| 1 | /////////////////////////////////////////////////////////////////////////////// |
| 2 | // Name: wx/tls.h |
| 3 | // Purpose: Implementation of thread local storage |
| 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_TLS_H_ |
| 12 | #define _WX_TLS_H_ |
| 13 | |
| 14 | #include "wx/defs.h" |
| 15 | |
| 16 | // ---------------------------------------------------------------------------- |
| 17 | // check for compiler support of thread-specific variables |
| 18 | // ---------------------------------------------------------------------------- |
| 19 | |
| 20 | // when not using threads at all, there is no need for thread-specific |
| 21 | // values to be really thread-specific |
| 22 | #if !wxUSE_THREADS |
| 23 | #define wxHAS_COMPILER_TLS |
| 24 | #define wxTHREAD_SPECIFIC_DECL |
| 25 | // __thread keyword is supported if configure detected it or when using mingw32 |
| 26 | // >= 4.3 which is known to have it too |
| 27 | #elif defined(HAVE___THREAD_KEYWORD) || \ |
| 28 | (defined(__MINGW32__) && wxCHECK_GCC_VERSION(4, 3)) |
| 29 | #define wxHAS_COMPILER_TLS |
| 30 | #define wxTHREAD_SPECIFIC_DECL __thread |
| 31 | // MSVC has its own version which might be supported by some other Windows |
| 32 | // compilers, to be tested |
| 33 | #elif wxCHECK_VISUALC_VERSION(7) |
| 34 | #define wxHAS_COMPILER_TLS |
| 35 | #define wxTHREAD_SPECIFIC_DECL __declspec(thread) |
| 36 | #endif |
| 37 | |
| 38 | // ---------------------------------------------------------------------------- |
| 39 | // define wxTLS_TYPE() |
| 40 | // ---------------------------------------------------------------------------- |
| 41 | |
| 42 | #ifdef wxHAS_COMPILER_TLS |
| 43 | #define wxTLS_TYPE(T) wxTHREAD_SPECIFIC_DECL T |
| 44 | #define wxTLS_PTR(var) (&(var)) |
| 45 | #define wxTLS_VALUE(var) (var) |
| 46 | #else // !wxHAS_COMPILER_TLS |
| 47 | #ifdef __WXMSW__ |
| 48 | #include "wx/msw/tls.h" |
| 49 | #elif defined(__OS2__) |
| 50 | #include "wx/os2/tls.h" |
| 51 | #elif defined(__UNIX__) |
| 52 | #include "wx/unix/tls.h" |
| 53 | #else |
| 54 | // TODO: we could emulate TLS for such platforms... |
| 55 | #error Neither compiler nor OS support thread-specific variables. |
| 56 | #endif |
| 57 | |
| 58 | #include <stdlib.h> // for calloc() |
| 59 | |
| 60 | // wxTlsValue<T> represents a thread-specific value of type T but, unlike |
| 61 | // with native compiler thread-specific variables, it behaves like a |
| 62 | // (never NULL) pointer to T and so needs to be dereferenced before use |
| 63 | template <typename T> |
| 64 | class wxTlsValue |
| 65 | { |
| 66 | public: |
| 67 | typedef T ValueType; |
| 68 | |
| 69 | // ctor doesn't do anything, the object is created on first access |
| 70 | // |
| 71 | // FIXME: the thread-specific values are currently not freed under |
| 72 | // Windows, resulting in memory leaks, this must be implemented |
| 73 | // there somehow (probably by keeping a list of all TLS objects |
| 74 | // and cleaning them up in wxThread cleanup) |
| 75 | wxTlsValue() |
| 76 | #if !defined(__OS2__) && defined(__UNIX__) |
| 77 | : m_key(free) |
| 78 | #endif |
| 79 | { |
| 80 | } |
| 81 | |
| 82 | // dtor is only called in the main thread context and so is not enough |
| 83 | // to free memory allocated by us for the other threads, we use |
| 84 | // destructor function when using Pthreads for this (which is not |
| 85 | // called for the main thread as it doesn't call pthread_exit() but |
| 86 | // just to be safe we also reset the key anyhow) and simply leak the |
| 87 | // memory under Windows (see the FIXME above) |
| 88 | ~wxTlsValue() |
| 89 | { |
| 90 | void * const value = m_key.Get(); |
| 91 | if ( value) |
| 92 | { |
| 93 | free(value); |
| 94 | m_key.Set(NULL); |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | // access the object creating it on demand |
| 99 | ValueType *Get() |
| 100 | { |
| 101 | void *value = m_key.Get(); |
| 102 | if ( !value ) |
| 103 | { |
| 104 | // ValueType must be POD to be used in wxHAS_COMPILER_TLS case |
| 105 | // anyhow (at least gcc doesn't accept non-POD values being |
| 106 | // declared with __thread) so initialize it as a POD too |
| 107 | value = calloc(1, sizeof(ValueType)); |
| 108 | |
| 109 | if ( !m_key.Set(value) ) |
| 110 | { |
| 111 | free(value); |
| 112 | |
| 113 | // this will probably result in a crash in the caller but |
| 114 | // it's arguably better to crash immediately instead of |
| 115 | // slowly dying from out-of-memory errors which would |
| 116 | // happen as the next access to this object would allocate |
| 117 | // another ValueType instance and so on forever |
| 118 | value = NULL; |
| 119 | } |
| 120 | } |
| 121 | |
| 122 | return static_cast<ValueType *>(value); |
| 123 | } |
| 124 | |
| 125 | // pointer-like accessors |
| 126 | ValueType *operator->() { return Get(); } |
| 127 | ValueType& operator*() { return *Get(); } |
| 128 | |
| 129 | private: |
| 130 | wxTlsKey m_key; |
| 131 | |
| 132 | DECLARE_NO_COPY_TEMPLATE_CLASS(wxTlsValue, T) |
| 133 | }; |
| 134 | |
| 135 | #define wxTLS_TYPE(T) wxTlsValue<T> |
| 136 | #define wxTLS_PTR(var) (var) |
| 137 | #define wxTLS_VALUE(var) (*(var)) |
| 138 | #endif // wxHAS_COMPILER_TLS/!wxHAS_COMPILER_TLS |
| 139 | |
| 140 | #endif // _WX_TLS_H_ |
| 141 | |