Zstandard, or zstd as short version, is a fast lossless compression algorithm, targeting real-time compression, providing high compression ratios. It offers a very wide range of compression / speed trade-off and is deployed within Facebook
Tools for using Zstd : 7-Zip with support Zstd - Zstd plugin for 7-Zip
.Net Wrapper for Zstd : ZstdNet - Zstandard.Net
آموزش ASP.NET Web API
فایل ARCHITECTURE.md
If you maintain an open-source project in the range of 10k-200k lines of code, I strongly encourage you to add an ARCHITECTURE document next to README and CONTRIBUTING. Before going into the details of why and how, I want to emphasize that this is not another “docs are good, write more docs” advice. I am pretty sloppy about documentation, and, eg, I often use just “simplify” as a commit message. Nonetheless, I feel strongly about the issue, even to the point of pestering you:-)
Deno v1.0 منتشر شد
لیست کامل ویدیوهای NET Conf 2020.
نکتهای در مورد مدیریت طول عمر اشیاء در حالت HybridHttpOrThreadLocalScoped در برنامههای دسکتاپ
cfg.For<IUnitOfWork>().Use(() => new MyWpfFrameworkContext());
ThreadLocal - A single instance will be created for each requesting thread. Caches the instances with ThreadLocalStorage. Hybrid - Uses HttpContext storage if it exists, otherwise uses ThreadLocal storage
خوب، مشکل کجا است؟ در یک برنامه دسکتاپ اگر ترد جدیدی را ایجاد نکنیم، کل برنامه در طول مدتی که در حال اجرا است در یک ترد اصلی اجرا میشود. در نتیجه استفاده از حالت HybridHttpOrThreadLocalScoped در برنامههای دسکتاپ، بسیار شبیه به حالت Singleton است. به این ترتیب با بسته شدن یک پنجره یا هدایت به صفحهای دیگر، Context برنامه و EF رها نخواهند شد (چون تضمین شده است که یک وهله از این شیء در طول عمر ترد جاری وجود داشته باشد). نتیجه آن روبرو شدن با خطاهایی است که ردیابی و دیباگ بسیار مشکلی دارند. برای مثال چندی قبل در سایت مطرح شده بود که چرا در یک برنامه WinForms خطای زیر را دریافت میکنم:
An object with the same key already exists in the ObjectStateManager
در برنامههای وب چطور؟
در برنامههای وب، به ازای هر درخواست رسیده، یک ترد جدید ایجاد میشود. به همین جهت استفاده از حالت HybridHttpOrThreadLocalScoped برای داشتن تنها یک Context در طول یک درخواست ضروری است.
نتیجه گیری
در برنامههای دسکتاپ خود اگر از ترد استفاده نمیکنید، از حالت HybridHttpOrThreadLocalScoped برای مدیریت طول عمر UOW استفاده نکنید.
public class HandleConcurrencyExceptionAttribute : FilterAttribute, IExceptionFilter { private PropertyMatchingMode _propertyMatchingMode; /// <summary> /// This defines when the concurrencyexception happens, /// </summary> public enum PropertyMatchingMode { /// <summary> /// Uses only the field names in the model to check against the entity. This option is best when you are using /// View Models with limited fields as opposed to an entity that has many fields. The ViewModel (or model) field names will /// be used to check current posted values vs. db values on the entity itself. /// </summary> UseViewModelNamesToCheckEntity = 0, /// <summary> /// Use any non-matching value fields on the entity (except timestamp fields) to add errors to the ModelState. /// </summary> UseEntityFieldsOnly = 1, /// <summary> /// Tells the filter to not attempt to add field differences to the model state. /// This means the end user will not see the specifics of which fields caused issues /// </summary> DontDisplayFieldClashes = 2 } public HandleConcurrencyExceptionAttribute() { _propertyMatchingMode = PropertyMatchingMode.UseViewModelNamesToCheckEntity; } public HandleConcurrencyExceptionAttribute(PropertyMatchingMode propertyMatchingMode) { _propertyMatchingMode = propertyMatchingMode; } /// <summary> /// The main method, called by the mvc runtime when an exception has occured. /// This must be added as a global filter, or as an attribute on a class or action method. /// </summary> /// <param name="filterContext"></param> public void OnException(ExceptionContext filterContext) { if (!filterContext.ExceptionHandled && filterContext.Exception is DbUpdateConcurrencyException) { //Get original and current entity values DbUpdateConcurrencyException ex = (DbUpdateConcurrencyException)filterContext.Exception; var entry = ex.Entries.Single(); //problems with ef4.1/4.2 here because of context/model in different projects. //var databaseValues = entry.CurrentValues.Clone().ToObject(); //var clientValues = entry.Entity; //So - if using EF 4.1/4.2 you may use this workaround var clientValues = entry.CurrentValues.Clone().ToObject(); entry.Reload(); var databaseValues = entry.CurrentValues.ToObject(); List<string> propertyNames; filterContext.Controller.ViewData.ModelState.AddModelError(string.Empty, "The record you attempted to edit " + "was modified by another user after you got the original value. The " + "edit operation was canceled and the current values in the database " + "have been displayed. If you still want to edit this record, click " + "the Save button again to cause your changes to be the current saved values."); PropertyInfo[] entityFromDbProperties = databaseValues.GetType().GetProperties(BindingFlags.FlattenHierarchy | BindingFlags.Public | BindingFlags.Instance); if (_propertyMatchingMode == PropertyMatchingMode.UseViewModelNamesToCheckEntity) { //We dont have access to the model here on an exception. Get the field names from modelstate: propertyNames = filterContext.Controller.ViewData.ModelState.Keys.ToList(); } else if (_propertyMatchingMode == PropertyMatchingMode.UseEntityFieldsOnly) { propertyNames = databaseValues.GetType().GetProperties(BindingFlags.Public).Select(o => o.Name).ToList(); } else { filterContext.ExceptionHandled = true; UpdateTimestampField(filterContext, entityFromDbProperties, databaseValues); filterContext.Result = new ViewResult() { ViewData = filterContext.Controller.ViewData }; return; } UpdateTimestampField(filterContext, entityFromDbProperties, databaseValues); //Get all public properties of the entity that have names matching those in our modelstate. foreach (var propertyInfo in entityFromDbProperties) { //If this value is not in the ModelState values, don't compare it as we don't want //to attempt to emit model errors for fields that don't exist. //Compare db value to the current value from the entity we posted. if (propertyNames.Contains(propertyInfo.Name)) { if (propertyInfo.GetValue(databaseValues, null) != propertyInfo.GetValue(clientValues, null)) { var currentValue = propertyInfo.GetValue(databaseValues, null); if (currentValue == null || string.IsNullOrEmpty(currentValue.ToString())) { currentValue = "Empty"; } filterContext.Controller.ViewData.ModelState.AddModelError(propertyInfo.Name, "Current value: " + currentValue); } } //TODO: hmm.... how can we only check values applicable to the model/modelstate rather than the entity we saved? //The problem here is we may only have a few fields used in the viewmodel, but many in the entity //so we could have a problem here with that. //object o = propertyInfo.GetValue(myObject, null); } filterContext.ExceptionHandled = true; filterContext.Result = new ViewResult() { ViewData = filterContext.Controller.ViewData }; } }