fix increase default BufferSize for bufio.Scanner (minio#1272)

Use a higher buffer to handle proxy caching
issues might occur.

api-notification.go

@@ -138,6 +138,8 @@ type NotificationInfo struct {
 // ListenBucketNotification - listen on bucket notifications.
 func (c Client) ListenBucketNotification(bucketName, prefix, suffix string, events []string, doneCh <-chan struct{}) <-chan NotificationInfo {
 	notificationInfoCh := make(chan NotificationInfo, 1)
+	const notificationCapacity = 1024 * 1024
+	notificationEventBuffer := make([]byte, notificationCapacity)
 	// Only success, start a routine to start reading line by line.
 	go func(notificationInfoCh chan<- NotificationInfo) {
 		defer close(notificationInfoCh)
@@ -198,6 +200,10 @@ func (c Client) ListenBucketNotification(bucketName, prefix, suffix string, even
 			// Initialize a new bufio scanner, to read line by line.
 			bio := bufio.NewScanner(resp.Body)
 
+			// Use a higher buffer to support unexpected
+			// caching done by proxies
+			bio.Buffer(notificationEventBuffer, notificationCapacity)
+
 			// Unmarshal each line, returns marshalled values.
 			for bio.Scan() {
 				var notificationInfo NotificationInfo