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 /* -*- 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 nsWindowMemoryReporter_h__

 #define nsWindowMemoryReporter_h__

 #include "nsIMemoryReporter.h"

 #include "nsIObserver.h"

 #include "nsITimer.h"

 #include "nsDataHashtable.h"

 #include "nsWeakReference.h"

 #include "nsAutoPtr.h"

 #include "mozilla/Attributes.h"

 #include "mozilla/Assertions.h"

 #include "mozilla/MemoryReporting.h"

 #include "mozilla/PodOperations.h"

 #include "mozilla/TimeStamp.h"

 #include "nsArenaMemoryStats.h"

 class nsWindowSizes {

 #define FOR_EACH_SIZE(macro) \

   macro(DOM,   mDOMElementNodesSize) \

   macro(DOM,   mDOMTextNodesSize) \

   macro(DOM,   mDOMCDATANodesSize) \

   macro(DOM,   mDOMCommentNodesSize) \

   macro(DOM,   mDOMEventTargetsSize) \

   macro(DOM,   mDOMOtherSize) \

   macro(Style, mStyleSheetsSize) \

   macro(Other, mLayoutPresShellSize) \

   macro(Style, mLayoutStyleSetsSize) \

   macro(Other, mLayoutTextRunsSize) \

   macro(Other, mLayoutPresContextSize) \

   macro(Other, mPropertyTablesSize) \

 public:

   nsWindowSizes(mozilla::MallocSizeOf aMallocSizeOf)

     :

       #define ZERO_SIZE(kind, mSize)  mSize(0),

       FOR_EACH_SIZE(ZERO_SIZE)

       #undef ZERO_SIZE

       mDOMEventTargetsCount(0),

       mDOMEventListenersCount(0),

       mArenaStats(),

       mMallocSizeOf(aMallocSizeOf)

   {}

   void addToTabSizes(nsTabSizes *sizes) const {

     #define ADD_TO_TAB_SIZES(kind, mSize) sizes->add(nsTabSizes::kind, mSize);

     FOR_EACH_SIZE(ADD_TO_TAB_SIZES)

     #undef ADD_TO_TAB_SIZES

     mArenaStats.addToTabSizes(sizes);

   }

   #define DECL_SIZE(kind, mSize) size_t mSize;

   FOR_EACH_SIZE(DECL_SIZE);

   #undef DECL_SIZE

   uint32_t mDOMEventTargetsCount;

   uint32_t mDOMEventListenersCount;

   nsArenaMemoryStats mArenaStats;

   mozilla::MallocSizeOf mMallocSizeOf;

 #undef FOR_EACH_SIZE

 };

 /**

  * nsWindowMemoryReporter is responsible for the 'explicit/window-objects'

  * memory reporter.

  *

  * We classify DOM window objects into one of three categories:

  *

  *   - "active" windows, which are displayed in a tab (as the top-level window

  *     or an iframe),

  *

  *   - "cached" windows, which are in the fastback cache (aka the bfcache), and

  *

  *   - "detached" windows, which have a null docshell.  A window becomes

  *     detached when its <iframe> or tab containing the window is destroyed --

  *     i.e., when the window is no longer active or cached.

  *

  * Additionally, we classify a subset of detached windows as "ghost" windows.

  * Although ghost windows can happen legitimately (a page can hold a reference

  * to a cross-domain window and then close its container), the presence of

  * ghost windows is often indicative of a memory leak.

  *

  * A window is a ghost if it meets the following three criteria:

  *

  *   1) The window is detached.

  *

  *   2) There exist no non-detached windows with the same base domain as

  *      the window's principal.  (For example, the base domain of

  *      "wiki.mozilla.co.uk" is "mozilla.co.uk".)  This criterion makes us less

  *      likely to flag a legitimately held-alive detached window as a ghost.

  *

  *   3) The window has met criteria (1) and (2) above for at least

  *      memory.ghost_window_timeout_seconds.  This criterion is in place so we

  *      don't immediately declare a window a ghost before the GC/CC has had a

  *      chance to run.

  *

  * nsWindowMemoryReporter observes window detachment and uses mDetachedWindows

  * to remember when a window first met criteria (1) and (2).  When we generate

  * a memory report, we use this accounting to determine which windows are

  * ghosts.

  *

  *

  * We use the following memory reporter path for active and cached windows:

  *

  *   explicit/window-objects/top(<top-outer-uri>, id=<top-outer-id>)/<category>/window(<window-uri>)/...

  *

  * For detached and ghost windows, we use

  *

  *   explicit/window-objects/top(none)/<category>/window(<window-uri>)/...

