michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /**
michael@0:  * A worker dedicated to handle I/O for Session Store.
michael@0:  */
michael@0: 
michael@0: "use strict";
michael@0: 
michael@0: importScripts("resource://gre/modules/osfile.jsm");
michael@0: 
michael@0: let File = OS.File;
michael@0: let Encoder = new TextEncoder();
michael@0: let Decoder = new TextDecoder();
michael@0: 
michael@0: /**
michael@0:  * Communications with the controller.
michael@0:  *
michael@0:  * Accepts messages:
michael@0:  * {fun:function_name, args:array_of_arguments_or_null, id: custom_id}
michael@0:  *
michael@0:  * Sends messages:
michael@0:  * {ok: result, id: custom_id, telemetry: {}} /
michael@0:  * {fail: serialized_form_of_OS.File.Error, id: custom_id}
michael@0:  */
michael@0: self.onmessage = function (msg) {
michael@0:   let data = msg.data;
michael@0:   if (!(data.fun in Agent)) {
michael@0:     throw new Error("Cannot find method " + data.fun);
michael@0:   }
michael@0: 
michael@0:   let result;
michael@0:   let id = data.id;
michael@0: 
michael@0:   try {
michael@0:     result = Agent[data.fun].apply(Agent, data.args) || {};
michael@0:   } catch (ex if ex instanceof OS.File.Error) {
michael@0:     // Instances of OS.File.Error know how to serialize themselves
michael@0:     // (deserialization ensures that we end up with OS-specific
michael@0:     // instances of |OS.File.Error|)
michael@0:     self.postMessage({fail: OS.File.Error.toMsg(ex), id: id});
michael@0:     return;
michael@0:   }
michael@0: 
michael@0:   // Other exceptions do not, and should be propagated through DOM's
michael@0:   // built-in mechanism for uncaught errors, although this mechanism
michael@0:   // may lose interesting information.
michael@0:   self.postMessage({
michael@0:     ok: result.result,
michael@0:     id: id,
michael@0:     telemetry: result.telemetry || {}
michael@0:   });
michael@0: };
michael@0: 
michael@0: let Agent = {
michael@0:   // Boolean that tells whether we already made a
michael@0:   // call to write(). We will only attempt to move
michael@0:   // sessionstore.js to sessionstore.bak on the
michael@0:   // first write.
michael@0:   hasWrittenState: false,
michael@0: 
michael@0:   // The path to sessionstore.js
michael@0:   path: OS.Path.join(OS.Constants.Path.profileDir, "sessionstore.js"),
michael@0: 
michael@0:   // The path to sessionstore.bak
michael@0:   backupPath: OS.Path.join(OS.Constants.Path.profileDir, "sessionstore.bak"),
michael@0: 
michael@0:   /**
michael@0:    * NO-OP to start the worker.
michael@0:    */
michael@0:   init: function () {
michael@0:     return {result: true};
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Write the session to disk.
michael@0:    */
michael@0:   write: function (stateString) {
michael@0:     let exn;
michael@0:     let telemetry = {};
michael@0: 
michael@0:     if (!this.hasWrittenState) {
michael@0:       try {
michael@0:         let startMs = Date.now();
michael@0:         File.move(this.path, this.backupPath);
michael@0:         telemetry.FX_SESSION_RESTORE_BACKUP_FILE_MS = Date.now() - startMs;
michael@0:       } catch (ex if isNoSuchFileEx(ex)) {
michael@0:         // Ignore exceptions about non-existent files.
michael@0:       } catch (ex) {
michael@0:         // Throw the exception after we wrote the state to disk
michael@0:         // so that the backup can't interfere with the actual write.
michael@0:         exn = ex;
michael@0:       }
michael@0: 
michael@0:       this.hasWrittenState = true;
michael@0:     }
michael@0: 
michael@0:     let ret = this._write(stateString, telemetry);
michael@0: 
michael@0:     if (exn) {
michael@0:       throw exn;
michael@0:     }
michael@0: 
michael@0:     return ret;
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Extract all sorts of useful statistics from a state string,
michael@0:    * for use with Telemetry.
