LightweightPackageInstaller.cs

/// <summary>
/// Given a 180mb NuGet package, NuGet.Core's PackageManager uses 1.17GB of memory and 55 seconds to extract it. 
/// This is because it continually takes package files and copies them to byte arrays in memory to work with. 
/// This class simply uses the packaging API's directly to extract, and only uses 6mb and takes 10 seconds on the 
/// same 180mb file. 
/// </summary>
public class LightweightPackageInstaller
{
    private static readonly string[] ExcludePaths = new[] { "_rels", "package\\services\\metadata" };

    public void Install(string packageFile, string directory)
    {
        using (var package = Package.Open(packageFile, FileMode.Open, FileAccess.Read, FileShare.Read))
        {
            var files = (from part in package.GetParts()
                         where IsPackageFile(part)
                         select part).ToList();

            foreach (var part in files)
            {
                Console.WriteLine(" " + part.Uri);

                var path = UriUtility.GetPath(part.Uri);
                path = Path.Combine(directory, path);

                var parent = Path.GetDirectoryName(path);
                if (parent != null && !Directory.Exists(parent))
                {
                    Directory.CreateDirectory(parent);
                }

                using (var fileStream = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.Read))
                {
                    using (var stream = part.GetStream())
                    {
                        stream.CopyTo(fileStream);
                        fileStream.Flush();
                        fileStream.Dispose();
                    }
                }
            }
        }
    }

    internal static bool IsPackageFile(PackagePart part)
    {
        var path = UriUtility.GetPath(part.Uri);
        return !ExcludePaths.Any(p => path.StartsWith(p, StringComparison.OrdinalIgnoreCase)) &&
               !PackageUtility.IsManifest(path);
    }
}