6 files changed, 1405 insertions, 0 deletions
diff --git a/node_modules/mongodb/lib/cmap/connection.js b/node_modules/mongodb/lib/cmap/connection.js
new file mode 100644
index 0000000..bf71562
--- /dev/null
+++ b/node_modules/mongodb/lib/cmap/connection.js
@@ -0,0 +1,384 @@
+'use strict';
+
+const EventEmitter = require('events');
+const MessageStream = require('./message_stream');
+const MongoError = require('../core/error').MongoError;
+const MongoNetworkError = require('../core/error').MongoNetworkError;
+const MongoNetworkTimeoutError = require('../core/error').MongoNetworkTimeoutError;
+const MongoWriteConcernError = require('../core/error').MongoWriteConcernError;
+const CommandResult = require('../core/connection/command_result');
+const StreamDescription = require('./stream_description').StreamDescription;
+const wp = require('../core/wireprotocol');
+const apm = require('../core/connection/apm');
+const updateSessionFromResponse = require('../core/sessions').updateSessionFromResponse;
+const uuidV4 = require('../core/utils').uuidV4;
+const now = require('../utils').now;
+const calculateDurationInMs = require('../utils').calculateDurationInMs;
+
+const kStream = Symbol('stream');
+const kQueue = Symbol('queue');
+const kMessageStream = Symbol('messageStream');
+const kGeneration = Symbol('generation');
+const kLastUseTime = Symbol('lastUseTime');
+const kClusterTime = Symbol('clusterTime');
+const kDescription = Symbol('description');
+const kIsMaster = Symbol('ismaster');
+const kAutoEncrypter = Symbol('autoEncrypter');
+
+class Connection extends EventEmitter {
+  constructor(stream, options) {
+    super(options);
+
+    this.id = options.id;
+    this.address = streamIdentifier(stream);
+    this.bson = options.bson;
+    this.socketTimeout = typeof options.socketTimeout === 'number' ? options.socketTimeout : 0;
+    this.host = options.host || 'localhost';
+    this.port = options.port || 27017;
+    this.monitorCommands =
+      typeof options.monitorCommands === 'boolean' ? options.monitorCommands : false;
+    this.closed = false;
+    this.destroyed = false;
+
+    this[kDescription] = new StreamDescription(this.address, options);
+    this[kGeneration] = options.generation;
+    this[kLastUseTime] = now();
+
+    // retain a reference to an `AutoEncrypter` if present
+    if (options.autoEncrypter) {
+      this[kAutoEncrypter] = options.autoEncrypter;
+    }
+
+    // setup parser stream and message handling
+    this[kQueue] = new Map();
+    this[kMessageStream] = new MessageStream(options);
+    this[kMessageStream].on('message', messageHandler(this));
+    this[kStream] = stream;
+    stream.on('error', () => {
+      /* ignore errors, listen to `close` instead */
+    });
+
+    stream.on('close', () => {
+      if (this.closed) {
+        return;
+      }
+
+      this.closed = true;
+      this[kQueue].forEach(op =>
+        op.cb(new MongoNetworkError(`connection ${this.id} to ${this.address} closed`))
+      );
+      this[kQueue].clear();
+
+      this.emit('close');
+    });
+
+    stream.on('timeout', () => {
+      if (this.closed) {
+        return;
+      }
+
+      stream.destroy();
+      this.closed = true;
+      this[kQueue].forEach(op =>
+        op.cb(
+          new MongoNetworkTimeoutError(`connection ${this.id} to ${this.address} timed out`, {
+            beforeHandshake: this[kIsMaster] == null
+          })
+        )
+      );
+
+      this[kQueue].clear();
+      this.emit('close');
+    });
+
+    // hook the message stream up to the passed in stream
+    stream.pipe(this[kMessageStream]);
+    this[kMessageStream].pipe(stream);
+  }
+
+  get description() {
+    return this[kDescription];
+  }
+
+  get ismaster() {
+    return this[kIsMaster];
+  }
+
+  // the `connect` method stores the result of the handshake ismaster on the connection
+  set ismaster(response) {
+    this[kDescription].receiveResponse(response);
+
+    // TODO: remove this, and only use the `StreamDescription` in the future
+    this[kIsMaster] = response;
+  }
+
+  get generation() {
+    return this[kGeneration] || 0;
+  }
+
+  get idleTime() {
+    return calculateDurationInMs(this[kLastUseTime]);
+  }
+
+  get clusterTime() {
+    return this[kClusterTime];
+  }
+
+  get stream() {
+    return this[kStream];
+  }
+
+  markAvailable() {
+    this[kLastUseTime] = now();
+  }
+
+  destroy(options, callback) {
+    if (typeof options === 'function') {
+      callback = options;
+      options = {};
+    }
+
+    options = Object.assign({ force: false }, options);
+    if (this[kStream] == null || this.destroyed) {
+      this.destroyed = true;
+      if (typeof callback === 'function') {
+        callback();
+      }
+
+      return;
+    }
+
+    if (options.force) {
+      this[kStream].destroy();
+      this.destroyed = true;
+      if (typeof callback === 'function') {
+        callback();
+      }
+
+      return;
+    }
+
+    this[kStream].end(err => {
+      this.destroyed = true;
+      if (typeof callback === 'function') {
+        callback(err);
+      }
+    });
+  }
+
+  // Wire protocol methods
+  command(ns, cmd, options, callback) {
+    wp.command(makeServerTrampoline(this), ns, cmd, options, callback);
+  }
+
+  query(ns, cmd, cursorState, options, callback) {
+    wp.query(makeServerTrampoline(this), ns, cmd, cursorState, options, callback);
+  }
+
+  getMore(ns, cursorState, batchSize, options, callback) {
+    wp.getMore(makeServerTrampoline(this), ns, cursorState, batchSize, options, callback);
+  }
+
+  killCursors(ns, cursorState, callback) {
+    wp.killCursors(makeServerTrampoline(this), ns, cursorState, callback);
+  }
+
+  insert(ns, ops, options, callback) {
+    wp.insert(makeServerTrampoline(this), ns, ops, options, callback);
+  }
+
+  update(ns, ops, options, callback) {
+    wp.update(makeServerTrampoline(this), ns, ops, options, callback);
+  }
+
+  remove(ns, ops, options, callback) {
+    wp.remove(makeServerTrampoline(this), ns, ops, options, callback);
+  }
+}
+
+/// This lets us emulate a legacy `Server` instance so we can work with the existing wire
+/// protocol methods. Eventually, the operation executor will return a `Connection` to execute
+/// against.
