1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/browser/components/sessionstore/src/SessionWorker.js Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,329 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this file,
1.6 + * You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +/**
1.9 + * A worker dedicated to handle I/O for Session Store.
1.10 + */
1.11 +
1.12 +"use strict";
1.13 +
1.14 +importScripts("resource://gre/modules/osfile.jsm");
1.15 +
1.16 +let File = OS.File;
1.17 +let Encoder = new TextEncoder();
1.18 +let Decoder = new TextDecoder();
1.19 +
1.20 +/**
1.21 + * Communications with the controller.
1.22 + *
1.23 + * Accepts messages:
1.24 + * {fun:function_name, args:array_of_arguments_or_null, id: custom_id}
1.25 + *
1.26 + * Sends messages:
1.27 + * {ok: result, id: custom_id, telemetry: {}} /
1.28 + * {fail: serialized_form_of_OS.File.Error, id: custom_id}
1.29 + */
1.30 +self.onmessage = function (msg) {
1.31 + let data = msg.data;
1.32 + if (!(data.fun in Agent)) {
1.33 + throw new Error("Cannot find method " + data.fun);
1.34 + }
1.35 +
1.36 + let result;
1.37 + let id = data.id;
1.38 +
1.39 + try {
1.40 + result = Agent[data.fun].apply(Agent, data.args) || {};
1.41 + } catch (ex if ex instanceof OS.File.Error) {
1.42 + // Instances of OS.File.Error know how to serialize themselves
1.43 + // (deserialization ensures that we end up with OS-specific
1.44 + // instances of |OS.File.Error|)
1.45 + self.postMessage({fail: OS.File.Error.toMsg(ex), id: id});
1.46 + return;
1.47 + }
1.48 +
1.49 + // Other exceptions do not, and should be propagated through DOM's
1.50 + // built-in mechanism for uncaught errors, although this mechanism
1.51 + // may lose interesting information.
1.52 + self.postMessage({
1.53 + ok: result.result,
1.54 + id: id,
1.55 + telemetry: result.telemetry || {}
1.56 + });
1.57 +};
1.58 +
1.59 +let Agent = {
1.60 + // Boolean that tells whether we already made a
1.61 + // call to write(). We will only attempt to move
1.62 + // sessionstore.js to sessionstore.bak on the
1.63 + // first write.
1.64 + hasWrittenState: false,
1.65 +
1.66 + // The path to sessionstore.js
1.67 + path: OS.Path.join(OS.Constants.Path.profileDir, "sessionstore.js"),
1.68 +
1.69 + // The path to sessionstore.bak
1.70 + backupPath: OS.Path.join(OS.Constants.Path.profileDir, "sessionstore.bak"),
1.71 +
1.72 + /**
1.73 + * NO-OP to start the worker.
1.74 + */
1.75 + init: function () {
1.76 + return {result: true};
1.77 + },
1.78 +
1.79 + /**
1.80 + * Write the session to disk.
1.81 + */
1.82 + write: function (stateString) {
1.83 + let exn;
1.84 + let telemetry = {};
1.85 +
1.86 + if (!this.hasWrittenState) {
1.87 + try {
1.88 + let startMs = Date.now();
1.89 + File.move(this.path, this.backupPath);
1.90 + telemetry.FX_SESSION_RESTORE_BACKUP_FILE_MS = Date.now() - startMs;
1.91 + } catch (ex if isNoSuchFileEx(ex)) {
1.92 + // Ignore exceptions about non-existent files.
1.93 + } catch (ex) {
1.94 + // Throw the exception after we wrote the state to disk
1.95 + // so that the backup can't interfere with the actual write.
1.96 + exn = ex;
1.97 + }
1.98 +
1.99 + this.hasWrittenState = true;
1.100 + }
1.101 +
1.102 + let ret = this._write(stateString, telemetry);
1.103 +
1.104 + if (exn) {
1.105 + throw exn;
1.106 + }
1.107 +
1.108 + return ret;
1.109 + },
1.110 +
1.111 + /**
1.112 + * Extract all sorts of useful statistics from a state string,
1.113 + * for use with Telemetry.
