Return cursor index (#98)

This PR adds `Index()` function to the transaction, returning the
current cursor index.

Author: kelindar

txn.go

@@ -89,6 +89,11 @@ type Txn struct {
 	reader  *commit.Reader   // The commit reader to re-use
 }
 
+// Index returns the current index
+func (txn *Txn) Index() uint32 {
+	return txn.cursor
+}
+
 // Reset resets the transaction state so it can be used again.
 func (txn *Txn) reset() {
 	for i := range txn.updates {

txn_row.go

@@ -15,6 +15,11 @@ type Row struct {
 	txn *Txn
 }
 
+// Index returns the index of the row
+func (r Row) Index() uint32 {
+	return r.txn.Index()
+}
+
 // --------------------------- Numbers ----------------------------
 
 // Int loads a int value at a particular column

txn_test.go

@@ -5,12 +5,12 @@ package column
 
 import (
 	"fmt"
+	"strconv"
 	"sync"
 	"testing"
-	"strconv"
 
-	"github.com/kelindar/xxrand"
 	"github.com/kelindar/column/commit"
+	"github.com/kelindar/xxrand"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -283,46 +283,47 @@ func TestSortIndex(t *testing.T) {
 	})
 
 	// Inserts
-	c.Insert(func (r Row) error {
+	c.Insert(func(r Row) error {
 		r.SetString("col1", "bob")
 		return nil
 	})
-	c.Insert(func (r Row) error {
+	c.Insert(func(r Row) error {
 		r.SetString("col1", "carter")
 		return nil
 	})
-	c.Insert(func (r Row) error {
+	c.Insert(func(r Row) error {
 		r.SetString("col1", "dan")
 		return nil
 	})
-	c.Insert(func (r Row) error {
+	c.Insert(func(r Row) error {
 		r.SetString("col1", "alice")
 		return nil
 	})
-	
+
 	// Update
 	assert.NoError(t, c.QueryAt(3, func(r Row) error {
+		assert.Equal(t, uint32(3), r.Index())
 		r.SetString("col1", "rob")
 		return nil
 	}))
 	assert.Equal(t, 4, indexCol.Column.(*columnSortIndex).btree.Len())
-	
+
 	// Delete
 	assert.Equal(t, true, c.DeleteAt(1))
 	assert.Equal(t, 3, indexCol.Column.(*columnSortIndex).btree.Len())
 
 	// Range
-	assert.Error(t, c.Query(func (txn *Txn) error {
-		return txn.Ascend("nonexistent", func (i uint32) {
+	assert.Error(t, c.Query(func(txn *Txn) error {
+		return txn.Ascend("nonexistent", func(i uint32) {
 			return
 		})
 	}))
 
 	var res [3]string
 	var resN int = 0
-	c.Query(func (txn *Txn) error {
+	c.Query(func(txn *Txn) error {
 		col1 := txn.String("col1")
-		return txn.Ascend("sortedCol1", func (i uint32) {
+		return txn.Ascend("sortedCol1", func(i uint32) {
 			name, _ := col1.Get()
 			res[resN] = name
 			resN++
@@ -341,16 +342,16 @@ func TestSortIndexLoad(t *testing.T) {
 
 	checkN := 0
 	checks := map[int]string{
-		4: "Buckner Frazier",
+		4:  "Buckner Frazier",
 		16: "Marla Todd",
 		30: "Shelly Kirk",
 		35: "out of range",
 	}
 
-	players.Query(func (txn *Txn) error {
+	players.Query(func(txn *Txn) error {
 		txn = txn.With("human", "mage")
 		name := txn.String("name")
-		txn.Ascend("sorted_names", func (i uint32) {
+		txn.Ascend("sorted_names", func(i uint32) {
 			n, _ := name.Get()
 			if res, exists := checks[checkN]; exists {
 				assert.Equal(t, res, n)
@@ -365,7 +366,7 @@ func TestSortIndexLoad(t *testing.T) {
 func TestSortIndexChunks(t *testing.T) {
 	N := 100_000
 	obj := map[string]any{
-		"name": "1",
+		"name":    "1",
 		"balance": 12.5,
 	}
 
@@ -374,19 +375,19 @@ func TestSortIndexChunks(t *testing.T) {
 	players.CreateSortIndex("sorted_names", "name")
 
 	for i := 0; i < N; i++ {
-		players.Insert(func (r Row) error {
+		players.Insert(func(r Row) error {
 			return r.SetMany(map[string]any{
-				"name": strconv.Itoa(i),
+				"name":    strconv.Itoa(i),
 				"balance": float64(i) + 0.5,
 			})
 		})
 	}
 
-	players.Query(func (txn *Txn) error {
+	players.Query(func(txn *Txn) error {
 		name := txn.String("name")
-		txn.Ascend("sorted_names", func (i uint32) {
+		txn.Ascend("sorted_names", func(i uint32) {
 			n, _ := name.Get()
-			if i % 400 == 0 {
+			if i%400 == 0 {
 				nInt, _ := strconv.Atoi(n)
 				assert.Equal(t, nInt, int(i))
 			}
@@ -402,12 +403,12 @@ func TestSortIndexChunks(t *testing.T) {
 
 	// Do the same test as before at the same time as other updates
 	go func() {
-		players.Query(func (txn *Txn) error {
+		players.Query(func(txn *Txn) error {
 			name := txn.String("name")
 			order.Done() // Ensure this txn begins before update
-			txn.Ascend("sorted_names", func (i uint32) {
+			txn.Ascend("sorted_names", func(i uint32) {
 				n, _ := name.Get()
-				if i % 400 == 0 {
+				if i%400 == 0 {
 					nInt, _ := strconv.Atoi(n)
 					assert.Equal(t, nInt, int(i))
 				}
@@ -416,17 +417,17 @@ func TestSortIndexChunks(t *testing.T) {
 		})
 		wg.Done()
 	}()
-	
+
 	go func() {
-		order.Wait() // Wait for scan to begin
-		idx1 := xxrand.Uint32n(uint32(N / 400)) * 400 // hit checked idxs only
-		idx2 := xxrand.Uint32n(uint32(N / 400)) * 400
-		players.Insert(func (r Row) error {
+		order.Wait()                                // Wait for scan to begin
+		idx1 := xxrand.Uint32n(uint32(N/400)) * 400 // hit checked idxs only
+		idx2 := xxrand.Uint32n(uint32(N/400)) * 400
+		players.Insert(func(r Row) error {
 			r.SetString("name", "new")
 			r.SetFloat64("balance", 43.2)
 			return nil
 		})
-		players.QueryAt(idx1, func (r Row) error {
+		players.QueryAt(idx1, func(r Row) error {
 			r.SetString("name", "updated")
 			return nil
 		})