Commit 6023de86 authored by James Teh's avatar James Teh
Browse files

Bug 1821963 part 4: Remove alertable wait from IPC message loops. r=handyman 

This was only ever used by the old accessibility architecture based on content process COM proxies, which is now being removed.

Differential Revision: https://phabricator.services.mozilla.com/D177964
parent cd328c40

dom/ipc/ContentChild.cpp

+0 −3
Original line number Diff line number Diff line
@@ -770,9 +770,6 @@ void ContentChild::Init(mozilla::ipc::UntypedEndpoint&& aEndpoint, 
  // If communications with the parent have broken down, take the process

  // down so it's not hanging around.

  GetIPCChannel()->SetAbortOnError(true);

#if defined(XP_WIN) && defined(ACCESSIBILITY)

  GetIPCChannel()->SetChannelFlags(MessageChannel::REQUIRE_A11Y_REENTRY);

#endif



  // This must be checked before any IPDL message, which may hit sentinel

  // errors due to parent and content processes having different

ipc/glue/MessageChannel.h

+0 −8
Original line number Diff line number Diff line
@@ -224,11 +224,6 @@ class MessageChannel : HasResultCodes { 
    // that manage child processes which might create native UI, like

    // plugins.

    REQUIRE_DEFERRED_MESSAGE_PROTECTION = 1 << 0,

    // Windows: When this flag is specified, any wait that occurs during

    // synchronous IPC will be alertable, thus allowing a11y code in the

    // chrome process to reenter content while content is waiting on a

    // synchronous call.

    REQUIRE_A11Y_REENTRY = 1 << 1,

  };

  void SetChannelFlags(ChannelFlags aFlags) { mFlags = aFlags; }

  ChannelFlags GetChannelFlags() { return mFlags; }
@@ -363,9 +358,6 @@ class MessageChannel : HasResultCodes { 


 private:

  void SpinInternalEventLoop();

#  if defined(ACCESSIBILITY)

  bool WaitForSyncNotifyWithA11yReentry();

#  endif  // defined(ACCESSIBILITY)

#endif    // defined(OS_WIN)



 private:

ipc/glue/WindowsMessageLoop.cpp

+0 −89
Original line number Diff line number Diff line
@@ -850,88 +850,6 @@ SuppressedNeuteringRegion::~SuppressedNeuteringRegion() { 


bool SuppressedNeuteringRegion::sSuppressNeutering = false;



#if defined(ACCESSIBILITY)

static DWORD WaitForSingleObjectExWrapper(HANDLE aEvent, DWORD aTimeout) {

  return ::WaitForSingleObjectEx(aEvent, aTimeout, TRUE);

}



static DWORD CoWaitForMultipleHandlesWrapper(HANDLE aEvent, DWORD aTimeout) {

  DWORD waitResult = 0;

  ::SetLastError(ERROR_SUCCESS);

  HRESULT hr = ::CoWaitForMultipleHandles(COWAIT_ALERTABLE, aTimeout, 1,

                                          &aEvent, &waitResult);

  if (hr == S_OK) {

    return waitResult;

  }

  if (hr == RPC_S_CALLPENDING) {

    return WAIT_TIMEOUT;

  }

  return WAIT_FAILED;

}



bool MessageChannel::WaitForSyncNotifyWithA11yReentry() {

  mMonitor->AssertCurrentThreadOwns();

  MonitorAutoUnlock unlock(*mMonitor);



  static auto* sWaitForEvent = IsWin32kLockedDown()

                                   ? WaitForSingleObjectExWrapper

                                   : CoWaitForMultipleHandlesWrapper;



  const DWORD waitStart = ::GetTickCount();

  DWORD elapsed = 0;

  DWORD timeout =

      mTimeoutMs == kNoTimeout ? INFINITE : static_cast<DWORD>(mTimeoutMs);

  bool timedOut = false;



  while (true) {

    {  // Scope for lock

      MonitorAutoLock lock(*mMonitor);

      if (!Connected()) {

        break;

      }

    }



    if (timeout != static_cast<DWORD>(kNoTimeout)) {

      elapsed = ::GetTickCount() - waitStart;

    }



    if (elapsed >= timeout) {

      timedOut = true;

      break;

    }



    DWORD waitResult = sWaitForEvent(mEvent, timeout - elapsed);



    if (waitResult == WAIT_OBJECT_0) {

      // mEvent is signaled

      BOOL success = ::ResetEvent(mEvent);

      if (!success) {

        gfxDevCrash(mozilla::gfx::LogReason::MessageChannelInvalidHandle)

            << "WindowsMessageChannel::WaitForSyncNotifyWithA11yReentry "

               "failed to reset event. GetLastError: "

            << GetLastError();

      }

      break;

    }



    if (waitResult == WAIT_IO_COMPLETION) {

      // APC fired, keep waiting

      continue;

    }



    if (waitResult == WAIT_TIMEOUT) {

      timeout = true;

      break;

    }



    NS_ERROR("WaitForSyncNotifyWithA11yReentry failed");

    break;

  }



  return WaitResponse(timedOut);

}

#endif



bool MessageChannel::WaitForSyncNotify(bool aHandleWindowsMessages) {

  mMonitor->AssertCurrentThreadOwns();
@@ -939,13 +857,6 @@ bool MessageChannel::WaitForSyncNotify(bool aHandleWindowsMessages) { 
    mozilla::ipc::windows::InitUIThread();

  }



#if defined(ACCESSIBILITY)

  if (mFlags & REQUIRE_A11Y_REENTRY) {

    MOZ_ASSERT(!(mFlags & REQUIRE_DEFERRED_MESSAGE_PROTECTION));

    return WaitForSyncNotifyWithA11yReentry();

  }

#endif



  // Use a blocking wait if this channel does not require

  // Windows message deferral behavior.

  if (!(mFlags & REQUIRE_DEFERRED_MESSAGE_PROTECTION) ||

ipc/mscom/EnsureMTA.cpp

+1 −7
Original line number Diff line number Diff line
@@ -228,15 +228,9 @@ void EnsureMTA::SyncDispatchToPersistentThread(nsIRunnable* aRunnable) { 
    return;

  }



#if defined(ACCESSIBILITY)

  const BOOL alertable = XRE_IsContentProcess() && NS_IsMainThread();

#else

  const BOOL alertable = FALSE;

#endif  // defined(ACCESSIBILITY)



  AUTO_PROFILER_THREAD_SLEEP;

  DWORD waitResult;

  while ((waitResult = ::WaitForSingleObjectEx(event, INFINITE, alertable)) ==

  while ((waitResult = ::WaitForSingleObjectEx(event, INFINITE, FALSE)) ==

         WAIT_IO_COMPLETION) {

  }

  MOZ_ASSERT(waitResult == WAIT_OBJECT_0);