1.114 + *
1.115 + * @return {object}
1.116 + */
1.117 + gatherTelemetry: function (stateString) {
1.118 + return Statistics.collect(stateString);
1.119 + },
1.120 +
1.121 + /**
1.122 + * Write a stateString to disk
1.123 + */
1.124 + _write: function (stateString, telemetry = {}) {
1.125 + let bytes = Encoder.encode(stateString);
1.126 + let startMs = Date.now();
1.127 + let result = File.writeAtomic(this.path, bytes, {tmpPath: this.path + ".tmp"});
1.128 + telemetry.FX_SESSION_RESTORE_WRITE_FILE_MS = Date.now() - startMs;
1.129 + telemetry.FX_SESSION_RESTORE_FILE_SIZE_BYTES = bytes.byteLength;
1.130 + return {result: result, telemetry: telemetry};
1.131 + },
1.132 +
1.133 + /**
1.134 + * Creates a copy of sessionstore.js.
1.135 + */
1.136 + createBackupCopy: function (ext) {
1.137 + try {
1.138 + return {result: File.copy(this.path, this.backupPath + ext)};
1.139 + } catch (ex if isNoSuchFileEx(ex)) {
1.140 + // Ignore exceptions about non-existent files.
1.141 + return {result: true};
1.142 + }
1.143 + },
1.144 +
1.145 + /**
1.146 + * Removes a backup copy.
1.147 + */
1.148 + removeBackupCopy: function (ext) {
1.149 + try {
1.150 + return {result: File.remove(this.backupPath + ext)};
1.151 + } catch (ex if isNoSuchFileEx(ex)) {
1.152 + // Ignore exceptions about non-existent files.
1.153 + return {result: true};
1.154 + }
1.155 + },
1.156 +
1.157 + /**
1.158 + * Wipes all files holding session data from disk.
1.159 + */
1.160 + wipe: function () {
1.161 + let exn;
1.162 +
1.163 + // Erase session state file
1.164 + try {
1.165 + File.remove(this.path);
1.166 + } catch (ex if isNoSuchFileEx(ex)) {
1.167 + // Ignore exceptions about non-existent files.
1.168 + } catch (ex) {
1.169 + // Don't stop immediately.
1.170 + exn = ex;
1.171 + }
1.172 +
1.173 + // Erase any backup, any file named "sessionstore.bak[-buildID]".
1.174 + let iter = new File.DirectoryIterator(OS.Constants.Path.profileDir);
1.175 + for (let entry in iter) {
1.176 + if (!entry.isDir && entry.path.startsWith(this.backupPath)) {
1.177 + try {
1.178 + File.remove(entry.path);
1.179 + } catch (ex) {
1.180 + // Don't stop immediately.
1.181 + exn = exn || ex;
1.182 + }
1.183 + }
1.184 + }
1.185 +
1.186 + if (exn) {
1.187 + throw exn;
1.188 + }
1.189 +
1.190 + return {result: true};
1.191 + }
1.192 +};
1.193 +
1.194 +function isNoSuchFileEx(aReason) {
1.195 + return aReason instanceof OS.File.Error && aReason.becauseNoSuchFile;
1.196 +}
1.197 +
1.198 +/**
1.199 + * Estimate the number of bytes that a data structure will use on disk
1.200 + * once serialized.
1.201 + */
1.202 +function getByteLength(str) {
1.203 + return Encoder.encode(JSON.stringify(str)).byteLength;
1.204 +}
1.205 +
1.206 +/**
1.207 + * Tools for gathering statistics on a state string.
1.208 + */
1.209 +let Statistics = {
1.210 + collect: function(stateString) {
1.211 + let start = Date.now();
1.212 + let TOTAL_PREFIX = "FX_SESSION_RESTORE_TOTAL_";
1.213 + let INDIVIDUAL_PREFIX = "FX_SESSION_RESTORE_INDIVIDUAL_";
1.214 + let SIZE_SUFFIX = "_SIZE_BYTES";
1.215 +
1.216 + let state = JSON.parse(stateString);
1.217 +
1.218 + // Gather all data
1.219 + let subsets = {};
1.220 + this.gatherSimpleData(state, subsets);
1.221 + this.gatherComplexData(state, subsets);
1.222 +
1.223 + // Extract telemetry
1.224 + let telemetry = {};
1.225 + for (let k of Object.keys(subsets)) {
1.226 + let obj = subsets[k];
1.227 + telemetry[TOTAL_PREFIX + k + SIZE_SUFFIX] = getByteLength(obj);
1.228 +
1.229 + if (Array.isArray(obj)) {
1.230 + let size = obj.map(getByteLength);
1.231 + telemetry[INDIVIDUAL_PREFIX + k + SIZE_SUFFIX] = size;
1.232 + }
1.233 + }
1.234 +
1.235 + let stop = Date.now();
1.236 + telemetry["FX_SESSION_RESTORE_EXTRACTING_STATISTICS_DURATION_MS"] = stop - start;
1.237 + return {
1.238 + telemetry: telemetry
1.239 + };
1.240 + },
1.241 +
1.242 + /**
1.243 + * Collect data that doesn't require a recursive walk through the
1.244 + * data structure.
