tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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wait-service.js (2024B)

      1 /* This Source Code Form is subject to the terms of the Mozilla Public
      2 * License, v. 2.0. If a copy of the MPL was not distributed with this
      3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      4 "use strict";
      5 
      6 /**
      7 * A middleware which acts like a service, because it is stateful
      8 * and "long-running" in the background. It provides the ability
      9 * for actions to install a function to be run once when a specific
     10 * condition is met by an action coming through the system. Think of
     11 * it as a thunk that blocks until the condition is met. Example:
     12 *
     13 * ```js
     14 * const services = { WAIT_UNTIL: require('wait-service').NAME };
     15 *
     16 * { type: services.WAIT_UNTIL,
     17 *   predicate: action => action.type === constants.ADD_ITEM,
     18 *   run: (dispatch, getState, action) => {
     19 *     // Do anything here. You only need to accept the arguments
     20 *     // if you need them. `action` is the action that satisfied
     21 *     // the predicate.
     22 *   }
     23 * }
     24 * ```
     25 */
     26 const NAME = (exports.NAME = "@@service/waitUntil");
     27 
     28 function waitUntilService({ dispatch, getState }) {
     29  let pending = [];
     30 
     31  function checkPending(action) {
     32    const readyRequests = [];
     33    const stillPending = [];
     34 
     35    // Find the pending requests whose predicates are satisfied with
     36    // this action. Wait to run the requests until after we update the
     37    // pending queue because the request handler may synchronously
     38    // dispatch again and run this service (that use case is
     39    // completely valid).
     40    for (const request of pending) {
     41      if (request.predicate(action)) {
     42        readyRequests.push(request);
     43      } else {
     44        stillPending.push(request);
     45      }
     46    }
     47 
     48    pending = stillPending;
     49    for (const request of readyRequests) {
     50      request.run(dispatch, getState, action);
     51    }
     52  }
     53 
     54  return next => action => {
     55    if (action.type === NAME) {
     56      pending.push(action);
     57      return null;
     58    }
     59    const result = next(action);
     60    checkPending(action);
     61    return result;
     62  };
     63 }
     64 exports.waitUntilService = waitUntilService;