[GitHub] [incubator-ratis] esahekmat commented on a change in pull request #60: RATIS-846: create simplest possible example, a replicated counter

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esahekmat commented on a change in pull request #60: RATIS-846: create simplest possible example, a replicated counter
URL: https://github.com/apache/incubator-ratis/pull/60#discussion_r409443045
 
 

 ##########
 File path: ratis-examples/src/main/java/org/apache/ratis/examples/counter/server/CounterServer.java
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 @@ -0,0 +1,64 @@
+package org.apache.ratis.examples.counter.server;
+
+import org.apache.ratis.conf.*;
+import org.apache.ratis.examples.counter.*;
+import org.apache.ratis.grpc.*;
+import org.apache.ratis.protocol.*;
+import org.apache.ratis.server.*;
+import org.apache.ratis.util.*;
+
+import java.io.*;
+import java.util.*;
+
+/**
+ * Simplest Ratis server, use a simple state machine {@link CounterStateMachine}
+ * which maintain a counter across multi server.
+ * This server application designed to run several times with different
+ * parameters (1,2 or 3). server addresses hard coded in {@link CounterCommon}
+ * <p>
+ * Run this application three times with three different parameter set-up a
+ * ratis cluster which maintain a counter value replicated in each server memory
+ */
+public class CounterServer {
+
+  public static void main(String[] args) throws IOException, InterruptedException {
+    if (args.length < 1) {
+      System.err.println("Usage: java -cp *.jar org.apache.ratis.examples.counter.server.CounterServer {serverIndex}");
+      System.err.println("{serverIndex} could be 1, 2 or 3");
+      System.exit(1);
+    }
+
+    //find current peer object based on application parameter
+    RaftPeer currentPeer =
+        CounterCommon.PEERS.get(Integer.parseInt(args[0]) - 1);
+
+    //create a property object
+    RaftProperties properties = new RaftProperties();
+
+    //set the storage directory (different for each peer) in RaftProperty object
+    File raftStorageDir = new File("./" + currentPeer.getId().toString());
+    RaftServerConfigKeys.setStorageDir(properties,
+        Collections.singletonList(raftStorageDir));
+
+    //set the port which server listen to in RaftProperty object
+    final int port = NetUtils.createSocketAddr(currentPeer.getAddress()).getPort();
+    GrpcConfigKeys.Server.setPort(properties, port);
+
+    //create the counter state machine which hold the counter value
+    CounterStateMachine counterStateMachine = new CounterStateMachine();
+
+    //create and start the Raft server
+    RaftServer server = RaftServer.newBuilder()
+        .setGroup(CounterCommon.RAFT_GROUP)
+        .setProperties(properties)
+        .setServerId(currentPeer.getId())
+        .setStateMachine(counterStateMachine)
+        .build();
+    server.start();
+
+    //exit when any input entered
+    Scanner scanner = new Scanner(System.in);
+    scanner.nextLine();
 
 Review comment:
   I tried this shutdown hook with no success, so I decided to go this way,
        Runtime.getRuntime().addShutdownHook(new Thread(()-> {
         try {
           server.close();
         } catch (IOException e) {
           e.printStackTrace();
         }
       }));

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