michael@0:    *
michael@0:    * @return {object}
michael@0:    */
michael@0:   gatherTelemetry: function (stateString) {
michael@0:     return Statistics.collect(stateString);
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Write a stateString to disk
michael@0:    */
michael@0:   _write: function (stateString, telemetry = {}) {
michael@0:     let bytes = Encoder.encode(stateString);
michael@0:     let startMs = Date.now();
michael@0:     let result = File.writeAtomic(this.path, bytes, {tmpPath: this.path + ".tmp"});
michael@0:     telemetry.FX_SESSION_RESTORE_WRITE_FILE_MS = Date.now() - startMs;
michael@0:     telemetry.FX_SESSION_RESTORE_FILE_SIZE_BYTES = bytes.byteLength;
michael@0:     return {result: result, telemetry: telemetry};
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Creates a copy of sessionstore.js.
michael@0:    */
michael@0:   createBackupCopy: function (ext) {
michael@0:     try {
michael@0:       return {result: File.copy(this.path, this.backupPath + ext)};
michael@0:     } catch (ex if isNoSuchFileEx(ex)) {
michael@0:       // Ignore exceptions about non-existent files.
michael@0:       return {result: true};
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Removes a backup copy.
michael@0:    */
michael@0:   removeBackupCopy: function (ext) {
michael@0:     try {
michael@0:       return {result: File.remove(this.backupPath + ext)};
michael@0:     } catch (ex if isNoSuchFileEx(ex)) {
michael@0:       // Ignore exceptions about non-existent files.
michael@0:       return {result: true};
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Wipes all files holding session data from disk.
michael@0:    */
michael@0:   wipe: function () {
michael@0:     let exn;
michael@0: 
michael@0:     // Erase session state file
michael@0:     try {
michael@0:       File.remove(this.path);
michael@0:     } catch (ex if isNoSuchFileEx(ex)) {
michael@0:       // Ignore exceptions about non-existent files.
michael@0:     } catch (ex) {
michael@0:       // Don't stop immediately.
michael@0:       exn = ex;
michael@0:     }
michael@0: 
michael@0:     // Erase any backup, any file named "sessionstore.bak[-buildID]".
michael@0:     let iter = new File.DirectoryIterator(OS.Constants.Path.profileDir);
michael@0:     for (let entry in iter) {
michael@0:       if (!entry.isDir && entry.path.startsWith(this.backupPath)) {
michael@0:         try {
michael@0:           File.remove(entry.path);
michael@0:         } catch (ex) {
michael@0:           // Don't stop immediately.
michael@0:           exn = exn || ex;
michael@0:         }
michael@0:       }
michael@0:     }
michael@0: 
michael@0:     if (exn) {
michael@0:       throw exn;
michael@0:     }
michael@0: 
michael@0:     return {result: true};
michael@0:   }
michael@0: };
michael@0: 
michael@0: function isNoSuchFileEx(aReason) {
michael@0:   return aReason instanceof OS.File.Error && aReason.becauseNoSuchFile;
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Estimate the number of bytes that a data structure will use on disk
michael@0:  * once serialized.
michael@0:  */
michael@0: function getByteLength(str) {
michael@0:   return Encoder.encode(JSON.stringify(str)).byteLength;
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * Tools for gathering statistics on a state string.
michael@0:  */
michael@0: let Statistics = {
michael@0:   collect: function(stateString) {
michael@0:     let start = Date.now();
michael@0:     let TOTAL_PREFIX = "FX_SESSION_RESTORE_TOTAL_";
michael@0:     let INDIVIDUAL_PREFIX = "FX_SESSION_RESTORE_INDIVIDUAL_";
michael@0:     let SIZE_SUFFIX = "_SIZE_BYTES";
michael@0: 
michael@0:     let state = JSON.parse(stateString);
michael@0: 
michael@0:     // Gather all data
michael@0:     let subsets = {};
michael@0:     this.gatherSimpleData(state, subsets);
michael@0:     this.gatherComplexData(state, subsets);
michael@0: 
michael@0:     // Extract telemetry
michael@0:     let telemetry = {};
michael@0:     for (let k of Object.keys(subsets)) {
michael@0:       let obj = subsets[k];
michael@0:       telemetry[TOTAL_PREFIX + k + SIZE_SUFFIX] = getByteLength(obj);
michael@0: 
michael@0:       if (Array.isArray(obj)) {
michael@0:         let size = obj.map(getByteLength);
michael@0:         telemetry[INDIVIDUAL_PREFIX + k + SIZE_SUFFIX] = size;
michael@0:       }
michael@0:     }
michael@0: 
michael@0:     let stop = Date.now();
michael@0:     telemetry["FX_SESSION_RESTORE_EXTRACTING_STATISTICS_DURATION_MS"] = stop - start;
michael@0:     return {
michael@0:       telemetry: telemetry
michael@0:     };
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Collect data that doesn't require a recursive walk through the
michael@0:    * data structure.