1.245 + */
1.246 + gatherSimpleData: function(state, subsets) {
1.247 + // The subset of sessionstore.js dealing with open windows
1.248 + subsets.OPEN_WINDOWS = state.windows;
1.249 +
1.250 + // The subset of sessionstore.js dealing with closed windows
1.251 + subsets.CLOSED_WINDOWS = state._closedWindows;
1.252 +
1.253 + // The subset of sessionstore.js dealing with closed tabs
1.254 + // in open windows
1.255 + subsets.CLOSED_TABS_IN_OPEN_WINDOWS = [];
1.256 +
1.257 + // The subset of sessionstore.js dealing with cookies
1.258 + // in both open and closed windows
1.259 + subsets.COOKIES = [];
1.260 +
1.261 + for (let winData of state.windows) {
1.262 + let closedTabs = winData._closedTabs || [];
1.263 + subsets.CLOSED_TABS_IN_OPEN_WINDOWS.push(...closedTabs);
1.264 +
1.265 + let cookies = winData.cookies || [];
1.266 + subsets.COOKIES.push(...cookies);
1.267 + }
1.268 +
1.269 + for (let winData of state._closedWindows) {
1.270 + let cookies = winData.cookies || [];
1.271 + subsets.COOKIES.push(...cookies);
1.272 + }
1.273 + },
1.274 +
1.275 + /**
1.276 + * Walk through a data structure, recursively.
1.277 + *
1.278 + * @param {object} root The object from which to start walking.
1.279 + * @param {function(key, value)} cb Callback, called for each
1.280 + * item except the root. Returns |true| to walk the subtree rooted
1.281 + * at |value|, |false| otherwise */
1.282 + walk: function(root, cb) {
1.283 + if (!root || typeof root !== "object") {
1.284 + return;
1.285 + }
1.286 + for (let k of Object.keys(root)) {
1.287 + let obj = root[k];
1.288 + let stepIn = cb(k, obj);
1.289 + if (stepIn) {
1.290 + this.walk(obj, cb);
1.291 + }
1.292 + }
1.293 + },
1.294 +
1.295 + /**
1.296 + * Collect data that requires walking through the data structure
1.297 + */
1.298 + gatherComplexData: function(state, subsets) {
1.299 + // The subset of sessionstore.js dealing with DOM storage
1.300 + subsets.DOM_STORAGE = [];
1.301 + // The subset of sessionstore.js storing form data
1.302 + subsets.FORMDATA = [];
1.303 + // The subset of sessionstore.js storing history
1.304 + subsets.HISTORY = [];
1.305 +
1.306 +
1.307 + this.walk(state, function(k, value) {
1.308 + let dest;
1.309 + switch (k) {
1.310 + case "entries":
1.311 + subsets.HISTORY.push(value);
1.312 + return true;
1.313 + case "storage":
1.314 + subsets.DOM_STORAGE.push(value);
1.315 + // Never visit storage, it's full of weird stuff
1.316 + return false;
1.317 + case "formdata":
1.318 + subsets.FORMDATA.push(value);
1.319 + // Never visit formdata, it's full of weird stuff
1.320 + return false;
1.321 + case "cookies": // Don't visit these places, they are full of weird stuff
1.322 + case "extData":
1.323 + return false;
1.324 + default:
1.325 + return true;
1.326 + }
1.327 + });
1.328 +
1.329 + return subsets;
1.330 + },
1.331 +
1.332 +};
