Spring Cloud 2.2.2 源码之六十七nacos的raft选举原理解析二

raft竞选基本流程

RaftCore的HeartBeat心跳

我们可以看到，心跳也有超时时间，到了后重置然后发心跳。

@Override
        public void run() {
            try {

                if (!peers.isReady()) {
                    return;
                }

                RaftPeer local = peers.local();
                local.heartbeatDueMs -= GlobalExecutor.TICK_PERIOD_MS;
                if (local.heartbeatDueMs > 0) {
                    return;
                }
                //重置心跳任期
                local.resetHeartbeatDue();

                sendBeat();
            } catch (Exception e) {
                Loggers.RAFT.warn("[RAFT] error while sending beat {}", e);
            }

        }

RaftCore的HeartBeat心跳

但是可惜的是集群环境不是leader不能发，所以只有选为leader的那个结点才会发。每次发后会刷新任期时间，保证不用去竞选逻辑。然后封装leader结点信息，服务数据Service和InstanceList的key等信息，发送给其他结点。收到响应后异步更新其他结点信息。

  public void sendBeat() throws IOException, InterruptedException {
            RaftPeer local = peers.local();
            if (local.state != RaftPeer.State.LEADER && !STANDALONE_MODE) {//不是leader且集群模式不能发
                return;
            }

            if (Loggers.RAFT.isDebugEnabled()) {
                Loggers.RAFT.debug("[RAFT] send beat with {} keys.", datums.size());
            }
            //重置任期
            local.resetLeaderDue();

            // build data
            JSONObject packet = new JSONObject();
            packet.put("peer", local);//放入leader结点信息

            JSONArray array = new JSONArray();

            if (switchDomain.isSendBeatOnly()) {
                Loggers.RAFT.info("[SEND-BEAT-ONLY] {}", String.valueOf(switchDomain.isSendBeatOnly()));
            }

            if (!switchDomain.isSendBeatOnly()) {
            	//还要带数据key
                for (Datum datum : datums.values()) {

                    JSONObject element = new JSONObject();
					//加入不同类型的key
                    if (KeyBuilder.matchServiceMetaKey(datum.key)) {
                        element.put("key", KeyBuilder.briefServiceMetaKey(datum.key));
                    } else if (KeyBuilder.matchInstanceListKey(datum.key)) {
                        element.put("key", KeyBuilder.briefInstanceListkey(datum.key));
                    }
                    element.put("timestamp", datum.timestamp);

                    array.add(element);
                }
            }
			//带上数据的key
            packet.put("datums", array);
            // broadcast
            Map<String, String> params = new HashMap<String, String>(1);
            params.put("beat", JSON.toJSONString(packet));

            String content = JSON.toJSONString(params);

            ByteArrayOutputStream out = new ByteArrayOutputStream();
            GZIPOutputStream gzip = new GZIPOutputStream(out);
            gzip.write(content.getBytes(StandardCharsets.UTF_8));
            gzip.close();

            byte[] compressedBytes = out.toByteArray();
            String compressedContent = new String(compressedBytes, StandardCharsets.UTF_8);

            if (Loggers.RAFT.isDebugEnabled()) {
                Loggers.RAFT.debug("raw beat data size: {}, size of compressed data: {}",
                    content.length(), compressedContent.length());
            }
            //发送给除了自己以外的
            for (final String server : peers.allServersWithoutMySelf()) {
                try {
                    final String url = buildURL(server, API_BEAT);
                    if (Loggers.RAFT.isDebugEnabled()) {
                        Loggers.RAFT.debug("send beat to server " + server);
                    }
                    HttpClient.asyncHttpPostLarge(url, null, compressedBytes, new AsyncCompletionHandler<Integer>() {
                        @Override
                        public Integer onCompleted(Response response) throws Exception {
                            if (response.getStatusCode() != HttpURLConnection.HTTP_OK) {
                                Loggers.RAFT.error("NACOS-RAFT beat failed: {}, peer: {}",
                                    response.getResponseBody(), server);
                                MetricsMonitor.getLeaderSendBeatFailedException().increment();
                                return 1;
                            }
                            //收到响应就添加RaftPeer
                            peers.update(JSON.parseObject(response.getResponseBody(), RaftPeer.class));
                            if (Loggers.RAFT.isDebugEnabled()) {
                                Loggers.RAFT.debug("receive beat response from: {}", url);
                            }
                            return 0;
                        }

                        @Override
                        public void onThrowable(Throwable t) {
                            Loggers.RAFT.error("NACOS-RAFT error while sending heart-beat to peer: {} {}", server, t);
                            MetricsMonitor.getLeaderSendBeatFailedException().increment();
                        }
                    });
                } catch (Exception e) {
                    Loggers.RAFT.error("error while sending heart-beat to peer: {} {}", server, e);
                    MetricsMonitor.getLeaderSendBeatFailedException().increment();
                }
            }

        }

RaftPeerSet的update更新结点信息

其实就是新的结点信息覆盖旧的。

    public RaftPeer update(RaftPeer peer) {
        peers.put(peer.ip, peer);
        return peer;
    }

然后就是其他结点收到心跳后的处理，我们下次说吧。

好了，今天就到这里了，希望对学习理解有帮助，大神看见勿喷，仅为自己的学习理解，能力有限，请多包涵。