Description

This class reports progress when you start a task with Progress.RunTask(...).

[MenuItem("Progress/Run Task 1 (MD5 all assets)", priority = 25)]
static void RunTask1()
{
    Progress.RunTask("Compute MD5", null, (id, data) => EnumerateMD5());
}

static string CalculateMD5(string filename)
{
    using (var md5 = MD5.Create())
    {
        using (var stream = File.OpenRead(filename))
        {
            var hash = md5.ComputeHash(stream);
            return BitConverter.ToString(hash).Replace("-", "").ToLowerInvariant();
        }
    }
}

private static IEnumerator EnumerateMD5()
{
    var assets = AssetDatabase.GetAllAssetPaths();
    var index = 0;
    foreach (var assetPath in assets)
    {
        if (Directory.Exists(assetPath))
            continue;
        // Do some calculations with the asset.
        var md5 = CalculateMD5(assetPath);
        yield return new Progress.TaskReport(index++ / (float)assets.Length, md5);
    }
}

Additional resources: Progress.Progress.