The Tor Browser: ipc/chromium/src/base/message_pump

ipc/chromium/src/base/message_pump_win.cc@6474c204b198 (annotated)

ipc/chromium/src/base/message_pump_win.cc

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 #include "base/message_pump_win.h"
 #include <math.h>
 #include "base/message_loop.h"
 #include "base/histogram.h"
 #include "base/win_util.h"
 using base::Time;
 namespace base {
 static const wchar_t kWndClass[] = L"Chrome_MessagePumpWindow";
 // Message sent to get an additional time slice for pumping (processing) another
 // task (a series of such messages creates a continuous task pump).
 static const int kMsgHaveWork = WM_USER + 1;
 //-----------------------------------------------------------------------------
 // MessagePumpWin public:
 void MessagePumpWin::AddObserver(Observer* observer) {
   observers_.AddObserver(observer);
 }
 void MessagePumpWin::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 void MessagePumpWin::WillProcessMessage(const MSG& msg) {
   FOR_EACH_OBSERVER(Observer, observers_, WillProcessMessage(msg));
 }
 void MessagePumpWin::DidProcessMessage(const MSG& msg) {
   FOR_EACH_OBSERVER(Observer, observers_, DidProcessMessage(msg));
 }
 void MessagePumpWin::RunWithDispatcher(
     Delegate* delegate, Dispatcher* dispatcher) {
   RunState s;
   s.delegate = delegate;
   s.dispatcher = dispatcher;
   s.should_quit = false;
   s.run_depth = state_ ? state_->run_depth + 1 : 1;
   RunState* previous_state = state_;
   state_ = &s;
   DoRunLoop();
   state_ = previous_state;
 }
 void MessagePumpWin::Quit() {
   DCHECK(state_);
   state_->should_quit = true;
 }
 //-----------------------------------------------------------------------------
 // MessagePumpWin protected:
 int MessagePumpWin::GetCurrentDelay() const {
   if (delayed_work_time_.is_null())
     return -1;
   // Be careful here.  TimeDelta has a precision of microseconds, but we want a
   // value in milliseconds.  If there are 5.5ms left, should the delay be 5 or
   // 6?  It should be 6 to avoid executing delayed work too early.
   double timeout =
       ceil((delayed_work_time_ - TimeTicks::Now()).InMillisecondsF());
   // If this value is negative, then we need to run delayed work soon.
   int delay = static_cast<int>(timeout);
   if (delay < 0)
     delay = 0;
   return delay;
 }
 //-----------------------------------------------------------------------------
 // MessagePumpForUI public:
 MessagePumpForUI::MessagePumpForUI() {
   InitMessageWnd();
 }
 MessagePumpForUI::~MessagePumpForUI() {
   DestroyWindow(message_hwnd_);
   UnregisterClass(kWndClass, GetModuleHandle(NULL));
 }
 void MessagePumpForUI::ScheduleWork() {
   if (InterlockedExchange(&have_work_, 1))
     return;  // Someone else continued the pumping.
   // Make sure the MessagePump does some work for us.
   PostMessage(message_hwnd_, kMsgHaveWork, reinterpret_cast<WPARAM>(this), 0);
   // In order to wake up any cross-process COM calls which may currently be
   // pending on the main thread, we also have to post a UI message.
   PostMessage(message_hwnd_, WM_NULL, 0, 0);
 }
 void MessagePumpForUI::ScheduleDelayedWork(const TimeTicks& delayed_work_time) {
   //
   // We would *like* to provide high resolution timers.  Windows timers using
   // SetTimer() have a 10ms granularity.  We have to use WM_TIMER as a wakeup
   // mechanism because the application can enter modal windows loops where it
   // is not running our MessageLoop; the only way to have our timers fire in
   // these cases is to post messages there.
   //
   // To provide sub-10ms timers, we process timers directly from our run loop.
   // For the common case, timers will be processed there as the run loop does
   // its normal work.  However, we *also* set the system timer so that WM_TIMER
   // events fire.  This mops up the case of timers not being able to work in
   // modal message loops.  It is possible for the SetTimer to pop and have no
   // pending timers, because they could have already been processed by the
   // run loop itself.
   //
   // We use a single SetTimer corresponding to the timer that will expire
   // soonest.  As new timers are created and destroyed, we update SetTimer.
