widget/windows/WidgetTraceEvent.cpp

   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/. */
   4
   5 /*
   6  * Windows widget support for event loop instrumentation.
   7  * See toolkit/xre/EventTracer.cpp for more details.
   8  */
   9
  10 #include <stdio.h>
  11 #include <windows.h>
  12
  13 #include "mozilla/RefPtr.h"
  14 #include "mozilla/WidgetTraceEvent.h"
  15 #include "nsAppShellCID.h"
  16 #include "nsComponentManagerUtils.h"
  17 #include "nsCOMPtr.h"
  18 #include "nsIAppShellService.h"
  19 #include "nsIBaseWindow.h"
  20 #include "nsIDocShell.h"
  21 #include "nsISupportsImpl.h"
  22 #include "nsIWidget.h"
  23 #include "nsIAppWindow.h"
  24 #include "nsServiceManagerUtils.h"
  25 #include "nsThreadUtils.h"
  26 #include "nsWindowDefs.h"
  27
  28 namespace {
  29
  30 // Used for signaling the background thread from the main thread.
  31 HANDLE sEventHandle = nullptr;
  32
  33 // We need a runnable in order to find the hidden window on the main
  34 // thread.
  35 class HWNDGetter : public mozilla::Runnable {
  36  public:
  37   HWNDGetter() : Runnable("HWNDGetter"), hidden_window_hwnd(nullptr) {}
  38
  39   HWND hidden_window_hwnd;
  40
  41   NS_IMETHOD Run() override {
  42     // Jump through some hoops to locate the hidden window.
  43     nsCOMPtr<nsIAppShellService> appShell(
  44         do_GetService(NS_APPSHELLSERVICE_CONTRACTID));
  45     nsCOMPtr<nsIAppWindow> hiddenWindow;
  46
  47     nsresult rv = appShell->GetHiddenWindow(getter_AddRefs(hiddenWindow));
  48     if (NS_FAILED(rv)) {
  49       return rv;
  50     }
  51
  52     nsCOMPtr<nsIDocShell> docShell;
  53     rv = hiddenWindow->GetDocShell(getter_AddRefs(docShell));
  54     if (NS_FAILED(rv) || !docShell) {
  55       return rv;
  56     }
  57
  58     nsCOMPtr<nsIBaseWindow> baseWindow(do_QueryInterface(docShell));
  59
  60     if (!baseWindow) return NS_ERROR_FAILURE;
  61
  62     nsCOMPtr<nsIWidget> widget;
  63     baseWindow->GetMainWidget(getter_AddRefs(widget));
  64
  65     if (!widget) return NS_ERROR_FAILURE;
  66
  67     hidden_window_hwnd = (HWND)widget->GetNativeData(NS_NATIVE_WINDOW);
  68
  69     return NS_OK;
  70   }
  71 };
  72
  73 HWND GetHiddenWindowHWND() {
  74   // Need to dispatch this to the main thread because plenty of
  75   // the things it wants to access are main-thread-only.
  76   RefPtr<HWNDGetter> getter = new HWNDGetter();
  77   NS_DispatchToMainThread(getter, NS_DISPATCH_SYNC);
  78   return getter->hidden_window_hwnd;
  79 }
  80
  81 }  // namespace
  82
  83 namespace mozilla {
  84
  85 bool InitWidgetTracing() {
  86   sEventHandle = CreateEventW(nullptr, FALSE, FALSE, nullptr);
  87   return sEventHandle != nullptr;
  88 }
  89
  90 void CleanUpWidgetTracing() {
  91   CloseHandle(sEventHandle);
  92   sEventHandle = nullptr;
  93 }
  94
  95 // This function is called from the main (UI) thread.
  96 void SignalTracerThread() {
  97   if (sEventHandle != nullptr) SetEvent(sEventHandle);
  98 }
  99
 100 // This function is called from the background tracer thread.
 101 bool FireAndWaitForTracerEvent() {
 102   MOZ_ASSERT(sEventHandle, "Tracing not initialized!");
 103
 104   // First, try to find the hidden window.
 105   static HWND hidden_window = nullptr;
 106   if (hidden_window == nullptr) {
 107     hidden_window = GetHiddenWindowHWND();
 108   }
 109
 110   if (hidden_window == nullptr) return false;
 111
 112   // Post the tracer message into the hidden window's message queue,
 113   // and then block until it's processed.
 114   PostMessage(hidden_window, MOZ_WM_TRACE, 0, 0);
 115   WaitForSingleObject(sEventHandle, INFINITE);
 116   return true;
 117 }
 118
 119 }  // namespace mozilla