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feat: add tree node encode/decode (#8)
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,83 @@ | ||
package btree | ||
|
||
import ( | ||
"io" | ||
|
||
"github.com/kevmo314/appendable/pkg/encoding" | ||
) | ||
|
||
type Node struct { | ||
Size uint8 | ||
Keys [8]DataPointer | ||
Children [9]uint64 | ||
Leaf bool | ||
} | ||
|
||
type DataPointer struct { | ||
RecordOffset uint64 | ||
FieldOffset, Length uint32 | ||
} | ||
|
||
func (n *Node) encode(w io.Writer) error { | ||
size := n.Size | ||
if n.Leaf { | ||
// mark the first bit | ||
size |= 1 << 7 | ||
} | ||
if err := encoding.WriteUint8(w, size); err != nil { | ||
return err | ||
} | ||
for i := 0; i < int(n.Size); i++ { | ||
if err := encoding.WriteUint64(w, n.Keys[i].RecordOffset); err != nil { | ||
return err | ||
} | ||
if err := encoding.WriteUint32(w, n.Keys[i].FieldOffset); err != nil { | ||
return err | ||
} | ||
if err := encoding.WriteUint32(w, n.Keys[i].Length); err != nil { | ||
return err | ||
} | ||
} | ||
for i := 0; i < int(n.Size)+1; i++ { | ||
if err := encoding.WriteUint64(w, n.Children[i]); err != nil { | ||
return err | ||
} | ||
} | ||
return nil | ||
} | ||
|
||
func (n *Node) decode(r io.Reader) error { | ||
size, err := encoding.ReadByte(r) | ||
if err != nil { | ||
return err | ||
} | ||
n.Size = size & 0x7f | ||
n.Leaf = size&(1<<7) != 0 | ||
for i := 0; i < int(n.Size); i++ { | ||
recordOffset, err := encoding.ReadUint64(r) | ||
if err != nil { | ||
return err | ||
} | ||
fieldOffset, err := encoding.ReadUint32(r) | ||
if err != nil { | ||
return err | ||
} | ||
length, err := encoding.ReadUint32(r) | ||
if err != nil { | ||
return err | ||
} | ||
n.Keys[i] = DataPointer{ | ||
RecordOffset: recordOffset, | ||
FieldOffset: fieldOffset, | ||
Length: length, | ||
} | ||
} | ||
for i := 0; i < int(n.Size)+1; i++ { | ||
child, err := encoding.ReadUint64(r) | ||
if err != nil { | ||
return err | ||
} | ||
n.Children[i] = child | ||
} | ||
return nil | ||
} |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,67 @@ | ||
package btree | ||
|
||
import ( | ||
"bytes" | ||
"reflect" | ||
"testing" | ||
) | ||
|
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func TestNode(t *testing.T) { | ||
t.Run("encode", func(t *testing.T) { | ||
n := &Node{ | ||
Size: 2, | ||
Keys: [8]DataPointer{ | ||
{ | ||
RecordOffset: 0, | ||
FieldOffset: 0, | ||
Length: 5, | ||
}, | ||
{ | ||
RecordOffset: 0, | ||
FieldOffset: 5, | ||
Length: 5, | ||
}, | ||
}, | ||
Children: [9]uint64{0, 1, 2}, | ||
Leaf: true, | ||
} | ||
buf := &bytes.Buffer{} | ||
if err := n.encode(buf); err != nil { | ||
t.Fatal(err) | ||
} | ||
if buf.Len() != 1+16*2+8*3 { | ||
t.Fatalf("expected buffer length to be 1+16*2+8*3, got %d", buf.Len()) | ||
} | ||
}) | ||
|
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t.Run("decode", func(t *testing.T) { | ||
n := &Node{ | ||
Size: 2, | ||
Keys: [8]DataPointer{ | ||
{ | ||
RecordOffset: 0, | ||
FieldOffset: 0, | ||
Length: 5, | ||
}, | ||
{ | ||
RecordOffset: 0, | ||
FieldOffset: 5, | ||
Length: 5, | ||
}, | ||
}, | ||
Children: [9]uint64{0, 1, 2}, | ||
Leaf: true, | ||
} | ||
buf := &bytes.Buffer{} | ||
if err := n.encode(buf); err != nil { | ||
t.Fatal(err) | ||
} | ||
m := &Node{} | ||
if err := m.decode(buf); err != nil { | ||
t.Fatal(err) | ||
} | ||
if !reflect.DeepEqual(n, m) { | ||
t.Fatalf("expected decoded node to be equal to original node") | ||
} | ||
}) | ||
} |
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