+function makeServerTrampoline(connection) {
+  const server = {
+    description: connection.description,
+    clusterTime: connection[kClusterTime],
+    s: {
+      bson: connection.bson,
+      pool: { write: write.bind(connection), isConnected: () => true }
+    }
+  };
+
+  if (connection[kAutoEncrypter]) {
+    server.autoEncrypter = connection[kAutoEncrypter];
+  }
+
+  return server;
+}
+
+function messageHandler(conn) {
+  return function messageHandler(message) {
+    // always emit the message, in case we are streaming
+    conn.emit('message', message);
+    if (!conn[kQueue].has(message.responseTo)) {
+      return;
+    }
+
+    const operationDescription = conn[kQueue].get(message.responseTo);
+    const callback = operationDescription.cb;
+
+    // SERVER-45775: For exhaust responses we should be able to use the same requestId to
+    // track response, however the server currently synthetically produces remote requests
+    // making the `responseTo` change on each response
+    conn[kQueue].delete(message.responseTo);
+    if (message.moreToCome) {
+      // requeue the callback for next synthetic request
+      conn[kQueue].set(message.requestId, operationDescription);
+    } else if (operationDescription.socketTimeoutOverride) {
+      conn[kStream].setTimeout(conn.socketTimeout);
+    }
+
+    try {
+      // Pass in the entire description because it has BSON parsing options
+      message.parse(operationDescription);
+    } catch (err) {
+      callback(new MongoError(err));
+      return;
+    }
+
+    if (message.documents[0]) {
+      const document = message.documents[0];
+      const session = operationDescription.session;
+      if (session) {
+        updateSessionFromResponse(session, document);
+      }
+
+      if (document.$clusterTime) {
+        conn[kClusterTime] = document.$clusterTime;
+        conn.emit('clusterTimeReceived', document.$clusterTime);
+      }
+
+      if (operationDescription.command) {
+        if (document.writeConcernError) {
+          callback(new MongoWriteConcernError(document.writeConcernError, document));
+          return;
+        }
+
+        if (document.ok === 0 || document.$err || document.errmsg || document.code) {
+          callback(new MongoError(document));
+          return;
+        }
+      }
+    }
+
+    // NODE-2382: reenable in our glorious non-leaky abstraction future
+    // callback(null, operationDescription.fullResult ? message : message.documents[0]);
+
+    callback(
+      undefined,
+      new CommandResult(
+        operationDescription.fullResult ? message : message.documents[0],
+        conn,
+        message
+      )
+    );
+  };
+}
+
+function streamIdentifier(stream) {
+  if (typeof stream.address === 'function') {
+    return `${stream.remoteAddress}:${stream.remotePort}`;
+  }
+
+  return uuidV4().toString('hex');
+}
+
+// Not meant to be called directly, the wire protocol methods call this assuming it is a `Pool` instance
+function write(command, options, callback) {
+  if (typeof options === 'function') {
+    callback = options;
+  }
+
+  options = options || {};
+  const operationDescription = {
+    requestId: command.requestId,
+    cb: callback,
+    session: options.session,
+    fullResult: typeof options.fullResult === 'boolean' ? options.fullResult : false,
+    noResponse: typeof options.noResponse === 'boolean' ? options.noResponse : false,
+    documentsReturnedIn: options.documentsReturnedIn,
+    command: !!options.command,
+
+    // for BSON parsing
+    promoteLongs: typeof options.promoteLongs === 'boolean' ? options.promoteLongs : true,
+    promoteValues: typeof options.promoteValues === 'boolean' ? options.promoteValues : true,
+    promoteBuffers: typeof options.promoteBuffers === 'boolean' ? options.promoteBuffers : false,
+    raw: typeof options.raw === 'boolean' ? options.raw : false
+  };
+
+  if (this[kDescription] && this[kDescription].compressor) {
+    operationDescription.agreedCompressor = this[kDescription].compressor;
+
+    if (this[kDescription].zlibCompressionLevel) {
+      operationDescription.zlibCompressionLevel = this[kDescription].zlibCompressionLevel;
+    }
+  }
+
+  if (typeof options.socketTimeout === 'number') {
+    operationDescription.socketTimeoutOverride = true;
+    this[kStream].setTimeout(options.socketTimeout);
+  }
+
+  // if command monitoring is enabled we need to modify the callback here
+  if (this.monitorCommands) {
+    this.emit('commandStarted', new apm.CommandStartedEvent(this, command));
+
+    operationDescription.started = now();
+    operationDescription.cb = (err, reply) => {
+      if (err) {
+        this.emit(
+          'commandFailed',
+          new apm.CommandFailedEvent(this, command, err, operationDescription.started)
+        );
+      } else {
+        if (reply && reply.result && (reply.result.ok === 0 || reply.result.$err)) {
+          this.emit(
+            'commandFailed',
+            new apm.CommandFailedEvent(this, command, reply.result, operationDescription.started)
+          );
+        } else {
+          this.emit(
+            'commandSucceeded',
+            new apm.CommandSucceededEvent(this, command, reply, operationDescription.started)
+          );
+        }
+      }
+
+      if (typeof callback === 'function') {
