fixed issue alibaba#4864 , connector.disconnect optimize

connector/tcp-connector/src/main/java/com/alibaba/otter/canal/connector/tcp/consumer/CanalTCPConsumer.java

@@ -1,5 +1,13 @@
 package com.alibaba.otter.canal.connector.tcp.consumer;
 
+import java.net.InetSocketAddress;
+import java.net.SocketAddress;
+import java.util.List;
+import java.util.Properties;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.commons.lang.StringUtils;
+
 import com.alibaba.otter.canal.client.CanalConnector;
 import com.alibaba.otter.canal.client.impl.ClusterCanalConnector;
 import com.alibaba.otter.canal.client.impl.ClusterNodeAccessStrategy;
@@ -12,14 +20,6 @@
 import com.alibaba.otter.canal.connector.tcp.config.TCPConstants;
 import com.alibaba.otter.canal.protocol.Message;
 
-import org.apache.commons.lang.StringUtils;
-
-import java.net.InetSocketAddress;
-import java.net.SocketAddress;
-import java.util.List;
-import java.util.Properties;
-import java.util.concurrent.TimeUnit;
-
 /**
  * TCP 消费者连接器, 一个destination对应一个SPI实例
  *
@@ -99,7 +99,9 @@ public void ack() {
 
     @Override
     public void disconnect() {
-        canalConnector.unsubscribe();
+        // tcp模式下，因为是单tcp消费，避免adapter异常断开时直接unsubscribe
+        // unsubscribe发送给canal-server会导致清理cursor位点,如果此时canal-server出现重启,就会丢失binlog数据
+        // canalConnector.unsubscribe();
         canalConnector.disconnect();
     }
 }