValid()
+	} else {
+		return iter.Second.IsValid()
+	}
+}
+
+func (iter *TwoMergeIterator) Next() error {
+	if iter.ChooseFirst {
+		if err := iter.First.Next(); err != nil {
+			return errors.Wrap(err, "First Next")
+		}
+	} else {
+		if err := iter.Second.Next(); err != nil {
+			return errors.Wrap(err, "Second Next")
+		}
+	}
+	if err := iter.skipSecond(); err != nil {
+		return errors.Wrap(err, "skipSecond")
+	}
+	iter.ChooseFirst = iter.chooseFirst()
+	return nil
+}

mvcc/iterator_test.go

@@ -130,4 +130,27 @@ func Test_Tx_Iteraotr(t *testing.T) {
 		assert.Nil(t, iter.Next())
 		i++
 	}
+
+	iter, err = tx6.Iter("c", "f")
+	assert.Nil(t, err)
+	datas = []struct {
+		key string
+		val []byte
+	}{
+		{"e", []byte("e_1")},
+		{"f", []byte("f_2")},
+	}
+	i = 0
+	for iter.IsValid() {
+		assert.Equal(t, datas[i].key, iter.Key())
+		assert.Equal(t, datas[i].val, iter.Value())
+		t.Log(iter.Key())
+		t.Log(string(iter.Value()))
+		assert.Nil(t, iter.Next())
+		i++
+	}
+
+	iter, err = tx6.Iter("g", "y")
+	assert.Nil(t, err)
+	assert.False(t, iter.IsValid())
 }