   // Getting a spurrious SetTimer event firing is benign, as we'll just be
   // processing an empty timer queue.
   //
   delayed_work_time_ = delayed_work_time;
   int delay_msec = GetCurrentDelay();
   DCHECK(delay_msec >= 0);
   if (delay_msec < USER_TIMER_MINIMUM)
     delay_msec = USER_TIMER_MINIMUM;
   // Create a WM_TIMER event that will wake us up to check for any pending
   // timers (in case we are running within a nested, external sub-pump).
   SetTimer(message_hwnd_, reinterpret_cast<UINT_PTR>(this), delay_msec, NULL);
 }
 void MessagePumpForUI::PumpOutPendingPaintMessages() {
   // If we are being called outside of the context of Run, then don't try to do
   // any work.
   if (!state_)
     return;
   // Create a mini-message-pump to force immediate processing of only Windows
   // WM_PAINT messages.  Don't provide an infinite loop, but do enough peeking
   // to get the job done.  Actual common max is 4 peeks, but we'll be a little
   // safe here.
   const int kMaxPeekCount = 20;
   bool win2k = win_util::GetWinVersion() <= win_util::WINVERSION_2000;
   int peek_count;
   for (peek_count = 0; peek_count < kMaxPeekCount; ++peek_count) {
     MSG msg;
     if (win2k) {
       if (!PeekMessage(&msg, NULL, WM_PAINT, WM_PAINT, PM_REMOVE))
         break;
     } else {
       if (!PeekMessage(&msg, NULL, 0, 0, PM_REMOVE | PM_QS_PAINT))
         break;
     }
     ProcessMessageHelper(msg);
     if (state_->should_quit)  // Handle WM_QUIT.
       break;
   }
   // Histogram what was really being used, to help to adjust kMaxPeekCount.
   DHISTOGRAM_COUNTS("Loop.PumpOutPendingPaintMessages Peeks", peek_count);
 }
 //-----------------------------------------------------------------------------
 // MessagePumpForUI private:
 // static
 LRESULT CALLBACK MessagePumpForUI::WndProcThunk(
     HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
   switch (message) {
     case kMsgHaveWork:
       reinterpret_cast<MessagePumpForUI*>(wparam)->HandleWorkMessage();
       break;
     case WM_TIMER:
       reinterpret_cast<MessagePumpForUI*>(wparam)->HandleTimerMessage();
       break;
   }
   return DefWindowProc(hwnd, message, wparam, lparam);
 }
 void MessagePumpForUI::DoRunLoop() {
   // IF this was just a simple PeekMessage() loop (servicing all possible work
   // queues), then Windows would try to achieve the following order according
   // to MSDN documentation about PeekMessage with no filter):
   //    * Sent messages
   //    * Posted messages
   //    * Sent messages (again)
   //    * WM_PAINT messages
   //    * WM_TIMER messages
   //
   // Summary: none of the above classes is starved, and sent messages has twice
   // the chance of being processed (i.e., reduced service time).
   for (;;) {
     // If we do any work, we may create more messages etc., and more work may
     // possibly be waiting in another task group.  When we (for example)
     // ProcessNextWindowsMessage(), there is a good chance there are still more
     // messages waiting.  On the other hand, when any of these methods return
     // having done no work, then it is pretty unlikely that calling them again
     // quickly will find any work to do.  Finally, if they all say they had no
     // work, then it is a good time to consider sleeping (waiting) for more
     // work.
     bool more_work_is_plausible = ProcessNextWindowsMessage();
     if (state_->should_quit)
       break;
     more_work_is_plausible |= state_->delegate->DoWork();
     if (state_->should_quit)
       break;
     more_work_is_plausible |=
         state_->delegate->DoDelayedWork(&delayed_work_time_);
     // If we did not process any delayed work, then we can assume that our
     // existing WM_TIMER if any will fire when delayed work should run.  We
     // don't want to disturb that timer if it is already in flight.  However,
     // if we did do all remaining delayed work, then lets kill the WM_TIMER.
     if (more_work_is_plausible && delayed_work_time_.is_null())
       KillTimer(message_hwnd_, reinterpret_cast<UINT_PTR>(this));
     if (state_->should_quit)
       break;
     if (more_work_is_plausible)
       continue;
     more_work_is_plausible = state_->delegate->DoIdleWork();
     if (state_->should_quit)
       break;
     if (more_work_is_plausible)
       continue;
     WaitForWork();  // Wait (sleep) until we have work to do again.
