tor-browser

message_pump_qt.cc (4929B)

---

/* -*- 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) 2010 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 <qabstracteventdispatcher.h>
#include <qevent.h>
#include <QCoreApplication>
#include <QThread>
#include <qtimer.h>

#include "base/message_pump_qt.h"

#include <fcntl.h>
#include <limits>
#include <math.h>

#include "base/eintr_wrapper.h"
#include "base/logging.h"
#include "base/platform_thread.h"

namespace {
// Cached QEvent user type, registered for our event system
static int sPokeEvent;
}  // namespace

namespace base {

MessagePumpForUI::MessagePumpForUI() : state_(NULL), qt_pump(*this) {}

MessagePumpForUI::~MessagePumpForUI() {}

MessagePumpQt::MessagePumpQt(MessagePumpForUI& aPump)
   : pump(aPump), mTimer(new QTimer(this)) {
 // Register our custom event type, to use in qApp event loop
 sPokeEvent = QEvent::registerEventType();
 connect(mTimer, SIGNAL(timeout()), this, SLOT(dispatchDelayed()));
 mTimer->setSingleShot(true);
}

MessagePumpQt::~MessagePumpQt() {
 mTimer->stop();
 delete mTimer;
}

bool MessagePumpQt::event(QEvent* e) {
 if (e->type() == sPokeEvent) {
   pump.HandleDispatch();
   return true;
 }
 return false;
}

void MessagePumpQt::scheduleDelayedIfNeeded(
   const TimeTicks& delayed_work_time) {
 if (delayed_work_time.is_null()) {
   return;
 }

 if (mTimer->isActive()) {
   mTimer->stop();
 }

 TimeDelta later = delayed_work_time - TimeTicks::Now();
 // later.InMilliseconds() returns an int64_t, QTimer only accepts int's for
 // start(), std::min only works on exact same types.
 int laterMsecs = later.InMilliseconds() > std::numeric_limits<int>::max()
                      ? std::numeric_limits<int>::max()
                      : later.InMilliseconds();
 mTimer->start(laterMsecs > 0 ? laterMsecs : 0);
}

void MessagePumpQt::dispatchDelayed() { pump.HandleDispatch(); }

void MessagePumpForUI::Run(Delegate* delegate) {
 RunState state;
 state.delegate = delegate;
 state.should_quit = false;
 state.run_depth = state_ ? state_->run_depth + 1 : 1;
 // We really only do a single task for each iteration of the loop.  If we
 // have done something, assume there is likely something more to do.  This
 // will mean that we don't block on the message pump until there was nothing
 // more to do.  We also set this to true to make sure not to block on the
 // first iteration of the loop, so RunAllPending() works correctly.
 bool more_work_is_plausible = true;

 RunState* previous_state = state_;
 state_ = &state;

 for (;;) {
   QEventLoop::ProcessEventsFlags block = QEventLoop::AllEvents;
   if (!more_work_is_plausible) {
     block |= QEventLoop::WaitForMoreEvents;
   }

   QAbstractEventDispatcher* dispatcher =
       QAbstractEventDispatcher::instance(QThread::currentThread());
   // An assertion seems too much here, as during startup,
   // the dispatcher might not be ready yet.
   if (!dispatcher) {
     return;
   }

   // processEvent's returns true if an event has been processed.
   more_work_is_plausible = dispatcher->processEvents(block);

   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 (state_->should_quit) {
     break;
   }

   qt_pump.scheduleDelayedIfNeeded(delayed_work_time_);

   if (more_work_is_plausible) {
     continue;
   }

   more_work_is_plausible = state_->delegate->DoIdleWork();
   if (state_->should_quit) {
     break;
   }
 }

 state_ = previous_state;
}

void MessagePumpForUI::HandleDispatch() {
 if (state_->should_quit) {
   return;
 }

 if (state_->delegate->DoWork()) {
   // there might be more, see more_work_is_plausible
   // variable above, that's why we ScheduleWork() to keep going.
   ScheduleWork();
 }

 if (state_->should_quit) {
   return;
 }

 state_->delegate->DoDelayedWork(&delayed_work_time_);
 qt_pump.scheduleDelayedIfNeeded(delayed_work_time_);
}

void MessagePumpForUI::Quit() {
 if (state_) {
   state_->should_quit = true;
 } else {
   NOTREACHED() << "Quit called outside Run!";
 }
}

void MessagePumpForUI::ScheduleWork() {
 QCoreApplication::postEvent(&qt_pump, new QEvent((QEvent::Type)sPokeEvent));
}

void MessagePumpForUI::ScheduleDelayedWork(const TimeTicks& delayed_work_time) {
 // On GLib implementation, a work source is defined which explicitly checks
 // the time that has passed. Here, on Qt we can use a QTimer that enqueues our
 // event signal in an event queue.
 delayed_work_time_ = delayed_work_time;
 qt_pump.scheduleDelayedIfNeeded(delayed_work_time_);
}

}  // namespace base