// Purpose: Implementation of thread local storage
// Author: Vadim Zeitlin
// Created: 2008-08-08
-// RCS-ID: $Id$
// Copyright: (c) 2008 Vadim Zeitlin <vadim@wxwidgets.org>
// Licence: wxWindows licence
///////////////////////////////////////////////////////////////////////////////
// check for compiler support of thread-specific variables
// ----------------------------------------------------------------------------
-#ifdef HAVE___THREAD_KEYWORD
+// when not using threads at all, there is no need for thread-specific
+// values to be really thread-specific
+#if !wxUSE_THREADS
+ #define wxHAS_COMPILER_TLS
+ #define wxTHREAD_SPECIFIC_DECL
+// otherwise try to find the compiler-specific way to handle TLS unless
+// explicitly disabled by setting wxUSE_COMPILER_TLS to 0 (it is 1 by default).
+#elif wxUSE_COMPILER_TLS
+// __thread keyword is not supported correctly by MinGW, at least in some
+// configurations, see http://sourceforge.net/support/tracker.php?aid=2837047
+// and when in doubt we prefer to not use it at all.
+#if defined(HAVE___THREAD_KEYWORD) && !defined(__MINGW32__)
#define wxHAS_COMPILER_TLS
#define wxTHREAD_SPECIFIC_DECL __thread
+// MSVC has its own version which might be supported by some other Windows
+// compilers, to be tested
#elif wxCHECK_VISUALC_VERSION(7)
#define wxHAS_COMPILER_TLS
#define wxTHREAD_SPECIFIC_DECL __declspec(thread)
-#endif
+#endif // compilers
+#endif // wxUSE_COMPILER_TLS
// ----------------------------------------------------------------------------
// define wxTLS_TYPE()
#ifdef wxHAS_COMPILER_TLS
#define wxTLS_TYPE(T) wxTHREAD_SPECIFIC_DECL T
+ #define wxTLS_PTR(var) (&(var))
+ #define wxTLS_VALUE(var) (var)
#else // !wxHAS_COMPILER_TLS
- #ifdef __WXMSW__
+
+ extern "C"
+ {
+ typedef void (*wxTlsDestructorFunction)(void*);
+ }
+
+ #if defined(__WINDOWS__)
#include "wx/msw/tls.h"
+ #elif defined(__OS2__)
+ #include "wx/os2/tls.h"
#elif defined(__UNIX__)
#include "wx/unix/tls.h"
#else
#error Neither compiler nor OS support thread-specific variables.
#endif
- // wxTlsValue<T> represents a thread-specific value of type T
+ #include <stdlib.h> // for calloc()
+
+ // wxTlsValue<T> represents a thread-specific value of type T but, unlike
+ // with native compiler thread-specific variables, it behaves like a
+ // (never NULL) pointer to T and so needs to be dereferenced before use
+ //
+ // Note: T must be a POD!
+ //
+ // Note: On Unix, thread-specific T value is freed when the thread exits.
+ // On Windows, thread-specific values are freed later, when given
+ // wxTlsValue<T> is destroyed. The only exception to this is the
+ // value for the main thread, which is always freed when
+ // wxTlsValue<T> is destroyed.
template <typename T>
class wxTlsValue
{
public:
typedef T ValueType;
- wxTlsValue() { *this = static_cast<T>(0); }
+ // ctor doesn't do anything, the object is created on first access
+ wxTlsValue() : m_key(free) {}
- wxTlsValue& operator=(T value)
+ // dtor is only called in the main thread context and so is not enough
+ // to free memory allocated by us for the other threads, we use
+ // destructor function when using Pthreads for this (which is not
+ // called for the main thread as it doesn't call pthread_exit() but
+ // just to be safe we also reset the key anyhow)
+ ~wxTlsValue()
{
- m_key.Set(wxUIntToPtr(value));
+ if ( m_key.Get() )
+ m_key.Set(NULL); // this deletes the value
+ }
- return *this;
+ // access the object creating it on demand
+ ValueType *Get()
+ {
+ void *value = m_key.Get();
+ if ( !value )
+ {
+ // ValueType must be POD to be used in wxHAS_COMPILER_TLS case
+ // anyhow (at least gcc doesn't accept non-POD values being
+ // declared with __thread) so initialize it as a POD too
+ value = calloc(1, sizeof(ValueType));
+
+ if ( !m_key.Set(value) )
+ {
+ free(value);
+
+ // this will probably result in a crash in the caller but
+ // it's arguably better to crash immediately instead of
+ // slowly dying from out-of-memory errors which would
+ // happen as the next access to this object would allocate
+ // another ValueType instance and so on forever
+ value = NULL;
+ }
+ }
+
+ return static_cast<ValueType *>(value);
}
- operator T() const { return wxPtrToUInt(m_key.Get()); }
+ // pointer-like accessors
+ ValueType *operator->() { return Get(); }
+ ValueType& operator*() { return *Get(); }
private:
wxTlsKey m_key;
};
#define wxTLS_TYPE(T) wxTlsValue<T>
+ #define wxTLS_PTR(var) ((var).Get())
+ #define wxTLS_VALUE(var) (*(var))
#endif // wxHAS_COMPILER_TLS/!wxHAS_COMPILER_TLS
#endif // _WX_TLS_H_