+        callback(err, reply);
+      }
+    };
+  }
+
+  if (!operationDescription.noResponse) {
+    this[kQueue].set(operationDescription.requestId, operationDescription);
+  }
+
+  try {
+    this[kMessageStream].writeCommand(command, operationDescription);
+  } catch (e) {
+    if (!operationDescription.noResponse) {
+      this[kQueue].delete(operationDescription.requestId);
+      operationDescription.cb(e);
+      return;
+    }
+  }
+
+  if (operationDescription.noResponse) {
+    operationDescription.cb();
+  }
+}
+
+module.exports = {
+  Connection
+};
diff --git a/node_modules/mongodb/lib/cmap/connection_pool.js b/node_modules/mongodb/lib/cmap/connection_pool.js
new file mode 100644
index 0000000..4500d9a
--- /dev/null
+++ b/node_modules/mongodb/lib/cmap/connection_pool.js
@@ -0,0 +1,591 @@
+'use strict';
+
+const Denque = require('denque');
+const EventEmitter = require('events').EventEmitter;
+const Logger = require('../core/connection/logger');
+const makeCounter = require('../utils').makeCounter;
+const MongoError = require('../core/error').MongoError;
+const Connection = require('./connection').Connection;
+const eachAsync = require('../core/utils').eachAsync;
+const connect = require('../core/connection/connect');
+const relayEvents = require('../core/utils').relayEvents;
+
+const errors = require('./errors');
+const PoolClosedError = errors.PoolClosedError;
+const WaitQueueTimeoutError = errors.WaitQueueTimeoutError;
+
+const events = require('./events');
+const ConnectionPoolCreatedEvent = events.ConnectionPoolCreatedEvent;
+const ConnectionPoolClosedEvent = events.ConnectionPoolClosedEvent;
+const ConnectionCreatedEvent = events.ConnectionCreatedEvent;
+const ConnectionReadyEvent = events.ConnectionReadyEvent;
+const ConnectionClosedEvent = events.ConnectionClosedEvent;
+const ConnectionCheckOutStartedEvent = events.ConnectionCheckOutStartedEvent;
+const ConnectionCheckOutFailedEvent = events.ConnectionCheckOutFailedEvent;
+const ConnectionCheckedOutEvent = events.ConnectionCheckedOutEvent;
+const ConnectionCheckedInEvent = events.ConnectionCheckedInEvent;
+const ConnectionPoolClearedEvent = events.ConnectionPoolClearedEvent;
+
+const kLogger = Symbol('logger');
+const kConnections = Symbol('connections');
+const kPermits = Symbol('permits');
+const kMinPoolSizeTimer = Symbol('minPoolSizeTimer');
+const kGeneration = Symbol('generation');
+const kConnectionCounter = Symbol('connectionCounter');
+const kCancellationToken = Symbol('cancellationToken');
+const kWaitQueue = Symbol('waitQueue');
+const kCancelled = Symbol('cancelled');
+
+const VALID_POOL_OPTIONS = new Set([
+  // `connect` options
+  'ssl',
+  'bson',
+  'connectionType',
+  'monitorCommands',
+  'socketTimeout',
+  'credentials',
+  'compression',
+
+  // node Net options
+  'host',
+  'port',
+  'localAddress',
+  'localPort',
+  'family',
+  'hints',
+  'lookup',
+  'path',
+
+  // node TLS options
+  'ca',
+  'cert',
+  'sigalgs',
+  'ciphers',
+  'clientCertEngine',
+  'crl',
+  'dhparam',
+  'ecdhCurve',
+  'honorCipherOrder',
+  'key',
+  'privateKeyEngine',
+  'privateKeyIdentifier',
+  'maxVersion',
+  'minVersion',
+  'passphrase',
+  'pfx',
+  'secureOptions',
+  'secureProtocol',
+  'sessionIdContext',
+  'allowHalfOpen',
+  'rejectUnauthorized',
+  'pskCallback',
+  'ALPNProtocols',
+  'servername',
+  'checkServerIdentity',
+  'session',
+  'minDHSize',
+  'secureContext',
+
+  // spec options
+  'maxPoolSize',
+  'minPoolSize',
+  'maxIdleTimeMS',
+  'waitQueueTimeoutMS'
+]);
+
+function resolveOptions(options, defaults) {
+  const newOptions = Array.from(VALID_POOL_OPTIONS).reduce((obj, key) => {
+    if (Object.prototype.hasOwnProperty.call(options, key)) {
+      obj[key] = options[key];
+    }
+
+    return obj;
+  }, {});
+
+  return Object.freeze(Object.assign({}, defaults, newOptions));
+}
+
+/**
+ * Configuration options for drivers wrapping the node driver.
+ *
+ * @typedef {Object} ConnectionPoolOptions
+ * @property
+ * @property {string} [host] The host to connect to
+ * @property {number} [port] The port to connect to
+ * @property {bson} [bson] The BSON instance to use for new connections
+ * @property {number} [maxPoolSize=100] The maximum number of connections that may be associated with a pool at a given time. This includes in use and available connections.
+ * @property {number} [minPoolSize=0] The minimum number of connections that MUST exist at any moment in a single connection pool.
+ * @property {number} [maxIdleTimeMS] The maximum amount of time a connection should remain idle in the connection pool before being marked idle.
+ * @property {number} [waitQueueTimeoutMS=0] The maximum amount of time operation execution should wait for a connection to become available. The default is 0 which means there is no limit.
+ */
+
+/**
+ * A pool of connections which dynamically resizes, and emit events related to pool activity
+ *
+ * @property {number} generation An integer representing the SDAM generation of the pool
+ * @property {number} totalConnectionCount An integer expressing how many total connections (active + in use) the pool currently has
+ * @property {number} availableConnectionCount An integer expressing how many connections are currently available in the pool.
