Elasticsearch入门：一、单个节点的启动

    private Node stop() {
        if (!lifecycle.moveToStopped()) {
            return this;
        }
        logger.info("stopping ...");


        injector.getInstance(ResourceWatcherService.class).stop();
        injector.getInstance(HttpServerTransport.class).stop();


        injector.getInstance(SnapshotsService.class).stop();
        injector.getInstance(SnapshotShardsService.class).stop();
        // stop any changes happening as a result of cluster state changes
        injector.getInstance(IndicesClusterStateService.class).stop();
        // close discovery early to not react to pings anymore.
        // This can confuse other nodes and delay things - mostly if we're the master and we're running tests.
        injector.getInstance(Discovery.class).stop();
        // we close indices first, so operations won't be allowed on it
        injector.getInstance(ClusterService.class).stop();
        injector.getInstance(NodeConnectionsService.class).stop();
        nodeService.getMonitorService().stop();
        injector.getInstance(GatewayService.class).stop();
        injector.getInstance(SearchService.class).stop();
        injector.getInstance(TransportService.class).stop();


        pluginLifecycleComponents.forEach(LifecycleComponent::stop);
        // we should stop this last since it waits for resources to get released
        // if we had scroll searchers etc or recovery going on we wait for to finish.
        injector.getInstance(IndicesService.class).stop();
        logger.info("stopped");


        return this;
    }
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        discovery.start(); // start before cluster service so that it can set initial state on ClusterApplierService
        clusterService.start();
        assert clusterService.localNode().equals(localNodeFactory.getNode())
            : "clusterService has a different local node than the factory provided";
        transportService.acceptIncomingRequests();
        discovery.startInitialJoin();
        final TimeValue initialStateTimeout = DiscoverySettings.INITIAL_STATE_TIMEOUT_SETTING.get(settings());
        configureNodeAndClusterIdStateListener(clusterService);


        if (initialStateTimeout.millis() > 0) {
            final ThreadPool thread = injector.getInstance(ThreadPool.class);
            ClusterState clusterState = clusterService.state();
            ClusterStateObserver observer =
                new ClusterStateObserver(clusterState, clusterService, null, logger, thread.getThreadContext());


            if (clusterState.nodes().getMasterNodeId() == null) {
                logger.debug("waiting to join the cluster. timeout [{}]", initialStateTimeout);
                final CountDownLatch latch = new CountDownLatch(1);
                observer.waitForNextChange(new ClusterStateObserver.Listener() {
                    @Override
                    public void onNewClusterState(ClusterState state) { latch.countDown(); }


                    @Override
                    public void onClusterServiceClose() {
                        latch.countDown();
                    }


                    @Override
                    public void onTimeout(TimeValue timeout) {
                        logger.warn("timed out while waiting for initial discovery state - timeout: {}",
                            initialStateTimeout);
                        latch.countDown();
                    }
                }, state -> state.nodes().getMasterNodeId() != null, initialStateTimeout);


                try {
                    latch.await();
                } catch (InterruptedException e) {
                    throw new ElasticsearchTimeoutException("Interrupted while waiting for initial discovery state");
                }
            }
        }


        injector.getInstance(HttpServerTransport.class).start();
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    private DiscoveryNode findMaster() {
        logger.trace("starting to ping");
        List<ZenPing.PingResponse> fullPingResponses = pingAndWait(pingTimeout).toList();
        if (fullPingResponses == null) {
            logger.trace("No full ping responses");
            return null;
        }
        if (logger.isTraceEnabled()) {
            StringBuilder sb = new StringBuilder();
            if (fullPingResponses.size() == 0) {
                sb.append(" {none}");
            } else {
                for (ZenPing.PingResponse pingResponse : fullPingResponses) {
                    sb.append("\n\t--> ").append(pingResponse);
                }
            }
            logger.trace("full ping responses:{}", sb);
        }


        final DiscoveryNode localNode = transportService.getLocalNode();


        // add our selves
        assert fullPingResponses.stream().map(ZenPing.PingResponse::node)
            .filter(n -> n.equals(localNode)).findAny().isPresent() == false;


        fullPingResponses.add(new ZenPing.PingResponse(localNode, null, this.clusterState()));


