The Tor Browser: comparison dom/base/nsWindowMemoryReporter.h

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+:689fab4f5734
+/* -*- 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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comparison: dom/base/nsWindowMemoryReporter.h

dom/base/nsWindowMemoryReporter.h