Use result readers in next/get fashion

pgconn/pgconn.go

@@ -538,10 +538,9 @@ type PgResultReader struct {
 	cleanupContext     func()
 }
 
-// GetResult returns a PgResultReader for the next result. If all results are consumed it returns nil. If an error
+// NextResult reads until a result is ready to be read or no results are pending. Returns true if a result is available.
-// occurs it will be reported on the returned PgResultReader. Returned PgResultReader is only valid until next call of
+// Use ResultReader() to acquire a reader for the result.
-// GetResult.
+func (pgConn *PgConn) NextResult(ctx context.Context) bool {
-func (pgConn *PgConn) GetResult(ctx context.Context) *PgResultReader {
 	cleanupContext := contextDoneToConnDeadline(ctx, pgConn.conn)
 
 	for pgConn.pendingReadyForQueryCount > 0 {
@@ -549,29 +548,34 @@ func (pgConn *PgConn) GetResult(ctx context.Context) *PgResultReader {
 		if err != nil {
 			cleanupContext()
 			pgConn.resultReader = PgResultReader{pgConn: pgConn, ctx: ctx, err: preferContextOverNetTimeoutError(ctx, err), complete: true}
-			return &pgConn.resultReader
+			return true
 		}
 
 		switch msg := msg.(type) {
 		case *pgproto3.RowDescription:
 			pgConn.resultReader = PgResultReader{pgConn: pgConn, ctx: ctx, cleanupContext: cleanupContext, fieldDescriptions: msg.Fields}
-			return &pgConn.resultReader
+			return true
 		case *pgproto3.DataRow:
 			pgConn.resultReader = PgResultReader{pgConn: pgConn, ctx: ctx, cleanupContext: cleanupContext, rowValues: msg.Values, preloadedRowValues: true}
-			return &pgConn.resultReader
+			return true
 		case *pgproto3.CommandComplete:
 			cleanupContext()
 			pgConn.resultReader = PgResultReader{pgConn: pgConn, ctx: ctx, commandTag: CommandTag(msg.CommandTag), complete: true}
-			return &pgConn.resultReader
+			return true
 		case *pgproto3.ErrorResponse:
 			cleanupContext()
 			pgConn.resultReader = PgResultReader{pgConn: pgConn, ctx: ctx, err: errorResponseToPgError(msg), complete: true}
-			return &pgConn.resultReader
+			return true
 		}
 	}
 
 	cleanupContext()
-	return nil
+	return false
+}
+
+// ResultReader returns the result reader prepared by next result. It is only valid until the result is completed.
+func (pgConn *PgConn) ResultReader() *PgResultReader {
+	return &pgConn.resultReader
 }
 
 // NextRow returns advances the PgResultReader to the next row and returns true if a row is available.
@@ -806,7 +810,8 @@ func (pgConn *PgConn) Exec(ctx context.Context, sql string) (*PgResult, error) {
 func (pgConn *PgConn) bufferLastResult(ctx context.Context) (*PgResult, error) {
 	var result *PgResult
 
-	for resultReader := pgConn.GetResult(ctx); resultReader != nil; resultReader = pgConn.GetResult(ctx) {
+	for pgConn.NextResult(ctx) {
+		resultReader := pgConn.ResultReader()
 		rows := [][][]byte{}
 		for resultReader.NextRow() {
 			row := make([][]byte, len(resultReader.Values()))

pgconn/pgconn_stress_test.go

@@ -84,10 +84,10 @@ func stressBatch(pgConn *pgconn.PgConn) error {
 	}
 
 	// Query 1
-	resultReader := pgConn.GetResult(context.Background())
+	if !pgConn.NextResult(context.Background()) {
-	if resultReader == nil {
+		return errors.New("missing result")
-		return errors.New("missing resultReader")
 	}
+	resultReader := pgConn.ResultReader()
 
 	for resultReader.NextRow() {
 	}
@@ -97,10 +97,10 @@ func stressBatch(pgConn *pgconn.PgConn) error {
 	}
 
 	// Query 2
-	resultReader = pgConn.GetResult(context.Background())
+	if !pgConn.NextResult(context.Background()) {
-	if resultReader == nil {
+		return errors.New("missing result")
-		return errors.New("missing resultReader")
 	}
+	resultReader = pgConn.ResultReader()
 
 	for resultReader.NextRow() {
 	}
@@ -110,8 +110,7 @@ func stressBatch(pgConn *pgconn.PgConn) error {
 	}
 
