(fix) peer context should not be shared between connections, see #461 (#528)

* (fix) peer context should not be shared between connections, see #461

* (feat) minor change

Author: killme2008

jraft-core/src/main/java/com/alipay/sofa/jraft/rpc/Connection.java

@@ -17,6 +17,8 @@
 package com.alipay.sofa.jraft.rpc;
 
 /**
+ *
+ * RPC connection
  * @author jiachun.fjc
  */
 public interface Connection {
@@ -37,6 +39,16 @@ public interface Connection {
      */
     void setAttribute(final String key, final Object value);
 
+    /**
+     * Set the attribute to the connection if the key's item doesn't exist, otherwise returns the present item.
+     *
+     * @param key   the attribute key
+     * @param value the attribute value
+     * @return the previous value associated with the specified key, or
+     *         <tt>null</tt> if there was no mapping for the key.
+     */
+    Object setAttributeIfAbsent(final String key, final Object value);
+
     /**
      * Close the connection.
      */

jraft-core/src/main/java/com/alipay/sofa/jraft/rpc/impl/BoltRpcServer.java

@@ -38,7 +38,7 @@ public class BoltRpcServer implements RpcServer {
 
     private final com.alipay.remoting.rpc.RpcServer rpcServer;
 
-    public BoltRpcServer(com.alipay.remoting.rpc.RpcServer rpcServer) {
+    public BoltRpcServer(final com.alipay.remoting.rpc.RpcServer rpcServer) {
         this.rpcServer = Requires.requireNonNull(rpcServer, "rpcServer");
     }
 
@@ -66,6 +66,11 @@ public Object getAttribute(final String key) {
                     return conn.getAttribute(key);
                 }
 
+                @Override
+                public Object setAttributeIfAbsent(final String key, final Object value) {
+                    return conn.setAttributeIfAbsent(key, value);
+                }
+
                 @Override
                 public void setAttribute(final String key, final Object value) {
                     conn.setAttribute(key, value);
@@ -140,14 +145,14 @@ public Executor getExecutor() {
     }
 
     public com.alipay.remoting.rpc.RpcServer getServer() {
-        return rpcServer;
+        return this.rpcServer;
     }
 
     private static class BoltConnection implements Connection {
 
         private final com.alipay.remoting.Connection conn;
 
-        private BoltConnection(com.alipay.remoting.Connection conn) {
+        private BoltConnection(final com.alipay.remoting.Connection conn) {
             this.conn = Requires.requireNonNull(conn, "conn");
         }
 
@@ -156,6 +161,11 @@ public Object getAttribute(final String key) {
             return this.conn.getAttribute(key);
         }
 
+        @Override
+        public Object setAttributeIfAbsent(final String key, final Object value) {
+            return this.conn.setAttributeIfAbsent(key, value);
+        }
+
         @Override
         public void setAttribute(final String key, final Object value) {
             this.conn.setAttribute(key, value);