finish

Signed-off-by: OneSizeFitQuorum <[email protected]>

ratis-server-api/src/main/java/org/apache/ratis/statemachine/StateMachine.java

@@ -150,6 +150,13 @@ interface EventApi {
      */
     default void notifyLeaderChanged(RaftGroupMemberId groupMemberId, RaftPeerId newLeaderId) {}
 
+    /**
+     * Notify the {@link StateMachine} that current node has become the leader and recovered successfully.
+     * Note that only leader will call this function.
+     *
+     */
+    default void notifyLeaderReady() {}
+
     /**
      * Notify the {@link StateMachine} a term-index update event.
      * This method will be invoked when a {@link MetadataProto}

ratis-server/src/main/java/org/apache/ratis/server/impl/RaftServerImpl.java

@@ -1801,7 +1801,11 @@ CompletableFuture<Message> applyLogToStateMachine(LogEntryProto next) throws Raf
       // the reply should have already been set. only need to record
       // the new conf in the metadata file and notify the StateMachine.
       state.writeRaftConfiguration(next);
-      stateMachine.event().notifyConfigurationChanged(next.getTerm(), next.getIndex(), next.getConfigurationEntry());
+      stateMachine.event().notifyConfigurationChanged(next.getTerm(), next.getIndex(),
+          next.getConfigurationEntry());
+      if (isFirstLogAppliedByCurrentLeaderInCurrentTerm(next.getTerm())) {
+        stateMachine.event().notifyLeaderReady();
+      }
     } else if (next.hasStateMachineLogEntry()) {
       // check whether there is a TransactionContext because we are the leader.
       TransactionContext trx = role.getLeaderState()
@@ -1825,6 +1829,11 @@ CompletableFuture<Message> applyLogToStateMachine(LogEntryProto next) throws Raf
     return null;
   }
 
+  boolean isFirstLogAppliedByCurrentLeaderInCurrentTerm(long term) {
+    return term != state.getLastEntry().getTerm()
+        && role.getLeaderState().map(leader -> leader.getCurrentTerm() == term).orElse(false);
+  }
+
   /**
    * The given log entry is being truncated.
    * Fail the corresponding client request, if there is any.