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#pragma once
/**
* Copyright (C) 2011 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <boost/thread/tss.hpp>
namespace mongo {
using boost::thread_specific_ptr;
/* thread local "value" rather than a pointer
good for things which have copy constructors (and the copy constructor is fast enough)
e.g.
ThreadLocalValue<int> myint;
*/
template<class T>
class ThreadLocalValue {
public:
ThreadLocalValue( T def = 0 ) : _default( def ) { }
T get() const {
T * val = _val.get();
if ( val )
return *val;
return _default;
}
void set( const T& i ) {
T *v = _val.get();
if( v ) {
*v = i;
return;
}
v = new T(i);
_val.reset( v );
}
T& getRef() {
T *v = _val.get();
if( v ) {
return *v;
}
v = new T(_default);
_val.reset( v );
return *v;
}
private:
boost::thread_specific_ptr<T> _val;
const T _default;
};
/* TSP
These macros use intrinsics which are faster than boost::thread_specific_ptr.
However the intrinsics don't free up objects on thread closure. Thus we use
a combination here, with the assumption that reset's are infrequent, so that
get's are fast.
*/
#if defined(_WIN32) || (defined(__GNUC__) && defined(__linux__))
template< class T >
struct TSP {
boost::thread_specific_ptr<T> tsp;
public:
T* get() const;
void reset(T* v);
};
# if defined(_WIN32)
# define TSP_DECLARE(T,p) extern TSP<T> p;
# define TSP_DEFINE(T,p) __declspec( thread ) T* _ ## p; \
TSP<T> p; \
template<> T* TSP<T>::get() const { return _ ## p; } \
void TSP<T>::reset(T* v) { \
tsp.reset(v); \
_ ## p = v; \
}
# else
# define TSP_DECLARE(T,p) \
extern __thread T* _ ## p; \
template<> inline T* TSP<T>::get() const { return _ ## p; } \
extern TSP<T> p;
# define TSP_DEFINE(T,p) \
__thread T* _ ## p; \
template<> void TSP<T>::reset(T* v) { \
tsp.reset(v); \
_ ## p = v; \
} \
TSP<T> p;
# endif
#else
template< class T >
struct TSP {
thread_specific_ptr<T> tsp;
public:
T* get() const { return tsp.get(); }
void reset(T* v) { tsp.reset(v); }
};
# define TSP_DECLARE(T,p) extern TSP<T> p;
# define TSP_DEFINE(T,p) TSP<T> p;
#endif
}
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