1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/toolkit/components/jsdownloads/src/DownloadStore.jsm Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,193 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=2 et sw=2 tw=80 filetype=javascript: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +/**
1.11 + * Handles serialization of Download objects and persistence into a file, so
1.12 + * that the state of downloads can be restored across sessions.
1.13 + *
1.14 + * The file is stored in JSON format, without indentation. With indentation
1.15 + * applied, the file would look like this:
1.16 + *
1.17 + * {
1.18 + * "list": [
1.19 + * {
1.20 + * "source": "http://www.example.com/download.txt",
1.21 + * "target": "/home/user/Downloads/download.txt"
1.22 + * },
1.23 + * {
1.24 + * "source": {
1.25 + * "url": "http://www.example.com/download.txt",
1.26 + * "referrer": "http://www.example.com/referrer.html"
1.27 + * },
1.28 + * "target": "/home/user/Downloads/download-2.txt"
1.29 + * }
1.30 + * ]
1.31 + * }
1.32 + */
1.33 +
1.34 +"use strict";
1.35 +
1.36 +this.EXPORTED_SYMBOLS = [
1.37 + "DownloadStore",
1.38 +];
1.39 +
1.40 +////////////////////////////////////////////////////////////////////////////////
1.41 +//// Globals
1.42 +
1.43 +const Cc = Components.classes;
1.44 +const Ci = Components.interfaces;
1.45 +const Cu = Components.utils;
1.46 +const Cr = Components.results;
1.47 +
1.48 +Cu.import("resource://gre/modules/XPCOMUtils.jsm");
1.49 +
1.50 +XPCOMUtils.defineLazyModuleGetter(this, "Downloads",
1.51 + "resource://gre/modules/Downloads.jsm");
1.52 +XPCOMUtils.defineLazyModuleGetter(this, "OS",
1.53 + "resource://gre/modules/osfile.jsm")
1.54 +XPCOMUtils.defineLazyModuleGetter(this, "Task",
1.55 + "resource://gre/modules/Task.jsm");
1.56 +
1.57 +XPCOMUtils.defineLazyGetter(this, "gTextDecoder", function () {
1.58 + return new TextDecoder();
1.59 +});
1.60 +
1.61 +XPCOMUtils.defineLazyGetter(this, "gTextEncoder", function () {
1.62 + return new TextEncoder();
1.63 +});
1.64 +
1.65 +////////////////////////////////////////////////////////////////////////////////
1.66 +//// DownloadStore
1.67 +
1.68 +/**
1.69 + * Handles serialization of Download objects and persistence into a file, so
1.70 + * that the state of downloads can be restored across sessions.
1.71 + *
1.72 + * @param aList
1.73 + * DownloadList object to be populated or serialized.
1.74 + * @param aPath
1.75 + * String containing the file path where data should be saved.
1.76 + */
1.77 +this.DownloadStore = function (aList, aPath)
1.78 +{
1.79 + this.list = aList;
1.80 + this.path = aPath;
1.81 +}
1.82 +
1.83 +this.DownloadStore.prototype = {
1.84 + /**
1.85 + * DownloadList object to be populated or serialized.
1.86 + */
1.87 + list: null,
1.88 +
1.89 + /**
1.90 + * String containing the file path where data should be saved.
1.91 + */
1.92 + path: "",
1.93 +
1.94 + /**
1.95 + * This function is called with a Download object as its first argument, and
1.96 + * should return true if the item should be saved.
1.97 + */
1.98 + onsaveitem: () => true,
1.99 +
1.100 + /**
1.101 + * Loads persistent downloads from the file to the list.
1.102 + *
1.103 + * @return {Promise}
1.104 + * @resolves When the operation finished successfully.
1.105 + * @rejects JavaScript exception.
1.106 + */
1.107 + load: function DS_load()
1.108 + {
1.109 + return Task.spawn(function task_DS_load() {
1.110 + let bytes;
1.111 + try {
1.112 + bytes = yield OS.File.read(this.path);
1.113 + } catch (ex if ex instanceof OS.File.Error && ex.becauseNoSuchFile) {
1.114 + // If the file does not exist, there are no downloads to load.
1.115 + return;
1.116 + }
1.117 +
1.118 + let storeData = JSON.parse(gTextDecoder.decode(bytes));
1.119 +
1.120 + // Create live downloads based on the static snapshot.
1.121 + for (let downloadData of storeData.list) {
1.122 + try {
1.123 + let download = yield Downloads.createDownload(downloadData);
1.124 + try {
1.125 + if (!download.succeeded && !download.canceled && !download.error) {
1.126 + // Try to restart the download if it was in progress during the
1.127 + // previous session.
1.128 + download.start();
1.129 + } else {
1.130 + // If the download was not in progress, try to update the current
1.131 + // progress from disk. This is relevant in case we retained
1.132 + // partially downloaded data.
1.133 + yield download.refresh();
1.134 + }
1.135 + } finally {
1.136 + // Add the download to the list if we succeeded in creating it,
1.137 + // after we have updated its initial state.
1.138 + yield this.list.add(download);
1.139 + }
1.140 + } catch (ex) {
1.141 + // If an item is unrecognized, don't prevent others from being loaded.
1.142 + Cu.reportError(ex);
1.143 + }
1.144 + }
1.145 + }.bind(this));
1.146 + },
1.147 +
1.148 + /**
1.149 + * Saves persistent downloads from the list to the file.
1.150 + *
1.151 + * If an error occurs, the previous file is not deleted.
1.152 + *
1.153 + * @return {Promise}
1.154 + * @resolves When the operation finished successfully.
1.155 + * @rejects JavaScript exception.
1.156 + */
1.157 + save: function DS_save()
1.158 + {
1.159 + return Task.spawn(function task_DS_save() {
1.160 + let downloads = yield this.list.getAll();
1.161 +
1.162 + // Take a static snapshot of the current state of all the downloads.
1.163 + let storeData = { list: [] };
1.164 + let atLeastOneDownload = false;
1.165 + for (let download of downloads) {
1.166 + try {
1.167 + if (!this.onsaveitem(download)) {
1.168 + continue;
1.169 + }
1.170 + storeData.list.push(download.toSerializable());
1.171 + atLeastOneDownload = true;
1.172 + } catch (ex) {
1.173 + // If an item cannot be converted to a serializable form, don't
1.174 + // prevent others from being saved.
1.175 + Cu.reportError(ex);
1.176 + }
1.177 + }
1.178 +
1.179 + if (atLeastOneDownload) {
1.180 + // Create or overwrite the file if there are downloads to save.
1.181 + let bytes = gTextEncoder.encode(JSON.stringify(storeData));
1.182 + yield OS.File.writeAtomic(this.path, bytes,
1.183 + { tmpPath: this.path + ".tmp" });
1.184 + } else {
1.185 + // Remove the file if there are no downloads to save at all.
1.186 + try {
1.187 + yield OS.File.remove(this.path);
1.188 + } catch (ex if ex instanceof OS.File.Error &&
1.189 + (ex.becauseNoSuchFile || ex.becauseAccessDenied)) {
1.190 + // On Windows, we may get an access denied error instead of a no such
1.191 + // file error if the file existed before, and was recently deleted.
1.192 + }
1.193 + }
1.194 + }.bind(this));
1.195 + },
1.196 +};
