1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/dom/base/nsWindowMemoryReporter.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,247 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=8 sts=2 et sw=2 tw=80: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#ifndef nsWindowMemoryReporter_h__
1.11 +#define nsWindowMemoryReporter_h__
1.12 +
1.13 +#include "nsIMemoryReporter.h"
1.14 +#include "nsIObserver.h"
1.15 +#include "nsITimer.h"
1.16 +#include "nsDataHashtable.h"
1.17 +#include "nsWeakReference.h"
1.18 +#include "nsAutoPtr.h"
1.19 +#include "mozilla/Attributes.h"
1.20 +#include "mozilla/Assertions.h"
1.21 +#include "mozilla/MemoryReporting.h"
1.22 +#include "mozilla/PodOperations.h"
1.23 +#include "mozilla/TimeStamp.h"
1.24 +#include "nsArenaMemoryStats.h"
1.25 +
1.26 +class nsWindowSizes {
1.27 +#define FOR_EACH_SIZE(macro) \
1.28 + macro(DOM, mDOMElementNodesSize) \
1.29 + macro(DOM, mDOMTextNodesSize) \
1.30 + macro(DOM, mDOMCDATANodesSize) \
1.31 + macro(DOM, mDOMCommentNodesSize) \
1.32 + macro(DOM, mDOMEventTargetsSize) \
1.33 + macro(DOM, mDOMOtherSize) \
1.34 + macro(Style, mStyleSheetsSize) \
1.35 + macro(Other, mLayoutPresShellSize) \
1.36 + macro(Style, mLayoutStyleSetsSize) \
1.37 + macro(Other, mLayoutTextRunsSize) \
1.38 + macro(Other, mLayoutPresContextSize) \
1.39 + macro(Other, mPropertyTablesSize) \
1.40 +
1.41 +public:
1.42 + nsWindowSizes(mozilla::MallocSizeOf aMallocSizeOf)
1.43 + :
1.44 + #define ZERO_SIZE(kind, mSize) mSize(0),
1.45 + FOR_EACH_SIZE(ZERO_SIZE)
1.46 + #undef ZERO_SIZE
1.47 + mDOMEventTargetsCount(0),
1.48 + mDOMEventListenersCount(0),
1.49 + mArenaStats(),
1.50 + mMallocSizeOf(aMallocSizeOf)
1.51 + {}
1.52 +
1.53 + void addToTabSizes(nsTabSizes *sizes) const {
1.54 + #define ADD_TO_TAB_SIZES(kind, mSize) sizes->add(nsTabSizes::kind, mSize);
1.55 + FOR_EACH_SIZE(ADD_TO_TAB_SIZES)
1.56 + #undef ADD_TO_TAB_SIZES
1.57 + mArenaStats.addToTabSizes(sizes);
1.58 + }
1.59 +
1.60 + #define DECL_SIZE(kind, mSize) size_t mSize;
1.61 + FOR_EACH_SIZE(DECL_SIZE);
1.62 + #undef DECL_SIZE
1.63 +
1.64 + uint32_t mDOMEventTargetsCount;
1.65 + uint32_t mDOMEventListenersCount;
1.66 +
1.67 + nsArenaMemoryStats mArenaStats;
1.68 + mozilla::MallocSizeOf mMallocSizeOf;
1.69 +
1.70 +#undef FOR_EACH_SIZE
1.71 +};
1.72 +
1.73 +/**
1.74 + * nsWindowMemoryReporter is responsible for the 'explicit/window-objects'
1.75 + * memory reporter.
1.76 + *
1.77 + * We classify DOM window objects into one of three categories:
1.78 + *
1.79 + * - "active" windows, which are displayed in a tab (as the top-level window
1.80 + * or an iframe),
1.81 + *
1.82 + * - "cached" windows, which are in the fastback cache (aka the bfcache), and
1.83 + *
1.84 + * - "detached" windows, which have a null docshell. A window becomes
1.85 + * detached when its <iframe> or tab containing the window is destroyed --
1.86 + * i.e., when the window is no longer active or cached.
