chore: add transaction support for SpannerLib

conn.go

@@ -1071,6 +1071,34 @@ func (c *conn) getBatchReadOnlyTransactionOptions() BatchReadOnlyTransactionOpti
 	return BatchReadOnlyTransactionOptions{TimestampBound: c.ReadOnlyStaleness()}
 }
 
+// BeginReadOnlyTransaction is not part of the public API of the database/sql driver.
+// It is exported for internal reasons, and may receive breaking changes without prior notice.
+//
+// BeginReadOnlyTransaction starts a new read-only transaction on this connection.
+func (c *conn) BeginReadOnlyTransaction(ctx context.Context, options *ReadOnlyTransactionOptions) (driver.Tx, error) {
+	c.withTempReadOnlyTransactionOptions(options)
+	tx, err := c.BeginTx(ctx, driver.TxOptions{ReadOnly: true})
+	if err != nil {
+		c.withTempReadOnlyTransactionOptions(nil)
+		return nil, err
+	}
+	return tx, nil
+}
+
+// BeginReadWriteTransaction is not part of the public API of the database/sql driver.
+// It is exported for internal reasons, and may receive breaking changes without prior notice.
+//
+// BeginReadWriteTransaction starts a new read/write transaction on this connection.
+func (c *conn) BeginReadWriteTransaction(ctx context.Context, options *ReadWriteTransactionOptions) (driver.Tx, error) {
+	c.withTempTransactionOptions(options)
+	tx, err := c.BeginTx(ctx, driver.TxOptions{})
+	if err != nil {
+		c.withTempTransactionOptions(nil)
+		return nil, err
+	}
+	return tx, nil
+}
+
 func (c *conn) Begin() (driver.Tx, error) {
 	return c.BeginTx(context.Background(), driver.TxOptions{})
 }
@@ -1254,18 +1282,29 @@ func (c *conn) inReadWriteTransaction() bool {
 	return false
 }
 
-func (c *conn) commit(ctx context.Context) (*spanner.CommitResponse, error) {
+// Commit is not part of the public API of the database/sql driver.
+// It is exported for internal reasons, and may receive breaking changes without prior notice.
+//
+// Commit commits the current transaction on this connection.
+func (c *conn) Commit(ctx context.Context) (*spanner.CommitResponse, error) {
 	if !c.inTransaction() {
 		return nil, status.Errorf(codes.FailedPrecondition, "this connection does not have a transaction")
 	}
 	// TODO: Pass in context to the tx.Commit() function.
 	if err := c.tx.Commit(); err != nil {
 		return nil, err
 	}
-	return c.CommitResponse()
+
+	// This will return either the commit response or nil, depending on whether the transaction was a
+	// read/write transaction or a read-only transaction.
+	return propertyCommitResponse.GetValueOrDefault(c.state), nil
 }
 
-func (c *conn) rollback(ctx context.Context) error {
+// Rollback is not part of the public API of the database/sql driver.
+// It is exported for internal reasons, and may receive breaking changes without prior notice.
+//
+// Rollback rollbacks the current transaction on this connection.
+func (c *conn) Rollback(ctx context.Context) error {
 	if !c.inTransaction() {
 		return status.Errorf(codes.FailedPrecondition, "this connection does not have a transaction")
 	}

conn_with_mockserver_test.go

@@ -82,6 +82,26 @@ func TestTwoTransactionsOnOneConn(t *testing.T) {
 	}
 }
 
+func TestTwoQueriesOnOneConn(t *testing.T) {
+	t.Parallel()
+
+	db, _, teardown := setupTestDBConnection(t)
+	defer teardown()
+	ctx := context.Background()
+
+	c, _ := db.Conn(ctx)
+	defer silentClose(c)
+
+	for range 2 {
+		r, err := c.QueryContext(context.Background(), testutil.SelectFooFromBar)
+		if err != nil {
+			t.Fatal(err)
+		}
+		_ = r.Next()
+		defer silentClose(r)
+	}
+}
+
 func TestExplicitBeginTx(t *testing.T) {
 	t.Parallel()
 

