SwappableDmbProvider.cs

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using System;
using System.Threading;
using System.Threading.Tasks;
 
using Tgstation.Server.Host.IO;
using Tgstation.Server.Host.Models;
 
namespace Tgstation.Server.Host.Components.Deployment
{
    sealed class SwappableDmbProvider : IDmbProvider
    {
        public const string LiveGameDirectory = "Live";
 
        public string DmbName => baseProvider.DmbName;
 
        public string Directory => ioManager.ResolvePath(LiveGameDirectory);
 
        public CompileJob CompileJob => baseProvider.CompileJob;
 
        public bool Swapped => swapped != 0;
 
        readonly IDmbProvider baseProvider;
 
        readonly IIOManager ioManager;
 
        readonly ISymlinkFactory symlinkFactory;
 
        volatile int swapped;
 
        public SwappableDmbProvider(IDmbProvider baseProvider, IIOManager ioManager, ISymlinkFactory symlinkFactory)
        {
            this.baseProvider = baseProvider ?? throw new ArgumentNullException(nameof(baseProvider));
            this.ioManager = ioManager ?? throw new ArgumentNullException(nameof(ioManager));
            this.symlinkFactory = symlinkFactory ?? throw new ArgumentNullException(nameof(symlinkFactory));
        }
 
        public void Dispose() => baseProvider.Dispose();
 
        public void KeepAlive() => baseProvider.KeepAlive();
 
        public async Task MakeActive(CancellationToken cancellationToken)
        {
            if (Interlocked.Exchange(ref swapped, 1) != 0)
                throw new InvalidOperationException("Already swapped!");
 
            if (symlinkFactory.SymlinkedDirectoriesAreDeletedAsFiles)
                await ioManager.DeleteFile(LiveGameDirectory, cancellationToken);
            else
                await ioManager.DeleteDirectory(LiveGameDirectory, cancellationToken);
 
            await symlinkFactory.CreateSymbolicLink(
                ioManager.ResolvePath(baseProvider.Directory),
                ioManager.ResolvePath(LiveGameDirectory),
                cancellationToken);
        }
    }
}