1.87 + *
1.88 + * Additionally, we classify a subset of detached windows as "ghost" windows.
1.89 + * Although ghost windows can happen legitimately (a page can hold a reference
1.90 + * to a cross-domain window and then close its container), the presence of
1.91 + * ghost windows is often indicative of a memory leak.
1.92 + *
1.93 + * A window is a ghost if it meets the following three criteria:
1.94 + *
1.95 + * 1) The window is detached.
1.96 + *
1.97 + * 2) There exist no non-detached windows with the same base domain as
1.98 + * the window's principal. (For example, the base domain of
1.99 + * "wiki.mozilla.co.uk" is "mozilla.co.uk".) This criterion makes us less
1.100 + * likely to flag a legitimately held-alive detached window as a ghost.
1.101 + *
1.102 + * 3) The window has met criteria (1) and (2) above for at least
1.103 + * memory.ghost_window_timeout_seconds. This criterion is in place so we
1.104 + * don't immediately declare a window a ghost before the GC/CC has had a
1.105 + * chance to run.
1.106 + *
1.107 + * nsWindowMemoryReporter observes window detachment and uses mDetachedWindows
1.108 + * to remember when a window first met criteria (1) and (2). When we generate
1.109 + * a memory report, we use this accounting to determine which windows are
1.110 + * ghosts.
1.111 + *
1.112 + *
1.113 + * We use the following memory reporter path for active and cached windows:
1.114 + *
1.115 + * explicit/window-objects/top(<top-outer-uri>, id=<top-outer-id>)/<category>/window(<window-uri>)/...
1.116 + *
1.117 + * For detached and ghost windows, we use
1.118 + *
1.119 + * explicit/window-objects/top(none)/<category>/window(<window-uri>)/...
1.120 + *
1.121 + * Where
1.122 + *
1.123 + * - <category> is "active", "cached", "detached", or "ghost", as described
1.124 + * above.
1.125 + *
1.126 + * - <top-outer-id> is the window id of the top outer window (i.e. the tab, or
1.127 + * the top level chrome window). Exposing this ensures that each tab gets
1.128 + * its own sub-tree, even if multiple tabs are showing the same URI.
1.129 + *
1.130 + * - <top-uri> is the URI of the top window. Excepting special windows (such
1.131 + * as browser.xul or hiddenWindow.html) it's what the address bar shows for
1.132 + * the tab.
1.133 + *
1.134 + */
1.135 +class nsWindowMemoryReporter MOZ_FINAL : public nsIMemoryReporter,
1.136 + public nsIObserver,
1.137 + public nsSupportsWeakReference
1.138 +{
1.139 +public:
1.140 + NS_DECL_ISUPPORTS
1.141 + NS_DECL_NSIMEMORYREPORTER
1.142 + NS_DECL_NSIOBSERVER
1.143 +
1.144 + static void Init();
1.145 +
1.146 + ~nsWindowMemoryReporter();
1.147 +
1.148 +#ifdef DEBUG
1.149 + /**
1.150 + * Unlink all known ghost windows, to enable investigating what caused them
1.151 + * to become ghost windows in the first place.
1.152 + */
1.153 + static void UnlinkGhostWindows();
1.154 +#endif
1.155 +
1.156 +private:
1.157 + /**
1.158 + * nsGhostWindowReporter generates the "ghost-windows" report, which counts
1.159 + * the number of ghost windows present.
