drpcjs/index.js

Apache storm DRPC client for Node.js

const { EventEmitter } = require("events");

const thrift = require("./src/thrift");
const DistributedRPC = require("./src/thrift-gen-nodejs/DistributedRPC");

class DRPC extends EventEmitter {
	constructor({ host, port = 3772, timeout = null, keepAlive = true, maxConnectCounts = 10 }) {
		super();
		if (!(this instanceof DRPC)) {
			return new DRPC({
				host, port, timeout, keepAlive, maxConnectCounts,
			});
		}
		if (!host) throw new Error("Param `options.host` required.");
		this.host = host;
		this.port = port;
		this.timeout = timeout;
		this.keepAlive = keepAlive;
		this.maxConnectCounts = maxConnectCounts;
		if (this.keepAlive) this.connect();
		this.connectCounts = 0;
		return this;
	}

	connect() {
		const self = this;
		let connection;
		const maxCounts = this.maxConnectCounts;
		if (!this.timeout) {
			connection = thrift.createConnection(this.host, this.port);
		} else {
			connection = thrift.createConnection(this.host, this.port, this.timeout);
		}
		if (maxCounts > 0) {
			this.connectCounts += 1;
			if (this.connectCounts > maxCounts) throw new Error("Maximum connect counts limit.");
		}

		connection.on("connect", () => self.emit("connect"));
		connection.on("timeout", () => self.emit("timeout"));
		connection.on("error", (err) => self.emit("error", err));

		if (self.keepAlive) {
			connection.on("close", () => {
				self.emit("close");
				self.connect();
			});
		}
		this.connection = connection;
		this.client = thrift.createClient(DistributedRPC, connection);
		return this;
	}

	execute(spoutName, emitValue) {
		if (typeof spoutName !== "string" || typeof emitValue !== "string") {
			throw new TypeError("Params `spoutName[String]` and `emitValue[String]` required.");
		}
		return new Promise((yes, no) => {
			const self = this;
			if (!this.keepAlive) this.connect();
			if (!this.client) throw new Error("DRPC client does not exist.");
			this.client.execute(spoutName, emitValue, (err, res) => {
				if (err) {
					no(err);
				} else {
					yes(res);
				}
				if (!self.keepAlive && self.connection) {
					self.connection.end();
					self.connection = null;
					self.client = null;
				}
			});
		});
	}
}

module.exports = DRPC;