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WindowsMessageLoop.cpp
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WindowsMessageLoop.cpp
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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: sw=2 ts=2 et :
*/
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla Plugin App.
*
* The Initial Developer of the Original Code is
* Ben Turner <bent.mozilla@gmail.com>
* Portions created by the Initial Developer are Copyright (C) 2009
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Jim Mathies <jmathies@mozilla.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include "WindowsMessageLoop.h"
#include "RPCChannel.h"
#include "nsAutoPtr.h"
#include "nsServiceManagerUtils.h"
#include "nsStringGlue.h"
#include "nsIXULAppInfo.h"
#include "mozilla/Mutex.h"
#include "mozilla/PaintTracker.h"
using mozilla::ipc::SyncChannel;
using mozilla::ipc::RPCChannel;
using mozilla::MutexAutoUnlock;
using namespace mozilla::ipc::windows;
/**
* The Windows-only code below exists to solve a general problem with deadlocks
* that we experience when sending synchronous IPC messages to processes that
* contain native windows (i.e. HWNDs). Windows (the OS) sends synchronous
* messages between parent and child HWNDs in multiple circumstances (e.g.
* WM_PARENTNOTIFY, WM_NCACTIVATE, etc.), even when those HWNDs are controlled
* by different threads or different processes. Thus we can very easily end up
* in a deadlock by a call stack like the following:
*
* Process A:
* - CreateWindow(...) creates a "parent" HWND.
* - SendCreateChildWidget(HWND) is a sync IPC message that sends the "parent"
* HWND over to Process B. Process A blocks until a response is received
* from Process B.
*
* Process B:
* - RecvCreateWidget(HWND) gets the "parent" HWND from Process A.
* - CreateWindow(..., HWND) creates a "child" HWND with the parent from
* process A.
* - Windows (the OS) generates a WM_PARENTNOTIFY message that is sent
* synchronously to Process A. Process B blocks until a response is
* received from Process A. Process A, however, is blocked and cannot
* process the message. Both processes are deadlocked.
*
* The example above has a few different workarounds (e.g. setting the
* WS_EX_NOPARENTNOTIFY style on the child window) but the general problem is
* persists. Once two HWNDs are parented we must not block their owning
* threads when manipulating either HWND.
*
* Windows requires any application that hosts native HWNDs to always process
* messages or risk deadlock. Given our architecture the only way to meet
* Windows' requirement and allow for synchronous IPC messages is to pump a
* miniature message loop during a sync IPC call. We avoid processing any
* queued messages during the loop (with one exception, see below), but
* "nonqueued" messages (see
* http://msdn.microsoft.com/en-us/library/ms644927(VS.85).aspx under the
* section "Nonqueued messages") cannot be avoided. Those messages are trapped
* in a special window procedure where we can either ignore the message or
* process it in some fashion.
*
* Queued and "non-queued" messages will be processed during RPC calls if
* modal UI related api calls block an RPC in-call in the child. To prevent
* windows from freezing, and to allow concurrent processing of critical
* events (such as painting), we spin a native event dispatch loop while
* these in-calls are blocked.
*/
namespace {
const wchar_t kOldWndProcProp[] = L"MozillaIPCOldWndProc";
// This isn't defined before Windows XP.
enum { WM_XP_THEMECHANGED = 0x031A };
PRUnichar gAppMessageWindowName[256] = { 0 };
PRInt32 gAppMessageWindowNameLength = 0;
nsTArray<HWND>* gNeuteredWindows = nsnull;
typedef nsTArray<nsAutoPtr<DeferredMessage> > DeferredMessageArray;
DeferredMessageArray* gDeferredMessages = nsnull;
HHOOK gDeferredGetMsgHook = NULL;
HHOOK gDeferredCallWndProcHook = NULL;
DWORD gUIThreadId = 0;
int gEventLoopDepth = 0;
LRESULT CALLBACK
DeferredMessageHook(int nCode,
WPARAM wParam,
LPARAM lParam)
{
// XXX This function is called for *both* the WH_CALLWNDPROC hook and the
// WH_GETMESSAGE hook, but they have different parameters. We don't
// use any of them except nCode which has the same meaning.