+ * @property {string} address The address of the endpoint the pool is connected to
+ *
+ * @emits ConnectionPool#connectionPoolCreated
+ * @emits ConnectionPool#connectionPoolClosed
+ * @emits ConnectionPool#connectionCreated
+ * @emits ConnectionPool#connectionReady
+ * @emits ConnectionPool#connectionClosed
+ * @emits ConnectionPool#connectionCheckOutStarted
+ * @emits ConnectionPool#connectionCheckOutFailed
+ * @emits ConnectionPool#connectionCheckedOut
+ * @emits ConnectionPool#connectionCheckedIn
+ * @emits ConnectionPool#connectionPoolCleared
+ */
+class ConnectionPool extends EventEmitter {
+  /**
+   * Create a new Connection Pool
+   *
+   * @param {ConnectionPoolOptions} options
+   */
+  constructor(options) {
+    super();
+    options = options || {};
+
+    this.closed = false;
+    this.options = resolveOptions(options, {
+      connectionType: Connection,
+      maxPoolSize: typeof options.maxPoolSize === 'number' ? options.maxPoolSize : 100,
+      minPoolSize: typeof options.minPoolSize === 'number' ? options.minPoolSize : 0,
+      maxIdleTimeMS: typeof options.maxIdleTimeMS === 'number' ? options.maxIdleTimeMS : 0,
+      waitQueueTimeoutMS:
+        typeof options.waitQueueTimeoutMS === 'number' ? options.waitQueueTimeoutMS : 0,
+      autoEncrypter: options.autoEncrypter,
+      metadata: options.metadata
+    });
+
+    if (options.minSize > options.maxSize) {
+      throw new TypeError(
+        'Connection pool minimum size must not be greater than maxiumum pool size'
+      );
+    }
+
+    this[kLogger] = Logger('ConnectionPool', options);
+    this[kConnections] = new Denque();
+    this[kPermits] = this.options.maxPoolSize;
+    this[kMinPoolSizeTimer] = undefined;
+    this[kGeneration] = 0;
+    this[kConnectionCounter] = makeCounter(1);
+    this[kCancellationToken] = new EventEmitter();
+    this[kCancellationToken].setMaxListeners(Infinity);
+    this[kWaitQueue] = new Denque();
+
+    process.nextTick(() => {
+      this.emit('connectionPoolCreated', new ConnectionPoolCreatedEvent(this));
+      ensureMinPoolSize(this);
+    });
+  }
+
+  get address() {
+    return `${this.options.host}:${this.options.port}`;
+  }
+
+  get generation() {
+    return this[kGeneration];
+  }
+
+  get totalConnectionCount() {
+    return this[kConnections].length + (this.options.maxPoolSize - this[kPermits]);
+  }
+
+  get availableConnectionCount() {
+    return this[kConnections].length;
+  }
+
+  get waitQueueSize() {
+    return this[kWaitQueue].length;
+  }
+
+  /**
+   * Check a connection out of this pool. The connection will continue to be tracked, but no reference to it
+   * will be held by the pool. This means that if a connection is checked out it MUST be checked back in or
+   * explicitly destroyed by the new owner.
+   *
+   * @param {ConnectionPool~checkOutCallback} callback
+   */
+  checkOut(callback) {
+    this.emit('connectionCheckOutStarted', new ConnectionCheckOutStartedEvent(this));
+
+    if (this.closed) {
+      this.emit('connectionCheckOutFailed', new ConnectionCheckOutFailedEvent(this, 'poolClosed'));
+      callback(new PoolClosedError(this));
+      return;
+    }
+
+    const waitQueueMember = { callback };
+
+    const pool = this;
+    const waitQueueTimeoutMS = this.options.waitQueueTimeoutMS;
+    if (waitQueueTimeoutMS) {
+      waitQueueMember.timer = setTimeout(() => {
+        waitQueueMember[kCancelled] = true;
+        waitQueueMember.timer = undefined;
+
+        pool.emit('connectionCheckOutFailed', new ConnectionCheckOutFailedEvent(pool, 'timeout'));
+        waitQueueMember.callback(new WaitQueueTimeoutError(pool));
+      }, waitQueueTimeoutMS);
+    }
+
+    this[kWaitQueue].push(waitQueueMember);
+    process.nextTick(() => processWaitQueue(this));
+  }
+
+  /**
+   * Check a connection into the pool.
+   *
+   * @param {Connection} connection The connection to check in
+   */
+  checkIn(connection) {
+    const poolClosed = this.closed;
+    const stale = connectionIsStale(this, connection);
+    const willDestroy = !!(poolClosed || stale || connection.closed);
+
+    if (!willDestroy) {
+      connection.markAvailable();
+      this[kConnections].push(connection);
+    }
+
+    this.emit('connectionCheckedIn', new ConnectionCheckedInEvent(this, connection));
+
+    if (willDestroy) {
+      const reason = connection.closed ? 'error' : poolClosed ? 'poolClosed' : 'stale';
+      destroyConnection(this, connection, reason);
+    }
+
+    process.nextTick(() => processWaitQueue(this));
+  }
+
+  /**
+   * Clear the pool
+   *
+   * Pool reset is handled by incrementing the pool's generation count. Any existing connection of a
+   * previous generation will eventually be pruned during subsequent checkouts.
+   */
+  clear() {
+    this[kGeneration] += 1;
+    this.emit('connectionPoolCleared', new ConnectionPoolClearedEvent(this));
+  }
+
+  /**
+   * Close the pool
+   *
+   * @param {object} [options] Optional settings
+   * @param {boolean} [options.force] Force close connections
+   * @param {Function} callback
+   */
+  close(options, callback) {
+    if (typeof options === 'function') {
+      callback = options;
+    }
+
+    options = Object.assign({ force: false }, options);
+    if (this.closed) {
+      return callback();
+    }
+
+    // immediately cancel any in-flight connections
+    this[kCancellationToken].emit('cancel');
+
+    // drain the wait queue
+    while (this.waitQueueSize) {
+      const waitQueueMember = this[kWaitQueue].pop();
+      clearTimeout(waitQueueMember.timer);
+      if (!waitQueueMember[kCancelled]) {
+        waitQueueMember.callback(new MongoError('connection pool closed'));
+      }
+    }
+
+    // clear the min pool size timer
+    if (this[kMinPoolSizeTimer]) {
+      clearTimeout(this[kMinPoolSizeTimer]);
+    }
+
+    // end the connection counter
+    if (typeof this[kConnectionCounter].return === 'function') {
+      this[kConnectionCounter].return();
+    }
+
+    // mark the pool as closed immediately
+    this.closed = true;
+
+    eachAsync(
+      this[kConnections].toArray(),
+      (conn, cb) => {
+        this.emit('connectionClosed', new ConnectionClosedEvent(this, conn, 'poolClosed'));
+        conn.destroy(options, cb);
+      },
+      err => {
+        this[kConnections].clear();
+        this.emit('connectionPoolClosed', new ConnectionPoolClosedEvent(this));
+        callback(err);
+      }
+    );
+  }
+
+  /**
+   * Runs a lambda with an implicitly checked out connection, checking that connection back in when the lambda
+   * has completed by calling back.
