| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.jackrabbit.oak.segment.standby.server; |
| |
| import io.netty.channel.ChannelHandlerContext; |
| import io.netty.channel.SimpleChannelInboundHandler; |
| import org.apache.jackrabbit.oak.segment.standby.codec.GetHeadRequest; |
| import org.apache.jackrabbit.oak.segment.standby.codec.GetHeadResponse; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * Handles 'get head' requests and produces 'get head' responses. A response is |
| * generated only iff the record ID of the head root state can be read. |
| */ |
| class GetHeadRequestHandler extends SimpleChannelInboundHandler<GetHeadRequest> { |
| |
| private static final Logger log = LoggerFactory.getLogger(GetHeadRequest.class); |
| |
| private final StandbyHeadReader reader; |
| |
| GetHeadRequestHandler(StandbyHeadReader reader) { |
| this.reader = reader; |
| } |
| |
| @Override |
| protected void channelRead0(ChannelHandlerContext ctx, GetHeadRequest msg) throws Exception { |
| log.debug("Reading head for client {}", msg.getClientId()); |
| |
| String id = reader.readHeadRecordId(); |
| |
| if (id == null) { |
| log.debug("Head not found, discarding request from client {}", msg.getClientId()); |
| return; |
| } |
| |
| ctx.writeAndFlush(new GetHeadResponse(msg.getClientId(), id)); |
| } |
| |
| } |