GeneralFileConverter.cs

using System;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using System.Threading.Tasks.Dataflow;

namespace unicon {
    class GeneralFileConverter : IConverter {
        readonly ProcessStartInfo[] psis;

        public GeneralFileConverter(Preset[] presets, string path) {
            //scan
            DirectoryInfo di = new(path);
            var fileInfos = di.EnumerateFiles("*.*", SearchOption.AllDirectories).ToArray();
            psis = presets.SelectMany(preset => preset.GetProcess(fileInfos)).ToArray();
        }
        public void Convert() {
            if (psis.Length == 0) return;

            var counter = 0;
            Console.WriteLine($"\n\n{psis.Length} files detected\n");

            var flattenBlock = new TransformManyBlock<ProcessStartInfo[], ProcessStartInfo>(psi => psi);
            
            var processBlock = new TransformBlock<ProcessStartInfo, bool>(async psi => {
                using Process p = Process.Start(psi);
                await p.WaitForExitAsync();
                return p.ExitCode == 0;
            }, new ExecutionDataflowBlockOptions() { MaxDegreeOfParallelism = 3 });
            
            var progressBlock = new ActionBlock<bool>(success => {
                if (!success) throw new Exception("ExitCode NEQ 0");
                Console.Write($"\r{++counter}/{psis.Length}");
            });
            
            var dataflowLinkOptions = new DataflowLinkOptions() { PropagateCompletion = true };
            
            flattenBlock.LinkTo(processBlock, dataflowLinkOptions);
            processBlock.LinkTo(progressBlock, dataflowLinkOptions);

            flattenBlock.Post(psis);
            flattenBlock.Complete();
            progressBlock.Completion.Wait();
            Console.WriteLine();
        }
    }
}