chrome/browser/resources/bluetooth_internals/device_broker.js

// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * Javascript for device_broker, served from chrome://bluetooth-internals/.
 * Provides a single source to access DeviceProxys. DeviceProxys are cached for
 * for repeated use. Multiple connection requests will result in the same
 * DeviceProxy being shared among all requesters.
 */

// Expose for testing.
/**
 * @type {?Map<string,
 *     !bluetooth.mojom.DeviceProxy|!Promise<!bluetooth.mojom.DeviceProxy>>}
 */
var connectedDevices = null;

cr.define('device_broker', function() {
  connectedDevices = new Map();

  /**
   * Creates a GATT connection to the device with |address|. If a connection to
   * the device already exists, the promise is resolved with the existing
   * DeviceProxy. If a connection is in progress, the promise resolves when
   * the existing connection request promise is fulfilled.
   * @param {string} address
   * @return {!Promise<!bluetooth.mojom.DeviceProxy>}
   */
  function connectToDevice(address) {
    var deviceOrPromise = connectedDevices.get(address) || null;
    if (deviceOrPromise !== null) {
      return Promise.resolve(deviceOrPromise);
    }

    var promise = /** @type {!Promise<!bluetooth.mojom.DeviceProxy>} */ (
        adapter_broker.getAdapterBroker()
            .then(function(adapterBroker) {
              return adapterBroker.connectToDevice(address);
            })
            .then(function(device) {
              connectedDevices.set(address, device);

              device.onConnectionError.addListener(
                  () => connectedDevices.delete(address));

              return device;
            })
            .catch(function(error) {
              connectedDevices.delete(address);
              throw error;
            }));

    connectedDevices.set(address, promise);
    return promise;
  }

  return {connectToDevice: connectToDevice};
});