Fix swap and record index (#76)

## Bugfixes
* `Swap...` was not properly swapping when an underlying buffer was
re-allocated due to `append()`
* Index for `Record` types was not working when strings are being merged
due to the fact that it could not see the newly appended values.

## Optimizations
* When swapping strings, if the string is of exactly the same size as
before, it will be swapped in-place (same as for other values).

column_index.go

@@ -14,6 +14,7 @@ import (
 type Reader interface {
 	Index() uint32
 	String() string
+	Bytes() []byte
 	Float() float64
 	Int() int
 	Uint() uint
@@ -65,7 +66,7 @@ func (c *columnIndex) Apply(chunk commit.Chunk, r *commit.Reader) {
 	// on the actual column.
 	for r.Next() {
 		switch r.Type {
-		case commit.Put, commit.Merge:
+		case commit.Put:
 			if c.rule(r) {
 				c.fill.Set(uint32(r.Offset))
 			} else {

column_test.go

@@ -580,17 +580,30 @@ func TestRecord(t *testing.T) {
 	col.CreateColumn("ts", ForRecord(func() *time.Time {
 		return new(time.Time)
 	}))
+	col.CreateIndex("recent", "ts", func(r Reader) bool {
+		var ts time.Time
+		if err := ts.UnmarshalBinary(r.Bytes()); err == nil {
+			return ts.After(time.Unix(1667745800, 0))
+		}
+		return false
+	})
 
 	// Insert the time, it implements binary marshaler
 	idx, _ := col.Insert(func(r Row) error {
-		now := time.Unix(1667745766, 0)
+		now := time.Unix(1667745700, 0)
 		r.SetRecord("ts", &now)
 		return nil
 	})
 
+	// Index should not have any recent
+	col.Query(func(txn *Txn) error {
+		assert.Equal(t, 1, txn.Without("recent").Count())
+		return nil
+	})
+
 	// We should be able to read back the time
 	col.QueryAt(idx, func(r Row) error {
-		now := time.Unix(1667745766, 0)
+		now := time.Unix(1667745900, 0)
 		r.MergeRecord("ts", &now)
 		return nil
 	})
@@ -602,6 +615,12 @@ func TestRecord(t *testing.T) {
 		assert.Equal(t, "November", ts.(*time.Time).UTC().Month().String())
 		return nil
 	})
+
+	// Merge should have updated the index as well
+	col.Query(func(txn *Txn) error {
+		assert.Equal(t, 1, txn.With("recent").Count())
+		return nil
+	})
 }
 
 func TestRecord_Errors(t *testing.T) {
@@ -686,22 +705,31 @@ func TestNumberMerge(t *testing.T) {
 		return v
 	})))
 
+	col.CreateIndex("young", "age", func(r Reader) bool {
+		return r.Int() < 50
+	})
+
 	// Insert the time, it implements binary marshaler
 	idx, _ := col.Insert(func(r Row) error {
-		r.SetInt32("age", 10)
+		r.SetInt32("age", 100)
 		return nil
 	})
 
-	for i := 0; i < 10; i++ {
+	for i := 0; i < 7; i++ {
 		col.QueryAt(idx, func(r Row) error {
-			r.MergeInt32("age", 1)
+			r.MergeInt32("age", 10)
 			return nil
 		})
 	}
 
 	col.QueryAt(idx, func(r Row) error {
 		age, _ := r.Int32("age")
-		assert.Equal(t, int32(0), age)
+		assert.Equal(t, int32(30), age)
+		return nil
+	})
+
+	col.Query(func(txn *Txn) error {
+		assert.Equal(t, 1, txn.With("young").Count())
 		return nil
 	})
 }

commit/buffer.go

@@ -36,6 +36,24 @@ const (
 	Skip     OpType = 4 // Skips the value
 )
 
+// String returns a string representation
+func (o OpType) String() string {
+	switch o {
+	case Delete:
+		return "delete"
+	case Insert:
+		return "insert"
+	case Put:
+		return "put"
+	case Merge:
+		return "merge"
+	case Skip:
+		return "skip"
+	default:
+		return "unknown"
+	}
+}
+
 // --------------------------- Delta log ----------------------------
 
 // Buffer represents a buffer of delta operations.

commit/buffer_test.go

@@ -135,8 +135,8 @@ func run(name string, b *testing.B, count int, fn func(buf *Buffer, r *Reader))
 }
 
 func TestSizeof(t *testing.T) {
-	assert.LessOrEqual(t, int(unsafe.Sizeof(Reader{})), 80)
-	assert.LessOrEqual(t, int(unsafe.Sizeof(Buffer{})), 80)
+	assert.Equal(t, 96, int(unsafe.Sizeof(Reader{})))
+	assert.Equal(t, 80, int(unsafe.Sizeof(Buffer{})))
 }
 
 func TestReadWrite(t *testing.T) {
@@ -320,3 +320,9 @@ func FuzzBufferString(f *testing.F) {
 		assert.Equal(t, v, r.String())
 	})
 }
+
+func TestOpString(t *testing.T) {
+	for i := 0; i < 255; i++ {
+		assert.NotEmpty(t, OpType(i).String())
+	}
+}

commit/commit.go

@@ -128,8 +128,8 @@ func (c *Commit) WriteTo(dst io.Writer) (int64, error) {
 		// Write chunk information
 		offset := uint32(0)
 		reader.Range(buffer, c.Chunk, func(r *Reader) {
-			w.WriteUint32(uint32(r.Offset)) // Value
-			w.WriteUint32(offset)           // Offset
+			_ = w.WriteUint32(uint32(r.Offset)) // Value
+			_ = w.WriteUint32(offset)           // Offset
 			offset += uint32(len(r.buffer))
 		})
 
@@ -140,7 +140,7 @@ func (c *Commit) WriteTo(dst io.Writer) (int64, error) {
 
 		// Write all chunk bytes together
 		reader.Range(buffer, c.Chunk, func(r *Reader) {
-			w.Write(r.buffer)
+			_, _ = w.Write(r.buffer)
 		})
 		return nil
 	}); err != nil {