1.160 + */
1.161 + class GhostWindowsReporter MOZ_FINAL : public nsIMemoryReporter
1.162 + {
1.163 + public:
1.164 + NS_DECL_ISUPPORTS
1.165 +
1.166 + static int64_t DistinguishedAmount();
1.167 +
1.168 + NS_IMETHOD
1.169 + CollectReports(nsIHandleReportCallback* aHandleReport, nsISupports* aData)
1.170 + {
1.171 + return MOZ_COLLECT_REPORT(
1.172 + "ghost-windows", KIND_OTHER, UNITS_COUNT, DistinguishedAmount(),
1.173 +"The number of ghost windows present (the number of nodes underneath "
1.174 +"explicit/window-objects/top(none)/ghost, modulo race conditions). A ghost "
1.175 +"window is not shown in any tab, does not share a domain with any non-detached "
1.176 +"windows, and has met these criteria for at least "
1.177 +"memory.ghost_window_timeout_seconds, or has survived a round of "
1.178 +"about:memory's minimize memory usage button.\n\n"
1.179 +"Ghost windows can happen legitimately, but they are often indicative of "
1.180 +"leaks in the browser or add-ons.");
1.181 + }
1.182 + };
1.183 +
1.184 + // Protect ctor, use Init() instead.
1.185 + nsWindowMemoryReporter();
1.186 +
1.187 + /**
1.188 + * Get the number of seconds for which a window must satisfy ghost criteria
1.189 + * (1) and (2) before we deem that it satisfies criterion (3).
1.190 + */
1.191 + uint32_t GetGhostTimeout();
1.192 +
1.193 + void ObserveDOMWindowDetached(nsISupports* aWindow);
1.194 + void ObserveAfterMinimizeMemoryUsage();
1.195 +
1.196 + /**
1.197 + * Iterate over all weak window pointers in mDetachedWindows and update our
1.198 + * accounting of which windows meet ghost criterion (2).
1.199 + *
1.200 + * This method also cleans up mDetachedWindows, removing entries for windows
1.201 + * which have been destroyed or are no longer detached.
1.202 + *
1.203 + * If aOutGhostIDs is non-null, we populate it with the Window IDs of the
1.204 + * ghost windows.
1.205 + *
1.206 + * This is called asynchronously after we observe a DOM window being detached
1.207 + * from its docshell, and also right before we generate a memory report.
1.208 + */
1.209 + void CheckForGhostWindows(nsTHashtable<nsUint64HashKey> *aOutGhostIDs = nullptr);
1.210 +
1.211 + /**
1.212 + * Eventually do a check for ghost windows, if we haven't done one recently
1.213 + * and we aren't already planning to do one soon.
1.214 + */
1.215 + void AsyncCheckForGhostWindows();
1.216 +
1.217 + /**
1.218 + * Kill the check timer, if it exists.
1.219 + */
1.220 + void KillCheckTimer();
1.221 +
1.222 + static void CheckTimerFired(nsITimer* aTimer, void* aClosure);
1.223 +
1.224 + /**
1.225 + * Maps a weak reference to a detached window (nsIWeakReference) to the time
1.226 + * when we observed that the window met ghost criterion (2) above.
1.227 + *
1.228 + * If the window has not yet met criterion (2) it maps to the null timestamp.
1.229 + *
1.230 + * (Although windows are not added to this table until they're detached, it's
1.231 + * possible for a detached window to become non-detached, and we won't
1.232 + * remove it from the table until CheckForGhostWindows runs.)
1.233 + */
1.234 + nsDataHashtable<nsISupportsHashKey, mozilla::TimeStamp> mDetachedWindows;
1.235 +
1.236 + /**
1.237 + * Track the last time we ran CheckForGhostWindows(), to avoid running it
1.238 + * too often after a DOM window is detached.
1.239 + */
1.240 + mozilla::TimeStamp mLastCheckForGhostWindows;
1.241 +
1.242 + nsCOMPtr<nsITimer> mCheckTimer;
1.243 +
1.244 + bool mCycleCollectorIsRunning;
1.245 +
1.246 + bool mCheckTimerWaitingForCCEnd;
1.247 +};
1.248 +
1.249 +#endif // nsWindowMemoryReporter_h__
1.250 +
