Delphi and the C# lock statement

If you have studied the C# language, you might be aware of the lock statement.

This is a very handy statement in multi-threaded applications. But, if you are a Delphi developed trying to hack together some example code from the net, you are at loss because Delphi doesn't support this statement.

But, since we all have a IL disassembler, it is easy to see what kind of code a C# creates when using the lock statement.

When I wrote a very simple C# application like this:

class Test
{
   public static void Main()
   {
        System.Console.WriteLine("Before");
        lock (new Test()) {
          System.Console.WriteLine("Inside");
        }
        System.Console.WriteLine("After");
   }
}

...it turned out that the generated IL code was this:

.method public hidebysig static void  Main() cil managed
{
  .entrypoint
  // Code size       52 (0x34)
  .maxstack  2
  .locals init (class Test V_0)
  IL_0000:  ldstr      "Before"
  IL_0005:  call       void [mscorlib]System.Console::WriteLine(string)
  IL_000a:  newobj     instance void Test::.ctor()
  IL_000f:  dup
  IL_0010:  stloc.0
  IL_0011:  call       void [mscorlib]System.Threading.Monitor::Enter(object)
  .try
  {
    IL_0016:  ldstr      "Inside"
    IL_001b:  call       void [mscorlib]System.Console::WriteLine(string)
    IL_0020:  leave.s    IL_0029
  }  // end .try
  finally
  {
    IL_0022:  ldloc.0
    IL_0023:  call       void [mscorlib]System.Threading.Monitor::Exit(object)
    IL_0028:  endfinally
  }  // end handler
  IL_0029:  ldstr      "After"
  IL_002e:  call       void [mscorlib]System.Console::WriteLine(string)
  IL_0033:  ret
} // end of method Test::Main

So, the conclusion is that the C# lock statement uses the System.Threading.Monitor class internally.

The conclusion: if you encounted the C# lock statement in code you need to translate into Delphi code, simply use the Monitor.Enter and Monitor.Exit methods around the statement(s). And don't forget try-finally!