LazyUpdate
Using LazyUpdate for MT correct lazy evaluation
LazyUpdate.cpp
#include <Core/Core.h>
using namespace Upp;
struct DblSum {
Vector<double> d;
mutable double sum;
LazyUpdate dirty;
public:
void Add(double x) {
d.Add(x);
dirty.Invalidate();
}
double Sum() const {
if(dirty.BeginUpdate()) {
Vector<int> o = GetSortOrder(d);
sum = 0;
for(int i = 0; i < o.GetCount(); i++)
sum += d[o[i]];
dirty.EndUpdate();
}
return sum;
}
};
CONSOLE_APP_MAIN
{
DblSum x;
x.Add(100);
for(int i = 0; i < 1000*1000; i++)
x.Add(1e-10);
Cout() << x.Sum() << "\n";
}
|
