Zabed Akbar's Blog

Using XOR for computing hash codes works great for most of the cases specially when order of computation does not matter. It also has the following benefits: XOR has the best bit shuffling properties of all bit-operations and provides better distributions of hash values. It is a quick single cycle operation in most computer  Order of computation does not matter. i.e. a^b = b^a However, if ordering of elements matter then it is often not a good choice. Example For simplicity consider you have a class with two string properties named Prop1 and Prop2  and your GetHashCode returns the xor of their hash code. It will work fine for most of the cases except cases where same values are assigned to different properties. It will generate same hash-code i.e. collision in that case as can be seen in the below example . However, using the modified approach as recommenced by Joshua Bloch's in Effective Java which uses prime multiplication and hash chaining provides more unif

I recently came across an interesting bug which emphasize how different line endings format can break your custom equality implementation if you do not carefully consider them. Context We have an application that periodically updates the local assets with latest updated resources. In a nutshell,  it makes an web api call to get the latest set of metadata and compare them against a locally stored metadata file. If they differs then we update the locally stored metadata file and download new/updated resources. Bug For a particular asset, associated metadata file was always getting updated although there were no visible changes detected using the revision history. Investigation My obvious suspect was the code responsible for doing the equality check between local metadata and the metadata received from the Web API. For verification, I setup a conditional break-point which will be hit when the equality returns false. After my debug hit the break-point, I looked into all the

A showcase of things I have learned today: Learn Regex the easy way Reactive Programming Kendo grid Angular 2- Server side page loading

Recently, I have dealt with an interesting performance issue with one of my SQL query and thought I will share the experience here. Context: We had a legacy stored procedure responsible for saving large amount of excel row data to our database tables. It was using   User Defined Table Types as one of the parameter to get a list of row data from excel. However, the stored procedure was taking very long time to save the large data set. Root Cause: After quite a bit of investigation using execution plan in SSMS, I was able to narrow down the performance issue to the following: Joining with User defined table type was taking >90 percent of the time A custom hash function which has been used multiple times as a join criteria was also quite expensive to compute. After doing additional research using stack overflow , I was able to figure out that the primary reason for the poor performance doing a  JOIN on Table Valued parameters is that : it does not keep statistics and a

It is quite common for many applications to send automated email notifications. Couple of months ago, I have worked on improving our old email template format to make it more user friendly . In this tutorial I will walk you though regarding how I took advantage of Microsoft Outlook to quickly generate custom email template and later using the html template for building an automated custom email application using C#. Steps: Creating Templates: Using the rich text editor support  in Outlook create a nicely formatted email. Use placeholder text for the values you like to change dynamically based on your task completion status. To keep this tutorial simple, I have created a  simple table with placeholder text inside the third bracket  [place holder text]. However, you can use anything supported by outlook editor. Figure: Email Template Getting HTML code: Send the created email to your own address. After that, open the sent email and right click to view source . It

This guide will show step-by-step instructions of setting up a remote machine for remote debugging using Visual Studio 2013 Prerequisite: Visual Studio 2013 or later Remote machine running Windows 7 within a VM player Note: Since Visual Studio 2012, Microsoft only supports remote debugging for Windows 7 or newer. To remote debug Windows XP, you'll need to use an older version of Visual Studio and its respective remote debugging tools.  Step-by-step guide: Download and copy the Remote Tools in your Win7 VM. You must get the update version of the Remote Tools for Visual Studio 2013 that matches the update version of your Visual Studio installation. Install the Remote tools in your VM. After installation, run the Remote Debugger  Navigate to Tools->Options Menu Ensure that Windows Authentication is selected. Press OK. Open Visual Studio in your local machine. Make sure you have setup the remote machine in the project you like to remote debug as shown in

What is WCF? Windows Communication Foundation (WCF) is a framework for building service-oriented applications. It is a unified, simplified and optimized evolution of a number of communication technologies into a single  model. [Ref: MSDN] Why it is important? Enables you to create service oriented applications.  Provide a unified way to communicate with different system. Developers can focus on designing  data and service contracts without having to make prior decisions on which transport, messaging or security protocols and policies to adopt. Allows one to configure service properties such as transport (http/pipes/tcp/Tibco EMS), security models (any of the W3C standards), compression, encoding, timeouts, etc, without changing ANY code.  Learning WCF History Service oriented Architecture [Video] How we end up with SOA? Good Place to Start WCF Basics WCF Hello World Code WCF MSDN Article Intermediate Developer's introduction to WCF Book Learning