Process pending delayed tasks in kMsgHaveWork

base/message_loop/message_pump_win.cc

 // Copyright (c) 2012 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_loop/message_pump_win.h"
 
 #include <limits>
 #include <math.h>
 
 #include "base/message_loop/message_loop.h"
@@ skipping 104 matching lines @@
   // We could abort here, but the fear is that this failure mode is plausibly
   // common (queue is full, of about 2000 messages), so we'll do a near-graceful
   // recovery.  Nested loops are pretty transient (we think), so this will
   // probably be recoverable.
   InterlockedExchange(&have_work_, 0);  // Clarify that we didn't really insert.
   UMA_HISTOGRAM_ENUMERATION("Chrome.MessageLoopProblem", MESSAGE_POST_ERROR,
                             MESSAGE_LOOP_PROBLEM_MAX);
 }
 
 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_GE(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).
-  BOOL ret = SetTimer(message_hwnd_, reinterpret_cast<UINT_PTR>(this),
-                      delay_msec, NULL);
-  if (ret)
-    return;
-  // If we can't set timers, we are in big trouble... but cross our fingers for
-  // now.
-  // TODO(jar): If we don't see this error, use a CHECK() here instead.
-  UMA_HISTOGRAM_ENUMERATION("Chrome.MessageLoopProblem", SET_TIMER_ERROR,
-                            MESSAGE_LOOP_PROBLEM_MAX);
+  RescheduleTimer();
 }
 
 //-----------------------------------------------------------------------------
 // MessagePumpForUI private:
 
 // static
 LRESULT CALLBACK MessagePumpForUI::WndProcThunk(
     HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
   // TODO(vadimt): Remove ScopedTracker below once crbug.com/440919 is fixed.
   tracked_objects::ScopedTracker tracking_profile1(
@@ skipping 138 matching lines @@
 
   // 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();
+  state_->delegate->DoDelayedWork(&delayed_work_time_);
+  RescheduleTimer();
 }
 
 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_);
+  RescheduleTimer();
+}
+
+void MessagePumpForUI::RescheduleTimer() {
+  if (delayed_work_time_.is_null())
+    return;
+  //
+  // 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.
+  //
+  int delay_msec = GetCurrentDelay();
+  DCHECK_GE(delay_msec, 0);
+  if (delay_msec == 0) {
+    ScheduleWork();
+  } else {
+    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).
+    BOOL ret = SetTimer(message_hwnd_, reinterpret_cast<UINT_PTR>(this),
+                        delay_msec, NULL);
+    if (ret)
+      return;
+    // If we can't set timers, we are in big trouble... but cross our fingers
+    // for now.
+    // TODO(jar): If we don't see this error, use a CHECK() here instead.
+    UMA_HISTOGRAM_ENUMERATION("Chrome.MessageLoopProblem", SET_TIMER_ERROR,
+                              MESSAGE_LOOP_PROBLEM_MAX);
   }
 }
 
 bool MessagePumpForUI::ProcessNextWindowsMessage() {
   // TODO(vadimt): Remove ScopedTracker below once crbug.com/440919 is fixed.
   tracked_objects::ScopedTracker tracking_profile1(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "440919 MessagePumpForUI::ProcessNextWindowsMessage1"));
 
   // If there are sent messages in the queue then PeekMessage internally
@@ skipping 344 matching lines @@
 
 // static
 MessagePumpForIO::IOHandler* MessagePumpForIO::KeyToHandler(
     ULONG_PTR key,
     bool* has_valid_io_context) {
   *has_valid_io_context = ((key & 1) == 0);
   return reinterpret_cast<IOHandler*>(key & ~static_cast<ULONG_PTR>(1));
 }
 
 }  // namespace base