TypeScript Events.topic方法代碼示例

  before(async function setup() {
    cfg = sconfig(process.cwd() + '/test');
    const logger = new chassis.Logger(cfg.get('logger'));

    events = new Events(cfg.get('events:kafka'), logger);
    await events.start();

    const topics = cfg.get('events:kafka:topics');
    testTopic = events.topic(cfg.get('events:kafka:topics:test.resource:topic'));
    commandTopic = events.topic(cfg.get('events:kafka:topics:command:topic'));
    // subscribe all response events
    for (let eventName of cfg.get('events:kafka:topics:command:events')) {
      await commandTopic.on(eventName, eventListener);
    }

    server = new Server(cfg.get('server'), logger);
    db = await database.get(cfg.get('database:arango'), logger);
    await db.truncate();

    const config = cfg.get();
    delete config.database.nedb;  // not supported in default implementation

    const cis = new CommandInterface(server, config, logger, events);
    await server.bind('commandinterface', cis);
    await server.start();

    const client = new Client(cfg.get('client:commandinterface'), logger);
    service = await client.connect();
  });

    async function testConsumeListener() {
      this.timeout(4000);
      // emit testMessage to kafka
      topic = await events.topic(topicName);
      await topic.emit(eventName, testMessage);

      // start offsetTracker subscribing to previous offset value read
      // from redis and consume the above message
      offsetStore = new OffsetStore(events, cfg, logger);
      const listener = async function listener(message, context) {
        testMessage.value.should.equal(message.value);
        testMessage.count.should.equal(message.count);
      };

      // get the current offsetValue for 'test' topic before emitting message
      let startingOffset = await offsetStore.getOffset(topicName);
      await topic.on(eventName, listener, { startingOffset });

      // wait for 2sec so that message is consumed and
      // test is not ended immediately
      return new Promise((resolve, reject) => {
        setTimeout(() => {
          resolve();
        }, 2000);
      });
    });

 /**
 * updates the topic offset in redis periodically
 *
 */
 updateTopicOffsets(): any {
   // Iterate through the topics and updateOffsets periodically for each topic
   // events.topic(TopicName) - gives the topic object
   const kafkaCfg = this.config.get('events:kafka');
   const topicTypes = _.keys(kafkaCfg.topics);
   for (let i = 0; i < topicTypes.length; i += 1) {
     const topicType = topicTypes[i];
     const topicName = kafkaCfg.topics[topicType].topic;
     this.topics[topicType] = this.kafkaEvents.topic(topicName);
     this.timerID[i] = setInterval(this.storeOffset.bind(this),
       this.config.get('redis:offsetStoreInterval'), this.topics[topicType], topicName);
   }
 }

    async function testStoredOffsetValue() {
      this.timeout(10000);
      offsetStore = new OffsetStore(events, cfg, logger);
      topic = await (events.topic(topicName));

      const listener = function listener(message, context) {
        testMessage.value.should.equal(message.value);
        testMessage.count.should.equal(message.count);
      };
      // get the current offsetValue for 'test' topic before emitting message
      const currentOffset = await topic.$offset(-1);
      // emit message to kafka
      await topic.on(eventName, listener);
      await topic.emit(eventName, testMessage);
      const newOffset = await new Promise((resolve, reject) => {
        setTimeout(async () => {
          const offsetValue = await offsetStore.getOffset(topicName);
          resolve(offsetValue);
        }, 8000);
      });
      should.exist(newOffset);
      Number(newOffset).should.equal(currentOffset + 1);
    });

  constructor(server: Server, config: any, logger: Logger, events: Events) {
    if (_.isNil(events)) {
      if (logger.error) {
        logger.error('No Kafka client was provided. Disabling all commands.');
        return;
      }
    }
    if (!_.has(config, 'server.services')) {
      throw new Error('missing config server.services');
    }

    this.config = config;
    this.logger = logger;

    if (!_.has(this.config, 'events')
      || !_.has(this.config.events, 'kafka')
      || !_.has(this.config.events.kafka, 'topics')
      || !_.has(this.config.events.kafka.topics, 'command')) {
      throw new Error('Commands topic configuration was not provided.');
    }

    this.kafkaEvents = events;

    // Health
    this.health = {
      status: ServingStatus.UNKNOWN,
    };
    this.service = {};
    const service = this.service;
    const health = this.health;
    _.forEach(config.server.services, (serviceCfg, serviceName) => {
      service[serviceName] = {
        bound: false,
        transport: {},
      };
    });
    server.on('bound', (serviceName) => {
      service[serviceName].bound = true;
      health.status = ServingStatus.NOT_SERVING;
    });
    server.on('serving', (transports) => {
      health.status = ServingStatus.SERVING;
      _.forEach(transports, (transport, transportName) => {
        _.forEach(service, (srv, serviceName) => {
          service[serviceName].transport[transportName] = ServingStatus.SERVING;
        });
      });
    });
    server.on('stopped', (transports) => {
      health.status = ServingStatus.NOT_SERVING;
      _.forEach(transports, (transport, transportName) => {
        _.forEach(service, (srv, serviceName) => {
          service[serviceName].transport[transportName] = ServingStatus.NOT_SERVING;
        });
      });
    });