michael@0:    */
michael@0:   gatherSimpleData: function(state, subsets) {
michael@0:     // The subset of sessionstore.js dealing with open windows
michael@0:     subsets.OPEN_WINDOWS = state.windows;
michael@0: 
michael@0:     // The subset of sessionstore.js dealing with closed windows
michael@0:     subsets.CLOSED_WINDOWS = state._closedWindows;
michael@0: 
michael@0:     // The subset of sessionstore.js dealing with closed tabs
michael@0:     // in open windows
michael@0:     subsets.CLOSED_TABS_IN_OPEN_WINDOWS = [];
michael@0: 
michael@0:     // The subset of sessionstore.js dealing with cookies
michael@0:     // in both open and closed windows
michael@0:     subsets.COOKIES = [];
michael@0: 
michael@0:     for (let winData of state.windows) {
michael@0:       let closedTabs = winData._closedTabs || [];
michael@0:       subsets.CLOSED_TABS_IN_OPEN_WINDOWS.push(...closedTabs);
michael@0: 
michael@0:       let cookies = winData.cookies || [];
michael@0:       subsets.COOKIES.push(...cookies);
michael@0:     }
michael@0: 
michael@0:     for (let winData of state._closedWindows) {
michael@0:       let cookies = winData.cookies || [];
michael@0:       subsets.COOKIES.push(...cookies);
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Walk through a data structure, recursively.
michael@0:    *
michael@0:    * @param {object} root The object from which to start walking.
michael@0:    * @param {function(key, value)} cb Callback, called for each
michael@0:    * item except the root. Returns |true| to walk the subtree rooted
michael@0:    * at |value|, |false| otherwise   */
michael@0:   walk: function(root, cb) {
michael@0:     if (!root || typeof root !== "object") {
michael@0:       return;
michael@0:     }
michael@0:     for (let k of Object.keys(root)) {
michael@0:       let obj = root[k];
michael@0:       let stepIn = cb(k, obj);
michael@0:       if (stepIn) {
michael@0:         this.walk(obj, cb);
michael@0:       }
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Collect data that requires walking through the data structure
michael@0:    */
michael@0:   gatherComplexData: function(state, subsets) {
michael@0:     // The subset of sessionstore.js dealing with DOM storage
michael@0:     subsets.DOM_STORAGE = [];
michael@0:     // The subset of sessionstore.js storing form data
michael@0:     subsets.FORMDATA = [];
michael@0:     // The subset of sessionstore.js storing history
michael@0:     subsets.HISTORY = [];
michael@0: 
michael@0: 
michael@0:     this.walk(state, function(k, value) {
michael@0:       let dest;
michael@0:       switch (k) {
michael@0:         case "entries":
michael@0:           subsets.HISTORY.push(value);
michael@0:           return true;
michael@0:         case "storage":
michael@0:           subsets.DOM_STORAGE.push(value);
michael@0:           // Never visit storage, it's full of weird stuff
michael@0:           return false;
michael@0:         case "formdata":
michael@0:           subsets.FORMDATA.push(value);
michael@0:           // Never visit formdata, it's full of weird stuff
michael@0:           return false;
michael@0:         case "cookies": // Don't visit these places, they are full of weird stuff
michael@0:         case "extData":
michael@0:           return false;
michael@0:         default:
michael@0:           return true;
michael@0:       }
michael@0:     });
michael@0: 
michael@0:     return subsets;
michael@0:   },
michael@0: 
michael@0: };