RATIS-2348. GrpcLogAppender may print a lot of messages in an error condition.

ratis-grpc/src/main/java/org/apache/ratis/grpc/server/GrpcLogAppender.java

@@ -73,7 +73,11 @@ public class GrpcLogAppender extends LogAppenderBase {
   private enum BatchLogKey implements BatchLogger.Key {
     RESET_CLIENT,
     INCONSISTENCY_REPLY,
-    APPEND_LOG_RESPONSE_HANDLER_ON_ERROR
+    APPEND_LOG_RESPONSE_HANDLER_ON_ERROR,
+    INSTALL_SNAPSHOT_NOTIFY,
+    INSTALL_SNAPSHOT_REPLY,
+    INSTALL_SNAPSHOT_IN_PROGRESS,
+    SNAPSHOT_UNAVAILABLE
   }
 
   public static final int INSTALL_SNAPSHOT_NOTIFICATION_INDEX = 0;
@@ -234,7 +238,7 @@ private void resetClient(AppendEntriesRequest request, Event event) {
       }
       getFollower().computeNextIndex(getNextIndexForError(nextIndex));
     } catch (IOException ie) {
-      LOG.warn(this + ": Failed to getClient for " + getFollowerId(), ie);
+      LOG.warn("{}: Failed to resetClient for {}", this, getFollowerId(), ie);
     }
   }
 
@@ -497,8 +501,8 @@ public void onNext(AppendEntriesReplyProto reply) {
       try {
         onNextImpl(request, reply);
       } catch(Exception t) {
-        LOG.error("Failed onNext request=" + request
-            + ", reply=" + ServerStringUtils.toAppendEntriesReplyString(reply), t);
+        LOG.error("Failed onNext(reply), request={}, reply={}",
+            request, ServerStringUtils.toAppendEntriesReplyString(reply), t);
       }
     }
 
@@ -573,8 +577,8 @@ private void updateNextIndex(long replyNextIndex) {
   }
 
   private class InstallSnapshotResponseHandler implements StreamObserver<InstallSnapshotReplyProto> {
-    private final String name = getFollower().getName() + "-" + JavaUtils.getClassSimpleName(getClass());
-    private final Queue<Integer> pending;
+    private final String name;
+    private final Queue<Integer> pending = new LinkedList<>();
     private final CompletableFuture<Void> done = new CompletableFuture<>();
     private final boolean isNotificationOnly;
 
@@ -583,8 +587,8 @@ private class InstallSnapshotResponseHandler implements StreamObserver<InstallSn
     }
 
     InstallSnapshotResponseHandler(boolean notifyOnly) {
-      pending = new LinkedList<>();
       this.isNotificationOnly = notifyOnly;
+      this.name = getFollower().getName() + "-InstallSnapshot" + (isNotificationOnly ? "Notification" : "");
     }
 
     void addPending(InstallSnapshotRequestProto request) {
@@ -626,8 +630,8 @@ void onFollowerCatchup(long followerSnapshotIndex) {
       final long leaderStartIndex = getRaftLog().getStartIndex();
       final long followerNextIndex = followerSnapshotIndex + 1;
       if (followerNextIndex >= leaderStartIndex) {
-        LOG.info("{}: Follower can catch up leader after install the snapshot, as leader's start index is {}",
-            this, followerNextIndex);
+        LOG.info("{}: follower nextIndex = {} >= leader startIndex = {}",
+            this, followerNextIndex, leaderStartIndex);
         notifyInstallSnapshotFinished(InstallSnapshotResult.SUCCESS, followerSnapshotIndex);
       }
     }
@@ -659,10 +663,10 @@ boolean hasAllResponse() {
 
     @Override
     public void onNext(InstallSnapshotReplyProto reply) {
-      if (LOG.isInfoEnabled()) {
-        LOG.info("{}: received {} reply {}", this, replyState.isFirstReplyReceived()? "a" : "the first",
-            ServerStringUtils.toInstallSnapshotReplyString(reply));
-      }
+      BatchLogger.print(BatchLogKey.INSTALL_SNAPSHOT_REPLY, name,
+          suffix -> LOG.info("{}: received {} reply {} {}", this,
+              replyState.isFirstReplyReceived() ? "a" : "the first",
+              ServerStringUtils.toInstallSnapshotReplyString(reply), suffix));
 