   }
 }
 void MessagePumpForUI::InitMessageWnd() {
   HINSTANCE hinst = GetModuleHandle(NULL);
   WNDCLASSEX wc = {0};
   wc.cbSize = sizeof(wc);
   wc.lpfnWndProc = WndProcThunk;
   wc.hInstance = hinst;
   wc.lpszClassName = kWndClass;
   RegisterClassEx(&wc);
   message_hwnd_ =
       CreateWindow(kWndClass, 0, 0, 0, 0, 0, 0, HWND_MESSAGE, 0, hinst, 0);
   DCHECK(message_hwnd_);
 }
 void MessagePumpForUI::WaitForWork() {
   // Wait until a message is available, up to the time needed by the timer
   // manager to fire the next set of timers.
   int delay = GetCurrentDelay();
   if (delay < 0)  // Negative value means no timers waiting.
     delay = INFINITE;
   DWORD result;
   result = MsgWaitForMultipleObjectsEx(0, NULL, delay, QS_ALLINPUT,
                                        MWMO_INPUTAVAILABLE);
   if (WAIT_OBJECT_0 == result) {
     // A WM_* message is available.
     // If a parent child relationship exists between windows across threads
     // then their thread inputs are implicitly attached.
     // This causes the MsgWaitForMultipleObjectsEx API to return indicating
     // that messages are ready for processing (specifically mouse messages
     // intended for the child window. Occurs if the child window has capture)
     // The subsequent PeekMessages call fails to return any messages thus
     // causing us to enter a tight loop at times.
     // The WaitMessage call below is a workaround to give the child window
     // sometime to process its input messages.
     MSG msg = {0};
     DWORD queue_status = GetQueueStatus(QS_MOUSE);
     if (HIWORD(queue_status) & QS_MOUSE &&
        !PeekMessage(&msg, NULL, WM_MOUSEFIRST, WM_MOUSELAST, PM_NOREMOVE)) {
       WaitMessage();
     }
     return;
   }
   DCHECK_NE(WAIT_FAILED, result) << GetLastError();
 }
 void MessagePumpForUI::HandleWorkMessage() {
   // If we are being called outside of the context of Run, then don't try to do
   // any work.  This could correspond to a MessageBox call or something of that
   // sort.
   if (!state_) {
     // Since we handled a kMsgHaveWork message, we must still update this flag.
     InterlockedExchange(&have_work_, 0);
     return;
   }
   // Let whatever would have run had we not been putting messages in the queue
   // run now.  This is an attempt to make our dummy message not starve other
   // messages that may be in the Windows message queue.
   ProcessPumpReplacementMessage();
   // Now give the delegate a chance to do some work.  He'll let us know if he
   // needs to do more work.
   if (state_->delegate->DoWork())
     ScheduleWork();
 }
 void MessagePumpForUI::HandleTimerMessage() {
   KillTimer(message_hwnd_, reinterpret_cast<UINT_PTR>(this));
   // If we are being called outside of the context of Run, then don't do
   // anything.  This could correspond to a MessageBox call or something of
   // that sort.
   if (!state_)
     return;
   state_->delegate->DoDelayedWork(&delayed_work_time_);
   if (!delayed_work_time_.is_null()) {
     // A bit gratuitous to set delayed_work_time_ again, but oh well.
     ScheduleDelayedWork(delayed_work_time_);
   }
 }
 bool MessagePumpForUI::ProcessNextWindowsMessage() {
   // If there are sent messages in the queue then PeekMessage internally
   // dispatches the message and returns false. We return true in this
   // case to ensure that the message loop peeks again instead of calling
   // MsgWaitForMultipleObjectsEx again.
   bool sent_messages_in_queue = false;
   DWORD queue_status = GetQueueStatus(QS_SENDMESSAGE);
   if (HIWORD(queue_status) & QS_SENDMESSAGE)
     sent_messages_in_queue = true;
   MSG msg;
   if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
     return ProcessMessageHelper(msg);
   return sent_messages_in_queue;
 }
 bool MessagePumpForUI::ProcessMessageHelper(const MSG& msg) {
   if (WM_QUIT == msg.message) {
     // Repost the QUIT message so that it will be retrieved by the primary
     // GetMessage() loop.