// Only run deferred messages if all of these conditions are met:
// 1. The |nCode| indicates that this hook should do something.
// 2. We have deferred messages to run.
// 3. We're not being called from the PeekMessage within the WaitForNotify
// function (indicated with SyncChannel::IsPumpingMessages). We really
// only want to run after returning to the main event loop.
if (nCode >= 0 && gDeferredMessages && !SyncChannel::IsPumpingMessages()) {
NS_ASSERTION(gDeferredGetMsgHook && gDeferredCallWndProcHook,
"These hooks must be set if we're being called!");
NS_ASSERTION(gDeferredMessages->Length(), "No deferred messages?!");
// Unset hooks first, in case we reenter below.
UnhookWindowsHookEx(gDeferredGetMsgHook);
UnhookWindowsHookEx(gDeferredCallWndProcHook);
gDeferredGetMsgHook = 0;
gDeferredCallWndProcHook = 0;
// Unset the global and make sure we delete it when we're done here.
nsAutoPtr<DeferredMessageArray> messages(gDeferredMessages);
gDeferredMessages = nsnull;
// Run all the deferred messages in order.
PRUint32 count = messages->Length();
for (PRUint32 index = 0; index < count; index++) {
messages->ElementAt(index)->Run();
}
}
// Always call the next hook.
return CallNextHookEx(NULL, nCode, wParam, lParam);
}
void
ScheduleDeferredMessageRun()
{
if (gDeferredMessages &&
!(gDeferredGetMsgHook && gDeferredCallWndProcHook)) {
NS_ASSERTION(gDeferredMessages->Length(), "No deferred messages?!");
gDeferredGetMsgHook = ::SetWindowsHookEx(WH_GETMESSAGE, DeferredMessageHook,
NULL, gUIThreadId);
gDeferredCallWndProcHook = ::SetWindowsHookEx(WH_CALLWNDPROC,
DeferredMessageHook, NULL,
gUIThreadId);
NS_ASSERTION(gDeferredGetMsgHook && gDeferredCallWndProcHook,
"Failed to set hooks!");
}
}
LRESULT
ProcessOrDeferMessage(HWND hwnd,
UINT uMsg,
WPARAM wParam,
LPARAM lParam)
{
DeferredMessage* deferred = nsnull;
// Most messages ask for 0 to be returned if the message is processed.
LRESULT res = 0;
switch (uMsg) {
// Messages that can be deferred as-is. These must not contain pointers in
// their wParam or lParam arguments!
case WM_ACTIVATE:
case WM_ACTIVATEAPP:
case WM_CANCELMODE:
case WM_CAPTURECHANGED:
case WM_CHILDACTIVATE:
case WM_DESTROY:
case WM_ENABLE:
case WM_IME_NOTIFY:
case WM_IME_SETCONTEXT:
case WM_KILLFOCUS:
case WM_MOUSEWHEEL:
case WM_NCDESTROY:
case WM_PARENTNOTIFY:
case WM_SETFOCUS:
case WM_SYSCOMMAND:
case WM_SHOWWINDOW: // Intentional fall-through.
case WM_XP_THEMECHANGED: {
deferred = new DeferredSendMessage(hwnd, uMsg, wParam, lParam);
break;
}
case WM_DEVICECHANGE:
case WM_NCACTIVATE: // Intentional fall-through.
case WM_SETCURSOR: {
// Friggin unconventional return value...
res = TRUE;
deferred = new DeferredSendMessage(hwnd, uMsg, wParam, lParam);
break;
}
case WM_MOUSEACTIVATE: {
res = MA_NOACTIVATE;
deferred = new DeferredSendMessage(hwnd, uMsg, wParam, lParam);
break;
}
// These messages need to use the RedrawWindow function to generate the
// right kind of message. We can't simply fake them as the MSDN docs say
// explicitly that paint messages should not be sent by an application.
