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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
// 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"
#include "mozilla/Maybe.h"
#include "mozilla/ProfilerLabels.h"
#include "mozilla/ProfilerThreadSleep.h"
#include "WinUtils.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;
int peek_count;
for (peek_count = 0; peek_count < kMaxPeekCount; ++peek_count) {
MSG msg;
if (!PeekMessage(&msg, NULL, 0, 0, PM_REMOVE | PM_QS_PAINT)) break;
ProcessMessageHelper(msg);
if (state_->should_quit) break;
}
}
//-----------------------------------------------------------------------------
// 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() {
AUTO_PROFILER_LABEL("MessagePumpForUI::WaitForWork", IDLE);
// 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;
mozilla::widget::WinUtils::WaitForMessage(delay);
}
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) {
// WM_QUIT is the standard way to exit a ::GetMessage() loop. Our
// MessageLoop has its own quit mechanism, so WM_QUIT is unexpected and
// should be ignored.
return true;
}
// 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;
if (WM_QUIT == msg.message) {
// If we're in a nested ::GetMessage() loop then we must let that loop see
// the WM_QUIT in order for it to exit. If we're in DoRunLoop then the re-
// posted WM_QUIT will be either ignored, or handled, by
// ProcessMessageHelper() called directly from ProcessNextWindowsMessage().
::PostQuitMessage(static_cast<int>(msg.wParam));
// Note: we *must not* ScheduleWork() here as WM_QUIT is a low-priority
// message on Windows (it is only returned by ::PeekMessage() when idle) :
// such posting a kMsgHaveWork message via ScheduleWork() would cause an
// infinite loop (kMsgHaveWork message handled first means we end up here
// again and repost WM_QUIT+ScheduleWork() again, etc.). Not leaving a
// kMsgHaveWork message behind however is also problematic as unwinding
// multiple layers of nested ::GetMessage() loops can result in starving
// The return value is mostly irrelevant but return true like we would after
// processing a QuitClosure() task.
return true;
}
// 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;
BOOL success;
{
AUTO_PROFILER_LABEL("MessagePumpForIO::GetIOItem::Wait", IDLE);
#ifdef MOZ_GECKO_PROFILER
mozilla::Maybe<mozilla::AutoProfilerThreadSleep> profilerThreadSleep;
if (timeout != 0) {
profilerThreadSleep.emplace();
}
#endif
success = GetQueuedCompletionStatus(port_.Get(), &item->bytes_transfered,
&key, &overlapped, timeout);
}
if (!success) {
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