+   *
+   * NOTE: please note the required signature of `fn`
+   *
+   * @param {ConnectionPool~withConnectionCallback} fn A function which operates on a managed connection
+   * @param {Function} callback The original callback
+   * @return {Promise}
+   */
+  withConnection(fn, callback) {
+    this.checkOut((err, conn) => {
+      // don't callback with `err` here, we might want to act upon it inside `fn`
+
+      fn(err, conn, (fnErr, result) => {
+        if (typeof callback === 'function') {
+          if (fnErr) {
+            callback(fnErr);
+          } else {
+            callback(undefined, result);
+          }
+        }
+
+        if (conn) {
+          this.checkIn(conn);
+        }
+      });
+    });
+  }
+}
+
+function ensureMinPoolSize(pool) {
+  if (pool.closed || pool.options.minPoolSize === 0) {
+    return;
+  }
+
+  const minPoolSize = pool.options.minPoolSize;
+  for (let i = pool.totalConnectionCount; i < minPoolSize; ++i) {
+    createConnection(pool);
+  }
+
+  pool[kMinPoolSizeTimer] = setTimeout(() => ensureMinPoolSize(pool), 10);
+}
+
+function connectionIsStale(pool, connection) {
+  return connection.generation !== pool[kGeneration];
+}
+
+function connectionIsIdle(pool, connection) {
+  return !!(pool.options.maxIdleTimeMS && connection.idleTime > pool.options.maxIdleTimeMS);
+}
+
+function createConnection(pool, callback) {
+  const connectOptions = Object.assign(
+    {
+      id: pool[kConnectionCounter].next().value,
+      generation: pool[kGeneration]
+    },
+    pool.options
+  );
+
+  pool[kPermits]--;
+  connect(connectOptions, pool[kCancellationToken], (err, connection) => {
+    if (err) {
+      pool[kPermits]++;
+      pool[kLogger].debug(`connection attempt failed with error [${JSON.stringify(err)}]`);
+      if (typeof callback === 'function') {
+        callback(err);
+      }
+
+      return;
+    }
+
+    // The pool might have closed since we started trying to create a connection
+    if (pool.closed) {
+      connection.destroy({ force: true });
+      return;
+    }
+
+    // forward all events from the connection to the pool
+    relayEvents(connection, pool, [
+      'commandStarted',
+      'commandFailed',
+      'commandSucceeded',
+      'clusterTimeReceived'
+    ]);
+
+    pool.emit('connectionCreated', new ConnectionCreatedEvent(pool, connection));
+
+    connection.markAvailable();
+    pool.emit('connectionReady', new ConnectionReadyEvent(pool, connection));
+
+    // if a callback has been provided, check out the connection immediately
+    if (typeof callback === 'function') {
+      callback(undefined, connection);
+      return;
+    }
+
+    // otherwise add it to the pool for later acquisition, and try to process the wait queue
+    pool[kConnections].push(connection);
+    process.nextTick(() => processWaitQueue(pool));
+  });
+}
+
+function destroyConnection(pool, connection, reason) {
+  pool.emit('connectionClosed', new ConnectionClosedEvent(pool, connection, reason));
+
+  // allow more connections to be created
+  pool[kPermits]++;
+
+  // destroy the connection
+  process.nextTick(() => connection.destroy());
+}
+
+function processWaitQueue(pool) {
+  if (pool.closed) {
+    return;
+  }
+
+  while (pool.waitQueueSize) {
+    const waitQueueMember = pool[kWaitQueue].peekFront();
+    if (waitQueueMember[kCancelled]) {
+      pool[kWaitQueue].shift();
+      continue;
+    }
+
+    if (!pool.availableConnectionCount) {
+      break;
+    }
+
+    const connection = pool[kConnections].shift();
+    const isStale = connectionIsStale(pool, connection);
+    const isIdle = connectionIsIdle(pool, connection);
+    if (!isStale && !isIdle && !connection.closed) {
+      pool.emit('connectionCheckedOut', new ConnectionCheckedOutEvent(pool, connection));
+      clearTimeout(waitQueueMember.timer);
+      pool[kWaitQueue].shift();
+      waitQueueMember.callback(undefined, connection);
+      return;
+    }
+
+    const reason = connection.closed ? 'error' : isStale ? 'stale' : 'idle';
+    destroyConnection(pool, connection, reason);
+  }
+
+  const maxPoolSize = pool.options.maxPoolSize;
+  if (pool.waitQueueSize && (maxPoolSize <= 0 || pool.totalConnectionCount < maxPoolSize)) {
+    createConnection(pool, (err, connection) => {
+      const waitQueueMember = pool[kWaitQueue].shift();
+      if (waitQueueMember == null || waitQueueMember[kCancelled]) {
+        if (err == null) {
+          pool[kConnections].push(connection);
+        }
+
+        return;
+      }
+
+      if (err) {
+        pool.emit('connectionCheckOutFailed', new ConnectionCheckOutFailedEvent(pool, err));
+      } else {
+        pool.emit('connectionCheckedOut', new ConnectionCheckedOutEvent(pool, connection));
+      }
+
+      clearTimeout(waitQueueMember.timer);
+      waitQueueMember.callback(err, connection);
+    });
+
+    return;
+  }
+}
+
+/**
+ * A callback provided to `withConnection`
+ *
+ * @callback ConnectionPool~withConnectionCallback
+ * @param {MongoError} error An error instance representing the error during the execution.
