xpcom/io/SnappyFrameUtils.h
author Jan Henning <jh+bugzilla@buttercookie.de>
Thu, 07 Feb 2019 20:41:16 +0000
changeset 512996 95b884dcbd6f001b990a6353980280050fab9ac6
parent 505383 6f3709b3878117466168c40affa7bca0b60cf75b
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: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#ifndef mozilla_SnappyFrameUtils_h__
#define mozilla_SnappyFrameUtils_h__

#include "mozilla/Attributes.h"
#include "nsError.h"

namespace mozilla {
namespace detail {

//
// Utility class providing primitives necessary to build streams based
// on the snappy compressor.  This essentially abstracts the framing format
// defined in:
//
//  other-licences/snappy/src/framing_format.txt
//
// NOTE: Currently only the StreamIdentifier and CompressedData chunks are
//       supported.
//
class SnappyFrameUtils {
 public:
  enum ChunkType {
    Unknown,
    StreamIdentifier,
    CompressedData,
    UncompressedData,
    Padding,
    Reserved,
    ChunkTypeCount
  };

  static const size_t kChunkTypeLength = 1;
  static const size_t kChunkLengthLength = 3;
  static const size_t kHeaderLength = kChunkTypeLength + kChunkLengthLength;
  static const size_t kStreamIdentifierDataLength = 6;
  static const size_t kCRCLength = 4;

  static nsresult WriteStreamIdentifier(char* aDest, size_t aDestLength,
                                        size_t* aBytesWrittenOut);

  static nsresult WriteCompressedData(char* aDest, size_t aDestLength,
                                      const char* aData, size_t aDataLength,
                                      size_t* aBytesWrittenOut);

  static nsresult ParseHeader(const char* aSource, size_t aSourceLength,
                              ChunkType* aTypeOut, size_t* aDataLengthOut);

  static nsresult ParseData(char* aDest, size_t aDestLength, ChunkType aType,
                            const char* aData, size_t aDataLength,
                            size_t* aBytesWrittenOut, size_t* aBytesReadOut);

  static nsresult ParseStreamIdentifier(char* aDest, size_t aDestLength,
                                        const char* aData, size_t aDataLength,
                                        size_t* aBytesWrittenOut,
                                        size_t* aBytesReadOut);

  static nsresult ParseCompressedData(char* aDest, size_t aDestLength,
                                      const char* aData, size_t aDataLength,
                                      size_t* aBytesWrittenOut,
                                      size_t* aBytesReadOut);

  static size_t MaxCompressedBufferLength(size_t aSourceLength);

 protected:
  SnappyFrameUtils() {}
  virtual ~SnappyFrameUtils() {}
};

}  // namespace detail
}  // namespace mozilla

#endif  // mozilla_SnappyFrameUtils_h__