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