The Tor Browser: widget/windows/WidgetTraceEvent.cpp@b8a032363ba2

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 /*

     6  * Windows widget support for event loop instrumentation.

     7  * See toolkit/xre/EventTracer.cpp for more details.

     8  */

    10 #include <stdio.h>

    11 #include <windows.h>

    13 #include "mozilla/WidgetTraceEvent.h"

    14 #include "nsAppShellCID.h"

    15 #include "nsComponentManagerUtils.h"

    16 #include "nsCOMPtr.h"

    17 #include "nsIAppShellService.h"

    18 #include "nsIBaseWindow.h"

    19 #include "nsIDocShell.h"

    20 #include "nsISupportsImpl.h"

    21 #include "nsIWidget.h"

    22 #include "nsIXULWindow.h"

    23 #include "nsAutoPtr.h"

    24 #include "nsServiceManagerUtils.h"

    25 #include "nsThreadUtils.h"

    26 #include "nsWindowDefs.h"

    28 namespace {

    30 // Used for signaling the background thread from the main thread.

    31 HANDLE sEventHandle = nullptr;

    33 // We need a runnable in order to find the hidden window on the main

    34 // thread.

    35 class HWNDGetter : public nsRunnable {

    36 public:

    37   HWNDGetter() : hidden_window_hwnd(nullptr) {

    38     MOZ_COUNT_CTOR(HWNDGetter);

    39   }

    40   ~HWNDGetter() {

    41     MOZ_COUNT_DTOR(HWNDGetter);

    42   }

    44   HWND hidden_window_hwnd;

    46   NS_IMETHOD Run() {

    47     // Jump through some hoops to locate the hidden window.

    48     nsCOMPtr<nsIAppShellService> appShell(do_GetService(NS_APPSHELLSERVICE_CONTRACTID));

    49     nsCOMPtr<nsIXULWindow> hiddenWindow;

    51     nsresult rv = appShell->GetHiddenWindow(getter_AddRefs(hiddenWindow));

    52     if (NS_FAILED(rv)) {

    53       return rv;

    54     }

    56     nsCOMPtr<nsIDocShell> docShell;

    57     rv = hiddenWindow->GetDocShell(getter_AddRefs(docShell));

    58     if (NS_FAILED(rv) || !docShell) {

    59       return rv;

    60     }

    62     nsCOMPtr<nsIBaseWindow> baseWindow(do_QueryInterface(docShell));

    64     if (!baseWindow)

    65       return NS_ERROR_FAILURE;

    67     nsCOMPtr<nsIWidget> widget;

    68     baseWindow->GetMainWidget(getter_AddRefs(widget));

    70     if (!widget)

    71       return NS_ERROR_FAILURE;

    73     hidden_window_hwnd = (HWND)widget->GetNativeData(NS_NATIVE_WINDOW);

    75     return NS_OK;

    76   }

    77 };

    79 HWND GetHiddenWindowHWND()

    80 {

    81   // Need to dispatch this to the main thread because plenty of

    82   // the things it wants to access are main-thread-only.

    83   nsRefPtr<HWNDGetter> getter = new HWNDGetter();

    84   NS_DispatchToMainThread(getter, NS_DISPATCH_SYNC);

    85   return getter->hidden_window_hwnd;

    86 }

    88 } // namespace

    90 namespace mozilla {

    92 bool InitWidgetTracing()

    93 {

    94   sEventHandle = CreateEvent(nullptr, FALSE, FALSE, nullptr);

    95   return sEventHandle != nullptr;

    96 }

    98 void CleanUpWidgetTracing()

    99 {

   100   CloseHandle(sEventHandle);

   101   sEventHandle = nullptr;

   102 }

   104 // This function is called from the main (UI) thread.

   105 void SignalTracerThread()

   106 {

   107   if (sEventHandle != nullptr)

   108     SetEvent(sEventHandle);

   109 }

   111 // This function is called from the background tracer thread.

   112 bool FireAndWaitForTracerEvent()

   113 {

   114   NS_ABORT_IF_FALSE(sEventHandle, "Tracing not initialized!");

   116   // First, try to find the hidden window.

   117   static HWND hidden_window = nullptr;

   118   if (hidden_window == nullptr) {

   119     hidden_window = GetHiddenWindowHWND();

   120   }

   122   if (hidden_window == nullptr)

   123     return false;

   125   // Post the tracer message into the hidden window's message queue,

   126   // and then block until it's processed.

   127   PostMessage(hidden_window, MOZ_WM_TRACE, 0, 0);

   128   WaitForSingleObject(sEventHandle, INFINITE);

   129   return true;

   130 }

   132 }  // namespace mozilla

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