2019-11-29-C # - -TryGetValue- dictionary -Dictionary- -ContainsKey- then determines the first performance comparison -Get-

Original: 2019-11-29-C # - -TryGetValue- dictionary -Dictionary- of the prior determination of the performance comparison -ContainsKey- then -Get-

title	author	date	CreateTime	categories
C # Dictionary dictionary of the prior TryGetValue ContainsKey then determines the performance comparison Get	lindexi	2019-11-29 10:13:19 +0800	2018-09-08 15:33:40 +0800	C#

As used herein, benchmarkdotnet performance test dictionary, to obtain the value in the use of a dictionary may be possible to use two different ways of writing, then writing of two performance analysis herein.

Presence determination value, if the value exists on the acquired value, the following two different use methods

One method is to use the code TryGetValue see below

            if (Dictionary.TryGetValue(xx, out var foo))
            {
            }

Another method is to determine whether there is then acquired, consider the following Code

if(Dictionary.ContainsKey(xx))
{
	var foo = Dictionary[xx];
}

So it is used herein benchmarkdotnet performance of the two test methods

The following is the test data, the test code in the final article. TryGetExist here is to try to obtain a value that is there. The ContainGetExist is to determine whether there is value, if there is to try to get this value.

BenchmarkDotNet=v0.10.14, OS=Windows 10.0.17134
Intel Core i7-6700 CPU 3.40GHz (Skylake), 1 CPU, 8 logical and 4 physical cores
Frequency=3328130 Hz, Resolution=300.4690 ns, Timer=TSC
  [Host]     : .NET Framework 4.7 (CLR 4.0.30319.42000), 64bit RyuJIT-v4.7.3132.0  [AttachedDebugger]
  DefaultJob : .NET Framework 4.7 (CLR 4.0.30319.42000), 64bit RyuJIT-v4.7.3132.0

Method	Mean	Error	StdDev	Median
TryGetExist	30.26 ns	0.6057 ns	0.5949 ns	30.11 ns
ContainGetExist	46.36 ns	1.0883 ns	3.1919 ns	44.90 ns
TryGetNoExist	20.23 ns	0.4661 ns	0.7658 ns	19.93 ns
ContainGetNoExist	18.68 ns	0.2569 ns	0.2403 ns	18.66 ns

Also compare the performance ConcurrentDictionary thread-safe class, that is, the dictionary will test Foo class above ConcurrentDictionary replaced by other code not modify, the following test data, you can see the performance is still better to use TryGetValue

BenchmarkDotNet=v0.10.14, OS=Windows 10.0.17134
Intel Core i7-6700 CPU 3.40GHz (Skylake), 1 CPU, 8 logical and 4 physical cores
Frequency=3328130 Hz, Resolution=300.4690 ns, Timer=TSC
  [Host]     : .NET Framework 4.7 (CLR 4.0.30319.42000), 64bit RyuJIT-v4.7.3132.0  [AttachedDebugger]
  DefaultJob : .NET Framework 4.7 (CLR 4.0.30319.42000), 64bit RyuJIT-v4.7.3132.0

Method	Mean	Error	StdDev	Median
TryGetExist	31.20 ns	0.4644 ns	0.3625 ns	31.17 ns
ContainGetExist	66.80 ns	2.4692 ns	7.2806 ns	63.84 ns
TryGetNoExist	20.07 ns	0.1254 ns	0.1112 ns	20.04 ns
ContainGetNoExist	27.63 ns	0.4230 ns	0.3956 ns	27.65 ns

All codes

    public  class  Foo
    {
        /// <inheritdoc />
        public Foo()
        {
            was  Ran  =  new  Random ();
            bool  seen  =  false ;
            for ( int  in  =  0 ; in  <  100000 ; of ++ )
            {
                LazyDictionary[ran.Next().ToString() + "-" + i.ToString()] = ran.Next().ToString();
                if (!set)
                {
                    if (ran.Next() < i)
                    {
                        set = true;
                        LazyDictionary["lindexi"] = "逗比";
                    }
                }
            }
        }

        [Benchmark]
        public void TryGetExist()
        {
            if (LazyDictionary.TryGetValue("lindexi", out var foo))
            {
                _foo = foo;
            }
        }

        [Benchmark]
        public void ContainGetExist()
        {
            if (LazyDictionary.ContainsKey("lindexi"))
            {
                _foo = LazyDictionary["lindexi"];
            }
        }


        [Benchmark]
        public void TryGetNoExist()
        {
            if (LazyDictionary.TryGetValue("lindexi123", out var foo))
            {
                _foo = foo;
            }
        }

        [Benchmark]
        public void ContainGetNoExist()
        {
            if (LazyDictionary.ContainsKey("lindexi123"))
            {
                _foo = LazyDictionary["lindexi123"];
            }
        }

        private object _foo;

        private Dictionary<string, object> LazyDictionary { get; } = new Dictionary<string, object>();

    }

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