The Tor Browser: dom/base/nsWindowMemoryReporter.h@6474c204b198 (annotated)

dom/base/nsWindowMemoryReporter.h@6474c204b198 (annotated)

dom/base/nsWindowMemoryReporter.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- 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__

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dom/base/nsWindowMemoryReporter.h@6474c204b198 (annotated)

dom/base/nsWindowMemoryReporter.h