       // update the last rpc time
       getFollower().updateLastRpcResponseTime();
@@ -671,12 +675,13 @@ public void onNext(InstallSnapshotReplyProto reply) {
       final long followerSnapshotIndex;
       switch (reply.getResult()) {
         case SUCCESS:
-          LOG.info("{}: Completed InstallSnapshot. Reply: {}", this, reply);
+          LOG.info("{}: Completed", this);
           getFollower().setAttemptedToInstallSnapshot();
           removePending(reply);
           break;
         case IN_PROGRESS:
-          LOG.info("{}: InstallSnapshot in progress.", this);
+          BatchLogger.print(BatchLogKey.INSTALL_SNAPSHOT_IN_PROGRESS,  name,
+              suffix -> LOG.info("{}: in progress, {}", this, suffix));
           removePending(reply);
           break;
         case ALREADY_INSTALLED:
@@ -692,7 +697,7 @@ public void onNext(InstallSnapshotReplyProto reply) {
           onFollowerTerm(reply.getTerm());
           break;
         case CONF_MISMATCH:
-          LOG.error("{}: Configuration Mismatch ({}): Leader {} has it set to {} but follower {} has it set to {}",
+          LOG.error("{}: CONF_MISMATCH ({}): Leader {} has it set to {} but follower {} has it set to {}",
               this, RaftServerConfigKeys.Log.Appender.INSTALL_SNAPSHOT_ENABLED_KEY,
               getServer().getId(), installSnapshotEnabled, getFollowerId(), !installSnapshotEnabled);
           break;
@@ -707,17 +712,19 @@ public void onNext(InstallSnapshotReplyProto reply) {
           removePending(reply);
           break;
         case SNAPSHOT_UNAVAILABLE:
-          LOG.info("{}: Follower could not install snapshot as it is not available.", this);
+          BatchLogger.print(BatchLogKey.SNAPSHOT_UNAVAILABLE,  name,
+              suffix -> LOG.info("{}: Follower failed since the snapshot is unavailable {}", this, suffix));
           getFollower().setAttemptedToInstallSnapshot();
           notifyInstallSnapshotFinished(InstallSnapshotResult.SNAPSHOT_UNAVAILABLE, RaftLog.INVALID_LOG_INDEX);
           removePending(reply);
           break;
         case UNRECOGNIZED:
-          LOG.error("Unrecognized the reply result {}: Leader is {}, follower is {}",
-              reply.getResult(), getServer().getId(), getFollowerId());
+          LOG.error("{}: Reply result {}, {}",
+              name, reply.getResult(), ServerStringUtils.toInstallSnapshotReplyString(reply));
           break;
         case SNAPSHOT_EXPIRED:
-          LOG.warn("{}: Follower could not install snapshot as it is expired.", this);
+          LOG.warn("{}: Follower failed since the request expired, {}",
+              name, ServerStringUtils.toInstallSnapshotReplyString(reply));
         default:
           break;
       }
@@ -796,8 +803,9 @@ private void installSnapshot(SnapshotInfo snapshot) {
    * @param firstAvailable the first available log's index on the Leader
    */
   private void notifyInstallSnapshot(TermIndex firstAvailable) {
-    LOG.info("{}: notifyInstallSnapshot with firstAvailable={}, followerNextIndex={}",
-        this, firstAvailable, getFollower().getNextIndex());
+    BatchLogger.print(BatchLogKey.INSTALL_SNAPSHOT_NOTIFY, getFollower().getName(),
+        suffix -> LOG.info("{}: notifyInstallSnapshot with firstAvailable={}, followerNextIndex={} {}",
+            this, firstAvailable, getFollower().getNextIndex(), suffix));
 
     final InstallSnapshotResponseHandler responseHandler = new InstallSnapshotResponseHandler(true);
     StreamObserver<InstallSnapshotRequestProto> snapshotRequestObserver = null;