     state_->should_quit = true;
     PostQuitMessage(static_cast<int>(msg.wParam));
     return false;
   }
   // While running our main message pump, we discard kMsgHaveWork messages.
   if (msg.message == kMsgHaveWork && msg.hwnd == message_hwnd_)
     return ProcessPumpReplacementMessage();
   WillProcessMessage(msg);
   if (state_->dispatcher) {
     if (!state_->dispatcher->Dispatch(msg))
       state_->should_quit = true;
   } else {
     TranslateMessage(&msg);
     DispatchMessage(&msg);
   }
   DidProcessMessage(msg);
   return true;
 }
 bool MessagePumpForUI::ProcessPumpReplacementMessage() {
   // When we encounter a kMsgHaveWork message, this method is called to peek
   // and process a replacement message, such as a WM_PAINT or WM_TIMER.  The
   // goal is to make the kMsgHaveWork as non-intrusive as possible, even though
   // a continuous stream of such messages are posted.  This method carefully
   // peeks a message while there is no chance for a kMsgHaveWork to be pending,
   // then resets the have_work_ flag (allowing a replacement kMsgHaveWork to
   // possibly be posted), and finally dispatches that peeked replacement.  Note
   // that the re-post of kMsgHaveWork may be asynchronous to this thread!!
   MSG msg;
   bool have_message = false;
   if (MessageLoop::current()->os_modal_loop()) {
     // We only peek out WM_PAINT and WM_TIMER here for reasons mentioned above.
     have_message = PeekMessage(&msg, NULL, WM_PAINT, WM_PAINT, PM_REMOVE) ||
                    PeekMessage(&msg, NULL, WM_TIMER, WM_TIMER, PM_REMOVE);
   } else {
     have_message = (0 != PeekMessage(&msg, NULL, 0, 0, PM_REMOVE));
     if (have_message && msg.message == WM_NULL)
       have_message = (0 != PeekMessage(&msg, NULL, 0, 0, PM_REMOVE));
   }
   DCHECK(!have_message || kMsgHaveWork != msg.message ||
          msg.hwnd != message_hwnd_);
   // Since we discarded a kMsgHaveWork message, we must update the flag.
   int old_have_work = InterlockedExchange(&have_work_, 0);
   DCHECK(old_have_work);
   // We don't need a special time slice if we didn't have_message to process.
   if (!have_message)
     return false;
   // Guarantee we'll get another time slice in the case where we go into native
   // windows code.   This ScheduleWork() may hurt performance a tiny bit when
   // tasks appear very infrequently, but when the event queue is busy, the
   // kMsgHaveWork events get (percentage wise) rarer and rarer.
   ScheduleWork();
   return ProcessMessageHelper(msg);
 }
 //-----------------------------------------------------------------------------
 // MessagePumpForIO public:
 MessagePumpForIO::MessagePumpForIO() {
   port_.Set(CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 1));
   DCHECK(port_.IsValid());
 }
 void MessagePumpForIO::ScheduleWork() {
   if (InterlockedExchange(&have_work_, 1))
     return;  // Someone else continued the pumping.
   // Make sure the MessagePump does some work for us.
   BOOL ret = PostQueuedCompletionStatus(port_, 0,
                                         reinterpret_cast<ULONG_PTR>(this),
                                         reinterpret_cast<OVERLAPPED*>(this));
   DCHECK(ret);
 }
 void MessagePumpForIO::ScheduleDelayedWork(const TimeTicks& delayed_work_time) {
   // We know that we can't be blocked right now since this method can only be
   // called on the same thread as Run, so we only need to update our record of
   // how long to sleep when we do sleep.
