141 lines
5.0 KiB
C++
141 lines
5.0 KiB
C++
///////////////////////////////////////////////////////////////////////////////
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// Name: wx/tls.h
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// Purpose: Implementation of thread local storage
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// Author: Vadim Zeitlin
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// Created: 2008-08-08
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// RCS-ID: $Id: tls.h 70796 2012-03-04 00:29:31Z VZ $
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// Copyright: (c) 2008 Vadim Zeitlin <vadim@wxwidgets.org>
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// Licence: wxWindows licence
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///////////////////////////////////////////////////////////////////////////////
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#ifndef _WX_TLS_H_
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#define _WX_TLS_H_
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#include "wx/defs.h"
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// ----------------------------------------------------------------------------
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// check for compiler support of thread-specific variables
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// ----------------------------------------------------------------------------
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// when not using threads at all, there is no need for thread-specific
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// values to be really thread-specific
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#if !wxUSE_THREADS
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#define wxHAS_COMPILER_TLS
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#define wxTHREAD_SPECIFIC_DECL
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// __thread keyword is not supported correctly by MinGW, at least in some
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// configurations, see http://sourceforge.net/support/tracker.php?aid=2837047
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// and when in doubt we prefer to not use it at all.
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#elif defined(HAVE___THREAD_KEYWORD) && !defined(__MINGW32__)
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#define wxHAS_COMPILER_TLS
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#define wxTHREAD_SPECIFIC_DECL __thread
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// MSVC has its own version which might be supported by some other Windows
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// compilers, to be tested
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#elif wxCHECK_VISUALC_VERSION(7)
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#define wxHAS_COMPILER_TLS
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#define wxTHREAD_SPECIFIC_DECL __declspec(thread)
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#endif
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// ----------------------------------------------------------------------------
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// define wxTLS_TYPE()
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// ----------------------------------------------------------------------------
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#ifdef wxHAS_COMPILER_TLS
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#define wxTLS_TYPE(T) wxTHREAD_SPECIFIC_DECL T
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#define wxTLS_PTR(var) (&(var))
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#define wxTLS_VALUE(var) (var)
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#else // !wxHAS_COMPILER_TLS
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extern "C"
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{
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typedef void (*wxTlsDestructorFunction)(void*);
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}
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#if defined(__WINDOWS__)
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#include "wx/msw/tls.h"
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#elif defined(__OS2__)
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#include "wx/os2/tls.h"
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#elif defined(__UNIX__)
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#include "wx/unix/tls.h"
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#else
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// TODO: we could emulate TLS for such platforms...
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#error Neither compiler nor OS support thread-specific variables.
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#endif
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#include <stdlib.h> // for calloc()
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// wxTlsValue<T> represents a thread-specific value of type T but, unlike
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// with native compiler thread-specific variables, it behaves like a
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// (never NULL) pointer to T and so needs to be dereferenced before use
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//
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// Note: T must be a POD!
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//
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// Note: On Unix, thread-specific T value is freed when the thread exits.
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// On Windows, thread-specific values are freed later, when given
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// wxTlsValue<T> is destroyed. The only exception to this is the
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// value for the main thread, which is always freed when
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// wxTlsValue<T> is destroyed.
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template <typename T>
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class wxTlsValue
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{
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public:
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typedef T ValueType;
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// ctor doesn't do anything, the object is created on first access
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wxTlsValue() : m_key(free) {}
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// dtor is only called in the main thread context and so is not enough
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// to free memory allocated by us for the other threads, we use
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// destructor function when using Pthreads for this (which is not
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// called for the main thread as it doesn't call pthread_exit() but
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// just to be safe we also reset the key anyhow)
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~wxTlsValue()
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{
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if ( m_key.Get() )
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m_key.Set(NULL); // this deletes the value
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}
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// access the object creating it on demand
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ValueType *Get()
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{
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void *value = m_key.Get();
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if ( !value )
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{
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// ValueType must be POD to be used in wxHAS_COMPILER_TLS case
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// anyhow (at least gcc doesn't accept non-POD values being
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// declared with __thread) so initialize it as a POD too
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value = calloc(1, sizeof(ValueType));
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if ( !m_key.Set(value) )
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{
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free(value);
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// this will probably result in a crash in the caller but
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// it's arguably better to crash immediately instead of
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// slowly dying from out-of-memory errors which would
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// happen as the next access to this object would allocate
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// another ValueType instance and so on forever
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value = NULL;
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}
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}
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return static_cast<ValueType *>(value);
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}
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// pointer-like accessors
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ValueType *operator->() { return Get(); }
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ValueType& operator*() { return *Get(); }
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private:
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wxTlsKey m_key;
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DECLARE_NO_COPY_TEMPLATE_CLASS(wxTlsValue, T)
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};
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#define wxTLS_TYPE(T) wxTlsValue<T>
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#define wxTLS_PTR(var) ((var).Get())
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#define wxTLS_VALUE(var) (*(var))
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#endif // wxHAS_COMPILER_TLS/!wxHAS_COMPILER_TLS
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#endif // _WX_TLS_H_
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