public static StructuralSingleton Instance()
{
// uses lazy instantiation, not thread safe
if (_instance == null)
{
_instance = new StructuralSingleton();
}
return(_instance);
}
static void Main()
{
/*
* Structural
*/
// constructors are protected, cannot use "new"
StructuralSingleton structuralSingletonOne = StructuralSingleton.Instance();
StructuralSingleton structuralSingletonTwo = StructuralSingleton.Instance();
// test for instance equality
if (structuralSingletonOne == structuralSingletonTwo)
{
Console.WriteLine("Objects are same instance");
}
/*
* Real-World
*/
RealWorldSingletonLoadBalancer balancerOne = RealWorldSingletonLoadBalancer.GetLoadBalancer();
RealWorldSingletonLoadBalancer balancerTwo = RealWorldSingletonLoadBalancer.GetLoadBalancer();
RealWorldSingletonLoadBalancer balancerThree = RealWorldSingletonLoadBalancer.GetLoadBalancer();
RealWorldSingletonLoadBalancer balancerFour = RealWorldSingletonLoadBalancer.GetLoadBalancer();
// test for equality
if (balancerOne == balancerTwo && balancerTwo == balancerThree && balancerThree == balancerFour)
{
Console.WriteLine("Same instance");
}
// load balance 15 server requests
RealWorldSingletonLoadBalancer loadBalancer = RealWorldSingletonLoadBalancer.GetLoadBalancer();
for (int i = 0; i < 15; i++)
{
string server = loadBalancer.Server;
Console.WriteLine("Dispatch request to: " + server);
}
/*
* .NET Optimized
*/
DotNetOptimizedSingleton dotNetBalancerOne = DotNetOptimizedSingleton.GetLoadBalancer();
DotNetOptimizedSingleton dotNetBalancerTwo = DotNetOptimizedSingleton.GetLoadBalancer();
DotNetOptimizedSingleton dotNetBalancerThree = DotNetOptimizedSingleton.GetLoadBalancer();
DotNetOptimizedSingleton dotNetBalancerFour = DotNetOptimizedSingleton.GetLoadBalancer();
// test for equality
if (dotNetBalancerOne == dotNetBalancerTwo && dotNetBalancerTwo ==
dotNetBalancerThree && dotNetBalancerThree == dotNetBalancerFour)
{
Console.WriteLine("Same instance");
}
// load balance 15 server requests
DotNetOptimizedSingleton dotNetBalancer = DotNetOptimizedSingleton.GetLoadBalancer();
for (int i = 0; i < 15; i++)
{
string server = dotNetBalancer.NextServer.Name;
Console.WriteLine("Dispatch request to: " + server);
}
/*
* Lazy
*/
LazySingleton lazySingletonOne = LazySingleton.Instance;
LazySingleton lazySingletonTwo = LazySingleton.Instance;
if (lazySingletonOne == lazySingletonTwo)
{
Console.WriteLine("Lazy Singletons are equal");
}
Console.WriteLine(lazySingletonOne.CheckCreation());
}
