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

src/unix/wakeuppipe.cpp

@@ -0,0 +1,137 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        src/unix/wakeuppipe.cpp
+// Purpose:     Implementation of wxWakeUpPipe class.
+// 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
+///////////////////////////////////////////////////////////////////////////////
+
+// ============================================================================
+// declarations
+// ============================================================================
+
+// ----------------------------------------------------------------------------
+// headers
+// ----------------------------------------------------------------------------
+
+// for compilers that support precompilation, includes "wx.h".
+#include "wx/wxprec.h"
+
+#ifdef __BORLANDC__
+    #pragma hdrstop
+#endif
+
+#ifndef WX_PRECOMP
+#endif // WX_PRECOMP
+
+#include "wx/unix/private/wakeuppipe.h"
+
+#include <errno.h>
+
+// ----------------------------------------------------------------------------
+// constants
+// ----------------------------------------------------------------------------
+
+#define TRACE_EVENTS wxT("events")
+
+// ============================================================================
+// wxWakeUpPipe implementation
+// ============================================================================
+
+// ----------------------------------------------------------------------------
+// initialization
+// ----------------------------------------------------------------------------
+
+wxWakeUpPipe::wxWakeUpPipe()
+{
+    m_pipeIsEmpty = true;
+
+    if ( !m_pipe.Create() )
+    {
+        wxLogError(_("Failed to create wake up pipe used by event loop."));
+        return;
+    }
+
+
+    if ( !m_pipe.MakeNonBlocking(wxPipe::Read) )
+    {
+        wxLogSysError(_("Failed to switch wake up pipe to non-blocking mode"));
+        return;
+    }
+
+    wxLogTrace(TRACE_EVENTS, wxT("Wake up pipe (%d, %d) created"),
+               m_pipe[wxPipe::Read], m_pipe[wxPipe::Write]);
+}
+
+// ----------------------------------------------------------------------------
+// wakeup handling
+// ----------------------------------------------------------------------------
+
+void wxWakeUpPipe::WakeUp()
+{
+    wxCriticalSectionLocker lock(m_pipeLock);
+
+    // No need to do anything if the pipe already contains something.
+    if ( !m_pipeIsEmpty )
+      return;
+
+    if ( write(m_pipe[wxPipe::Write], "s", 1) != 1 )
+    {
+        // don't use wxLog here, we can be in another thread and this could
+        // result in dead locks
+        perror("write(wake up pipe)");
+    }
+    else
+    {
+        // We just wrote to it, so it's not empty any more.
+        m_pipeIsEmpty = false;
+    }
+}
+
+void wxWakeUpPipe::OnReadWaiting()
+{
+    // got wakeup from child thread, remove the data that provoked it from the
+    // pipe
+
+    wxCriticalSectionLocker lock(m_pipeLock);
+
+    char buf[4];
+    for ( ;; )
+    {
+        const int size = read(GetReadFd(), buf, WXSIZEOF(buf));
+
+        if ( size > 0 )
+        {
+            wxASSERT_MSG( size == 1, "Too many writes to wake-up pipe?" );
+
+            break;
+        }
+
+        if ( size == 0 || (size == -1 && errno == EAGAIN) )
+        {
+            // No data available, not an error (but still surprising,
+            // spurious wakeup?)
+            break;
+        }
+
+        if ( errno == EINTR )
+        {
+            // We were interrupted, try again.
+            continue;
+        }
+
+        wxLogSysError(_("Failed to read from wake-up pipe"));
+
+        return;
+    }
+
+    // The pipe is empty now, so future calls to WakeUp() would need to write
+    // to it again.
+    m_pipeIsEmpty = true;
+
+    // writing to the wake up pipe will make wxConsoleEventLoop return from
+    // wxFDIODispatcher::Dispatch() it might be currently blocking in, nothing
+    // else needs to be done
+}