  *

  * Where

  *

  * - <category> is "active", "cached", "detached", or "ghost", as described

  *   above.

  *

  * - <top-outer-id> is the window id of the top outer window (i.e. the tab, or

  *   the top level chrome window).  Exposing this ensures that each tab gets

  *   its own sub-tree, even if multiple tabs are showing the same URI.

  *

  * - <top-uri> is the URI of the top window.  Excepting special windows (such

  *   as browser.xul or hiddenWindow.html) it's what the address bar shows for

  *   the tab.

  *

  */

 class nsWindowMemoryReporter MOZ_FINAL : public nsIMemoryReporter,

                                          public nsIObserver,

                                          public nsSupportsWeakReference

 {

 public:

   NS_DECL_ISUPPORTS

   NS_DECL_NSIMEMORYREPORTER

   NS_DECL_NSIOBSERVER

   static void Init();

   ~nsWindowMemoryReporter();

 #ifdef DEBUG

   /**

    * Unlink all known ghost windows, to enable investigating what caused them

    * to become ghost windows in the first place.

    */

   static void UnlinkGhostWindows();

 #endif

 private:

   /**

    * nsGhostWindowReporter generates the "ghost-windows" report, which counts

    * the number of ghost windows present.

    */

   class GhostWindowsReporter MOZ_FINAL : public nsIMemoryReporter

   {

   public:

     NS_DECL_ISUPPORTS

     static int64_t DistinguishedAmount();

     NS_IMETHOD

     CollectReports(nsIHandleReportCallback* aHandleReport, nsISupports* aData)

     {

       return MOZ_COLLECT_REPORT(

         "ghost-windows", KIND_OTHER, UNITS_COUNT, DistinguishedAmount(),

 "The number of ghost windows present (the number of nodes underneath "

 "explicit/window-objects/top(none)/ghost, modulo race conditions).  A ghost "

 "window is not shown in any tab, does not share a domain with any non-detached "

 "windows, and has met these criteria for at least "

 "memory.ghost_window_timeout_seconds, or has survived a round of "

 "about:memory's minimize memory usage button.\n\n"

 "Ghost windows can happen legitimately, but they are often indicative of "

 "leaks in the browser or add-ons.");

     }

   };

   // Protect ctor, use Init() instead.

   nsWindowMemoryReporter();

   /**

    * Get the number of seconds for which a window must satisfy ghost criteria

    * (1) and (2) before we deem that it satisfies criterion (3).

    */

   uint32_t GetGhostTimeout();

   void ObserveDOMWindowDetached(nsISupports* aWindow);

   void ObserveAfterMinimizeMemoryUsage();

   /**

    * Iterate over all weak window pointers in mDetachedWindows and update our

    * accounting of which windows meet ghost criterion (2).

    *

    * This method also cleans up mDetachedWindows, removing entries for windows

    * which have been destroyed or are no longer detached.

    *

    * If aOutGhostIDs is non-null, we populate it with the Window IDs of the

    * ghost windows.

    *

    * This is called asynchronously after we observe a DOM window being detached

    * from its docshell, and also right before we generate a memory report.

    */

   void CheckForGhostWindows(nsTHashtable<nsUint64HashKey> *aOutGhostIDs = nullptr);

   /**

    * Eventually do a check for ghost windows, if we haven't done one recently

    * and we aren't already planning to do one soon.

    */

   void AsyncCheckForGhostWindows();

   /**

    * Kill the check timer, if it exists.

    */

   void KillCheckTimer();

   static void CheckTimerFired(nsITimer* aTimer, void* aClosure);

   /**

    * Maps a weak reference to a detached window (nsIWeakReference) to the time

    * when we observed that the window met ghost criterion (2) above.

    *

    * If the window has not yet met criterion (2) it maps to the null timestamp.

    *

    * (Although windows are not added to this table until they're detached, it's

    * possible for a detached window to become non-detached, and we won't

    * remove it from the table until CheckForGhostWindows runs.)

    */

   nsDataHashtable<nsISupportsHashKey, mozilla::TimeStamp> mDetachedWindows;

   /**

    * Track the last time we ran CheckForGhostWindows(), to avoid running it

    * too often after a DOM window is detached.

    */

   mozilla::TimeStamp mLastCheckForGhostWindows;

   nsCOMPtr<nsITimer> mCheckTimer;

   bool mCycleCollectorIsRunning;

   bool mCheckTimerWaitingForCCEnd;

 };

 #endif // nsWindowMemoryReporter_h__