public static StructuralSingleton Instance()
        {
            // uses lazy instantiation, not thread safe
            if (_instance == null)
            {
                _instance = new StructuralSingleton();
            }

            return(_instance);
        }
Esempio n. 2
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        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());
        }