+ * @param {Connection} connection The managed connection which was checked out of the pool.
+ * @param {Function} callback A function to call back after connection management is complete
+ */
+
+/**
+ * A callback provided to `checkOut`
+ *
+ * @callback ConnectionPool~checkOutCallback
+ * @param {MongoError} error An error instance representing the error during checkout
+ * @param {Connection} connection A connection from the pool
+ */
+
+/**
+ * Emitted once when the connection pool is created
+ *
+ * @event ConnectionPool#connectionPoolCreated
+ * @type {PoolCreatedEvent}
+ */
+
+/**
+ * Emitted once when the connection pool is closed
+ *
+ * @event ConnectionPool#connectionPoolClosed
+ * @type {PoolClosedEvent}
+ */
+
+/**
+ * Emitted each time a connection is created
+ *
+ * @event ConnectionPool#connectionCreated
+ * @type {ConnectionCreatedEvent}
+ */
+
+/**
+ * Emitted when a connection becomes established, and is ready to use
+ *
+ * @event ConnectionPool#connectionReady
+ * @type {ConnectionReadyEvent}
+ */
+
+/**
+ * Emitted when a connection is closed
+ *
+ * @event ConnectionPool#connectionClosed
+ * @type {ConnectionClosedEvent}
+ */
+
+/**
+ * Emitted when an attempt to check out a connection begins
+ *
+ * @event ConnectionPool#connectionCheckOutStarted
+ * @type {ConnectionCheckOutStartedEvent}
+ */
+
+/**
+ * Emitted when an attempt to check out a connection fails
+ *
+ * @event ConnectionPool#connectionCheckOutFailed
+ * @type {ConnectionCheckOutFailedEvent}
+ */
+
+/**
+ * Emitted each time a connection is successfully checked out of the connection pool
+ *
+ * @event ConnectionPool#connectionCheckedOut
+ * @type {ConnectionCheckedOutEvent}
+ */
+
+/**
+ * Emitted each time a connection is successfully checked into the connection pool
+ *
+ * @event ConnectionPool#connectionCheckedIn
+ * @type {ConnectionCheckedInEvent}
+ */
+
+/**
+ * Emitted each time the connection pool is cleared and it's generation incremented
+ *
+ * @event ConnectionPool#connectionPoolCleared
+ * @type {PoolClearedEvent}
+ */
+
+module.exports = {
+  ConnectionPool
+};
diff --git a/node_modules/mongodb/lib/cmap/errors.js b/node_modules/mongodb/lib/cmap/errors.js
new file mode 100644
index 0000000..d933019
--- /dev/null
+++ b/node_modules/mongodb/lib/cmap/errors.js
@@ -0,0 +1,35 @@
+'use strict';
+const MongoError = require('../core/error').MongoError;
+
+/**
+ * An error indicating a connection pool is closed
+ *
+ * @property {string} address The address of the connection pool
+ * @extends MongoError
+ */
+class PoolClosedError extends MongoError {
+  constructor(pool) {
+    super('Attempted to check out a connection from closed connection pool');
+    this.name = 'MongoPoolClosedError';
+    this.address = pool.address;
+  }
+}
+
+/**
+ * An error thrown when a request to check out a connection times out
+ *
+ * @property {string} address The address of the connection pool
+ * @extends MongoError
+ */
+class WaitQueueTimeoutError extends MongoError {
+  constructor(pool) {
+    super('Timed out while checking out a connection from connection pool');
+    this.name = 'MongoWaitQueueTimeoutError';
+    this.address = pool.address;
+  }
+}
+
+module.exports = {
+  PoolClosedError,
+  WaitQueueTimeoutError
+};
diff --git a/node_modules/mongodb/lib/cmap/events.js b/node_modules/mongodb/lib/cmap/events.js
new file mode 100644
index 0000000..dcc8b67
--- /dev/null
+++ b/node_modules/mongodb/lib/cmap/events.js
@@ -0,0 +1,154 @@
+'use strict';
+
+/**
+ * The base class for all monitoring events published from the connection pool
+ *
+ * @property {number} time A timestamp when the event was created
+ * @property {string} address The address (host/port pair) of the pool
+ */
+class ConnectionPoolMonitoringEvent {
+  constructor(pool) {
+    this.time = new Date();
+    this.address = pool.address;
+  }
+}
+
+/**
+ * An event published when a connection pool is created
+ *
+ * @property {Object} options The options used to create this connection pool
+ */
+class ConnectionPoolCreatedEvent extends ConnectionPoolMonitoringEvent {
+  constructor(pool) {
+    super(pool);
+    this.options = pool.options;
+  }
+}
+
+/**
+ * An event published when a connection pool is closed
+ */
+class ConnectionPoolClosedEvent extends ConnectionPoolMonitoringEvent {
+  constructor(pool) {
+    super(pool);
+  }
+}
+
+/**
+ * An event published when a connection pool creates a new connection
+ *
+ * @property {number} connectionId A monotonically increasing, per-pool id for the newly created connection
+ */
+class ConnectionCreatedEvent extends ConnectionPoolMonitoringEvent {
+  constructor(pool, connection) {
+    super(pool);
+    this.connectionId = connection.id;
+  }
+}
+
+/**
+ * An event published when a connection is ready for use
+ *
+ * @property {number} connectionId The id of the connection
