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// set::insert
#include <iostream>
#include <set>
#include <vector>
#include <memory>
#include <functional>
//using namespace std;
///////////////////////1
class TInternalPool
{
public:
TInternalPool()
{
buf=NULL;
mem_cnt=0;
}
// I don't want objects of this class to be copied or assigned
TInternalPool(const TInternalPool&) = delete;
TInternalPool& operator=(const TInternalPool&) = delete;
~TInternalPool()
{
FreeBuf();
}
void FreeBuf()
{
if (buf)
{
delete [] buf;
buf=NULL;
}
}
void BufReserve(size_t count, size_t align)
{
count+=align-1; // to make available satisfy alignment for elements in future
if (mem_cnt<count)
{
FreeBuf();
mem_cnt=count;
buf = new char[count]; //>=count bytes, not aligned, aligning will be later
if (!buf)
throw std::bad_alloc();
last=buf+count;
}
curr=last;
}
inline char* allocate(size_t sz, size_t align)
{
curr-=sz;
curr=reinterpret_cast<char*>(reinterpret_cast<size_t>(curr) & (-align));
if (curr<buf)
throw("Space supposed to be pre-allocated!");
return curr;
}
inline void deallocate(size_t n)
{
// curr+=n; // no align control analysis so it's not invert to "allocate"
}
void Clear()
{
curr=last; // allocate from back as in stack
}
private:
char *buf, *last, *curr;
size_t mem_cnt;
};
///////////////////////2
template <class T>
class TBufferedAllocator: public std::allocator<T>
{
public:
typedef T* pointer;
typedef size_t size_type;
template<class _Other>
struct rebind
{
typedef TBufferedAllocator<_Other> other;
};
explicit TBufferedAllocator(TInternalPool &Apool): std::allocator<T>(), pool(Apool)
{
}
TBufferedAllocator(const TBufferedAllocator& copy_from_me) : pool(copy_from_me.pool)
{
}
template <typename A>
TBufferedAllocator(const A& copy_from_me) : pool(copy_from_me.pool)
{
}
virtual ~TBufferedAllocator()
{
}
virtual pointer allocate(size_type n, const void * hint=0)
{
std::cout << "TBufferedAllocator::allocate called, size="<<n <<std::endl;
std::cout << "size="<<sizeof(T) <<", name=" << std::endl;
pool.allocate(n*sizeof(T), alignof(T));
}
virtual void deallocate(pointer p, size_type n)
{
std::cout << "TBufferedAllocator::deallocate called, size="<<n <<std::endl;
pool.deallocate(n*sizeof(T));
// no implementation, shouldn't actually be. Memory REALLY deallocates only in destructor or via mem change
}
void reserve(size_t n_bytes)
{
pool.BufReserve(n_bytes, alignof(T));
}
protected:
TInternalPool &pool;
private:
// no default constructor accessable:
TBufferedAllocator();
template <typename U>
friend class TBufferedAllocator;
};
///////////////////////3
template <class T>
class TBufferedStdSetAllocator : public TBufferedAllocator<T>
{
public:
typedef T* pointer;
typedef size_t size_type;
template<class _Other>
struct rebind
{
typedef TBufferedStdSetAllocator<_Other> other;
};
explicit TBufferedStdSetAllocator(TInternalPool &Apool): TBufferedAllocator<T>(Apool)
{
}
TBufferedStdSetAllocator(const TBufferedStdSetAllocator& copy_from_me) : TBufferedAllocator<T>(copy_from_me)
{
}
template <typename A>
TBufferedStdSetAllocator(const A& copy_from_me) : TBufferedAllocator<T>(copy_from_me)
{
}
private:
template <class U>
class TBufferedStdSetAllocatorHelper : public std::allocator<U>
{
public:
size_t node_type_size;
typedef U* pointer;
typedef size_t size_type;
template<class _Other>
struct rebind
{
typedef TBufferedStdSetAllocatorHelper<_Other> other;
};
explicit TBufferedStdSetAllocatorHelper(): std::allocator<U>()
{
}
TBufferedStdSetAllocatorHelper(const TBufferedStdSetAllocatorHelper& copy_from_me)
{
}
template <typename A>
TBufferedStdSetAllocatorHelper(const A& copy_from_me)
{
}
virtual pointer allocate(size_type n, const void * hint=0)
{
node_type_size=sizeof(U);
return std::allocator<U>::allocate(n,hint);
}
};
public:
void reserve_set_items_cnt(size_t n_items, const T &dummy_val)
{
// hack to get node size in std::set :
TBufferedStdSetAllocatorHelper<T> hlpAlloc(this->pool);
std::set<T, std::less<T>, TBufferedStdSetAllocatorHelper<T>> help_set(std::less<T>(), hlpAlloc);
//
try
{
help_set.insert(dummy_val); // could be exception there, just ignore it
}
catch (...)
{
std::cout<<"gotcha!"<<std::endl;
}
this->pool.BufReserve(n_items*hlpAlloc.node_type_size, alignof(T));
}
};
class foo
{
int a;
double b;
void *c;
const char *d;
int *e();
int g;
public:
foo(int Aa, int Ag)
{
a=Aa;
g=Ag;
b=2012.0;
c=NULL;
d="Hello world";
//e=NULL;
}
inline bool operator <(const foo &other) const
{
return a>other.a;
}
} ;//__attribute__((aligned(64)));
int main ()
{
TInternalPool pool;
TBufferedStdSetAllocator<foo> MyAlloc(pool);
std::set<foo, std::less<foo>, TBufferedStdSetAllocator<foo> > v_foo(std::less<foo>(), MyAlloc);
//
MyAlloc.reserve_set_items_cnt(10, foo(1, 2));
for (int i=0;i<10;i++)
v_foo.insert(foo(i, i*i));
return 0;
}
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