case WM_ERASEBKGND: {
UINT flags = RDW_INVALIDATE | RDW_ERASE | RDW_NOINTERNALPAINT |
RDW_NOFRAME | RDW_NOCHILDREN | RDW_ERASENOW;
deferred = new DeferredRedrawMessage(hwnd, flags);
break;
}
case WM_NCPAINT: {
UINT flags = RDW_INVALIDATE | RDW_FRAME | RDW_NOINTERNALPAINT |
RDW_NOERASE | RDW_NOCHILDREN | RDW_ERASENOW;
deferred = new DeferredRedrawMessage(hwnd, flags);
break;
}
// This message will generate a WM_PAINT message if there are invalid
// areas.
case WM_PAINT: {
deferred = new DeferredUpdateMessage(hwnd);
break;
}
// This message holds a string in its lParam that we must copy.
case WM_SETTINGCHANGE: {
deferred = new DeferredSettingChangeMessage(hwnd, uMsg, wParam, lParam);
break;
}
// These messages are faked via a call to SetWindowPos.
case WM_WINDOWPOSCHANGED: {
deferred = new DeferredWindowPosMessage(hwnd, lParam);
break;
}
case WM_NCCALCSIZE: {
deferred = new DeferredWindowPosMessage(hwnd, lParam, true, wParam);
break;
}
case WM_COPYDATA: {
deferred = new DeferredCopyDataMessage(hwnd, uMsg, wParam, lParam);
res = TRUE;
break;
}
case WM_STYLECHANGED: {
deferred = new DeferredStyleChangeMessage(hwnd, wParam, lParam);
break;
}
case WM_SETICON: {
deferred = new DeferredSetIconMessage(hwnd, uMsg, wParam, lParam);
break;
}
// Messages that are safe to pass to DefWindowProc go here.
case WM_ENTERIDLE:
case WM_GETICON:
case WM_GETMINMAXINFO:
case WM_GETTEXT:
case WM_NCHITTEST:
case WM_STYLECHANGING:
case WM_SYNCPAINT: // Intentional fall-through.
case WM_WINDOWPOSCHANGING: {
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
// Unknown messages only.
default: {
#ifdef DEBUG
nsCAutoString log("Received \"nonqueued\" message ");
log.AppendInt(uMsg);
log.AppendLiteral(" during a synchronous IPC message for window ");
log.AppendInt((PRInt64)hwnd);
wchar_t className[256] = { 0 };
if (GetClassNameW(hwnd, className, sizeof(className) - 1) > 0) {
log.AppendLiteral(" (\"");
log.Append(NS_ConvertUTF16toUTF8((PRUnichar*)className));
log.AppendLiteral("\")");
}
log.AppendLiteral(", sending it to DefWindowProc instead of the normal "
"window procedure.");
NS_ERROR(log.get());
#endif
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
}
NS_ASSERTION(deferred, "Must have a message here!");
// Create the deferred message array if it doesn't exist already.
if (!gDeferredMessages) {
gDeferredMessages = new nsTArray<nsAutoPtr<DeferredMessage> >(20);
NS_ASSERTION(gDeferredMessages, "Out of memory!");
}
// Save for later. The array takes ownership of |deferred|.
gDeferredMessages->AppendElement(deferred);
return res;
}
LRESULT CALLBACK
NeuteredWindowProc(HWND hwnd,
UINT uMsg,
WPARAM wParam,
LPARAM lParam)
{
WNDPROC oldWndProc = (WNDPROC)GetProp(hwnd, kOldWndProcProp);
if (!oldWndProc) {
// We should really never ever get here.
