Make sure that the UI window created by base::MessagePumpForUI is destoyed on the same thread (Wind…

base/message_pump_win.cc

Index: base/message_pump_win.cc
diff --git a/base/message_pump_win.cc b/base/message_pump_win.cc
index 4658573f5b9ef75cdc380da5bc0eae7e6820714c..b61d0d225aba7d83b05ae418351e33e26dce1e2b 100644
--- a/base/message_pump_win.cc
+++ b/base/message_pump_win.cc
@@ -22,6 +22,18 @@ enum MessageLoopProblems {
   MESSAGE_LOOP_PROBLEM_MAX,
 };
 
+// Possible states of the message pump:
+//   - kPumpIdle: the thread is sleeping, waiting for work to be posted.
+//   - kPumpHaveWork: a window message or completion packet has been posted.
+//   - kPumpDisabled: the pump is disabled, no more work can be posted.
+static const LONG kPumpIdle = 0;

[rvargas (doing something else), 2013/06/12 00:22:22]

nit: don't need static

[alexeypa (please no reviews), 2013/06/12 18:05:22]

Done.

+static const LONG kPumpHaveWork = 1;
+static const LONG kPumpDisabled = 2;
+
+// Used to wake up the message loop thread in the case if it is waiting for

[rvargas (doing something else), 2013/06/12 00:22:22]

nit: remove "in the case"

[alexeypa (please no reviews), 2013/06/12 18:05:22]

Done.

+// another thread to exit MessagePumpForUI::ScheduleWork().
+VOID CALLBACK DummyApc(ULONG_PTR) {}
+
 }  // namespace
 
 namespace base {
@@ -35,6 +47,8 @@ static const int kMsgHaveWork = WM_USER + 1;
 //-----------------------------------------------------------------------------
 // MessagePumpWin public:
 
+MessagePumpWin::MessagePumpWin() : pump_state_(kPumpIdle), state_(NULL) {}
+
 void MessagePumpWin::AddObserver(MessagePumpObserver* observer) {
   observers_.AddObserver(observer);
 }
@@ -99,24 +113,33 @@ int MessagePumpWin::GetCurrentDelay() const {
 MessagePumpForUI::MessagePumpForUI()
     : atom_(0),
       message_filter_(new MessageFilter) {
+  CHECK(DuplicateHandle(GetCurrentProcess(),
+                        GetCurrentThread(),
+                        GetCurrentProcess(),
+                        thread_.Receive(),
+                        THREAD_SET_CONTEXT,
+                        FALSE,    // no not inherit this handle

[rvargas (doing something else), 2013/06/12 00:22:22]

fix comment

[alexeypa (please no reviews), 2013/06/12 18:05:22]

Done.

+                        0));
   InitMessageWnd();
 }
 
 MessagePumpForUI::~MessagePumpForUI() {
-  DestroyWindow(message_hwnd_);
-  UnregisterClass(MAKEINTATOM(atom_),
-                  base::GetModuleFromAddress(&WndProcThunk));
+  DCHECK(!atom_);
+  DCHECK(!message_hwnd_);
 }
 
 void MessagePumpForUI::ScheduleWork() {
-  if (InterlockedExchange(&have_work_, 1))
-    return;  // Someone else continued the pumping.
+  if (InterlockedCompareExchange(&pump_state_, kPumpHaveWork,
+                                 kPumpIdle) != kPumpIdle) {
+    // Either someone else continued the pumping or the pump is disabled.
+    return;
+  }
 
   // Make sure the MessagePump does some work for us.
-  BOOL ret = PostMessage(message_hwnd_, kMsgHaveWork,
-                         reinterpret_cast<WPARAM>(this), 0);
-  if (ret)
-    return;  // There was room in the Window Message queue.
+  if (PostMessage(message_hwnd_, kMsgHaveWork, reinterpret_cast<WPARAM>(this),
+                  0)) {
+    return;
+  }
 
   // We have failed to insert a have-work message, so there is a chance that we
   // will starve tasks/timers while sitting in a nested message loop.  Nested
@@ -126,9 +149,24 @@ void MessagePumpForUI::ScheduleWork() {
   // 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);
+
+
+
+  // Clarify that we didn't really insert.
+  InterlockedExchange(&pump_state_, kPumpIdle);
+
+  // Try to wake up the message loop thread by posting an APC. This might not
+  // work while a nested loop still running (see the comment above) but this
+  // will unblock WillDestroyCurrentMessageLoop() if it is waiting for
+  // ScheduleWork() to complete.
+  //
+  // According to the UMA metrics posting an I/O completion packet has very low
+  // error rate. Queuing an APC hits roughly the same path in the kernel so
+  // the error rate should be low as well. Given that we do it only when
+  // PostMessage() fails it should be safe to CHECK() here.
+  CHECK(QueueUserAPC(&DummyApc, thread_, 0));
 }
 
 void MessagePumpForUI::ScheduleDelayedWork(const TimeTicks& delayed_work_time) {
@@ -172,6 +210,35 @@ void MessagePumpForUI::ScheduleDelayedWork(const TimeTicks& delayed_work_time) {
                             MESSAGE_LOOP_PROBLEM_MAX);
 }
 
