include/wx/unix/private/wakeuppipe.h

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/unix/private/wakeuppipe.h
   3 // Purpose:     Helper class allowing to wake up the main thread.
   4 // Author:      Vadim Zeitlin
   5 // Created:     2013-06-09 (extracted from src/unix/evtloopunix.cpp)
   6 // RCS-ID:      $Id$
   7 // Copyright:   (c) 2013 Vadim Zeitlin <vadim@wxwidgets.org>
   8 // Licence:     wxWindows licence
   9 ///////////////////////////////////////////////////////////////////////////////
  10
  11 #ifndef _WX_UNIX_PRIVATE_WAKEUPPIPE_H_
  12 #define _WX_UNIX_PRIVATE_WAKEUPPIPE_H_
  13
  14 #include "wx/unix/pipe.h"
  15 #include "wx/evtloopsrc.h"
  16
  17 // ----------------------------------------------------------------------------
  18 // wxWakeUpPipe: allows to wake up the event loop by writing to it
  19 // ----------------------------------------------------------------------------
  20
  21 // This class is not MT-safe, see wxWakeUpPipeMT below for a wake up pipe
  22 // usable from other threads.
  23
  24 class wxWakeUpPipe : public wxEventLoopSourceHandler
  25 {
  26 public:
  27     // Create and initialize the pipe.
  28     //
  29     // It's the callers responsibility to add the read end of this pipe,
  30     // returned by GetReadFd(), to the code blocking on input.
  31     wxWakeUpPipe();
  32
  33     // Wake up the blocking operation involving this pipe.
  34     //
  35     // It simply writes to the write end of the pipe.
  36     //
  37     // As indicated by its name, this method does no locking and so can be
  38     // called only from the main thread.
  39     void WakeUpNoLock();
  40
  41     // Same as WakeUp() but without locking.
  42
  43     // Return the read end of the pipe.
  44     int GetReadFd() { return m_pipe[wxPipe::Read]; }
  45
  46
  47     // Implement wxEventLoopSourceHandler pure virtual methods
  48     virtual void OnReadWaiting();
  49     virtual void OnWriteWaiting() { }
  50     virtual void OnExceptionWaiting() { }
  51
  52 private:
  53     wxPipe m_pipe;
  54
  55     // This flag is set to true after writing to the pipe and reset to false
  56     // after reading from it in the main thread. Having it allows us to avoid
  57     // overflowing the pipe with too many writes if the main thread can't keep
  58     // up with reading from it.
  59     bool m_pipeIsEmpty;
  60 };
  61
  62 // ----------------------------------------------------------------------------
  63 // wxWakeUpPipeMT: thread-safe version of wxWakeUpPipe
  64 // ----------------------------------------------------------------------------
  65
  66 // This class can be used from multiple threads, i.e. its WakeUp() can be
  67 // called concurrently.
  68
  69 class wxWakeUpPipeMT : public wxWakeUpPipe
  70 {
  71 public:
  72     wxWakeUpPipeMT() { }
  73
  74     // Thread-safe wrapper around WakeUpNoLock(): can be called from another
  75     // thread to wake up the main one.
  76     void WakeUp()
  77     {
  78         wxCriticalSectionLocker lock(m_pipeLock);
  79
  80         WakeUpNoLock();
  81     }
  82
  83     virtual void OnReadWaiting()
  84     {
  85         wxCriticalSectionLocker lock(m_pipeLock);
  86
  87         wxWakeUpPipe::OnReadWaiting();
  88     }
  89
  90 private:
  91     // Protects access to m_pipeIsEmpty.
  92     wxCriticalSection m_pipeLock;
  93 };
  94
  95 #endif // _WX_UNIX_PRIVATE_WAKEUPPIPE_H_