8-配置信息是如何加载到内存空间的

8.1 配置信息的加载过程

在执行zkServer命令启动Zookeeper的时候，Zookeeper启动脚本在启动java进程时会主动为Java进程加上java参数conf文件位置，默认为Zookeeper文件夹的conf目录下的zoo.cfg文件，在Zookeeper入口函数QuorumPeerMain类中的main方法执行时可以通过args[0]获取conf文件路径在初始化的时候执行如下代码进行解析配置：

QuorumPeerConfig config = new QuorumPeerConfig();

//指定了conf配置文件则开始解析配置文件

if (args.length == 1) {
     config.parse(args[0]);
 }

如果存在Zookeeper配置文件参数则先调用QuorumPeerConfig的parse方法来解析当前配置类中存在的配置属性解析过程如下：

/**
 * Parse a ZooKeeper configuration file
 * @param path the patch of the configuration file
 * @throws ConfigException error processing configuration
 */
public void parse(String path) throws ConfigException {
    File configFile = new File(path);

    LOG.info("Reading configuration from: " + configFile);

    try {
        if (!configFile.exists()) {
            throw new IllegalArgumentException(configFile.toString()
                    + " file is missing");
        }

        Properties cfg = new Properties();
        FileInputStream in = new FileInputStream(configFile);
        try {
            cfg.load(in);
        } finally {
            in.close();
        }

