performance - What's the most efficient way to marshal C++ structs to C#?

Question

I am about to begin reading tons of binary files, each with 1000 or more records. New files are added constantly so I'm writing a Windows service to monitor the directories and process new files as they are received. The files were created with a c++ program. I've recreated the struct definitions in c# and can read the data fine, but I'm concerned that the way I'm doing it will eventually kill my application.

using (BinaryReader br = new BinaryReader(File.Open("myfile.bin", FileMode.Open)))
{
    long pos = 0L;
    long length = br.BaseStream.Length;

    CPP_STRUCT_DEF record;
    byte[] buffer = new byte[Marshal.SizeOf(typeof(CPP_STRUCT_DEF))];
    GCHandle pin;

    while (pos < length)
    {
        buffer = br.ReadBytes(buffer.Length);
        pin = GCHandle.Alloc(buffer, GCHandleType.Pinned);
        record = (CPP_STRUCT_DEF)Marshal.PtrToStructure(pin.AddrOfPinnedObject(), typeof(CPP_STRUCT_DEF));
        pin.Free();

        pos += buffer.Length;

        /* Do stuff with my record */
    }
}

I don't think I need to use GCHandle because I'm not actually communicating with the C++ app, everything is being done from managed code, but I don't know of an alternative method.

Answer 1

Using Marshal.PtrToStructure is rather slow. I found the following article on CodeProject which is comparing (and benchmarking) different ways of reading binary data very helpful:

Fast Binary File Reading with C#