Spring Cloud 2.2.2 源碼之六十七nacos的raft選舉原理解析二

raft競選基本流程

RaftCore的HeartBeat心跳

我們可以看到，心跳也有超時時間，到了後重置然後發心跳。

@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

但是可惜的是集羣環境不是leader不能發，所以只有選爲leader的那個結點纔會發。每次發後會刷新任期時間，保證不用去競選邏輯。然後封裝leader結點信息，服務數據Service和InstanceList的key等信息，發送給其他結點。收到響應後異步更新其他結點信息。

  public void sendBeat() throws IOException, InterruptedException {
            RaftPeer local = peers.local();
            if (local.state != RaftPeer.State.LEADER && !STANDALONE_MODE) {//不是leader且集羣模式不能發
                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結點信息

            JSONArray array = new JSONArray();

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

            if (!switchDomain.isSendBeatOnly()) {
            	//還要帶數據key
                for (Datum datum : datums.values()) {

                    JSONObject element = new JSONObject();
					//加入不同類型的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);
                }
            }
			//帶上數據的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());
            }
            //發送給除了自己以外的
            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;
                            }
                            //收到響應就添加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更新結點信息

其實就是新的結點信息覆蓋舊的。

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

然後就是其他結點收到心跳後的處理，我們下次說吧。

好了，今天就到這裏了，希望對學習理解有幫助，大神看見勿噴，僅爲自己的學習理解，能力有限，請多包涵。