+ */
+class ConnectionReadyEvent extends ConnectionPoolMonitoringEvent {
+  constructor(pool, connection) {
+    super(pool);
+    this.connectionId = connection.id;
+  }
+}
+
+/**
+ * An event published when a connection is closed
+ *
+ * @property {number} connectionId The id of the connection
+ * @property {string} reason The reason the connection was closed
+ */
+class ConnectionClosedEvent extends ConnectionPoolMonitoringEvent {
+  constructor(pool, connection, reason) {
+    super(pool);
+    this.connectionId = connection.id;
+    this.reason = reason || 'unknown';
+  }
+}
+
+/**
+ * An event published when a request to check a connection out begins
+ */
+class ConnectionCheckOutStartedEvent extends ConnectionPoolMonitoringEvent {
+  constructor(pool) {
+    super(pool);
+  }
+}
+
+/**
+ * An event published when a request to check a connection out fails
+ *
+ * @property {string} reason The reason the attempt to check out failed
+ */
+class ConnectionCheckOutFailedEvent extends ConnectionPoolMonitoringEvent {
+  constructor(pool, reason) {
+    super(pool);
+    this.reason = reason;
+  }
+}
+
+/**
+ * An event published when a connection is checked out of the connection pool
+ *
+ * @property {number} connectionId The id of the connection
+ */
+class ConnectionCheckedOutEvent extends ConnectionPoolMonitoringEvent {
+  constructor(pool, connection) {
+    super(pool);
+    this.connectionId = connection.id;
+  }
+}
+
+/**
+ * An event published when a connection is checked into the connection pool
+ *
+ * @property {number} connectionId The id of the connection
+ */
+class ConnectionCheckedInEvent extends ConnectionPoolMonitoringEvent {
+  constructor(pool, connection) {
+    super(pool);
+    this.connectionId = connection.id;
+  }
+}
+
+/**
+ * An event published when a connection pool is cleared
+ */
+class ConnectionPoolClearedEvent extends ConnectionPoolMonitoringEvent {
+  constructor(pool) {
+    super(pool);
+  }
+}
+
+const CMAP_EVENT_NAMES = [
+  'connectionPoolCreated',
+  'connectionPoolClosed',
+  'connectionCreated',
+  'connectionReady',
+  'connectionClosed',
+  'connectionCheckOutStarted',
+  'connectionCheckOutFailed',
+  'connectionCheckedOut',
+  'connectionCheckedIn',
+  'connectionPoolCleared'
+];
+
+module.exports = {
+  CMAP_EVENT_NAMES,
+  ConnectionPoolCreatedEvent,
+  ConnectionPoolClosedEvent,
+  ConnectionCreatedEvent,
+  ConnectionReadyEvent,
+  ConnectionClosedEvent,
+  ConnectionCheckOutStartedEvent,
+  ConnectionCheckOutFailedEvent,
+  ConnectionCheckedOutEvent,
+  ConnectionCheckedInEvent,
+  ConnectionPoolClearedEvent
+};
diff --git a/node_modules/mongodb/lib/cmap/message_stream.js b/node_modules/mongodb/lib/cmap/message_stream.js
new file mode 100644
index 0000000..c8f458e
--- /dev/null
+++ b/node_modules/mongodb/lib/cmap/message_stream.js
@@ -0,0 +1,196 @@
+'use strict';
+
+const Duplex = require('stream').Duplex;
+const BufferList = require('bl');
+const MongoParseError = require('../core/error').MongoParseError;
+const decompress = require('../core/wireprotocol/compression').decompress;
+const Response = require('../core/connection/commands').Response;
+const BinMsg = require('../core/connection/msg').BinMsg;
+const MongoError = require('../core/error').MongoError;
+const OP_COMPRESSED = require('../core/wireprotocol/shared').opcodes.OP_COMPRESSED;
+const OP_MSG = require('../core/wireprotocol/shared').opcodes.OP_MSG;
+const MESSAGE_HEADER_SIZE = require('../core/wireprotocol/shared').MESSAGE_HEADER_SIZE;
+const COMPRESSION_DETAILS_SIZE = require('../core/wireprotocol/shared').COMPRESSION_DETAILS_SIZE;
+const opcodes = require('../core/wireprotocol/shared').opcodes;
+const compress = require('../core/wireprotocol/compression').compress;
+const compressorIDs = require('../core/wireprotocol/compression').compressorIDs;
+const uncompressibleCommands = require('../core/wireprotocol/compression').uncompressibleCommands;
+const Msg = require('../core/connection/msg').Msg;
+
+const kDefaultMaxBsonMessageSize = 1024 * 1024 * 16 * 4;
+const kBuffer = Symbol('buffer');
+
+/**
+ * A duplex stream that is capable of reading and writing raw wire protocol messages, with
+ * support for optional compression
+ */
+class MessageStream extends Duplex {
+  constructor(options) {
+    options = options || {};
+    super(options);
+
+    this.bson = options.bson;
+    this.maxBsonMessageSize = options.maxBsonMessageSize || kDefaultMaxBsonMessageSize;
+
+    this[kBuffer] = new BufferList();
+  }
+
+  _write(chunk, _, callback) {
+    const buffer = this[kBuffer];
+    buffer.append(chunk);
+
+    processIncomingData(this, callback);
+  }
+
+  _read(/* size */) {
+    // NOTE: This implementation is empty because we explicitly push data to be read
+    //       when `writeMessage` is called.
