forked from mirrors/gecko-dev
402bc3a970
These are generally: - Code comments to browser.xhtml - Testcases, assertions that were mostly using browser.xul as a generic chrome URL - References to the browser.xul path in tree Differential Revision: https://phabricator.services.mozilla.com/D33208
178 lines
6 KiB
C++
178 lines
6 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsWindowMemoryReporter_h__
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#define nsWindowMemoryReporter_h__
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#include "nsGlobalWindow.h"
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#include "nsIMemoryReporter.h"
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#include "nsIObserver.h"
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#include "nsITimer.h"
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#include "nsDataHashtable.h"
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#include "nsWeakReference.h"
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#include "mozilla/Attributes.h"
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#include "mozilla/Assertions.h"
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#include "mozilla/MemoryReporting.h"
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#include "mozilla/PodOperations.h"
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#include "mozilla/TimeStamp.h"
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/**
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* nsWindowMemoryReporter is responsible for the 'explicit/window-objects'
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* memory reporter.
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*
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* We classify DOM window objects into one of three categories:
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*
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* - "active" windows, which are displayed in a tab (as the top-level window
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* or an iframe),
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*
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* - "cached" windows, which are in the fastback cache (aka the bfcache), and
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*
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* - "detached" windows, which have a null docshell. A window becomes
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* detached when its <iframe> or tab containing the window is destroyed --
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* i.e., when the window is no longer active or cached.
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*
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* Additionally, we classify a subset of detached windows as "ghost" windows.
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* Although ghost windows can happen legitimately (a page can hold a reference
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* to a cross-domain window and then close its container), the presence of
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* ghost windows is often indicative of a memory leak.
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*
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* A window is a ghost if it meets the following three criteria:
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*
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* 1) The window is detached.
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*
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* 2) There exist no non-detached windows with the same base domain as
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* the window's principal. (For example, the base domain of
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* "wiki.mozilla.co.uk" is "mozilla.co.uk".) This criterion makes us less
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* likely to flag a legitimately held-alive detached window as a ghost.
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*
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* 3) The window has met criteria (1) and (2) above for at least
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* memory.ghost_window_timeout_seconds. This criterion is in place so we
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* don't immediately declare a window a ghost before the GC/CC has had a
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* chance to run.
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*
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* nsWindowMemoryReporter observes window detachment and uses mDetachedWindows
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* to remember when a window first met criteria (1) and (2). When we generate
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* a memory report, we use this accounting to determine which windows are
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* ghosts.
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*
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*
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* We use the following memory reporter path for active and cached windows:
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*
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* explicit/window-objects/top(<top-outer-uri>, id=<top-outer-id>)/
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* <category>/window(<window-uri>)/...
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*
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* For detached and ghost windows, we use
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*
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* explicit/window-objects/top(none)/<category>/window(<window-uri>)/...
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*
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* Where
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*
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* - <category> is "active", "cached", "detached", or "ghost", as described
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* above.
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*
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* - <top-outer-id> is the window id of the top outer window (i.e. the tab, or
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* the top level chrome window). Exposing this ensures that each tab gets
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* its own sub-tree, even if multiple tabs are showing the same URI.
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*
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* - <top-uri> is the URI of the top window. Excepting special windows (such
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* as browser.xhtml or hiddenWindow.html) it's what the address bar shows for
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* the tab.
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*
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*/
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class nsWindowMemoryReporter final : public nsIMemoryReporter,
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public nsIObserver,
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public nsSupportsWeakReference {
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public:
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NS_DECL_ISUPPORTS
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NS_DECL_NSIMEMORYREPORTER
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NS_DECL_NSIOBSERVER
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static void Init();
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#ifdef DEBUG
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/**
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* Unlink all known ghost windows, to enable investigating what caused them
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* to become ghost windows in the first place.
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*/
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static void UnlinkGhostWindows();
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#endif
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static nsWindowMemoryReporter* Get();
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void ObserveDOMWindowDetached(nsGlobalWindowInner* aWindow);
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static int64_t GhostWindowsDistinguishedAmount();
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private:
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~nsWindowMemoryReporter();
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// Protect ctor, use Init() instead.
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nsWindowMemoryReporter();
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/**
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* Get the number of seconds for which a window must satisfy ghost criteria
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* (1) and (2) before we deem that it satisfies criterion (3).
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*/
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uint32_t GetGhostTimeout();
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void ObserveAfterMinimizeMemoryUsage();
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/**
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* Iterate over all weak window pointers in mDetachedWindows and update our
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* accounting of which windows meet ghost criterion (2).
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*
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* This method also cleans up mDetachedWindows, removing entries for windows
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* which have been destroyed or are no longer detached.
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*
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* If aOutGhostIDs is non-null, we populate it with the Window IDs of the
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* ghost windows.
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*
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* This is called asynchronously after we observe a DOM window being detached
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* from its docshell, and also right before we generate a memory report.
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*/
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void CheckForGhostWindows(
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nsTHashtable<nsUint64HashKey>* aOutGhostIDs = nullptr);
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/**
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* Eventually do a check for ghost windows, if we haven't done one recently
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* and we aren't already planning to do one soon.
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*/
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void AsyncCheckForGhostWindows();
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/**
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* Kill the check timer, if it exists.
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*/
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void KillCheckTimer();
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static void CheckTimerFired(nsITimer* aTimer, void* aClosure);
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/**
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* Maps a weak reference to a detached window (nsIWeakReference) to the time
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* when we observed that the window met ghost criterion (2) above.
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*
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* If the window has not yet met criterion (2) it maps to the null timestamp.
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*
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* (Although windows are not added to this table until they're detached, it's
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* possible for a detached window to become non-detached, and we won't
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* remove it from the table until CheckForGhostWindows runs.)
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*/
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nsDataHashtable<nsISupportsHashKey, mozilla::TimeStamp> mDetachedWindows;
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/**
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* Track the last time we ran CheckForGhostWindows(), to avoid running it
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* too often after a DOM window is detached.
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*/
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mozilla::TimeStamp mLastCheckForGhostWindows;
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nsCOMPtr<nsITimer> mCheckTimer;
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bool mCycleCollectorIsRunning;
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bool mCheckTimerWaitingForCCEnd;
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int64_t mGhostWindowCount;
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};
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#endif // nsWindowMemoryReporter_h__
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