spannerlib/api/connection.go

@@ -17,6 +17,7 @@ package api
 import (
 	"context"
 	"database/sql"
+	"database/sql/driver"
 	"fmt"
 	"strings"
 	"sync"
@@ -25,6 +26,9 @@ import (
 	"cloud.google.com/go/spanner"
 	"cloud.google.com/go/spanner/apiv1/spannerpb"
 	spannerdriver "github.com/googleapis/go-sql-spanner"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
 // CloseConnection looks up the connection with the given poolId and connId and closes it.
@@ -42,6 +46,35 @@ func CloseConnection(ctx context.Context, poolId, connId int64) error {
 	return conn.close(ctx)
 }
 
+// BeginTransaction starts a new transaction on the given connection.
+// A connection can have at most one transaction at any time. This function therefore returns an error if the
+// connection has an active transaction.
+func BeginTransaction(ctx context.Context, poolId, connId int64, txOpts *spannerpb.TransactionOptions) error {
+	conn, err := findConnection(poolId, connId)
+	if err != nil {
+		return err
+	}
+	return conn.BeginTransaction(ctx, txOpts)
+}
+
+// Commit commits the current transaction on the given connection.
+func Commit(ctx context.Context, poolId, connId int64) (*spannerpb.CommitResponse, error) {
+	conn, err := findConnection(poolId, connId)
+	if err != nil {
+		return nil, err
+	}
+	return conn.commit(ctx)
+}
+
+// Rollback rollbacks the current transaction on the given connection.
+func Rollback(ctx context.Context, poolId, connId int64) error {
+	conn, err := findConnection(poolId, connId)
+	if err != nil {
+		return err
+	}
+	return conn.rollback(ctx)
+}
+
 func Execute(ctx context.Context, poolId, connId int64, executeSqlRequest *spannerpb.ExecuteSqlRequest) (int64, error) {
 	conn, err := findConnection(poolId, connId)
 	if err != nil {
@@ -59,23 +92,141 @@ type Connection struct {
 	backend *sql.Conn
 }
 
+// spannerConn is an internal interface that contains the internal functions that are used by this API.
+// It is implemented by the spannerdriver.conn struct.
+type spannerConn interface {
+	BeginReadOnlyTransaction(ctx context.Context, options *spannerdriver.ReadOnlyTransactionOptions) (driver.Tx, error)
+	BeginReadWriteTransaction(ctx context.Context, options *spannerdriver.ReadWriteTransactionOptions) (driver.Tx, error)
+	Commit(ctx context.Context) (*spanner.CommitResponse, error)
+	Rollback(ctx context.Context) error
+}
+
 type queryExecutor interface {
 	ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error)
 	QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error)
 }
 
 func (conn *Connection) close(ctx context.Context) error {
 	conn.closeResults(ctx)
+	// Rollback any open transactions on the connection.
+	_ = conn.rollback(ctx)
+
 	err := conn.backend.Close()
 	if err != nil {
 		return err
 	}
 	return nil
 }
 
