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本篇内容主要讲解“nacos RaftCore中MasterElection的原理及应用”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“nacos RaftCore中MasterElection的原理及应用”吧!
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本文主要研究一下nacos RaftCore的MasterElection
nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/consistency/persistent/raft/RaftCore.java
@Component
public class RaftCore {
//......
@PostConstruct
public void init() throws Exception {
Loggers.RAFT.info("initializing Raft sub-system");
executor.submit(notifier);
long start = System.currentTimeMillis();
raftStore.loadDatums(notifier, datums);
setTerm(NumberUtils.toLong(raftStore.loadMeta().getProperty("term"), 0L));
Loggers.RAFT.info("cache loaded, datum count: {}, current term: {}", datums.size(), peers.getTerm());
while (true) {
if (notifier.tasks.size() <= 0) {
break;
}
Thread.sleep(1000L);
}
initialized = true;
Loggers.RAFT.info("finish to load data from disk, cost: {} ms.", (System.currentTimeMillis() - start));
GlobalExecutor.registerMasterElection(new MasterElection());
GlobalExecutor.registerHeartbeat(new HeartBeat());
Loggers.RAFT.info("timer started: leader timeout ms: {}, heart-beat timeout ms: {}",
GlobalExecutor.LEADER_TIMEOUT_MS, GlobalExecutor.HEARTBEAT_INTERVAL_MS);
}
//......
}RaftCore的init方法通过GlobalExecutor.registerMasterElection(new MasterElection())注册了MasterElection
nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/misc/GlobalExecutor.java
public class GlobalExecutor {
//......
public static final long TICK_PERIOD_MS = TimeUnit.MILLISECONDS.toMillis(500L);
public static void registerMasterElection(Runnable runnable) {
executorService.scheduleAtFixedRate(runnable, 0, TICK_PERIOD_MS, TimeUnit.MILLISECONDS);
}
//......
}registerMasterElection方法每隔TICK_PERIOD_MS毫秒调度一次runnable
nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/consistency/persistent/raft/RaftCore.java
public class MasterElection implements Runnable {
@Override
public void run() {
try {
if (!peers.isReady()) {
return;
}
RaftPeer local = peers.local();
local.leaderDueMs -= GlobalExecutor.TICK_PERIOD_MS;
if (local.leaderDueMs > 0) {
return;
}
// reset timeout
local.resetLeaderDue();
local.resetHeartbeatDue();
sendVote();
} catch (Exception e) {
Loggers.RAFT.warn("[RAFT] error while master election {}", e);
}
}
public void sendVote() {
RaftPeer local = peers.get(NetUtils.localServer());
Loggers.RAFT.info("leader timeout, start voting,leader: {}, term: {}",
JSON.toJSONString(getLeader()), local.term);
peers.reset();
local.term.incrementAndGet();
local.voteFor = local.ip;
local.state = RaftPeer.State.CANDIDATE;
Map params = new HashMap<>(1);
params.put("vote", JSON.toJSONString(local));
for (final String server : peers.allServersWithoutMySelf()) {
final String url = buildURL(server, API_VOTE);
try {
HttpClient.asyncHttpPost(url, null, params, new AsyncCompletionHandler() {
@Override
public Integer onCompleted(Response response) throws Exception {
if (response.getStatusCode() != HttpURLConnection.HTTP_OK) {
Loggers.RAFT.error("NACOS-RAFT vote failed: {}, url: {}", response.getResponseBody(), url);
return 1;
}
RaftPeer peer = JSON.parseObject(response.getResponseBody(), RaftPeer.class);
Loggers.RAFT.info("received approve from peer: {}", JSON.toJSONString(peer));
peers.decideLeader(peer);
return 0;
}
});
} catch (Exception e) {
Loggers.RAFT.warn("error while sending vote to server: {}", server);
}
}
}
} MasterElection实现了Runnable方法，其run方法在peers都是ready而且local.leaderDueMs减去TICK_PERIOD_MS小于等于0的时候会开始选举；它首先resetLeaderDue及resetHeartbeatDue，然后执行sendVote方法；sendVote方法首先重置peers，递增localPeer的term，并设置voteFor为自己，然后更新state为RaftPeer.State.CANDIDATE，最后遍历peers.allServersWithoutMySelf()，将自己的vote信息异步post给其他peer；如果其他peer返回成功则执行peers.decideLeader(peer)，返回1，否则返回0
RaftCore的init方法通过GlobalExecutor.registerMasterElection(new MasterElection())注册了MasterElection；registerMasterElection方法每隔TICK_PERIOD_MS毫秒调度一次；MasterElection实现了Runnable方法，其run方法在peers都是ready而且local.leaderDueMs减去TICK_PERIOD_MS小于等于0的时候会开始选举；它首先resetLeaderDue及resetHeartbeatDue，然后执行sendVote方法
到此，相信大家对“nacos RaftCore中MasterElection的原理及应用”有了更深的了解，不妨来实际操作一番吧！这里是创新互联网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！