前言

SubscriptionGroupManager 继承了ConfigManager配置管理组件，拥有将内存数据持久化到磁盘文件subscriptionGroup.json的能力。它主要负责维护所有消费组在内存中的订阅数据。

源码版本：4.9.3

源码架构图

核心数据结构

主要的数据结构比较简单，维护了Map<消费组名称, 订阅组配置>的映射关系。

// 订阅组管理组件
public class SubscriptionGroupManager extends ConfigManager {
    private static final InternalLogger log = InternalLoggerFactory.getLogger(LoggerName.BROKER_LOGGER_NAME);

    // Map<消费组名称，订阅组配置>
    private final ConcurrentMap<String, SubscriptionGroupConfig> subscriptionGroupTable =
        new ConcurrentHashMap<String, SubscriptionGroupConfig>(1024);
    // 内存数据版本号
    private final DataVersion dataVersion = new DataVersion();
}

深入看下SubscriptionGroupConfig 的数据结构。

public class SubscriptionGroupConfig {
    // 消费组名称
    private String groupName;
    // 是否开启消费
    private boolean consumeEnable = true;
    // 是否允许消费最早消息
    private boolean consumeFromMinEnable = true;
    // 是否允许广播消费
    private boolean consumeBroadcastEnable = true;
    // 重试队列数
    private int retryQueueNums = 1;
    // 重试最大次数
    private int retryMaxTimes = 16;
    // brokerId
    private long brokerId = MixAll.MASTER_ID;
    // 当产生慢消费时，选择第几个broker
    private long whichBrokerWhenConsumeSlowly = 1;
    // 是否通知消费者ids变化
    private boolean notifyConsumerIdsChangedEnable = true;
}

核心数据行为

数据行为主要都是对上面提到的数据结构的维护，代码 + 注释如下：

// 订阅组管理组件
public class SubscriptionGroupManager extends ConfigManager {
    
    public SubscriptionGroupManager() {
        this.init();
    }

    public SubscriptionGroupManager(BrokerController brokerController) {
        this.brokerController = brokerController;
        this.init();
    }

    private void init() {
        {
            // 初始化系统消费组
            SubscriptionGroupConfig subscriptionGroupConfig = new SubscriptionGroupConfig();
            subscriptionGroupConfig.setGroupName(MixAll.TOOLS_CONSUMER_GROUP);
            this.subscriptionGroupTable.put(MixAll.TOOLS_CONSUMER_GROUP, subscriptionGroupConfig);
        }

        {
            // 初始化过滤服务消费组
            SubscriptionGroupConfig subscriptionGroupConfig = new SubscriptionGroupConfig();
            subscriptionGroupConfig.setGroupName(MixAll.FILTERSRV_CONSUMER_GROUP);
            this.subscriptionGroupTable.put(MixAll.FILTERSRV_CONSUMER_GROUP, subscriptionGroupConfig);
        }

        {
            // 初始化自测消费组
            SubscriptionGroupConfig subscriptionGroupConfig = new SubscriptionGroupConfig();
            subscriptionGroupConfig.setGroupName(MixAll.SELF_TEST_CONSUMER_GROUP);
            this.subscriptionGroupTable.put(MixAll.SELF_TEST_CONSUMER_GROUP, subscriptionGroupConfig);
        }

        {
            // 初始化http代理消费组
            SubscriptionGroupConfig subscriptionGroupConfig = new SubscriptionGroupConfig();
            subscriptionGroupConfig.setGroupName(MixAll.ONS_HTTP_PROXY_GROUP);
            subscriptionGroupConfig.setConsumeBroadcastEnable(true);
            this.subscriptionGroupTable.put(MixAll.ONS_HTTP_PROXY_GROUP, subscriptionGroupConfig);
        }

        {
            // 初始化ONS_API_PULL消费组
            SubscriptionGroupConfig subscriptionGroupConfig = new SubscriptionGroupConfig();
            subscriptionGroupConfig.setGroupName(MixAll.CID_ONSAPI_PULL_GROUP);
            subscriptionGroupConfig.setConsumeBroadcastEnable(true); // 激活广播模式
            this.subscriptionGroupTable.put(MixAll.CID_ONSAPI_PULL_GROUP, subscriptionGroupConfig);
        }

        {
            // 初始化ONS_API_PERMISSION消费组
            SubscriptionGroupConfig subscriptionGroupConfig = new SubscriptionGroupConfig();
            subscriptionGroupConfig.setGroupName(MixAll.CID_ONSAPI_PERMISSION_GROUP);
            subscriptionGroupConfig.setConsumeBroadcastEnable(true);
            this.subscriptionGroupTable.put(MixAll.CID_ONSAPI_PERMISSION_GROUP, subscriptionGroupConfig);
        }

