SEARCH KEYWORD -- SYSTEM DESIGN


  Access control in Java -- Permission check order

Previously we showed you how to turn on SecurityManager in Java. After SecurityManager is turned on, a series of permission checks will be applied on the code you are calling in your application to protect some resources against malicious access such as files, sockets etc. To perform these permission checks, a set of Permissions will be created and checked using the AccessController. The AccessController has three purposes : To decide whether an access to a critical system resource is to be all...

   JAVA,SECURITY,ACCESSCONTROLLER     2016-03-07 04:17:40

  The new Surface RT may use Qualcomm Snapdragon processor

According to Sina Tech, Microsoft will launch its new Surface RT tablet equipped with Qualcomm processor . The source said, some of the new Surface RT will use Qualcomm Snapdragon processor, this processor will provide faster wireless data connection speed. The current Surface RT uses Nvidia's Tegra processor. Some versions of the Surface RT will continue to use Tegra processor. By adding Qualcomm processor as another option, Microsoft will further expand Surface RT function. Despite Microsoft h...

   Surface RT,Qualcomm,Processor     2013-06-19 08:11:03

  Linux Clock : CST,UTC and NTP setup

1. There is an option when you set up clock on installing Linux: system clock users UTC, so what does UTC mean? It's Universal Time Coordinated(UTC), there are two different times in GPS system: one is UTC , the other one is LT(Local Time). The difference between these two is just the timezone difference, UTC is the time in timezone 0. If the local time in Beijing is 8 o'clock in the morning, then UTC time is 0 o'clock, which is a 8 hour difference. 2. In Linux, when we use date to check the tim...

   Linux,Clock,UTC     2013-03-21 12:19:30

  Must read C++ book list

Every programmer should read some books to enhance their understanding about the language before the start to practice. But some of us often wonder what books we should read and in what order. Some books may not be suitable for beginners and some books may cover the similar topics. Here I summarize a C++ book list we should read.Stage 1"Essential C++" : It is short but powerful and it can enhance our understanding of C++'s features.This book is specifically designed to bring you up to speed in a...

   C++,Book list,Read,Effective C++     2012-05-23 13:03:30

  PHP to output string to client terminal

It is a common task to echo messages to the user using PHP. There are lots of ways where the message can be echoed to the client terminal(browser or console window) through PHP. These includes some well know debug methods like var_dump() and var_export() etc. In this post, we will show you some other methods shared by Laruence, one of the core members of PHP development team. 1. echo First comes with the most common one : echo. $str = "Hello PHP\n"; echo $str; 2. print Then comes another c...

   TRICKS,DEBUG,OUTPUT,PHP     2015-10-01 03:16:56

  Deep Understanding of ReentrantLock: Unlocking the Mysteries of Java Concurrent Programming

ReentrantLock introduction ReentrantLock is a class in the Java concurrent package, java.util.concurrent.locks, and is an implementation of the Lock interface. As its name suggests, it is a reentrant mutual exclusion lock. A mutual exclusion lock is a synchronization tool used to protect shared resources, ensuring that only one thread can access the resource at a given time. Reentrant means that a thread can acquire the same lock multiple times without causing a deadlock. This lock provides some...

   JAVA,REENTRANTLOCK,CONCURRENCY,MULTITHREADING     2023-05-22 08:01:13

  The significance of coding competition to actual work

Some friends asked this question: In secondary schools we participate in the NOI, in university we participate in ACM/ICPC, TopCoder.What's the significance of coding competition to actual work? I participated in the NOI from 1994 to 1996, ACM/ICPC from 1999 to 2000 and TopCoder in 2002 for six months. Later I paid little attention to coding competition, so I may not understand the changes in recent years and race mode . The capabilities we can get by participating the competition can be summari...

   ACM,Programming,Facebook,TopCoder     2013-02-28 20:38:23

  Using MemoryMappedBuffer to handle large file in Java

When handling large files, it will largely affect the process speed while using traditional FileInputStream, FileOutputStream or RandomAccessFile since they trigger lots of read and write operations. In Java NIO, a new way of handling large file is introduced which is to use MmeoryMappedBuffer to create memory mapped file. Memory-mapped I/O uses the filesystem to establish a virtual memory mapping from user space directly to the applicable filesystem pages. With a memory-mapped file, you can pre...

   JAVA,IO,NIO     2015-11-13 01:58:08

  Unix directory hierarchy history

As a beginner user of Unix or Linux, people would frequently get confused about the use of different directories of the system.  For example, there is a /bin directory under root(/), it is used to store binary files. However, there are /usr/bin and /usr/local/bin under /usr which are used for storing binary files as well. Some systems even have /opt/bin. What are the differences among them? Though there are articles explaining different directories in *nix such as Filesystem Hierarchy Stan...

   UNIX,LINUX,FILESSYTEM,DIRECTORY HIERARCHY,HISTORY     2016-10-21 23:47:17

  What is Hystrix and How does Hystrix work

Background In distributed systems, there is one effect where the unavailability of one service or some services will lead to the service unavailability of the whole system, this is called service avalanche effect. A common way to prevent service avalanche is do manual service fallback, in fact Hystrix also provides another option beside this. Definition of Service Avalanche Effect Service avalanche effect is a kind of effect where the service provider fails to provide service which causes t...

   AVALANCHE EFFECT,HYSTRIX,DISTRIBUTED SYSTEM     2019-02-04 06:00:38

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