[GitHub] [ratis] szetszwo commented on a diff in pull request #798: RATIS-1759. Support client use linearizable read per request

[GitBox <gi...@apache.org>]

szetszwo commented on code in PR #798:
URL: https://github.com/apache/ratis/pull/798#discussion_r1051570139


##########
ratis-client/src/main/java/org/apache/ratis/client/api/AsyncApi.java:
##########
@@ -45,15 +45,20 @@ default CompletableFuture<RaftClientReply> sendReadOnly(Message message) {
     return sendReadOnly(message, null);
   }
 
+  default CompletableFuture<RaftClientReply> sendReadOnly(Message message, RaftPeerId server) {
+    return sendReadOnly(message, null, false);
+  }
+
   /**
    * Send the given readonly message asynchronously to the raft service.
    * Note that the reply futures are completed in the same order of the messages being sent.
    *
    * @param message The request message.
    * @param server The target server.  When server == null, send the message to the leader.
+   * @param readIndex weather use linearizable read
    * @return a future of the reply.
    */
-  CompletableFuture<RaftClientReply> sendReadOnly(Message message, RaftPeerId server);
+  CompletableFuture<RaftClientReply> sendReadOnly(Message message, RaftPeerId server, boolean readIndex);

Review Comment:
   Since the server parameter does not make sense for non-linearizable read, how about we add a new method instead?
   ```java
     /**
      * Send the given readonly message asynchronously to the raft service using non-linearizable read.
      * This method is useful when linearizable read is enabled
      * but this client prefers not using it for performance reason.
      * When linearizable read is disabled, this method is the same as {@link #sendReadOnly(Message)}. 
      *
      * @param message The request message.
      * @return a future of the reply.
      */
     CompletableFuture<RaftClientReply> sendReadOnlyNonLinearizable(Message message);
   ```



##########
ratis-proto/src/main/proto/Raft.proto:
##########
@@ -296,6 +296,10 @@ message ForwardRequestTypeProto {
 message ReadRequestTypeProto {
 }
 
+message ReadIndexRequestTypeProto {
+
+}

Review Comment:
   Let's add a field to ReadRequestTypeProto.
   ```proto
   message ReadRequestTypeProto {
     bool preferNonLinearizable = 1;
   }
   ```



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