Add replication stop mechanism

replication.go

@@ -148,14 +148,27 @@ func (c *Conn) SendStandbyStatus(k *StandbyStatus) (err error) {
 
 	_, err = c.conn.Write(writeBuf.buf)
 	if err != nil {
-		fmt.Printf("Error sending standby status %v\n", err)
 		c.die(err)
 	}
-	fmt.Printf("Write complete, wal position is %s\n", FormatLsn(k.WalApplyPosition))
 
 	return
 }
 
+// Send the message to formally stop the replication stream. This
+// is done before calling Close() during a clean shutdown.
+func (c *Conn) StopReplication() (err error) {
+	writeBuf := newWriteBuf(c, copyDone)
+
+	writeBuf.closeMsg()
+
+	_, err = c.conn.Write(writeBuf.buf)
+	if err != nil {
+		c.die(err)
+	}
+	return
+}
+
+
 func (c *Conn) readReplicationMessage() (r *ReplicationMessage, err error) {
 	var t byte
 	var reader *msgReader
@@ -217,6 +230,9 @@ func (c *Conn) readReplicationMessage() (r *ReplicationMessage, err error) {
 // There is also a condition (during startup) which can cause both the replication message
 // to return as nil as well as the error, which is a normal part of the replication protocol
 // startup. It's important the client correctly handle (ignore) this scenario.
+//
+// This returns pgx.ErrNotificationTimeout when there is no replication message by the specified
+// duration.
 func (c *Conn) WaitForReplicationMessage(timeout time.Duration) (r *ReplicationMessage, err error) {
 	var zeroTime time.Time
 

replication_test.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 	"testing"
 	"time"
+	"reflect"
 )
 
 // This function uses a postgresql 9.6 specific column
@@ -92,6 +93,11 @@ func TestSimpleReplicationConnection(t *testing.T) {
 		var message *pgx.ReplicationMessage
 
 		message, err = replicationConn.WaitForReplicationMessage(time.Duration(1 * time.Second))
+		if err != nil {
+			if err != pgx.ErrNotificationTimeout {
+				t.Fatalf("Replication failed: %v %s", err, reflect.TypeOf(err))
+			}
+		}
 		if message != nil {
 			if message.WalMessage != nil {
 				// The waldata payload with the test_decoding plugin looks like:
@@ -144,6 +150,7 @@ func TestSimpleReplicationConnection(t *testing.T) {
 	// position, which should then be reflected if we fetch out our current wal position
 	// for the slot
 	replicationConn.SendStandbyStatus(pgx.NewStandbyStatus(maxWal))
+	replicationConn.StopReplication()
 
 	err = replicationConn.Close()
 	if err != nil {

stdlib/sql_test.go

@@ -30,7 +30,7 @@ func ensureConnValid(t *testing.T, db *sql.DB) {
 
 	rows, err := db.Query("select generate_series(1,$1)", 10)
 	if err != nil {
-		t.Fatalf("db.Query failed: ", err)
+		t.Fatalf("db.Query failed: %v", err)
 	}
 	defer rows.Close()
 
@@ -42,7 +42,7 @@ func ensureConnValid(t *testing.T, db *sql.DB) {
 	}
 
 	if rows.Err() != nil {
-		t.Fatalf("db.Query failed: ", err)
+		t.Fatalf("db.Query failed: %v", err)
 	}
 
 	if rowCount != 10 {