NS_ERROR("No old wndproc!");
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
// See if we care about this message. We may either ignore it, send it to
// DefWindowProc, or defer it for later.
return ProcessOrDeferMessage(hwnd, uMsg, wParam, lParam);
}
static bool
WindowIsDeferredWindow(HWND hWnd)
{
if (!IsWindow(hWnd)) {
NS_WARNING("Window has died!");
return false;
}
PRUnichar buffer[256] = { 0 };
int length = GetClassNameW(hWnd, (wchar_t*)buffer, sizeof(buffer) - 1);
if (length <= 0) {
NS_WARNING("Failed to get class name!");
return false;
}
// Common mozilla windows we must defer messages to.
nsDependentString className(buffer, length);
if (StringBeginsWith(className, NS_LITERAL_STRING("Mozilla")) ||
StringBeginsWith(className, NS_LITERAL_STRING("Gecko")) ||
className.EqualsLiteral("nsToolkitClass") ||
className.EqualsLiteral("nsAppShell:EventWindowClass")) {
return true;
}
// Plugin windows that can trigger ipc calls in child:
// 'ShockwaveFlashFullScreen' - flash fullscreen window
// 'AGFullScreenWinClass' - silverlight fullscreen window
if (className.EqualsLiteral("ShockwaveFlashFullScreen") ||
className.EqualsLiteral("AGFullScreenWinClass")) {
return true;
}
// nsNativeAppSupport makes a window like "FirefoxMessageWindow" based on the
// toolkit app's name. It's pretty expensive to calculate this so we only try
// once.
if (gAppMessageWindowNameLength == 0) {
nsCOMPtr<nsIXULAppInfo> appInfo =
do_GetService("@mozilla.org/xre/app-info;1");
if (appInfo) {
nsCAutoString appName;
if (NS_SUCCEEDED(appInfo->GetName(appName))) {
appName.Append("MessageWindow");
nsDependentString windowName(gAppMessageWindowName);
CopyUTF8toUTF16(appName, windowName);
gAppMessageWindowNameLength = windowName.Length();
}
}
// Don't try again if that failed.
if (gAppMessageWindowNameLength == 0) {
gAppMessageWindowNameLength = -1;
}
}
if (gAppMessageWindowNameLength != -1 &&
className.Equals(nsDependentString(gAppMessageWindowName,
gAppMessageWindowNameLength))) {
return true;
}
return false;
}
bool
NeuterWindowProcedure(HWND hWnd)
{
if (!WindowIsDeferredWindow(hWnd)) {
// Some other kind of window, skip.
return false;
}
NS_ASSERTION(!GetProp(hWnd, kOldWndProcProp), "This should always be null!");
// It's possible to get NULL out of SetWindowLongPtr, and the only way to know
// if that's a valid old value is to use GetLastError. Clear the error here so
// we can tell.
SetLastError(ERROR_SUCCESS);
LONG_PTR currentWndProc =
SetWindowLongPtr(hWnd, GWLP_WNDPROC, (LONG_PTR)NeuteredWindowProc);
if (!currentWndProc) {
if (ERROR_SUCCESS == GetLastError()) {
// No error, so we set something and must therefore reset it.
SetWindowLongPtr(hWnd, GWLP_WNDPROC, currentWndProc);
}
return false;
}
NS_ASSERTION(currentWndProc != (LONG_PTR)NeuteredWindowProc,
"This shouldn't be possible!");
if (!SetProp(hWnd, kOldWndProcProp, (HANDLE)currentWndProc)) {
// Cleanup
NS_WARNING("SetProp failed!");
SetWindowLongPtr(hWnd, GWLP_WNDPROC, currentWndProc);
RemoveProp(hWnd, kOldWndProcProp);
return false;
}
return true;
}
void
RestoreWindowProcedure(HWND hWnd)
{
NS_ASSERTION(WindowIsDeferredWindow(hWnd),
"Not a deferred window, this shouldn't be in our list!");
LONG_PTR oldWndProc = (LONG_PTR)RemoveProp(hWnd, kOldWndProcProp);
if (oldWndProc) {
NS_ASSERTION(oldWndProc != (LONG_PTR)NeuteredWindowProc,
"This shouldn't be possible!");
LONG_PTR currentWndProc =
SetWindowLongPtr(hWnd, GWLP_WNDPROC, oldWndProc);
NS_ASSERTION(currentWndProc == (LONG_PTR)NeuteredWindowProc,
"This should never be switched out from under us!");
}
}
LRESULT CALLBACK
CallWindowProcedureHook(int nCode,
WPARAM wParam,
LPARAM lParam)
{
if (nCode >= 0) {
NS_ASSERTION(gNeuteredWindows, "This should never be null!");
HWND hWnd = reinterpret_cast<CWPSTRUCT*>(lParam)->hwnd;
if (!gNeuteredWindows->Contains(hWnd) && NeuterWindowProcedure(hWnd)) {
if (!gNeuteredWindows->AppendElement(hWnd)) {
NS_ERROR("Out of memory!");
RestoreWindowProcedure(hWnd);
}
}
}
return CallNextHookEx(NULL, nCode, wParam, lParam);
}
inline void
AssertWindowIsNotNeutered(HWND hWnd)
{
#ifdef DEBUG
// Make sure our neutered window hook isn't still in place.
