include/wx/msw/tls.h

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/msw/tls.h
   3 // Purpose:     Win32 implementation of wxTlsValue<>
   4 // Author:      Vadim Zeitlin
   5 // Created:     2008-08-08
   6 // RCS-ID:      $Id$
   7 // Copyright:   (c) 2008 Vadim Zeitlin <vadim@wxwidgets.org>
   8 // Licence:     wxWindows licence
   9 ///////////////////////////////////////////////////////////////////////////////
  10
  11 #ifndef _WX_MSW_TLS_H_
  12 #define _WX_MSW_TLS_H_
  13
  14 #include "wx/msw/wrapwin.h"
  15 #include "wx/thread.h"
  16 #include "wx/vector.h"
  17
  18 // ----------------------------------------------------------------------------
  19 // wxTlsKey is a helper class encapsulating a TLS slot
  20 // ----------------------------------------------------------------------------
  21
  22 class wxTlsKey
  23 {
  24 public:
  25     // ctor allocates a new key
  26     wxTlsKey(wxTlsDestructorFunction destructor)
  27     {
  28         m_destructor = destructor;
  29         m_slot = ::TlsAlloc();
  30     }
  31
  32     // return true if the key was successfully allocated
  33     bool IsOk() const { return m_slot != TLS_OUT_OF_INDEXES; }
  34
  35     // get the key value, there is no error return
  36     void *Get() const
  37     {
  38         return ::TlsGetValue(m_slot);
  39     }
  40
  41     // change the key value, return true if ok
  42     bool Set(void *value)
  43     {
  44         void *old = Get();
  45
  46         if ( ::TlsSetValue(m_slot, value) == 0 )
  47             return false;
  48
  49         if ( old )
  50             m_destructor(old);
  51
  52         // update m_allValues list of all values - remove old, add new
  53         wxCriticalSectionLocker lock(m_csAllValues);
  54         if ( old )
  55         {
  56             for ( wxVector<void*>::iterator i = m_allValues.begin();
  57                   i != m_allValues.end();
  58                   ++i )
  59             {
  60                 if ( *i == old )
  61                 {
  62                     if ( value )
  63                         *i = value;
  64                     else
  65                         m_allValues.erase(i);
  66                     return true;
  67                 }
  68             }
  69             wxFAIL_MSG( "previous wxTlsKey value not recorded in m_allValues" );
  70         }
  71
  72         if ( value )
  73             m_allValues.push_back(value);
  74
  75         return true;
  76     }
  77
  78     // free the key
  79     ~wxTlsKey()
  80     {
  81         if ( !IsOk() )
  82             return;
  83
  84         // Win32 API doesn't have the equivalent of pthread's destructor, so we
  85         // have to keep track of all allocated values and destroy them manually;
  86         // ideally we'd do that at thread exit time, but since we could only
  87         // do that with wxThread and not otherwise created threads, we do it
  88         // here.
  89         //
  90         // TODO: We should still call destructors for wxTlsKey used in the
  91         //       thread from wxThread's thread shutdown code, *in addition*
  92         //       to doing it in ~wxTlsKey.
  93         //
  94         // NB: No need to lock m_csAllValues, by the time this code is called,
  95         //     no other thread can be using this key.
  96         for ( wxVector<void*>::iterator i = m_allValues.begin();
  97               i != m_allValues.end();
  98               ++i )
  99         {
 100             m_destructor(*i);
 101         }
 102
 103         ::TlsFree(m_slot);
 104     }
 105
 106 private:
 107     wxTlsDestructorFunction m_destructor;
 108     DWORD m_slot;
 109
 110     wxVector<void*> m_allValues;
 111     wxCriticalSection m_csAllValues;
 112
 113     wxDECLARE_NO_COPY_CLASS(wxTlsKey);
 114 };
 115
 116 #endif // _WX_MSW_TLS_H_
 117