tribune/lib/service.js

Holy advocate to the Roman Senate, your Tribune will ensure the Consuls have your interests in mind.

const httpMethods = require('http').METHODS;
const Endpoint    = require('./endpoint');


class Service {

  constructor(tribune, name) {
    this._tribune          = tribune;
    this._name             = name;
    this._endpoint         = null;
    this._endpointTags     = null;
    this._endpointUrl      = null;
    this._connectTimeoutId = null;
    this._requests         = [];
  }

  request(url, opts, cb = () => {}) {
    if (url && typeof url === 'object') {
      cb   = opts;
      opts = url;
      url  = undefined;
    }
    if (typeof opts === 'function') {
      cb   = opts;
      opts = {};
    }

    let   attempts    = 0;
    const makeRequest = () => {
      this.endpoint((err, endpoint) => {
        if (err) { return cb(err); }
        opts.baseUrl = endpoint.url;
        this._tribune._consul._request(url, opts, (err, res) => {
          if (!err || err && err.code !== 'ENOTFOUND') {
            return cb(err, res);
          }

          attempts += 1;
          if (attempts > 10) { return cb(err, res); }
          return makeRequest();
        });
      });
    };
    makeRequest();
  }

  endpoint(cb = () => {}) {
    if (this._endpoint) { return cb(null, this._endpoint); }

    const timeout = this._tribune._serviceTimeout;
    if (timeout > 0) {
      clearTimeout(this._connectTimeoutId);
      this._connectTimeoutId = setTimeout(() => {
        throw new Error(`Could not aquire connection to ${this._name} service`);
      }, timeout);
    }

    this._tribune._getConsulServiceEndpoint(this._name, (err, serviceEndpoint) => {
      if (err || serviceEndpoint) { clearTimeout(this._connectTimeoutId); }

      if (err) { return cb(err); }
      if (!serviceEndpoint) { return setTimeout(() => this.endpoint(cb), 300); }

      this._endpoint = new Endpoint(serviceEndpoint);
      setTimeout(() => { this._endpoint = null; }, this._tribune._serviceTtl).unref();

      cb(null, this._endpoint);
    });
  }
}

httpMethods.forEach((method) => {
  Service.prototype[method.toLowerCase()] = function(url, opts, cb) {
    if (url && typeof url === 'object') {
      cb   = opts;
      opts = url;
      url  = undefined;
    }
    if (typeof opts === 'function') {
      cb   = opts;
      opts = {};
    }
    opts.method = method;
    return this.request(url, opts, cb);
  };
});


module.exports = Service;