        parseProperties(cfg);
    } catch (IOException e) {
        throw new ConfigException("Error processing " + path, e);
    } catch (IllegalArgumentException e) {
        throw new ConfigException("Error processing " + path, e);
    }
}
解析过程就是使用File读取配置文件然后赋值给当前对象的成员变量。具体代码如下：
/**
 * Parse config from a Properties.
 * @param zkProp Properties to parse from.
 * @throws IOException
 * @throws ConfigException
 */
public void parseProperties(Properties zkProp) throws IOException, ConfigException {
    int clientPort = 0;
    int secureClientPort = 0;
    int observerMasterPort = 0;
    String clientPortAddress = null;
    String secureClientPortAddress = null;
    VerifyingFileFactory vff = new VerifyingFileFactory.Builder(LOG).warnForRelativePath().build();
    for (Entry<Object, Object> entry : zkProp.entrySet()) {
        String key = entry.getKey().toString().trim();
        String value = entry.getValue().toString().trim();
        if (key.equals("dataDir")) {
            dataDir = vff.create(value);
        } else if (key.equals("dataLogDir")) {
            dataLogDir = vff.create(value);
        } else if (key.equals("clientPort")) {
            clientPort = Integer.parseInt(value);
        } else if (key.equals("localSessionsEnabled")) {
            localSessionsEnabled = Boolean.parseBoolean(value);
        } else if (key.equals("localSessionsUpgradingEnabled")) {
            localSessionsUpgradingEnabled = Boolean.parseBoolean(value);
        } else if (key.equals("clientPortAddress")) {
            clientPortAddress = value.trim();
        } else if (key.equals("secureClientPort")) {
            secureClientPort = Integer.parseInt(value);
        } else if (key.equals("secureClientPortAddress")) {
            secureClientPortAddress = value.trim();
        } else if (key.equals("observerMasterPort")) {
            observerMasterPort = Integer.parseInt(value);
        } else if (key.equals("clientPortListenBacklog")) {
            clientPortListenBacklog = Integer.parseInt(value);
        } else if (key.equals("tickTime")) {
            tickTime = Integer.parseInt(value);
        } else if (key.equals("maxClientCnxns")) {
            maxClientCnxns = Integer.parseInt(value);
        } else if (key.equals("minSessionTimeout")) {
            minSessionTimeout = Integer.parseInt(value);
        } else if (key.equals("maxSessionTimeout")) {
            maxSessionTimeout = Integer.parseInt(value);
        } else if (key.equals("initLimit")) {
            initLimit = Integer.parseInt(value);
        } else if (key.equals("syncLimit")) {
            syncLimit = Integer.parseInt(value);
        } else if (key.equals("connectToLearnerMasterLimit")) {
            connectToLearnerMasterLimit = Integer.parseInt(value);
        } else if (key.equals("electionAlg")) {
            electionAlg = Integer.parseInt(value);
            if (electionAlg != 3) {
                throw new ConfigException("Invalid electionAlg value. Only 3 is supported.");
            }
        } else if (key.equals("quorumListenOnAllIPs")) {
            quorumListenOnAllIPs = Boolean.parseBoolean(value);
        } else if (key.equals("peerType")) {
            if (value.toLowerCase().equals("observer")) {
                peerType = LearnerType.OBSERVER;
            } else if (value.toLowerCase().equals("participant")) {
                peerType = LearnerType.PARTICIPANT;
            } else {
                throw new ConfigException("Unrecognised peertype: " + value);
            }
        } else if (key.equals("syncEnabled")) {
            syncEnabled = Boolean.parseBoolean(value);
        } else if (key.equals("dynamicConfigFile")) {
            dynamicConfigFileStr = value;
        } else if (key.equals("autopurge.snapRetainCount")) {
            snapRetainCount = Integer.parseInt(value);
        } else if (key.equals("autopurge.purgeInterval")) {
            purgeInterval = Integer.parseInt(value);
        } else if (key.equals("standaloneEnabled")) {
            if (value.toLowerCase().equals("true")) {
                setStandaloneEnabled(true);
            } else if (value.toLowerCase().equals("false")) {
                setStandaloneEnabled(false);
            } else {
                throw new ConfigException("Invalid option "
                                          + value
                                          + " for standalone mode. Choose 'true' or 'false.'");
            }
        } else if (key.equals("reconfigEnabled")) {
            if (value.toLowerCase().equals("true")) {
                setReconfigEnabled(true);
            } else if (value.toLowerCase().equals("false")) {
                setReconfigEnabled(false);
            } else {
                throw new ConfigException("Invalid option "
                                          + value
                                          + " for reconfigEnabled flag. Choose 'true' or 'false.'");
            }
        } else if (key.equals("sslQuorum")) {
            sslQuorum = Boolean.parseBoolean(value);
        } else if (key.equals("portUnification")) {
            shouldUsePortUnification = Boolean.parseBoolean(value);
        } else if (key.equals("sslQuorumReloadCertFiles")) {
            sslQuorumReloadCertFiles = Boolean.parseBoolean(value);
        } else if ((key.startsWith("server.") || key.startsWith("group") || key.startsWith("weight"))
                   && zkProp.containsKey("dynamicConfigFile")) {
            throw new ConfigException("parameter: " + key + " must be in a separate dynamic config file");
        } else if (key.equals(QuorumAuth.QUORUM_SASL_AUTH_ENABLED)) {
            quorumEnableSasl = Boolean.parseBoolean(value);
        } else if (key.equals(QuorumAuth.QUORUM_SERVER_SASL_AUTH_REQUIRED)) {
            quorumServerRequireSasl = Boolean.parseBoolean(value);
        } else if (key.equals(QuorumAuth.QUORUM_LEARNER_SASL_AUTH_REQUIRED)) {
            quorumLearnerRequireSasl = Boolean.parseBoolean(value);
        } else if (key.equals(QuorumAuth.QUORUM_LEARNER_SASL_LOGIN_CONTEXT)) {
            quorumLearnerLoginContext = value;
        } else if (key.equals(QuorumAuth.QUORUM_SERVER_SASL_LOGIN_CONTEXT)) {
            quorumServerLoginContext = value;
        } else if (key.equals(QuorumAuth.QUORUM_KERBEROS_SERVICE_PRINCIPAL)) {
            quorumServicePrincipal = value;
        } else if (key.equals("quorum.cnxn.threads.size")) {
            quorumCnxnThreadsSize = Integer.parseInt(value);
        } else if (key.equals(JvmPauseMonitor.INFO_THRESHOLD_KEY)) {
            jvmPauseInfoThresholdMs = Long.parseLong(value);
        } else if (key.equals(JvmPauseMonitor.WARN_THRESHOLD_KEY)) {
            jvmPauseWarnThresholdMs = Long.parseLong(value);
        } else if (key.equals(JvmPauseMonitor.SLEEP_TIME_MS_KEY)) {
            jvmPauseSleepTimeMs = Long.parseLong(value);
        } else if (key.equals(JvmPauseMonitor.JVM_PAUSE_MONITOR_FEATURE_SWITCH_KEY)) {
            jvmPauseMonitorToRun = Boolean.parseBoolean(value);
        } else if (key.equals("metricsProvider.className")) {
            metricsProviderClassName = value;
        } else if (key.startsWith("metricsProvider.")) {
            String keyForMetricsProvider = key.substring(16);
            metricsProviderConfiguration.put(keyForMetricsProvider, value);
        } else if (key.equals("multiAddress.enabled")) {
            multiAddressEnabled = Boolean.parseBoolean(value);
        } else if (key.equals("multiAddress.reachabilityCheckTimeoutMs")) {
            multiAddressReachabilityCheckTimeoutMs = Integer.parseInt(value);
        } else if (key.equals("multiAddress.reachabilityCheckEnabled")) {
            multiAddressReachabilityCheckEnabled = Boolean.parseBoolean(value);
        } else {
            System.setProperty("zookeeper." + key, value);
        }
    }

    if (!quorumEnableSasl && quorumServerRequireSasl) {
        throw new IllegalArgumentException(QuorumAuth.QUORUM_SASL_AUTH_ENABLED
                                           + " is disabled, so cannot enable "
                                           + QuorumAuth.QUORUM_SERVER_SASL_AUTH_REQUIRED);
    }
    if (!quorumEnableSasl && quorumLearnerRequireSasl) {
        throw new IllegalArgumentException(QuorumAuth.QUORUM_SASL_AUTH_ENABLED
                                           + " is disabled, so cannot enable "
                                           + QuorumAuth.QUORUM_LEARNER_SASL_AUTH_REQUIRED);
    }
    // If quorumpeer learner is not auth enabled then self won't be able to
    // join quorum. So this condition is ensuring that the quorumpeer learner
    // is also auth enabled while enabling quorum server require sasl.
    if (!quorumLearnerRequireSasl && quorumServerRequireSasl) {
        throw new IllegalArgumentException(QuorumAuth.QUORUM_LEARNER_SASL_AUTH_REQUIRED
                                           + " is disabled, so cannot enable "
                                           + QuorumAuth.QUORUM_SERVER_SASL_AUTH_REQUIRED);
    }

