Extract PipeIOHandler class into a header and rename to wxWakeUpPipe.

No real changes to the class, just make it possible to reuse it outside of
Unix wxEventLoop code.

See #10258.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74338 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/unix/private/wakeuppipe.h

@@ -0,0 +1,61 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/unix/private/wakeuppipe.h
+// Purpose:     Helper class allowing to wake up the main thread.
+// Author:      Vadim Zeitlin
+// Created:     2013-06-09 (extracted from src/unix/evtloopunix.cpp)
+// RCS-ID:      $Id$
+// Copyright:   (c) 2013 Vadim Zeitlin <vadim@wxwidgets.org>
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_UNIX_PRIVATE_WAKEUPPIPE_H_
+#define _WX_UNIX_PRIVATE_WAKEUPPIPE_H_
+
+#include "wx/private/fdiohandler.h"
+
+#include "wx/unix/pipe.h"
+
+// ----------------------------------------------------------------------------
+// wxWakeUpPipe: allows to wake up the event loop by writing to it
+// ----------------------------------------------------------------------------
+
+class wxWakeUpPipe : public wxFDIOHandler
+{
+public:
+    // Create and initialize the pipe.
+    //
+    // It's the callers responsibility to add the read end of this pipe,
+    // returned by GetReadFd(), to the code blocking on input.
+    wxWakeUpPipe();
+
+    // Wake up the blocking operation involving this pipe.
+    //
+    // It simply writes to the write end of the pipe.
+    //
+    // Notice that this method can be, and often is, called from another
+    // thread.
+    void WakeUp();
+
+    // Return the read end of the pipe.
+    int GetReadFd() { return m_pipe[wxPipe::Read]; }
+
+
+    // implement wxFDIOHandler pure virtual methods
+    virtual void OnReadWaiting();
+    virtual void OnWriteWaiting() { }
+    virtual void OnExceptionWaiting() { }
+
+private:
+    wxPipe m_pipe;
+
+    // Protects access to m_pipeIsEmpty.
+    wxCriticalSection m_pipeLock;
+
+    // This flag is set to true after writing to the pipe and reset to false
+    // after reading from it in the main thread. Having it allows us to avoid
+    // overflowing the pipe with too many writes if the main thread can't keep
+    // up with reading from it.
+    bool m_pipeIsEmpty;
+};
+
+#endif // _WX_UNIX_PRIVATE_WAKEUPPIPE_H_