    // list of available commands
    this.commands = {
      reset: this.reset,
      restore: this.restore,
      reconfigure: this.reconfigure,
      health_check: this.check,
      version: this.version
    };
    const topicCfg = config.events.kafka.topics.command;
    this.commandTopic = events.topic(topicCfg.topic);
    // check for buffer fields
    this.bufferedCollection = new Map<string, string>();
    if (this.config.fieldHandlers && this.config.fieldHandlers.bufferFields) {
      for (let bufferedCollection in this.config.fieldHandlers.bufferFields) {
        this.bufferedCollection.set(bufferedCollection,
          this.config.fieldHandlers.bufferFields[bufferedCollection]);
      }
      this.logger.info('Buffered collections are:', this.bufferedCollection);
    }
  }

  /**
   * Restore the system by re-reading Kafka messages.
   * This base implementation restores documents from a set of
   * ArangoDB database collections, using the chassis-srv database provider.
   * @param topics list of Kafka topics to be restored
   */
  async restore(payload: any): Promise<any> {
    if (_.isEmpty(payload) || _.isEmpty(payload.data)) {
      throw new errors.InvalidArgument('Invalid payload for restore command');
    }

    const restoreData: RestoreData[] = payload.data || [];

    // the Kafka config should contains a key-value pair, mapping
    // a label with the topic's name
    const kafkaEventsCfg = this.config.events.kafka;
    const kafkaCfg = this.config.events.kafka.topics;
    if (_.isNil(kafkaCfg) || kafkaCfg.length == 0) {
      throw new errors.Internal('Kafka topics config not available');
    }

    const topicLabels = _.keys(kafkaCfg).filter((elem, index) => {
      return elem.includes('.resource');
    }).map((elem) => {
      return elem.replace('.resource', '');
    });

    const restoreSetup = {};
    const restoreEventSetup = {};

    restoreData.forEach((data) => {
      const ignoreOffset = (data.ignore_offset || []).filter((offset) => {
        const isNumber = Number(offset) != NaN;
        if (!isNumber) {
          this.logger.warn(`Invalid value for "ignore_offset" parameter in restore: ${offset}`);
        }
        return isNumber;
      });
      restoreSetup[data.entity] = {
        baseOffset: Number(data.base_offset) || 0,
        ignoreOffset
      };
    });

    const restoreCollections = _.keys(restoreSetup);

    try {
      const dbCfgs = this.config.database;
      const dbCfgNames = _.keys(dbCfgs);
      for (let i = 0; i < dbCfgNames.length; i += 1) {
        const dbCfgName = dbCfgNames[i];
        const dbCfg = dbCfgs[dbCfgName];
        const collections = dbCfg.collections;
        let graphName;
        if (this.config.graph) {
          graphName = this.config.graph.graphName;
        }
        const db = await database.get(dbCfg, this.logger, graphName);

        if (_.isNil(collections)) {
          this.logger.warn('No collections found on DB config');
          return {};
        }

        let intersection: string[] = _.intersection(restoreCollections, collections);
        if (intersection.length > 0) {
          intersection = _.intersection(intersection, topicLabels);
          for (let resource of intersection) {
            const topicName = kafkaCfg[`${resource}.resource`].topic;
            restoreEventSetup[topicName] = {
              topic: this.kafkaEvents.topic(topicName),
              events: this.makeResourcesRestoreSetup(db, resource),
              baseOffset: restoreSetup[resource].baseOffset,
              ignoreOffset: restoreSetup[resource].ignoreOffset
            };
          }
        }
      }

      if (_.isEmpty(restoreEventSetup)) {
        this.logger.warn('No data was setup for the restore process.');
      } else {
        const that = this;
        // Start the restore process
        this.logger.warn('restoring data');

        for (let topicName in restoreEventSetup) {
          const topicSetup: any = restoreEventSetup[topicName];
          const restoreTopic: Topic = topicSetup.topic;
          const topicEvents: any = topicSetup.events;

          // saving listeners for potentially subscribed events on this topic,
          // so they don't get called during the restore process
          const previousEvents: string[] = _.cloneDeep(restoreTopic.subscribed);
          const listenersBackup = new Map<string, Function[]>();
          for (let event of previousEvents) {
            listenersBackup.set(event, (restoreTopic.emitter as EventEmitter).listeners(event));
            await restoreTopic.removeAllListeners(event);
          }

//.........這裏部分代碼省略.........