gecko/dom/base/nsWindowMemoryReporter.h

202 lines
7.2 KiB
C++

/* -*- 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 "nsDataHashtable.h"
#include "nsWeakReference.h"
#include "nsAutoPtr.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/TimeStamp.h"
#include "nsArenaMemoryStats.h"
#include "mozilla/Attributes.h"
// This should be used for any nsINode sub-class that has fields of its own
// that it needs to measure; any sub-class that doesn't use it will inherit
// SizeOfExcludingThis from its super-class. SizeOfIncludingThis() need not be
// defined, it is inherited from nsINode.
#define NS_DECL_SIZEOF_EXCLUDING_THIS \
virtual size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
class nsWindowSizes {
public:
nsWindowSizes(mozilla::MallocSizeOf aMallocSizeOf) {
memset(this, 0, sizeof(nsWindowSizes));
mMallocSizeOf = aMallocSizeOf;
}
mozilla::MallocSizeOf mMallocSizeOf;
nsArenaMemoryStats mArenaStats;
size_t mDOMElementNodes;
size_t mDOMTextNodes;
size_t mDOMCDATANodes;
size_t mDOMCommentNodes;
size_t mDOMEventTargets;
size_t mDOMOther;
size_t mStyleSheets;
size_t mLayoutPresShell;
size_t mLayoutStyleSets;
size_t mLayoutTextRuns;
size_t mLayoutPresContext;
size_t mPropertyTables;
};
/**
* 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* i.e., when the window is no longer active or cached.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();
private:
/**
* nsGhostWindowReporter generates the "ghost-windows" report, which counts
* the number of ghost windows present.
*/
class GhostWindowsReporter MOZ_FINAL : public mozilla::MemoryUniReporter
{
public:
GhostWindowsReporter()
: MemoryUniReporter("ghost-windows", KIND_OTHER, UNITS_COUNT,
"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.")
{}
static int64_t DistinguishedAmount();
private:
int64_t Amount() MOZ_OVERRIDE { return DistinguishedAmount(); }
};
// 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();
/**
* When we observe a DOM window being detached, we enqueue an asynchronous
* event which calls this method. This method then calls
* CheckForGhostWindows.
*/
void CheckForGhostWindowsCallback();
/**
* 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 = NULL);
/**
* 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;
/**
* True if we have an asynchronous call to CheckForGhostWindows pending.
*/
bool mCheckForGhostWindowsCallbackPending;
};
#endif // nsWindowMemoryReporter_h__