xpcom/io/nsISafeOutputStream.idl
author Jan Henning <jh+bugzilla@buttercookie.de>
Thu, 07 Feb 2019 20:41:16 +0000
changeset 512996 95b884dcbd6f001b990a6353980280050fab9ac6
parent 98529 f4157e8c410708d76703f19e4dfb61859bfe32d8
child 534859 020c8c871c0d3b3920fe95935cfef06501976c0f
permissions -rw-r--r--
Bug 1496684 - Dispatch commonly expected startup notifications when opening a GeckoView window. r=snorp a=lizzard Once a webextension using a blocking WebRequest listener has started loading, all network connections covered by the extension's manifest are held until the extension is ready the process them. One condition for the extension being ready apparently includes browser startup having progressed far enough, as signified by "browser-delayed-startup-finished" having been dispatched. Therefore, we have to start sending that notification when opening a new Gecko- View window, too, and copy Fennec's InitLater() system for that. Unlike Fennec, we cannot tie registration of those InitLater() runnables to the initial content load having progressed far enough because of a) e10s, which makes that approach neither easily possible nor really sensible, as content will load in a different process in that case, and b) because we're racing with extension startup here - if extensions are loaded quick enough to block even the initial page load, we'd be deadlocked: We cannot send the notification until the page finishes loading, but the page cannot load until we send the notification. Fennec isn't affected by the latter problem because "sessionstore-windows-restored", which Fennec will send in any case, serves as an alternative pathway for completing extension startup. And unlike Desktop, we don't really have any chrome content to paint, so we cannot tie delayed initialisation to a paint listener for that, either. Therefore, we simply fire off a runnable at the *end* of geckoview.js's startup() method, which should give more pressing initialisation tasks enough of a headstart. For completeness, we're also adding the "browser-idle-startup-tasks-finished" notification and thereby solve bug 1465832 as well, allowing the ScriptPreloader to detect which scripts are commonly loaded during GeckoView startup and to start caching and pre-parsing them. Differential Revision: https://phabricator.services.mozilla.com/D18865

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"

/**
 * This interface provides a mechanism to control an output stream
 * that takes care not to overwrite an existing target until it is known
 * that all writes to the destination succeeded.
 * 
 * An object that supports this interface is intended to also support
 * nsIOutputStream.
 *
 * For example, a file output stream that supports this interface writes to
 * a temporary file, and moves it over the original file when |finish| is
 * called only if the stream can be successfully closed and all writes
 * succeeded.  If |finish| is called but something went wrong during
 * writing, it will delete the temporary file and not touch the original.
 * If the stream is closed by calling |close| directly, or the stream
 * goes away, the original file will not be overwritten, and the temporary
 * file will be deleted.
 *
 * Currently, this interface is implemented only for file output streams.
 */
[scriptable, uuid(5f914307-5c34-4e1f-8e32-ec749d25b27a)]
interface nsISafeOutputStream : nsISupports
{
    /**
     * Call this method to close the stream and cause the original target
     * to be overwritten. Note: if any call to |write| failed to write out
     * all of the data given to it, then calling this method will |close| the
     * stream and return failure. Further, if closing the stream fails, this
     * method will return failure. The original target will be overwritten only
     * if all calls to |write| succeeded and the stream was successfully closed.
     */
    void finish();
};