LONG_PTR wndproc = GetWindowLongPtr(hWnd, GWLP_WNDPROC);
NS_ASSERTION(wndproc != (LONG_PTR)NeuteredWindowProc, "Window is neutered!");
#endif
}
void
UnhookNeuteredWindows()
{
if (!gNeuteredWindows)
return;
PRUint32 count = gNeuteredWindows->Length();
for (PRUint32 index = 0; index < count; index++) {
RestoreWindowProcedure(gNeuteredWindows->ElementAt(index));
}
gNeuteredWindows->Clear();
}
void
Init()
{
// If we aren't setup before a call to NotifyWorkerThread, we'll hang
// on startup.
if (!gUIThreadId) {
gUIThreadId = GetCurrentThreadId();
}
NS_ASSERTION(gUIThreadId, "ThreadId should not be 0!");
NS_ASSERTION(gUIThreadId == GetCurrentThreadId(),
"Running on different threads!");
}
// This timeout stuff assumes a sane value of mTimeoutMs (less than the overflow
// value for GetTickCount(), which is something like 50 days). It uses the
// cheapest (and least accurate) method supported by Windows 2000.
struct TimeoutData
{
DWORD startTicks;
DWORD targetTicks;
};
void
InitTimeoutData(TimeoutData* aData,
int32 aTimeoutMs)
{
aData->startTicks = GetTickCount();
if (!aData->startTicks) {
// How unlikely is this!
aData->startTicks++;
}
aData->targetTicks = aData->startTicks + aTimeoutMs;
}
bool
TimeoutHasExpired(const TimeoutData& aData)
{
if (!aData.startTicks) {
return false;
}
DWORD now = GetTickCount();
if (aData.targetTicks < aData.startTicks) {
// Overflow
return now < aData.startTicks && now >= aData.targetTicks;
}
return now >= aData.targetTicks;
}
} // anonymous namespace
RPCChannel::SyncStackFrame::SyncStackFrame(SyncChannel* channel, bool rpc)
: mRPC(rpc)
, mSpinNestedEvents(false)
, mChannel(channel)
, mPrev(mChannel->mTopFrame)
, mStaticPrev(sStaticTopFrame)
{
mChannel->mTopFrame = this;
sStaticTopFrame = this;
if (!mStaticPrev) {
NS_ASSERTION(!gNeuteredWindows, "Should only set this once!");
gNeuteredWindows = new nsAutoTArray<HWND, 20>();
NS_ASSERTION(gNeuteredWindows, "Out of memory!");
}
}
RPCChannel::SyncStackFrame::~SyncStackFrame()
{
NS_ASSERTION(this == mChannel->mTopFrame,
"Mismatched RPC stack frames");
NS_ASSERTION(this == sStaticTopFrame,
"Mismatched static RPC stack frames");
mChannel->mTopFrame = mPrev;
sStaticTopFrame = mStaticPrev;
if (!mStaticPrev) {
NS_ASSERTION(gNeuteredWindows, "Bad pointer!");
delete gNeuteredWindows;
gNeuteredWindows = NULL;
}
}
SyncChannel::SyncStackFrame* SyncChannel::sStaticTopFrame;
void
RPCChannel::ProcessNativeEventsInRPCCall()
{
if (!mTopFrame) {
NS_ERROR("Child logic error: no RPC frame");
return;
}
mTopFrame->mSpinNestedEvents = true;
}
// Spin loop is called in place of WaitForNotify when modal ui is being shown
// in a child. There are some intricacies in using it however. Spin loop is
// enabled for a particular RPC frame by the client calling
// RPCChannel::ProcessNativeEventsInRPCCall().