+func (conn *Connection) BeginTransaction(ctx context.Context, txOpts *spannerpb.TransactionOptions) error {
+	var err error
+	if txOpts.GetReadOnly() != nil {
+		return conn.beginReadOnlyTransaction(ctx, convertToReadOnlyOpts(txOpts))
+	} else if txOpts.GetPartitionedDml() != nil {
+		err = spanner.ToSpannerError(status.Error(codes.InvalidArgument, "transaction type not supported"))
+	} else {
+		return conn.beginReadWriteTransaction(ctx, convertToReadWriteTransactionOptions(txOpts))
+	}
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (conn *Connection) beginReadOnlyTransaction(ctx context.Context, opts *spannerdriver.ReadOnlyTransactionOptions) error {
+	return conn.backend.Raw(func(driverConn any) (err error) {
+		sc, _ := driverConn.(spannerConn)
+		_, err = sc.BeginReadOnlyTransaction(ctx, opts)
+		return err
+	})
+}
+
+func (conn *Connection) beginReadWriteTransaction(ctx context.Context, opts *spannerdriver.ReadWriteTransactionOptions) error {
+	return conn.backend.Raw(func(driverConn any) (err error) {
+		sc, _ := driverConn.(spannerConn)
+		_, err = sc.BeginReadWriteTransaction(ctx, opts)
+		return err
+	})
+}
+
+func (conn *Connection) commit(ctx context.Context) (*spannerpb.CommitResponse, error) {
+	var response *spanner.CommitResponse
+	if err := conn.backend.Raw(func(driverConn any) (err error) {
+		spannerConn, _ := driverConn.(spannerConn)
+		response, err = spannerConn.Commit(ctx)
+		if err != nil {
+			return err
+		}
+		return nil
+	}); err != nil {
+		return nil, err
+	}
+
+	// The commit response is nil for read-only transactions.
+	if response == nil {
+		return nil, nil
+	}
+	// TODO: Include commit stats
+	return &spannerpb.CommitResponse{CommitTimestamp: timestamppb.New(response.CommitTs)}, nil
+}
+
+func (conn *Connection) rollback(ctx context.Context) error {
+	return conn.backend.Raw(func(driverConn any) (err error) {
+		spannerConn, _ := driverConn.(spannerConn)
+		return spannerConn.Rollback(ctx)
+	})
+}
+
+func convertToReadOnlyOpts(txOpts *spannerpb.TransactionOptions) *spannerdriver.ReadOnlyTransactionOptions {
+	return &spannerdriver.ReadOnlyTransactionOptions{
+		TimestampBound: convertTimestampBound(txOpts),
+	}
+}
+
+func convertTimestampBound(txOpts *spannerpb.TransactionOptions) spanner.TimestampBound {
+	ro := txOpts.GetReadOnly()
+	if ro.GetStrong() {
+		return spanner.StrongRead()
+	} else if ro.GetReadTimestamp() != nil {
+		return spanner.ReadTimestamp(ro.GetReadTimestamp().AsTime())
+	} else if ro.GetMinReadTimestamp() != nil {
+		return spanner.ReadTimestamp(ro.GetMinReadTimestamp().AsTime())
+	} else if ro.GetExactStaleness() != nil {
+		return spanner.ExactStaleness(ro.GetExactStaleness().AsDuration())
+	} else if ro.GetMaxStaleness() != nil {
+		return spanner.MaxStaleness(ro.GetMaxStaleness().AsDuration())
+	}
+	return spanner.TimestampBound{}
+}
+
+func convertToReadWriteTransactionOptions(txOpts *spannerpb.TransactionOptions) *spannerdriver.ReadWriteTransactionOptions {
+	readLockMode := spannerpb.TransactionOptions_ReadWrite_READ_LOCK_MODE_UNSPECIFIED
+	if txOpts.GetReadWrite() != nil {
+		readLockMode = txOpts.GetReadWrite().GetReadLockMode()
+	}
+	return &spannerdriver.ReadWriteTransactionOptions{
+		TransactionOptions: spanner.TransactionOptions{
+			IsolationLevel: txOpts.GetIsolationLevel(),
+			ReadLockMode:   readLockMode,
+		},
+	}
+}
+
+func convertIsolationLevel(level spannerpb.TransactionOptions_IsolationLevel) sql.IsolationLevel {
+	switch level {
+	case spannerpb.TransactionOptions_SERIALIZABLE:
+		return sql.LevelSerializable
+	case spannerpb.TransactionOptions_REPEATABLE_READ:
+		return sql.LevelRepeatableRead
+	}
+	return sql.LevelDefault
+}
+
 func (conn *Connection) closeResults(ctx context.Context) {
 	conn.results.Range(func(key, value interface{}) bool {
-		// TODO: Implement
+		if r, ok := value.(*rows); ok {
+			_ = r.Close(ctx)
+		}
 		return true
 	})
 }