   delayed_work_time_ = delayed_work_time;
 }
 void MessagePumpForIO::RegisterIOHandler(HANDLE file_handle,
                                          IOHandler* handler) {
   ULONG_PTR key = reinterpret_cast<ULONG_PTR>(handler);
   HANDLE port = CreateIoCompletionPort(file_handle, port_, key, 1);
   DCHECK(port == port_.Get());
 }
 //-----------------------------------------------------------------------------
 // MessagePumpForIO private:
 void MessagePumpForIO::DoRunLoop() {
   for (;;) {
     // If we do any work, we may create more messages etc., and more work may
     // possibly be waiting in another task group.  When we (for example)
     // WaitForIOCompletion(), there is a good chance there are still more
     // messages waiting.  On the other hand, when any of these methods return
     // having done no work, then it is pretty unlikely that calling them
     // again quickly will find any work to do.  Finally, if they all say they
     // had no work, then it is a good time to consider sleeping (waiting) for
     // more work.
     bool more_work_is_plausible = state_->delegate->DoWork();
     if (state_->should_quit)
       break;
     more_work_is_plausible |= WaitForIOCompletion(0, NULL);
     if (state_->should_quit)
       break;
     more_work_is_plausible |=
         state_->delegate->DoDelayedWork(&delayed_work_time_);
     if (state_->should_quit)
       break;
     if (more_work_is_plausible)
       continue;
     more_work_is_plausible = state_->delegate->DoIdleWork();
     if (state_->should_quit)
       break;
     if (more_work_is_plausible)
       continue;
     WaitForWork();  // Wait (sleep) until we have work to do again.
   }
 }
 // Wait until IO completes, up to the time needed by the timer manager to fire
 // the next set of timers.
 void MessagePumpForIO::WaitForWork() {
   // We do not support nested IO message loops. This is to avoid messy
   // recursion problems.
   DCHECK(state_->run_depth == 1) << "Cannot nest an IO message loop!";
   int timeout = GetCurrentDelay();
   if (timeout < 0)  // Negative value means no timers waiting.
     timeout = INFINITE;
   WaitForIOCompletion(timeout, NULL);
 }
 bool MessagePumpForIO::WaitForIOCompletion(DWORD timeout, IOHandler* filter) {
   IOItem item;
   if (completed_io_.empty() || !MatchCompletedIOItem(filter, &item)) {
     // We have to ask the system for another IO completion.
     if (!GetIOItem(timeout, &item))
       return false;
     if (ProcessInternalIOItem(item))
       return true;
   }
   if (item.context->handler) {
     if (filter && item.handler != filter) {
       // Save this item for later
       completed_io_.push_back(item);
     } else {
       DCHECK(item.context->handler == item.handler);
       item.handler->OnIOCompleted(item.context, item.bytes_transfered,
                                   item.error);
     }
   } else {
     // The handler must be gone by now, just cleanup the mess.
     delete item.context;
   }
   return true;
 }
 // Asks the OS for another IO completion result.
 bool MessagePumpForIO::GetIOItem(DWORD timeout, IOItem* item) {
   memset(item, 0, sizeof(*item));
   ULONG_PTR key = 0;
   OVERLAPPED* overlapped = NULL;
   if (!GetQueuedCompletionStatus(port_.Get(), &item->bytes_transfered, &key,
                                  &overlapped, timeout)) {
     if (!overlapped)
       return false;  // Nothing in the queue.
     item->error = GetLastError();
     item->bytes_transfered = 0;
   }
   item->handler = reinterpret_cast<IOHandler*>(key);
   item->context = reinterpret_cast<IOContext*>(overlapped);
   return true;
 }
 bool MessagePumpForIO::ProcessInternalIOItem(const IOItem& item) {
   if (this == reinterpret_cast<MessagePumpForIO*>(item.context) &&
       this == reinterpret_cast<MessagePumpForIO*>(item.handler)) {
     // This is our internal completion.
     DCHECK(!item.bytes_transfered);
     InterlockedExchange(&have_work_, 0);
     return true;
   }
   return false;
 }
 // Returns a completion item that was previously received.
 bool MessagePumpForIO::MatchCompletedIOItem(IOHandler* filter, IOItem* item) {
   DCHECK(!completed_io_.empty());
   for (std::list<IOItem>::iterator it = completed_io_.begin();
        it != completed_io_.end(); ++it) {
     if (!filter || it->handler == filter) {
       *item = *it;
       completed_io_.erase(it);
       return true;
     }
   }
   return false;
 }
 }  // namespace base

The Tor Browser / annotate

ipc/chromium/src/base/message_pump_win.cc@6474c204b198 (annotated)

ipc/chromium/src/base/message_pump_win.cc