        {
            // 初始化ONS_API_OWNER消费组
            SubscriptionGroupConfig subscriptionGroupConfig = new SubscriptionGroupConfig();
            subscriptionGroupConfig.setGroupName(MixAll.CID_ONSAPI_OWNER_GROUP);
            subscriptionGroupConfig.setConsumeBroadcastEnable(true);
            this.subscriptionGroupTable.put(MixAll.CID_ONSAPI_OWNER_GROUP, subscriptionGroupConfig);
        }
    }

    // 更新订阅配置，且更新内存数据版本号
    public void updateSubscriptionGroupConfig(final SubscriptionGroupConfig config) {
        SubscriptionGroupConfig old = this.subscriptionGroupTable.put(config.getGroupName(), config);
        if (old != null) {
            log.info("update subscription group config, old: {} new: {}", old, config);
        } else {
            log.info("create new subscription group, {}", config);
        }

        this.dataVersion.nextVersion();

        this.persist();
    }

    // 失效消费组
    public void disableConsume(final String groupName) {
        SubscriptionGroupConfig old = this.subscriptionGroupTable.get(groupName);
        if (old != null) {
            old.setConsumeEnable(false);
            this.dataVersion.nextVersion();
        }
    }

    // 查找指定消费组的订阅配置
    public SubscriptionGroupConfig findSubscriptionGroupConfig(final String group) {
        SubscriptionGroupConfig subscriptionGroupConfig = this.subscriptionGroupTable.get(group);
        if (null == subscriptionGroupConfig) {
            if (brokerController.getBrokerConfig().isAutoCreateSubscriptionGroup() || MixAll.isSysConsumerGroup(group)) {
                subscriptionGroupConfig = new SubscriptionGroupConfig();
                subscriptionGroupConfig.setGroupName(group);
                SubscriptionGroupConfig preConfig = this.subscriptionGroupTable.putIfAbsent(group, subscriptionGroupConfig);
                if (null == preConfig) {
                    log.info("auto create a subscription group, {}", subscriptionGroupConfig.toString());
                }
                this.dataVersion.nextVersion();
                this.persist();
            }
        }

        return subscriptionGroupConfig;
    }

    // 将内存数据结构编码成字符串
    @Override
    public String encode() {
        return this.encode(false);
    }

    // 获取配置文件路径
    @Override
    public String configFilePath() {
        return BrokerPathConfigHelper.getSubscriptionGroupPath(this.brokerController.getMessageStoreConfig()
            .getStorePathRootDir());
    }

    // 从字符串中恢复数据，写回内存数据结构
    @Override
    public void decode(String jsonString) {
        if (jsonString != null) {
            SubscriptionGroupManager obj = RemotingSerializable.fromJson(jsonString, SubscriptionGroupManager.class);
            if (obj != null) {
                this.subscriptionGroupTable.putAll(obj.subscriptionGroupTable);
                this.dataVersion.assignNewOne(obj.dataVersion);
                this.printLoadDataWhenFirstBoot(obj);
            }
        }
    }

    // 将内存数据结构编码成字符串
    public String encode(final boolean prettyFormat) {
        return RemotingSerializable.toJson(this, prettyFormat);
    }

    // 当第一次启动时，打印加载数据时的日志
    private void printLoadDataWhenFirstBoot(final SubscriptionGroupManager sgm) {
        Iterator<Entry<String, SubscriptionGroupConfig>> it = sgm.getSubscriptionGroupTable().entrySet().iterator();
        while (it.hasNext()) {
            Entry<String, SubscriptionGroupConfig> next = it.next();
            log.info("load exist subscription group, {}", next.getValue().toString());
        }
    }

    public ConcurrentMap<String, SubscriptionGroupConfig> getSubscriptionGroupTable() {
        return subscriptionGroupTable;
    }

    public DataVersion getDataVersion() {
        return dataVersion;
    }

    // 删除指定消费组的订阅配置
    public void deleteSubscriptionGroupConfig(final String groupName) {
        SubscriptionGroupConfig old = this.subscriptionGroupTable.remove(groupName);
        if (old != null) {
            log.info("delete subscription group OK, subscription group:{}", old);
            this.dataVersion.nextVersion();
            this.persist();
        } else {
            log.warn("delete subscription group failed, subscription groupName: {} not exist", groupName);
        }
    }
}