SafeHandles.cs

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using System.Runtime.InteropServices;
 
namespace IDSImaging.Peak.ICV.Backend;
 
internal static class SafeHandles
{
    public static IntPtr[] ExtractHandles<T>(IList<T> objects, Func<T, SafeHandle> handleSelector, out Action release)
    {
        var handles = new IntPtr[objects.Count];
        var safeHandles = new List<SafeHandle>();
 
        for (var i = 0; i < objects.Count; i++)
        {
            SafeHandle sh = handleSelector(objects[i]);
            var added = false;
 
            try
            {
                sh.DangerousAddRef(ref added);
            }
            catch (ObjectDisposedException)
            {
                throw new IcvInternalErrorException("Region has already been disposed.",
                    Types.peak_icv_status
                        .PEAK_ICV_STATUS_INVALID_HANDLE);
            }
 
            if (!added)
            {
                throw new IcvInternalErrorException("Failed to pin SafeHandle",
                    Types.peak_icv_status
                        .PEAK_ICV_STATUS_INTERNAL_ERROR);
            }
 
            handles[i] = sh.DangerousGetHandle();
            safeHandles.Add(sh);
        }
 
        var released = 0;
 
        release = () =>
        {
            if (Interlocked.Exchange(ref released, 1) != 0)
            {
                return;
            }
 
            foreach (SafeHandle? safeHandle in safeHandles)
            {
                safeHandle.DangerousRelease();
            }
        };
 
        return handles;
    }
 
    public static IntPtr[] ExtractHandles<T>(IList<T> objects, out Action release) where T : IHasSafeHandle
    {
        return ExtractHandles(
            objects,
            obj => obj.Handle,
            out release);
    }
}
 
internal interface IHasSafeHandle
{
    SafeHandle Handle { get; }
}