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10863514cb
WTD-1051.
135 lines
5.5 KiB
JavaScript
135 lines
5.5 KiB
JavaScript
/*****************************************************************************
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* Open MCT Web, Copyright (c) 2014-2015, United States Government
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* as represented by the Administrator of the National Aeronautics and Space
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* Administration. All rights reserved.
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*
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* Open MCT Web is licensed under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0.
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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* Open MCT Web includes source code licensed under additional open source
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* licenses. See the Open Source Licenses file (LICENSES.md) included with
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* this source code distribution or the Licensing information page available
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* at runtime from the About dialog for additional information.
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*****************************************************************************/
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/*global define*/
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define(
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[],
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function () {
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"use strict";
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/**
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* The PersistenceQueue is used by the QueuingPersistenceCapability
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* to aggregrate calls for object persistence. These are then issued
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* in a group, such that if some or all are rejected, this result can
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* be shown to the user (again, in a group.)
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*
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* This implementation is separate out from PersistenceQueue, which
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* handles the wiring of injected dependencies into an instance of
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* this class.
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*
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* @param $timeout Angular's $timeout
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* @param {PersistenceQueueHandler} handler handles actual
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* persistence when the queue is flushed
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* @param {number} [DELAY] optional; delay in milliseconds between
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* attempts to flush the queue
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*/
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function PersistenceQueueImpl($q, $timeout, handler, DELAY) {
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var self,
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persistences = {},
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objects = {},
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lastObservedSize = 0,
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pendingTimeout,
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flushPromise,
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activeDefer = $q.defer();
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// Check if the queue's size has stopped increasing)
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function quiescent() {
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return Object.keys(persistences).length === lastObservedSize;
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}
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// Persist all queued objects
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function flush() {
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// Get a local reference to the active promise;
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// this will be replaced with a promise for the next round
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// of persistence calls, so we want to make sure we clear
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// the correct one when this flush completes.
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var flushingDefer = activeDefer;
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// Clear the active promise for a queue flush
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function clearFlushPromise(value) {
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flushPromise = undefined;
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flushingDefer.resolve(value);
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return value;
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}
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// Persist all queued objects
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flushPromise = handler.persist(persistences, objects, self)
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.then(clearFlushPromise, clearFlushPromise);
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// Reset queue, etc.
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persistences = {};
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objects = {};
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lastObservedSize = 0;
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pendingTimeout = undefined;
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activeDefer = $q.defer();
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}
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// Schedule a flushing of the queue (that is, plan to flush
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// all objects in the queue)
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function scheduleFlush() {
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function maybeFlush() {
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// Timeout fired, so clear it
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pendingTimeout = undefined;
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// Only flush when we've stopped receiving updates
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(quiescent() ? flush : scheduleFlush)();
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// Update lastObservedSize to detect quiescence
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lastObservedSize = Object.keys(persistences).length;
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}
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// If we are already flushing the queue...
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if (flushPromise) {
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// Wait until that's over before considering a flush
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flushPromise.then(maybeFlush);
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} else {
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// Otherwise, schedule a flush on a timeout (to give
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// a window for other updates to get aggregated)
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pendingTimeout = pendingTimeout ||
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$timeout(maybeFlush, DELAY, false);
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}
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return activeDefer.promise;
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}
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// If no delay is provided, use a default
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DELAY = DELAY || 0;
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self = {
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/**
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* Queue persistence of a domain object.
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* @param {DomainObject} domainObject the domain object
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* @param {PersistenceCapability} persistence the object's
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* undecorated persistence capability
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*/
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put: function (domainObject, persistence) {
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var id = domainObject.getId();
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persistences[id] = persistence;
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objects[id] = domainObject;
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return scheduleFlush();
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}
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};
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return self;
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}
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return PersistenceQueueImpl;
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}
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); |