// This call can be nested for multiple RPC frames in a single plugin or
// multiple unrelated plugins.
void
RPCChannel::SpinInternalEventLoop()
{
if (mozilla::PaintTracker::IsPainting()) {
NS_RUNTIMEABORT("Don't spin an event loop while painting.");
}
NS_ASSERTION(mTopFrame && mTopFrame->mSpinNestedEvents,
"Spinning incorrectly");
// Nested windows event loop we trigger when the child enters into modal
// event loops.
// Note, when we return, we always reset the notify worker event. So there's
// no need to reset it on return here.
do {
MSG msg = { 0 };
// Don't get wrapped up in here if the child connection dies.
{
MutexAutoLock lock(mMutex);
if (!Connected()) {
return;
}
}
// Retrieve window or thread messages
if (PeekMessageW(&msg, NULL, 0, 0, PM_REMOVE)) {
// The child UI should have been destroyed before the app is closed, in
// which case, we should never get this here.
if (msg.message == WM_QUIT) {
NS_ERROR("WM_QUIT received in SpinInternalEventLoop!");
} else {
TranslateMessage(&msg);
DispatchMessageW(&msg);
return;
}
}
// Note, give dispatching windows events priority over checking if
// mEvent is signaled, otherwise heavy ipc traffic can cause jittery
// playback of video. We'll exit out on each disaptch above, so ipc
// won't get starved.
// Wait for UI events or a signal from the io thread.
DWORD result = MsgWaitForMultipleObjects(1, &mEvent, FALSE, INFINITE,
QS_ALLINPUT);
if (result == WAIT_OBJECT_0) {
// Our NotifyWorkerThread event was signaled
return;
}
} while (true);
}
bool
SyncChannel::WaitForNotify()
{
mMutex.AssertCurrentThreadOwns();
// Initialize global objects used in deferred messaging.
Init();
NS_ASSERTION(mTopFrame && !mTopFrame->mRPC,
"Top frame is not a sync frame!");
MutexAutoUnlock unlock(mMutex);
bool retval = true;
UINT_PTR timerId = NULL;
TimeoutData timeoutData = { 0 };
if (mTimeoutMs != kNoTimeout) {
InitTimeoutData(&timeoutData, mTimeoutMs);
// We only do this to ensure that we won't get stuck in
// MsgWaitForMultipleObjects below.
timerId = SetTimer(NULL, 0, mTimeoutMs, NULL);
NS_ASSERTION(timerId, "SetTimer failed!");
}
// Setup deferred processing of native events while we wait for a response.
NS_ASSERTION(!SyncChannel::IsPumpingMessages(),
"Shouldn't be pumping already!");
SyncChannel::SetIsPumpingMessages(true);
HHOOK windowHook = SetWindowsHookEx(WH_CALLWNDPROC, CallWindowProcedureHook,
NULL, gUIThreadId);
NS_ASSERTION(windowHook, "Failed to set hook!");
{
while (1) {
MSG msg = { 0 };
// Don't get wrapped up in here if the child connection dies.
{
MutexAutoLock lock(mMutex);
if (!Connected()) {
break;
}
}
// Wait until we have a message in the queue. MSDN docs are a bit unclear
// but it seems that windows from two different threads (and it should be
// noted that a thread in another process counts as a "different thread")
// will implicitly have their message queues attached if they are parented
// to one another. This wait call, then, will return for a message
// delivered to *either* thread.
