wxWidgets/include/wx/unix/private/wakeuppipe.h
2017-02-24 23:37:44 +01:00

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///////////////////////////////////////////////////////////////////////////////
// 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() wxOVERRIDE;
virtual void OnWriteWaiting() wxOVERRIDE { }
virtual void OnExceptionWaiting() wxOVERRIDE { }
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.
class wxWakeUpPipeMT : public wxWakeUpPipe
{
#if wxUSE_THREADS
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() wxOVERRIDE
{
wxCriticalSectionLocker lock(m_pipeLock);
wxWakeUpPipe::OnReadWaiting();
}
private:
// Protects access to m_pipeIsEmpty.
wxCriticalSection m_pipeLock;
#endif // wxUSE_THREADS
};
#endif // _WX_UNIX_PRIVATE_WAKEUPPIPE_H_