+    return;
+  }
+
+  writeCommand(command, operationDescription) {
+    // TODO: agreed compressor should live in `StreamDescription`
+    const shouldCompress = operationDescription && !!operationDescription.agreedCompressor;
+    if (!shouldCompress || !canCompress(command)) {
+      const data = command.toBin();
+      this.push(Array.isArray(data) ? Buffer.concat(data) : data);
+      return;
+    }
+
+    // otherwise, compress the message
+    const concatenatedOriginalCommandBuffer = Buffer.concat(command.toBin());
+    const messageToBeCompressed = concatenatedOriginalCommandBuffer.slice(MESSAGE_HEADER_SIZE);
+
+    // Extract information needed for OP_COMPRESSED from the uncompressed message
+    const originalCommandOpCode = concatenatedOriginalCommandBuffer.readInt32LE(12);
+
+    // Compress the message body
+    compress({ options: operationDescription }, messageToBeCompressed, (err, compressedMessage) => {
+      if (err) {
+        operationDescription.cb(err, null);
+        return;
+      }
+
+      // Create the msgHeader of OP_COMPRESSED
+      const msgHeader = Buffer.alloc(MESSAGE_HEADER_SIZE);
+      msgHeader.writeInt32LE(
+        MESSAGE_HEADER_SIZE + COMPRESSION_DETAILS_SIZE + compressedMessage.length,
+        0
+      ); // messageLength
+      msgHeader.writeInt32LE(command.requestId, 4); // requestID
+      msgHeader.writeInt32LE(0, 8); // responseTo (zero)
+      msgHeader.writeInt32LE(opcodes.OP_COMPRESSED, 12); // opCode
+
+      // Create the compression details of OP_COMPRESSED
+      const compressionDetails = Buffer.alloc(COMPRESSION_DETAILS_SIZE);
+      compressionDetails.writeInt32LE(originalCommandOpCode, 0); // originalOpcode
+      compressionDetails.writeInt32LE(messageToBeCompressed.length, 4); // Size of the uncompressed compressedMessage, excluding the MsgHeader
+      compressionDetails.writeUInt8(compressorIDs[operationDescription.agreedCompressor], 8); // compressorID
+
+      this.push(Buffer.concat([msgHeader, compressionDetails, compressedMessage]));
+    });
+  }
+}
+
+// Return whether a command contains an uncompressible command term
+// Will return true if command contains no uncompressible command terms
+function canCompress(command) {
+  const commandDoc = command instanceof Msg ? command.command : command.query;
+  const commandName = Object.keys(commandDoc)[0];
+  return !uncompressibleCommands.has(commandName);
+}
+
+function processIncomingData(stream, callback) {
+  const buffer = stream[kBuffer];
+  if (buffer.length < 4) {
+    callback();
+    return;
+  }
+
+  const sizeOfMessage = buffer.readInt32LE(0);
+  if (sizeOfMessage < 0) {
+    callback(new MongoParseError(`Invalid message size: ${sizeOfMessage}`));
+    return;
+  }
+
+  if (sizeOfMessage > stream.maxBsonMessageSize) {
+    callback(
+      new MongoParseError(
+        `Invalid message size: ${sizeOfMessage}, max allowed: ${stream.maxBsonMessageSize}`
+      )
+    );
+    return;
+  }
+
+  if (sizeOfMessage > buffer.length) {
+    callback();
+    return;
+  }
+
+  const message = buffer.slice(0, sizeOfMessage);
+  buffer.consume(sizeOfMessage);
+
+  const messageHeader = {
+    length: message.readInt32LE(0),
+    requestId: message.readInt32LE(4),
+    responseTo: message.readInt32LE(8),
+    opCode: message.readInt32LE(12)
+  };
+
+  let ResponseType = messageHeader.opCode === OP_MSG ? BinMsg : Response;
+  const responseOptions = stream.responseOptions;
+  if (messageHeader.opCode !== OP_COMPRESSED) {
+    const messageBody = message.slice(MESSAGE_HEADER_SIZE);
+    stream.emit(
+      'message',
+      new ResponseType(stream.bson, message, messageHeader, messageBody, responseOptions)
+    );
+
+    if (buffer.length >= 4) {
+      processIncomingData(stream, callback);
+    } else {
+      callback();
+    }
+
+    return;
+  }
+
+  messageHeader.fromCompressed = true;
+  messageHeader.opCode = message.readInt32LE(MESSAGE_HEADER_SIZE);
+  messageHeader.length = message.readInt32LE(MESSAGE_HEADER_SIZE + 4);
+  const compressorID = message[MESSAGE_HEADER_SIZE + 8];
+  const compressedBuffer = message.slice(MESSAGE_HEADER_SIZE + 9);
+
+  // recalculate based on wrapped opcode
+  ResponseType = messageHeader.opCode === OP_MSG ? BinMsg : Response;
+
+  decompress(compressorID, compressedBuffer, (err, messageBody) => {
+    if (err) {
+      callback(err);
+      return;
+    }
+
+    if (messageBody.length !== messageHeader.length) {
+      callback(
+        new MongoError(
+          'Decompressing a compressed message from the server failed. The message is corrupt.'
+        )
+      );
+
+      return;
+    }
+
+    stream.emit(
+      'message',
+      new ResponseType(stream.bson, message, messageHeader, messageBody, responseOptions)
+    );
+
+    if (buffer.length >= 4) {
+      processIncomingData(stream, callback);
+    } else {
+      callback();
+    }
+  });
+}
+
+module.exports = MessageStream;
diff --git a/node_modules/mongodb/lib/cmap/stream_description.js b/node_modules/mongodb/lib/cmap/stream_description.js
new file mode 100644
index 0000000..e806a5f
--- /dev/null
+++ b/node_modules/mongodb/lib/cmap/stream_description.js
@@ -0,0 +1,45 @@
+'use strict';
+const parseServerType = require('../core/sdam/server_description').parseServerType;
+
+const RESPONSE_FIELDS = [
+  'minWireVersion',
+  'maxWireVersion',
+  'maxBsonObjectSize',
+  'maxMessageSizeBytes',
+  'maxWriteBatchSize',
+  '__nodejs_mock_server__'
+];
+
+class StreamDescription {
+  constructor(address, options) {
+    this.address = address;
+    this.type = parseServerType(null);
+    this.minWireVersion = undefined;
+    this.maxWireVersion = undefined;
+    this.maxBsonObjectSize = 16777216;
+    this.maxMessageSizeBytes = 48000000;
+    this.maxWriteBatchSize = 100000;
+    this.compressors =
+      options && options.compression && Array.isArray(options.compression.compressors)
+        ? options.compression.compressors
+        : [];
+  }
+
+  receiveResponse(response) {
+    this.type = parseServerType(response);
+
+    RESPONSE_FIELDS.forEach(field => {
+      if (typeof response[field] !== 'undefined') {
+        this[field] = response[field];
+      }
+    });
+
+    if (response.compression) {
+      this.compressor = this.compressors.filter(c => response.compression.indexOf(c) !== -1)[0];
+    }
+  }
+}
+
+module.exports = {
+  StreamDescription
+};