DWORD result = MsgWaitForMultipleObjects(1, &mEvent, FALSE, INFINITE,
QS_ALLINPUT);
if (result == WAIT_OBJECT_0) {
// Our NotifyWorkerThread event was signaled
ResetEvent(mEvent);
break;
} else
if (result != (WAIT_OBJECT_0 + 1)) {
NS_ERROR("Wait failed!");
break;
}
if (TimeoutHasExpired(timeoutData)) {
// A timeout was specified and we've passed it. Break out.
retval = false;
break;
}
// The only way to know on which thread the message was delivered is to
// use some logic on the return values of GetQueueStatus and PeekMessage.
// PeekMessage will return false if there are no "queued" messages, but it
// will run all "nonqueued" messages before returning. So if PeekMessage
// returns false and there are no "nonqueued" messages that were run then
// we know that the message we woke for was intended for a window on
// another thread.
bool haveSentMessagesPending =
(HIWORD(GetQueueStatus(QS_SENDMESSAGE)) & QS_SENDMESSAGE) != 0;
// This PeekMessage call will actually process all "nonqueued" messages
// that are pending before returning. If we have "nonqueued" messages
// pending then we should have switched out all the window procedures
// above. In that case this PeekMessage call won't actually cause any
// mozilla code (or plugin code) to run.
// If the following PeekMessage call fails to return a message for us (and
// returns false) and we didn't run any "nonqueued" messages then we must
// have woken up for a message designated for a window in another thread.
// If we loop immediately then we could enter a tight loop, so we'll give
// up our time slice here to let the child process its message.
if (!PeekMessageW(&msg, NULL, 0, 0, PM_NOREMOVE) &&
!haveSentMessagesPending) {
// Message was for child, we should wait a bit.
SwitchToThread();
}
}
}
// Unhook the neutered window procedure hook.
UnhookWindowsHookEx(windowHook);
// Unhook any neutered windows procedures so messages can be delivered
// normally.
UnhookNeuteredWindows();
// Before returning we need to set a hook to run any deferred messages that
// we received during the IPC call. The hook will unset itself as soon as
// someone else calls GetMessage, PeekMessage, or runs code that generates
// a "nonqueued" message.
ScheduleDeferredMessageRun();
if (timerId) {
KillTimer(NULL, timerId);
}
SyncChannel::SetIsPumpingMessages(false);
return retval;
}
bool
RPCChannel::WaitForNotify()
{
mMutex.AssertCurrentThreadOwns();
if (!StackDepth() && !mBlockedOnParent) {
// There is currently no way to recover from this condition.
NS_RUNTIMEABORT("StackDepth() is 0 in call to RPCChannel::WaitForNotify!");
}
// Initialize global objects used in deferred messaging.
Init();
NS_ASSERTION(mTopFrame && mTopFrame->mRPC,
"Top frame is not a sync frame!");
MutexAutoUnlock unlock(mMutex);
bool retval = true;
UINT_PTR timerId = NULL;
TimeoutData timeoutData = { 0 };
// windowHook is used as a flag variable for the loop below: if it is set
// and we start to spin a nested event loop, we need to clear the hook and
// process deferred/pending messages.
// If windowHook is NULL, SyncChannel::IsPumpingMessages should be false.
HHOOK windowHook = NULL;
while (1) {
NS_ASSERTION((!!windowHook) == SyncChannel::IsPumpingMessages(),
"windowHook out of sync with reality");
if (mTopFrame->mSpinNestedEvents) {
if (windowHook) {
UnhookWindowsHookEx(windowHook);
windowHook = NULL;
if (timerId) {
KillTimer(NULL, timerId);
timerId = NULL;
}
// Used by widget to assert on incoming native events
SyncChannel::SetIsPumpingMessages(false);
// Unhook any neutered windows procedures so messages can be delievered
// normally.
UnhookNeuteredWindows();
// Send all deferred "nonqueued" message to the intended receiver.
// We're dropping into SpinInternalEventLoop so we should be fairly
// certain these will get delivered soohn.
