Upgrade WX to r74856, mainly to support @2x.

Externals/wxWidgets3/include/wx/unix/private/wakeuppipe.h

@@ -0,0 +1,101 @@
+///////////////////////////////////////////////////////////////////////////////
+// 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)
+// 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/unix/pipe.h"
+#include "wx/evtloopsrc.h"
+
+// ----------------------------------------------------------------------------
+// wxWakeUpPipe: allows to wake up the event loop by writing to it
+// ----------------------------------------------------------------------------
+
+// This class is not MT-safe, see wxWakeUpPipeMT below for a wake up pipe
+// usable from other threads.
+
+class wxWakeUpPipe : public wxEventLoopSourceHandler
+{
+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.
+    //
+    // As indicated by its name, this method does no locking and so can be
+    // called only from the main thread.
+    void WakeUpNoLock();
+
+    // Same as WakeUp() but without locking.
+
+    // Return the read end of the pipe.
+    int GetReadFd() { return m_pipe[wxPipe::Read]; }
+
+
+    // Implement wxEventLoopSourceHandler pure virtual methods
+    virtual void OnReadWaiting();
+    virtual void OnWriteWaiting() { }
+    virtual void OnExceptionWaiting() { }
+
+private:
+    wxPipe m_pipe;
+
+    // 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;
+};
+
+// ----------------------------------------------------------------------------
+// wxWakeUpPipeMT: thread-safe version of wxWakeUpPipe
+// ----------------------------------------------------------------------------
+
+// This class can be used from multiple threads, i.e. its WakeUp() can be
+// called concurrently.
+#if wxUSE_THREADS
+
+class wxWakeUpPipeMT : public wxWakeUpPipe
+{
+public:
+    wxWakeUpPipeMT() { }
+
+    // Thread-safe wrapper around WakeUpNoLock(): can be called from another
+    // thread to wake up the main one.
+    void WakeUp()
+    {
+        wxCriticalSectionLocker lock(m_pipeLock);
+
+        WakeUpNoLock();
+    }
+
+    virtual void OnReadWaiting()
+    {
+        wxCriticalSectionLocker lock(m_pipeLock);
+
+        wxWakeUpPipe::OnReadWaiting();
+    }
+
+private:
+    // Protects access to m_pipeIsEmpty.
+    wxCriticalSection m_pipeLock;
+};
+
+#else // !wxUSE_THREADS
+
+typedef wxWakeUpPipe wxWakeUpPipeMT;
+
+#endif // wxUSE_THREADS/!wxUSE_THREADS
+
+#endif // _WX_UNIX_PRIVATE_WAKEUPPIPE_H_