meta admin (#2836)

server/src/main/java/com/alibaba/otter/canal/admin/CanalAdmin.java

@@ -115,4 +115,11 @@ public interface CanalAdmin {
      * @return 日志信息
      */
     String instanceLog(String destination, String fileName, int lines);
+
+    /**
+     * 获取meta
+     * @param destination
+     * @return
+     */
+    String instanceMeta(String destination,String fileName);
 }

server/src/main/java/com/alibaba/otter/canal/admin/handler/SessionHandler.java

@@ -116,6 +116,9 @@ public class SessionHandler extends SimpleChannelHandler {
                                 message = canalAdmin.instanceLog(destination, file, count);
                             }
                             break;
+                        case "meta":
+                            message = canalAdmin.instanceMeta(destination, file);
+                            break;
                         default:
                             byte[] errorBytes = AdminNettyUtils.errorPacket(301,
                                 MessageFormatter.format("LogAdmin type={} is unknown", type).getMessage());