@meteorjs/ddp-graceful-shutdown/lib/index.js

Close DDP connections gradually on server shutdown

"use strict";

var _slicedToArray = function () { function sliceIterator(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"]) _i["return"](); } finally { if (_d) throw _e; } } return _arr; } return function (arr, i) { if (Array.isArray(arr)) { return arr; } else if (Symbol.iterator in Object(arr)) { return sliceIterator(arr, i); } else { throw new TypeError("Invalid attempt to destructure non-iterable instance"); } }; }();

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

// DDPGracefulShutdown is a class which tracks open connections in a DDP server
// and shuts them down gradually when SIGTERM is received. Docker-base hosting
// environments typically send SIGTERM to processes, wait a grace period, and
// then send the un-ignorable SIGKILL. DDPGracefulShutdown allows you to detect
// SIGTERM and close connections over the whole grace period to ease load on new
// processes.
var DDPGracefulShutdown = function () {
  // gracePeriodMillis and server are required. Typically, server is set to
  // Meteor.server. On Galaxy, a good value for gracePeriodMillis is 1000 *
  // process.env.METEOR_SIGTERM_GRACE_PERIOD_SECONDS.
  function DDPGracefulShutdown(_ref) {
    var _this = this;

    var gracePeriodMillis = _ref.gracePeriodMillis,
        server = _ref.server;

    _classCallCheck(this, DDPGracefulShutdown);

    this.gracePeriodMillis = gracePeriodMillis;
    this.connections = new Map();
    server.onConnection(function (conn) {
      _this.connections.set(conn.id, conn);
      conn.onClose(function () {
        _this.connections.delete(conn.id);
      });
    });
  }

  // Sets up a SIGTERM handler to call closeConnections with logging. You should
  // either call this function or arrange for closeConnections to be called in
  // some other way.


  _createClass(DDPGracefulShutdown, [{
    key: "installSIGTERMHandler",
    value: function installSIGTERMHandler() {
      var _this2 = this;

      process.on("SIGTERM", function () {
        _this2.closeConnections({ log: true });
      });
    }

    // closeConnections calculates an interval for closing connections and starts
    // doing so. It is intended to be called when SIGTERM is received;
    // installSIGTERMHandler arranges for this to happen. If log is specified (the
    // default if this is called from the default SIGTERM handler) it will log one
    // line to stdout as well.

  }, {
    key: "closeConnections",
    value: function closeConnections() {
      var _ref2 = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {},
          log = _ref2.log;

      if (log) {
        console.log("Got SIGTERM; will close " + this.connections.size + " connection(s) in " + this.gracePeriodMillis + "ms");
      }
      var delay = void 0,
          batchSize = void 0;
      if (this.gracePeriodMillis >= this.connections.size) {
        delay = this.gracePeriodMillis / this.connections.size;
        batchSize = 1;
      } else {
        delay = 1;
        batchSize = this.connections.size / this.gracePeriodMillis;
      }
      this.closeOneBatchAndScheduleNext(delay, batchSize);
    }
    // Internal function which closes one batch of arbitrarily chosen connections
    // and waits to close the next one.
    //
    // conn.close needs to be called from within a Fiber, so this arranges to get
    // the code in a Fiber by calling it from meteor-promise's queue.

  }, {
    key: "closeOneBatchAndScheduleNext",
    value: function closeOneBatchAndScheduleNext(delay, batchSize) {
      var _this3 = this;

      Promise.resolve().then(function () {
        var closed = 0;
        while (_this3.connections.size > 0 && closed < batchSize) {
          _this3.closeOneConnection();
          closed++;
        }
        if (_this3.connections.size > 0) {
          setTimeout(function () {
            return _this3.closeOneBatchAndScheduleNext(delay, batchSize);
          }, delay);
        }
      });
    }
  }, {
    key: "closeOneConnection",
    value: function closeOneConnection() {
      var _this4 = this;

      Promise.resolve().then(function () {
        var _connections$entries$ = _this4.connections.entries().next(),
            done = _connections$entries$.done,
            value = _connections$entries$.value;

        if (done) {
          return;
        }

        var _value = _slicedToArray(value, 2),
            id = _value[0],
            conn = _value[1];

        _this4.connections.delete(id);
        conn.close();
      });
    }
  }]);

  return DDPGracefulShutdown;
}();

exports.DDPGracefulShutdown = DDPGracefulShutdown;