+void MessagePumpForUI::WillDestroyCurrentMessageLoop() {
+  // Disable the message pump. If |pump_state_ == kPumpHaveWork| then
+  // ScheduleWork() might be still running on a different thread. Wait until
+  // |kMsgHaveWork| is received or |pump_state_| is reset back to |kPumpIdle|.
+  while (InterlockedCompareExchange(&pump_state_, kPumpDisabled,
+                                    kPumpIdle) == kPumpHaveWork) {
+    MSG msg;
+    if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
+      if (msg.message == kMsgHaveWork && msg.hwnd == message_hwnd_) {
+        // Now that we received |kMsgHaveWork| the pump can be safely disabled.
+        InterlockedExchange(&pump_state_, kPumpDisabled);
+        break;
+      }
+    }
+
+    // Wait until |kMsgHaveWork| is posted or an APC is received.
+    WaitForWork();
+  }
+
+  // At this point the pump is disabled and other threads exited ScheduleWork().
+  DestroyWindow(message_hwnd_);
+  UnregisterClass(MAKEINTATOM(atom_),
+                  base::GetModuleFromAddress(&WndProcThunk));
+
+  // Let the destructor know that the resources have been freed.
+  message_hwnd_ = NULL;
+  atom_ = 0;
+}
+
 void MessagePumpForUI::PumpOutPendingPaintMessages() {
   // If we are being called outside of the context of Run, then don't try to do
   // any work.
@@ -297,7 +364,7 @@ void MessagePumpForUI::WaitForWork() {
 
   DWORD result;
   result = MsgWaitForMultipleObjectsEx(0, NULL, delay, QS_ALLINPUT,
-                                       MWMO_INPUTAVAILABLE);
+                                       MWMO_ALERTABLE | MWMO_INPUTAVAILABLE);
 
   if (WAIT_OBJECT_0 == result) {
     // A WM_* message is available.
@@ -318,6 +385,11 @@ void MessagePumpForUI::WaitForWork() {
       WaitMessage();
     }
     return;
+  } else if (WAIT_IO_COMPLETION == result) {
+    // The wait was ended by one or more APCs. It could be cause
+    // MessagePumpUI::ScheduleWork() is trying to wake up the message loop
+    // thread.
+    return;
   }
 
   DCHECK_NE(WAIT_FAILED, result) << GetLastError();
@@ -329,7 +401,7 @@ void MessagePumpForUI::HandleWorkMessage() {
   // sort.
   if (!state_) {
     // Since we handled a kMsgHaveWork message, we must still update this flag.
-    InterlockedExchange(&have_work_, 0);
+    InterlockedExchange(&pump_state_, kPumpIdle);
     return;
   }
 
@@ -417,7 +489,7 @@ bool MessagePumpForUI::ProcessPumpReplacementMessage() {
   // 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
+  // then resets the pump_state_ flag (allowing a replacement kMsgHaveWork to

[rvargas (doing something else), 2013/06/12 00:22:22]

nit: not a flag to be reset anymore.

[alexeypa (please no reviews), 2013/06/12 18:05:22]

Done.

   // possibly be posted), and finally dispatches that peeked replacement.  Note
   // that the re-post of kMsgHaveWork may be asynchronous to this thread!!
 
@@ -439,7 +511,7 @@ bool MessagePumpForUI::ProcessPumpReplacementMessage() {
          msg.hwnd != message_hwnd_);
 
   // Since we discarded a kMsgHaveWork message, we must update the flag.
-  int old_have_work = InterlockedExchange(&have_work_, 0);
+  int old_have_work = InterlockedExchange(&pump_state_, kPumpIdle);
   DCHECK(old_have_work);
 
   // We don't need a special time slice if we didn't have_message to process.
@@ -468,7 +540,7 @@ MessagePumpForIO::MessagePumpForIO() {
 }
 
 void MessagePumpForIO::ScheduleWork() {
-  if (InterlockedExchange(&have_work_, 1))
+  if (InterlockedExchange(&pump_state_, kPumpHaveWork))
     return;  // Someone else continued the pumping.
 
   // Make sure the MessagePump does some work for us.
@@ -479,7 +551,7 @@ void MessagePumpForIO::ScheduleWork() {
     return;  // Post worked perfectly.
 
   // See comment in MessagePumpForUI::ScheduleWork() for this error recovery.
-  InterlockedExchange(&have_work_, 0);  // Clarify that we didn't succeed.
+  InterlockedExchange(&pump_state_, kPumpIdle);
   UMA_HISTOGRAM_ENUMERATION("Chrome.MessageLoopProblem", COMPLETION_POST_ERROR,
                             MESSAGE_LOOP_PROBLEM_MAX);
 }
@@ -624,7 +696,7 @@ bool MessagePumpForIO::ProcessInternalIOItem(const IOItem& item) {
       this == reinterpret_cast<MessagePumpForIO*>(item.handler)) {
     // This is our internal completion.
     DCHECK(!item.bytes_transfered);
-    InterlockedExchange(&have_work_, 0);
+    InterlockedExchange(&pump_state_, kPumpIdle);
     return true;
   }
   return false;