EDIT: Mi rendo conto che la mia risposta non ha risposto esattamente alla domanda, mentre non c'è un vero svantaggio, dai miei risultati di cronometraggio non c'è nemmeno un vero vantaggio. La differenza tra un getter di proprietà in linea è di 0,002 secondi su 500 milioni di iterazioni. Il mio test case potrebbe anche non essere accurato al 100% dal momento che usa una struct perché ci sono alcuni avvertimenti sul jitter e l'inline con le strutture.
Come sempre, l'unico modo per sapere davvero è scrivere un test e capirlo. Ecco i miei risultati con la seguente configurazione:
Windows 7 Home
8GB ram
64bit os
i5-2300 2.8ghz
Svuota il progetto con le seguenti impostazioni:
.NET 4.5
Release mode
Start without debugger attached - CRUCIAL
Unchecked "Prefer 32-bit" under project build settings
Risultati
struct get property : 0.3097832 seconds
struct inline get property : 0.3079076 seconds
struct method call with params : 1.0925033 seconds
struct inline method call with params : 1.0930666 seconds
struct method call without params : 1.5211852 seconds
struct intline method call without params : 1.2235001 seconds
Testato con questo codice:
class Program
{
const int SAMPLES = 5;
const int ITERATIONS = 100000;
const int DATASIZE = 1000;
static Random random = new Random();
static Stopwatch timer = new Stopwatch();
static Dictionary<string, TimeSpan> timings = new Dictionary<string, TimeSpan>();
class SimpleTimer : IDisposable
{
private string name;
public SimpleTimer(string name)
{
this.name = name;
timer.Restart();
}
public void Dispose()
{
timer.Stop();
TimeSpan ts = TimeSpan.Zero;
if (timings.ContainsKey(name))
ts = timings[name];
ts += timer.Elapsed;
timings[name] = ts;
}
}
[StructLayout(LayoutKind.Sequential, Size = 4)]
struct TestStruct
{
private int x;
public int X { get { return x; } set { x = value; } }
}
[StructLayout(LayoutKind.Sequential, Size = 4)]
struct TestStruct2
{
private int x;
public int X
{
[MethodImpl(MethodImplOptions.AggressiveInlining)]
get { return x; }
set { x = value; }
}
}
[StructLayout(LayoutKind.Sequential, Size = 8)]
struct TestStruct3
{
private int x;
private int y;
public void Update(int _x, int _y)
{
x += _x;
y += _y;
}
}
[StructLayout(LayoutKind.Sequential, Size = 8)]
struct TestStruct4
{
private int x;
private int y;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void Update(int _x, int _y)
{
x += _x;
y += _y;
}
}
[StructLayout(LayoutKind.Sequential, Size = 8)]
struct TestStruct5
{
private int x;
private int y;
public void Update()
{
x *= x;
y *= y;
}
}
[StructLayout(LayoutKind.Sequential, Size = 8)]
struct TestStruct6
{
private int x;
private int y;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void Update()
{
x *= x;
y *= y;
}
}
static void RunTests()
{
for (var i = 0; i < SAMPLES; ++i)
{
Console.Write("Sample {0} ... ", i);
RunTest1();
RunTest2();
RunTest3();
RunTest4();
RunTest5();
RunTest6();
Console.WriteLine(" complate");
}
}
static int RunTest1()
{
var data = new TestStruct[DATASIZE];
var temp = 0;
unchecked
{
//init the data, just so jitter can't make assumptions
for (var j = 0; j < DATASIZE; ++j)
data[j].X = random.Next();
using (new SimpleTimer("struct get property"))
{
for (var j = 0; j < DATASIZE; ++j)
{
for (var i = 0; i < ITERATIONS; ++i)
{
//use some math to make sure its not optimized out (aka don't use an incrementor)
temp += data[j].X;
}
}
}
}
//again need variables to cross scopes to make sure the jitter doesn't do crazy optimizations
return temp;
}
static int RunTest2()
{
var data = new TestStruct2[DATASIZE];
var temp = 0;
unchecked
{
//init the data, just so jitter can't make assumptions
for (var j = 0; j < DATASIZE; ++j)
data[j].X = random.Next();
using (new SimpleTimer("struct inline get property"))
{
for (var j = 0; j < DATASIZE; ++j)
{
for (var i = 0; i < ITERATIONS; ++i)
{
//use some math to make sure its not optimized out (aka don't use an incrementor)
temp += data[j].X;
}
}
}
}
//again need variables to cross scopes to make sure the jitter doesn't do crazy optimizations
return temp;
}
static void RunTest3()
{
var data = new TestStruct3[DATASIZE];
unchecked
{
using (new SimpleTimer("struct method call with params"))
{
for (var j = 0; j < DATASIZE; ++j)
{
for (var i = 0; i < ITERATIONS; ++i)
{
//use some math to make sure its not optimized out (aka don't use an incrementor)
data[j].Update(j, i);
}
}
}
}
}
static void RunTest4()
{
var data = new TestStruct4[DATASIZE];
unchecked
{
using (new SimpleTimer("struct inline method call with params"))
{
for (var j = 0; j < DATASIZE; ++j)
{
for (var i = 0; i < ITERATIONS; ++i)
{
//use some math to make sure its not optimized out (aka don't use an incrementor)
data[j].Update(j, i);
}
}
}
}
}
static void RunTest5()
{
var data = new TestStruct5[DATASIZE];
unchecked
{
using (new SimpleTimer("struct method call without params"))
{
for (var j = 0; j < DATASIZE; ++j)
{
for (var i = 0; i < ITERATIONS; ++i)
{
//use some math to make sure its not optimized out (aka don't use an incrementor)
data[j].Update();
}
}
}
}
}
static void RunTest6()
{
var data = new TestStruct6[DATASIZE];
unchecked
{
using (new SimpleTimer("struct intline method call without params"))
{
for (var j = 0; j < DATASIZE; ++j)
{
for (var i = 0; i < ITERATIONS; ++i)
{
//use some math to make sure its not optimized out (aka don't use an incrementor)
data[j].Update();
}
}
}
}
}
static void Main(string[] args)
{
RunTests();
DumpResults();
Console.Read();
}
static void DumpResults()
{
foreach (var kvp in timings)
{
Console.WriteLine("{0,-50}: {1} seconds", kvp.Key, kvp.Value.TotalSeconds);
}
}
}