        // filter responses
        final List<ZenPing.PingResponse> pingResponses = filterPingResponses(fullPingResponses, masterElectionIgnoreNonMasters, logger);


        List<DiscoveryNode> activeMasters = new ArrayList<>();
        for (ZenPing.PingResponse pingResponse : pingResponses) {
            // We can't include the local node in pingMasters list, otherwise we may up electing ourselves without
            // any check  verifications from other nodes in ZenDiscover#innerJoinCluster()
            if (pingResponse.master() != null && !localNode.equals(pingResponse.master())) {
                activeMasters.add(pingResponse.master());
            }
        }


        // nodes discovered during pinging
        List<ElectMasterService.MasterCandidate> masterCandidates = new ArrayList<>();
        for (ZenPing.PingResponse pingResponse : pingResponses) {
            if (pingResponse.node().isMasterNode()) {
                masterCandidates.add(new ElectMasterService.MasterCandidate(pingResponse.node(), pingResponse.getClusterStateVersion()));
            }
        }


        if (activeMasters.isEmpty()) {
            if (electMaster.hasEnoughCandidates(masterCandidates)) {
                final ElectMasterService.MasterCandidate winner = electMaster.electMaster(masterCandidates);
                logger.trace("candidate {} won election", winner);
                return winner.getNode();
            } else {
                // if we don't have enough master nodes, we bail, because there are not enough master to elect from
                logger.warn("not enough master nodes discovered during pinging (found [{}], but needed [{}]), pinging again",
                            masterCandidates, electMaster.minimumMasterNodes());
                return null;
            }
        } else {
            assert !activeMasters.contains(localNode) :
                "local node should never be elected as master when other nodes indicate an active master";
            // lets tie break between discovered nodes
            return electMaster.tieBreakActiveMasters(activeMasters);
        }
    }
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    private void innerJoinCluster() {
        DiscoveryNode masterNode = null;
        final Thread currentThread = Thread.currentThread();
        nodeJoinController.startElectionContext();
        while (masterNode == null && joinThreadControl.joinThreadActive(currentThread)) {
            masterNode = findMaster();
        }


        if (!joinThreadControl.joinThreadActive(currentThread)) {
            logger.trace("thread is no longer in currentJoinThread. Stopping.");
            return;
        }


        if (transportService.getLocalNode().equals(masterNode)) {
            final int requiredJoins = Math.max(0, electMaster.minimumMasterNodes() - 1); // we count as one
            logger.debug("elected as master, waiting for incoming joins ([{}] needed)", requiredJoins);
            nodeJoinController.waitToBeElectedAsMaster(requiredJoins, masterElectionWaitForJoinsTimeout,
                    new NodeJoinController.ElectionCallback() {
                        @Override
                        public void onElectedAsMaster(ClusterState state) {
                            synchronized (stateMutex) {
                                joinThreadControl.markThreadAsDone(currentThread);
                            }
                        }


                        @Override
                        public void onFailure(Throwable t) {
                            logger.trace("failed while waiting for nodes to join, rejoining", t);
                            synchronized (stateMutex) {
                                joinThreadControl.markThreadAsDoneAndStartNew(currentThread);
                            }
                        }
                    }


            );
        } else {
            // process any incoming joins (they will fail because we are not the master)
            nodeJoinController.stopElectionContext(masterNode + " elected");


            // send join request
            final boolean success = joinElectedMaster(masterNode);


            synchronized (stateMutex) {
                if (success) {
                    DiscoveryNode currentMasterNode = this.clusterState().getNodes().getMasterNode();
                    if (currentMasterNode == null) {
                        // Post 1.3.0, the master should publish a new cluster state before acking our join request. we now should have
                        // a valid master.
                        logger.debug("no master node is set, despite of join request completing. retrying pings.");
                        joinThreadControl.markThreadAsDoneAndStartNew(currentThread);
                    } else if (currentMasterNode.equals(masterNode) == false) {
                        // update cluster state
                        joinThreadControl.stopRunningThreadAndRejoin("master_switched_while_finalizing_join");
                    }


                    joinThreadControl.markThreadAsDone(currentThread);
                } else {
                    // failed to join. Try again...
                    joinThreadControl.markThreadAsDoneAndStartNew(currentThread);
                }
            }
        }
    }
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