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node_modules/mongoose/lib/drivers/node-mongodb-native/connection.js

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+/*!
+ * Module dependencies.
+ */
+
+'use strict';
+
+const MongooseConnection = require('../../connection');
+const STATES = require('../../connectionstate');
+const immediate = require('../../helpers/immediate');
+const setTimeout = require('../../helpers/timers').setTimeout;
+
+/**
+ * A [node-mongodb-native](https://github.com/mongodb/node-mongodb-native) connection implementation.
+ *
+ * @inherits Connection
+ * @api private
+ */
+
+function NativeConnection() {
+  MongooseConnection.apply(this, arguments);
+  this._listening = false;
+}
+
+/**
+ * Expose the possible connection states.
+ * @api public
+ */
+
+NativeConnection.STATES = STATES;
+
+/*!
+ * Inherits from Connection.
+ */
+
+NativeConnection.prototype.__proto__ = MongooseConnection.prototype;
+
+/**
+ * Switches to a different database using the same connection pool.
+ *
+ * Returns a new connection object, with the new db. If you set the `useCache`
+ * option, `useDb()` will cache connections by `name`.
+ *
+ * **Note:** Calling `close()` on a `useDb()` connection will close the base connection as well.
+ *
+ * @param {String} name The database name
+ * @param {Object} [options]
+ * @param {Boolean} [options.useCache=false] If true, cache results so calling `useDb()` multiple times with the same name only creates 1 connection object.
+ * @param {Boolean} [options.noListener=false] If true, the new connection object won't listen to any events on the base connection. This is better for memory usage in cases where you're calling `useDb()` for every request.
+ * @return {Connection} New Connection Object
+ * @api public
+ */
+
+NativeConnection.prototype.useDb = function(name, options) {
+  // Return immediately if cached
+  options = options || {};
+  if (options.useCache && this.relatedDbs[name]) {
+    return this.relatedDbs[name];
+  }
+
+  // we have to manually copy all of the attributes...
+  const newConn = new this.constructor();
+  newConn.name = name;
+  newConn.base = this.base;
+  newConn.collections = {};
+  newConn.models = {};
+  newConn.replica = this.replica;
+  newConn.config = Object.assign({}, this.config, newConn.config);
+  newConn.name = this.name;
+  newConn.options = this.options;
+  newConn._readyState = this._readyState;
+  newConn._closeCalled = this._closeCalled;
+  newConn._hasOpened = this._hasOpened;
+  newConn._listening = false;
+
+  newConn.host = this.host;
+  newConn.port = this.port;
+  newConn.user = this.user;
+  newConn.pass = this.pass;
+
+  // First, when we create another db object, we are not guaranteed to have a
+  // db object to work with. So, in the case where we have a db object and it
+  // is connected, we can just proceed with setting everything up. However, if
+  // we do not have a db or the state is not connected, then we need to wait on
+  // the 'open' event of the connection before doing the rest of the setup
+  // the 'connected' event is the first time we'll have access to the db object
+
+  const _this = this;
+
+  newConn.client = _this.client;
+
+  if (this.db && this._readyState === STATES.connected) {
+    wireup();
+  } else {
+    this.once('connected', wireup);
+  }
+
+  function wireup() {
+    newConn.client = _this.client;
+    const _opts = {};
+    if (options.hasOwnProperty('noListener')) {
+      _opts.noListener = options.noListener;
+    }
+    newConn.db = _this.client.db(name, _opts);
+    newConn.onOpen();
+    // setup the events appropriately
+    if (options.noListener !== true) {
+      listen(newConn);
+    }
+  }
+
+  newConn.name = name;
+
+  // push onto the otherDbs stack, this is used when state changes
+  if (options.noListener !== true) {
+    this.otherDbs.push(newConn);
+  }
+  newConn.otherDbs.push(this);
+
+  // push onto the relatedDbs cache, this is used when state changes
+  if (options && options.useCache) {
+    this.relatedDbs[newConn.name] = newConn;
+    newConn.relatedDbs = this.relatedDbs;
+  }
+
+  return newConn;
+};
+
+/*!
+ * Register listeners for important events and bubble appropriately.
+ */
+
+function listen(conn) {
+  if (conn._listening) {
+    return;
+  }
+  conn._listening = true;
+
+  conn.client.on('close', function(force) {
+    if (conn._closeCalled) {
+      return;
+    }
+    conn._closeCalled = conn.client._closeCalled;
+
+    // the driver never emits an `open` event. auto_reconnect still
+    // emits a `close` event but since we never get another
+    // `open` we can't emit close
+    if (conn.db.serverConfig.autoReconnect) {
+      conn.readyState = STATES.disconnected;
+      conn.emit('close');
+      return;
+    }
+    conn.onClose(force);
+  });
+  conn.client.on('error', function(err) {
+    conn.emit('error', err);
+  });
+
+  if (!conn.client.s.options.useUnifiedTopology) {
+    conn.db.on('reconnect', function() {
+      conn.readyState = STATES.connected;
+      conn.emit('reconnect');
+      conn.emit('reconnected');
+      conn.onOpen();
+    });
+    conn.db.on('open', function(err, db) {
+      if (STATES.disconnected === conn.readyState && db && db.databaseName) {
+        conn.readyState = STATES.connected;
+        conn.emit('reconnect');
+        conn.emit('reconnected');
+      }
+    });
+  }
+
+  conn.client.on('timeout', function(err) {
+    conn.emit('timeout', err);
+  });
+  conn.client.on('parseError', function(err) {
+    conn.emit('parseError', err);
+  });
+}
+
+/**
+ * Closes the connection
+ *
+ * @param {Boolean} [force]
+ * @param {Function} [fn]
+ * @return {Connection} this
+ * @api private
+ */
+
+NativeConnection.prototype.doClose = function(force, fn) {
+  if (this.client == null) {
+    immediate(() => fn());
+    return this;
+  }
+
+  this.client.close(force, (err, res) => {
+    // Defer because the driver will wait at least 1ms before finishing closing
+    // the pool, see https://github.com/mongodb-js/mongodb-core/blob/a8f8e4ce41936babc3b9112bf42d609779f03b39/lib/connection/pool.js#L1026-L1030.
+    // If there's queued operations, you may still get some background work
+    // after the callback is called.
+    setTimeout(() => fn(err, res), 1);
+  });
+  return this;
+};
+
+/*!
+ * Module exports.
+ */
+
+module.exports = NativeConnection;