    // Reset to MIN_SNAP_RETAIN_COUNT if invalid (less than 3)
    // PurgeTxnLog.purge(File, File, int) will not allow to purge less
    // than 3.
    if (snapRetainCount < MIN_SNAP_RETAIN_COUNT) {
        LOG.warn("Invalid autopurge.snapRetainCount: "
                 + snapRetainCount
                 + ". Defaulting to "
                 + MIN_SNAP_RETAIN_COUNT);
        snapRetainCount = MIN_SNAP_RETAIN_COUNT;
    }

    if (dataDir == null) {
        throw new IllegalArgumentException("dataDir is not set");
    }
    if (dataLogDir == null) {
        dataLogDir = dataDir;
    }

    if (clientPort == 0) {
        LOG.info("clientPort is not set");
        if (clientPortAddress != null) {
            throw new IllegalArgumentException("clientPortAddress is set but clientPort is not set");
        }
    } else if (clientPortAddress != null) {
        this.clientPortAddress = new InetSocketAddress(InetAddress.getByName(clientPortAddress), clientPort);
        LOG.info("clientPortAddress is {}", formatInetAddr(this.clientPortAddress));
    } else {
        this.clientPortAddress = new InetSocketAddress(clientPort);
        LOG.info("clientPortAddress is {}", formatInetAddr(this.clientPortAddress));
    }

    if (secureClientPort == 0) {
        LOG.info("secureClientPort is not set");
        if (secureClientPortAddress != null) {
            throw new IllegalArgumentException("secureClientPortAddress is set but secureClientPort is not set");
        }
    } else if (secureClientPortAddress != null) {
        this.secureClientPortAddress = new InetSocketAddress(InetAddress.getByName(secureClientPortAddress), secureClientPort);
        LOG.info("secureClientPortAddress is {}", formatInetAddr(this.secureClientPortAddress));
    } else {
        this.secureClientPortAddress = new InetSocketAddress(secureClientPort);
        LOG.info("secureClientPortAddress is {}", formatInetAddr(this.secureClientPortAddress));
    }
    if (this.secureClientPortAddress != null) {
        configureSSLAuth();
    }

    if (observerMasterPort <= 0) {
        LOG.info("observerMasterPort is not set");
    } else {
        this.observerMasterPort = observerMasterPort;
        LOG.info("observerMasterPort is {}", observerMasterPort);
    }

    if (tickTime == 0) {
        throw new IllegalArgumentException("tickTime is not set");
    }

    minSessionTimeout = minSessionTimeout == -1 ? tickTime * 2 : minSessionTimeout;
    maxSessionTimeout = maxSessionTimeout == -1 ? tickTime * 20 : maxSessionTimeout;

    if (minSessionTimeout > maxSessionTimeout) {
        throw new IllegalArgumentException("minSessionTimeout must not be larger than maxSessionTimeout");
    }

    LOG.info("metricsProvider.className is {}", metricsProviderClassName);
    try {
        Class.forName(metricsProviderClassName, false, Thread.currentThread().getContextClassLoader());
    } catch (ClassNotFoundException error) {
        throw new IllegalArgumentException("metrics provider class was not found", error);
    }

    // backward compatibility - dynamic configuration in the same file as
    // static configuration params see writeDynamicConfig()
    if (dynamicConfigFileStr == null) {
        setupQuorumPeerConfig(zkProp, true);
        if (isDistributed() && isReconfigEnabled()) {
            // we don't backup static config for standalone mode.
            // we also don't backup if reconfig feature is disabled.
            backupOldConfig();
        }
    }
}

配置解析主要包含了两部分内容：

• 配置加载解析
• 配置合法性验证

8.2 配置大全

这里将常用配置列举了出来希望能对大家有所帮助

配置加载解析的过程主要是将zoo.cfg配置文件中的配置赋值给QuorumPeerConfig类型的成员变量中，方便在程序中使用用户的配置，那具体配置有哪些，配置的类型是什么，默认值又有哪些呢，我们可以详细来看下如下表格：

配置的加载就是将zoo.cfg中的配置信息设置到内存中，这里有个checkValidity()方法如果是在分布式模式下部署则必须设置initLimit，syncLimit，serverId（serverId在myid文件中必须提前创建好）

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