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  About short URL and its implementation

IntroductionURL shortening is a kind of technique to convert a long URL to a short URL. There are many companies now providing this kind of service, we now take Google's URL shortener service http://goo.gl/ as an example.First we navigate to http://goo.gl/, then we enter a random URL into the text field, here we use http://www.url-to-be-shortened.com as the input, it will return us an shortened URL : http://goo.gl/ZSVMM. URL ParsingWhen we type http://goo.gl/ZSVMM in browser address bar, the DNS...

       2012-07-02 07:15:09

  Redis Cluster and Common Partition Techniques in Distributed Cache

In this post, I will discuss a few common partition techniques in distributed cache. Especially, I will elaborate on my understanding on the use of Redis Cluster. Please understand that at the time of writing, the latest version of Redis is 4.0.10. Many articles on the same topic have a different idea from this post. This is mainly because, those articles are probably outdated. In particular, they may refer to the Redis Cluster implementation in Redis 3. Redis Cluster has been improved...

   REDIS,DISTRIBUTED CACHE,CLOUD COMPUTING     2019-01-17 08:10:37

  Arrays.equals() vs MessageDigest.isEqual()

Both Arrays.equals() and MessageDigest.isEqual() are used to compare the equality of two arrays. They can be interchangeably in many cases. However, they do have some differences which lead to different use cases in real applications. One difference is that the arrays passed to MessageDigest.isEqual() cannot be null while it's ok for Arrays.equals(). The one major difference between these two methods is that Arrays.equals() is not time-constant while MessageDigest.isEqual() is time-constant. Thi...

   Arrays.equal(),MessageDigest.isEqual(),Java,Security     2015-05-14 22:03:29

  Add compiler argument to build Maven project

Maven is a software project to manage a project's build, reporting and documentation from a central piece of information. It's now widely used t build and deploy projects. It can help automatically maintain the dependencies of projects. There is a central project configuration file named pom.xml. Here you can configure the project you want to build.  In this post, we will show you how to add compiler argument when using javac to compile Java source code. Sometimes we need to pass compi...

   Maven,compiler argument, compiler option, Java 8     2015-04-10 21:59:00

  Can two new objects point to the same memory address in GoLang?

Do you have any idea what the output will be for below GoLang snippet? package main import ( "fmt" ) type obj struct{} func main() { a := &obj{} fmt.Printf("%p\n", a) c := &obj{} fmt.Printf("%p\n", c) fmt.Println(a == c) } Many people would think that a and c are two different object instances which have different memory addresses. Hence a == c will be false. But if you try to run the above program, you would see below output 0x5781c8 0x5781c8 true To get to know the reason wh...

   GO,GOLANG,VARIABLE ESCAPE,ZEROBASE     2019-04-06 01:19:52

  Convert time to Unix time

Unix time is defined as the number of seconds that have elapsed since midnight Coordinated Universal Time (UTC), 1 January 1970,not counting leap seconds. It is used widely in Unix-like and many other operating systems and file formats. It is neither a linear representation of time nor a true representation of UTC. Unix time may be checked on some Unix systems by typing date +%s on the command line. Sometimes it's a bit difficult to compare times stored in different applications or systems with ...

   UNIX time, Oracle DATE, conversion, timestamp     2013-01-19 09:04:17

  Will nil == nil be true in GoLang

There is some interview question may ask whether nil == nil be true in GoLang. Wil it be true. false or compilation error? To know the answer, some knowledge about nil in GoLang needs to be explained first. nil definition According to Go's official documentation, the definition of nil is // nil is a predeclared identifier representing the zero value for a // pointer, channel, func, interface, map, or slice type. var nil Type // Type must be a pointer, channel, func, interface, map, or slice type...

   GOLANG,NIL,NIL EXPLANATION     2021-08-08 02:54:15

  Understanding How is Data Stored in RDBMS

We all know that DBMS (database management system) is used to store (a massive amount of) data. However, have you ever wondered how is data stored in DBMS? In this post, we will focus on data storage in RDBMS, the most traditional relational database systems. Physical Storage Data can be stored in many different kinds of medium or devices, from the fastest but costy registers to the slow but cheap hard drives, or even magnetic tapes. Nowadays, IaaS providers such as AWS...

   RDBMS,DATABASE     2019-02-04 09:25:36

  Apple.com is down

UPDATE : The service is back now! Apple.com is now inaccessible. It shows below "Access denied" message on its official site. It is still unknown why the service is down. And there is no ETA on when the service will be back to normal. From the error message, some people think this happens because Apple uses Akamai's security product and the security policy in place is violated. It's basically a WAF. The big issue is it takes 45 minutes for changes to propagate through Akamai's network. So, you ...

   IPHONE 6S,IPHONE 6S PLUS,APPLE     2015-09-12 00:50:17

  Top 10 WhatsApp Tips & Tricks To Try in 2017

v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false false EN-US X-NONE X-NONE

       2017-02-01 03:14:42

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