 	// No more
-	resultReader = pgConn.GetResult(context.Background())
+	if pgConn.NextResult(context.Background()) {
-	if resultReader != nil {
 		return errors.New("unexpected result reader")
 	}
 
@@ -162,10 +161,10 @@ func stressBatchCanceled(pgConn *pgconn.PgConn) error {
 	}
 
 	// Query 1
-	resultReader := pgConn.GetResult(context.Background())
+	if !pgConn.NextResult(context.Background()) {
-	if resultReader == nil {
+		return errors.New("missing result")
-		return errors.New("missing resultReader")
 	}
+	resultReader := pgConn.ResultReader()
 
 	for resultReader.NextRow() {
 	}
@@ -176,11 +175,11 @@ func stressBatchCanceled(pgConn *pgconn.PgConn) error {
 
 	// Query 2
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Millisecond)
-	resultReader = pgConn.GetResult(ctx)
+	if !pgConn.NextResult(ctx) {
-	cancel()
+		return errors.New("missing result")
-	if resultReader == nil {
-		return errors.New("missing resultReader")
 	}
+	cancel()
+	resultReader = pgConn.ResultReader()
 
 	for resultReader.NextRow() {
 	}

pgconn/pgconn_test.go

@@ -373,8 +373,8 @@ func TestConnBatchedQueries(t *testing.T) {
 	err = pgConn.Flush(context.Background())
 
 	// "select 'SendExec 1'"
-	resultReader := pgConn.GetResult(context.Background())
+	require.True(t, pgConn.NextResult(context.Background()))
-	require.NotNil(t, resultReader)
+	resultReader := pgConn.ResultReader()
 
 	rows := [][][]byte{}
 	for resultReader.NextRow() {
@@ -391,8 +391,8 @@ func TestConnBatchedQueries(t *testing.T) {
 	assert.Nil(t, err)
 
 	// "SendExecParams 1"
-	resultReader = pgConn.GetResult(context.Background())
+	require.True(t, pgConn.NextResult(context.Background()))
-	require.NotNil(t, resultReader)
+	resultReader = pgConn.ResultReader()
 
 	rows = [][][]byte{}
 	for resultReader.NextRow() {
@@ -409,8 +409,8 @@ func TestConnBatchedQueries(t *testing.T) {
 	assert.Nil(t, err)
 
 	// "SendExecPrepared 1"
-	resultReader = pgConn.GetResult(context.Background())
+	require.True(t, pgConn.NextResult(context.Background()))
-	require.NotNil(t, resultReader)
+	resultReader = pgConn.ResultReader()
 
 	rows = [][][]byte{}
 	for resultReader.NextRow() {
@@ -427,8 +427,8 @@ func TestConnBatchedQueries(t *testing.T) {
 	assert.Nil(t, err)
 
 	// "SendExec 2"
-	resultReader = pgConn.GetResult(context.Background())
+	require.True(t, pgConn.NextResult(context.Background()))
-	require.NotNil(t, resultReader)
+	resultReader = pgConn.ResultReader()
 
 	rows = [][][]byte{}
 	for resultReader.NextRow() {
@@ -445,8 +445,8 @@ func TestConnBatchedQueries(t *testing.T) {
 	assert.Nil(t, err)
 
 	// "SendExecParams 2"
-	resultReader = pgConn.GetResult(context.Background())
+	require.True(t, pgConn.NextResult(context.Background()))
-	require.NotNil(t, resultReader)
+	resultReader = pgConn.ResultReader()
 
 	rows = [][][]byte{}
 	for resultReader.NextRow() {
@@ -463,8 +463,7 @@ func TestConnBatchedQueries(t *testing.T) {
 	assert.Nil(t, err)
 
 	// Done
-	resultReader = pgConn.GetResult(context.Background())
+	require.False(t, pgConn.NextResult(context.Background()))
-	assert.Nil(t, resultReader)
 }
 
 func TestConnRecoverFromTimeout(t *testing.T) {
@@ -505,7 +504,8 @@ func TestConnCancelQuery(t *testing.T) {
 	err = pgConn.CancelRequest(context.Background())
 	require.Nil(t, err)
 
-	_, err = pgConn.GetResult(context.Background()).Close()
+	require.True(t, pgConn.NextResult(context.Background()))
+	_, err = pgConn.ResultReader().Close()
 	if err, ok := err.(*pgconn.PgError); ok {
 		assert.Equal(t, "57014", err.Code)
 	} else {