ScheduleDeferredMessageRun();
}
SpinInternalEventLoop();
ResetEvent(mEvent);
return true;
}
if (!windowHook) {
SyncChannel::SetIsPumpingMessages(true);
windowHook = SetWindowsHookEx(WH_CALLWNDPROC, CallWindowProcedureHook,
NULL, gUIThreadId);
NS_ASSERTION(windowHook, "Failed to set hook!");
NS_ASSERTION(!timerId, "Timer already initialized?");
if (mTimeoutMs != kNoTimeout) {
InitTimeoutData(&timeoutData, mTimeoutMs);
timerId = SetTimer(NULL, 0, mTimeoutMs, NULL);
NS_ASSERTION(timerId, "SetTimer failed!");
}
}
MSG msg = { 0 };
// Don't get wrapped up in here if the child connection dies.
{
MutexAutoLock lock(mMutex);
if (!Connected()) {
break;
}
}
DWORD result = MsgWaitForMultipleObjects(1, &mEvent, FALSE, INFINITE,
QS_ALLINPUT);
if (result == WAIT_OBJECT_0) {
// Our NotifyWorkerThread event was signaled
ResetEvent(mEvent);
break;
} else
if (result != (WAIT_OBJECT_0 + 1)) {
NS_ERROR("Wait failed!");
break;
}
if (TimeoutHasExpired(timeoutData)) {
// A timeout was specified and we've passed it. Break out.
retval = false;
break;
}
// See SyncChannel's WaitForNotify for details.
bool haveSentMessagesPending =
(HIWORD(GetQueueStatus(QS_SENDMESSAGE)) & QS_SENDMESSAGE) != 0;
// PeekMessage markes the messages as "old" so that they don't wake up
// MsgWaitForMultipleObjects every time.
if (!PeekMessageW(&msg, NULL, 0, 0, PM_NOREMOVE) &&
!haveSentMessagesPending) {
// Message was for child, we should wait a bit.
SwitchToThread();
}
}
if (windowHook) {
// Unhook the neutered window procedure hook.
UnhookWindowsHookEx(windowHook);
// Unhook any neutered windows procedures so messages can be delivered
// normally.
UnhookNeuteredWindows();
// Before returning we need to set a hook to run any deferred messages that
// we received during the IPC call. The hook will unset itself as soon as
// someone else calls GetMessage, PeekMessage, or runs code that generates
// a "nonqueued" message.
ScheduleDeferredMessageRun();
if (timerId) {
KillTimer(NULL, timerId);
}
}
SyncChannel::SetIsPumpingMessages(false);
return retval;
}
void
SyncChannel::NotifyWorkerThread()
{
mMutex.AssertCurrentThreadOwns();
NS_ASSERTION(mEvent, "No signal event to set, this is really bad!");
if (!SetEvent(mEvent)) {
NS_WARNING("Failed to set NotifyWorkerThread event!");
}
}
void
DeferredSendMessage::Run()
{
AssertWindowIsNotNeutered(hWnd);
if (!IsWindow(hWnd)) {
NS_ERROR("Invalid window!");
return;
}
WNDPROC wndproc =
reinterpret_cast<WNDPROC>(GetWindowLongPtr(hWnd, GWLP_WNDPROC));
if (!wndproc) {
NS_ERROR("Invalid window procedure!");
return;
}
CallWindowProc(wndproc, hWnd, message, wParam, lParam);
}
void
DeferredRedrawMessage::Run()
{
AssertWindowIsNotNeutered(hWnd);
if (!IsWindow(hWnd)) {
NS_ERROR("Invalid window!");
return;
}
#ifdef DEBUG
BOOL ret =
#endif
RedrawWindow(hWnd, NULL, NULL, flags);
NS_ASSERTION(ret, "RedrawWindow failed!");
}
void
DeferredUpdateMessage::Run()
{
AssertWindowIsNotNeutered(hWnd);
if (!IsWindow(hWnd)) {
NS_ERROR("Invalid window!");
return;
}
#ifdef DEBUG
BOOL ret =
#endif
UpdateWindow(hWnd);
NS_ASSERTION(ret, "UpdateWindow failed!");
}