[GitHub] [iotdb] CRZbulabula commented on a diff in pull request #10896: [IOTDB-6121] Consensus layer interface and exception handling refactoring

["CRZbulabula (via GitHub)" <gi...@apache.org>]

CRZbulabula commented on code in PR #10896:
URL: https://github.com/apache/iotdb/pull/10896#discussion_r1301660915


##########
iotdb-core/consensus/src/main/java/org/apache/iotdb/consensus/IConsensus.java:
##########
@@ -19,137 +19,179 @@
 
 package org.apache.iotdb.consensus;
 
+import org.apache.iotdb.common.rpc.thrift.TSStatus;
 import org.apache.iotdb.commons.consensus.ConsensusGroupId;
+import org.apache.iotdb.consensus.common.DataSet;
 import org.apache.iotdb.consensus.common.Peer;
 import org.apache.iotdb.consensus.common.request.IConsensusRequest;
-import org.apache.iotdb.consensus.common.response.ConsensusGenericResponse;
-import org.apache.iotdb.consensus.common.response.ConsensusReadResponse;
-import org.apache.iotdb.consensus.common.response.ConsensusWriteResponse;
 import org.apache.iotdb.consensus.exception.ConsensusException;
+import org.apache.iotdb.consensus.exception.ConsensusGroupAlreadyExistException;
+import org.apache.iotdb.consensus.exception.ConsensusGroupNotExistException;
+import org.apache.iotdb.consensus.exception.IllegalPeerEndpointException;
+import org.apache.iotdb.consensus.exception.IllegalPeerNumException;
+import org.apache.iotdb.consensus.exception.PeerAlreadyInConsensusGroupException;
+import org.apache.iotdb.consensus.exception.PeerNotInConsensusGroupException;
 
 import javax.annotation.concurrent.ThreadSafe;
 
 import java.io.IOException;
 import java.util.List;
 
-/** Consensus module base class. */
+/** Consensus module base interface. */
 @ThreadSafe
 public interface IConsensus {
 
+  /**
+   * Start the consensus module.
+   *
+   * @throws IOException when start consensus errors
+   */
   void start() throws IOException;
 
+  /**
+   * Stop the consensus module.
+   *
+   * @throws IOException when stop consensus errors
+   */
   void stop() throws IOException;
 
-  // write API
-  ConsensusWriteResponse write(ConsensusGroupId groupId, IConsensusRequest request);
+  /**
+   * Write data to the corresponding consensus group.
+   *
+   * @param groupId the consensus group this request belongs
+   * @param request write request
+   * @return write result
+   * @throws ConsensusGroupNotExistException when the specified consensus group doesn't exist
+   * @throws ConsensusException when write doesn't success with other reasons
+   */
+  TSStatus write(ConsensusGroupId groupId, IConsensusRequest request) throws ConsensusException;
 
-  // read API
-  ConsensusReadResponse read(ConsensusGroupId groupId, IConsensusRequest request);
+  /**
+   * Read data from the corresponding consensus group.
+   *
+   * @param groupId the consensus group this request belongs
+   * @param request read request
+   * @return read result
+   * @throws ConsensusGroupNotExistException when the specified consensus group doesn't exist
+   * @throws ConsensusException when read doesn't success with other reasons
+   */
+  DataSet read(ConsensusGroupId groupId, IConsensusRequest request) throws ConsensusException;
 
   // multi consensus group API
 
   /**
    * Require the <em>local node</em> to create a Peer and become a member of the given consensus
    * group. This node will prepare and initialize local statemachine {@link IStateMachine} and other
-   * data structures. After this method returns, we can call {@link #addPeer(ConsensusGroupId,
+   * data structures. After this method returns, we can call {@link #addRemotePeer(ConsensusGroupId,
    * Peer)} to notify original group that this new Peer is prepared to be added into the latest
-   * configuration. createPeer should be called on a node that does not contain any peer of the
+   * configuration. createLocalPeer should be called on a node that does not contain any peer of the
    * consensus group, to avoid one node having more than one replica.
    *
-   * @param groupId the consensus group this Peer belongs
+   * @param groupId the consensus group this peer belongs
    * @param peers other known peers in this group
+   * @throws ConsensusGroupAlreadyExistException when the specified consensus group already exists
+   * @throws IllegalPeerNumException when the peer num is illegal. The exception is that it is legal
+   *     to pass an empty list for RaftConsensus
+   * @throws IllegalPeerEndpointException when peers don't contain local node. The exception is that
+   *     it is legal to pass an empty list for RaftConsensus
+   * @throws ConsensusException when createLocalPeer doesn't success with other reasons
    */
-  ConsensusGenericResponse createPeer(ConsensusGroupId groupId, List<Peer> peers);
+  void createLocalPeer(ConsensusGroupId groupId, List<Peer> peers) throws ConsensusException;
 
   /**
    * When the <em>local node</em> is no longer a member of the given consensus group, call this
    * method to do cleanup works. This method will close local statemachine {@link IStateMachine},
-   * delete local data and do other cleanup works. Be sure this method is called after successfully
-   * removing this peer from current consensus group configuration (by calling {@link
-   * #removePeer(ConsensusGroupId, Peer)} or {@link #changePeer(ConsensusGroupId, List)}).
+   * delete local data and do other cleanup works. deleteLocalPeer should be called after
+   * successfully removing this peer from current consensus group configuration (by calling {@link
+   * #removeRemotePeer(ConsensusGroupId, Peer)}).
    *
-   * @param groupId the consensus group this Peer used to belong
+   * @param groupId the consensus group this peer used to belong
+   * @throws ConsensusGroupAlreadyExistException when the specified consensus group doesn't exist

Review Comment:
   ```suggestion
      * @throws ConsensusGroupDoesNotExistException when the specified consensus group doesn't exist
   ```



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