Implement timeouts and graceful shutdown

reader/enhanced_reader.go

@@ -59,8 +59,8 @@ func (r *EnhancedReader) WhitelistTables(database string, tables ...string) erro
 }
 
 // ReadEvent reads next event from the binary log.
-func (r *EnhancedReader) ReadEvent() (*Event, error) {
-	evt, err := r.reader.ReadEvent()
+func (r *EnhancedReader) ReadEvent(ctx context.Context) (*Event, error) {
+	evt, err := r.reader.ReadEvent(ctx)
 	if err != nil {
 		return nil, err
 	}
@@ -78,30 +78,8 @@ func (r *EnhancedReader) ReadEvent() (*Event, error) {
 // NextRowsEvent returns the next rows event for a whitelisted table. It blocks
 // until next event is received or context is cancelled.
 func (r *EnhancedReader) NextRowsEvent(ctx context.Context) (*EnhancedRowsEvent, error) {
-	evtch := make(chan *EnhancedRowsEvent)
-	errch := make(chan error)
-	go func() {
-		evt, err := r.nextRowsEvent()
-		if err != nil {
-			errch <- err
-		} else {
-			evtch <- evt
-		}
-	}()
-
-	select {
-	case evt := <-evtch:
-		return evt, nil
-	case err := <-errch:
-		return nil, err
-	case <-ctx.Done():
-		return nil, nil
-	}
-}
-
-func (r *EnhancedReader) nextRowsEvent() (*EnhancedRowsEvent, error) {
 	for {
-		evt, err := r.reader.ReadEvent()
+		evt, err := r.reader.ReadEvent(ctx)
 		if err != nil {
 			return nil, err
 		}

reader/reader.go

@@ -1,6 +1,8 @@
 package reader
 
 import (
+	"context"
+
 	"github.com/juju/errors"
 	"github.com/localhots/bocadillo/binlog"
 	"github.com/localhots/bocadillo/reader/slave"
@@ -61,8 +63,8 @@ func New(dsn string, sc slave.Config) (*Reader, error) {
 }
 
 // ReadEvent reads next event from the binary log.
-func (r *Reader) ReadEvent() (*Event, error) {
-	connBuff, err := r.conn.ReadPacket()
+func (r *Reader) ReadEvent(ctx context.Context) (*Event, error) {
+	connBuff, err := r.conn.ReadPacket(ctx)
 	if err != nil {
 		return nil, errors.Annotate(err, "read next event")
 	}

reader/slave/slave_conn.go

@@ -1,6 +1,7 @@
 package slave
 
 import (
+	"context"
 	"database/sql/driver"
 	"fmt"
 	"io"
@@ -65,8 +66,8 @@ func Connect(dsn string, conf Config) (*Conn, error) {
 
 // ReadPacket reads next packet from the server and processes the first status
 // byte.
-func (c *Conn) ReadPacket() ([]byte, error) {
-	data, err := c.conn.ReadPacket()
+func (c *Conn) ReadPacket(ctx context.Context) ([]byte, error) {
+	data, err := c.conn.ReadPacket(ctx)
 	if err != nil {
 		return nil, err
 	}