xpcom/io/nsStorageStream.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/. */

/*
 * The storage stream provides an internal buffer that can be filled by a
 * client using a single output stream.  One or more independent input streams
 * can be created to read the data out non-destructively.  The implementation
 * uses a segmented buffer internally to avoid realloc'ing of large buffers,
 * with the attendant performance loss and heap fragmentation.
 */

#ifndef _nsStorageStream_h_
#define _nsStorageStream_h_

#include "nsIStorageStream.h"
#include "nsIOutputStream.h"
#include "nsMemory.h"
#include "mozilla/Attributes.h"

#define NS_STORAGESTREAM_CID                         \
  { /* 669a9795-6ff7-4ed4-9150-c34ce2971b63 */       \
    0x669a9795, 0x6ff7, 0x4ed4, {                    \
      0x91, 0x50, 0xc3, 0x4c, 0xe2, 0x97, 0x1b, 0x63 \
    }                                                \
  }

#define NS_STORAGESTREAM_CONTRACTID "@mozilla.org/storagestream;1"

class nsSegmentedBuffer;

class nsStorageStream final : public nsIStorageStream, public nsIOutputStream {
 public:
  nsStorageStream();

  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSISTORAGESTREAM
  NS_DECL_NSIOUTPUTSTREAM

  friend class nsStorageInputStream;

 private:
  ~nsStorageStream();

  nsSegmentedBuffer* mSegmentedBuffer;
  uint32_t
      mSegmentSize;  // All segments, except possibly the last, are of this size
                     //   Must be power-of-2
  uint32_t mSegmentSizeLog2;  // log2(mSegmentSize)
  bool mWriteInProgress;      // true, if an un-Close'ed output stream exists
  int32_t mLastSegmentNum;    // Last segment # in use, -1 initially
  char* mWriteCursor;         // Pointer to next byte to be written
  char* mSegmentEnd;          // Pointer to one byte after end of segment
                              //   containing the write cursor
  uint32_t mLogicalLength;    // Number of bytes written to stream

  nsresult Seek(int32_t aPosition);
  uint32_t SegNum(uint32_t aPosition) { return aPosition >> mSegmentSizeLog2; }
  uint32_t SegOffset(uint32_t aPosition) {
    return aPosition & (mSegmentSize - 1);
  }
};

#endif  //  _nsStorageStream_h_