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  Smuggling data in pointers

While reading up on The ABA Problem I came across a fantastic hack.  The ABA problem, in a nutshell, results from the inability to atomically access both a pointer and a "marked" bit at the same time (read the wikipedia page).  One fun, but very hackish solution is to "smuggle" data in a pointer.  Example:#include "stdio.h"void * smuggle(void * ptr, int value){  return (void *)( (long long)ptr | (value & 3) );}int recoverData(void * ptr){  return (long long)ptr &...

   C,Pointer,Bit,Data,Atomic,Smuggle     2011-11-14 08:15:59

  Useful Bash Scripts

Many people hack together shell scripts quickly to do simple tasks, but these soon take on a life of their own. Unfortunately shell scripts are full of subtle effects which result in scripts failing in unusual ways. It's possible to write scripts which minimise these problems. In this article, I explain several techniques for writing robust bash scripts. Use set -u ...

   Linux,Shell,Bash,Command,Robust     2012-01-15 10:28:00

  Writing robust shellling scripts

Many people hack together shell scripts quickly to do simple tasks, but these soon take on a life of their own. Unfortunately shell scripts are full of subtle effects which result in scripts failing in unusual ways. It's possible to write scripts which minimise these problems. In this article, I explain several techniques for writing robust bash scripts. Use set -u ...

   Robust,Shell script,Set,Commands     2012-03-19 13:25:26

  errGroup in GoLang explained

Today, let's talk about the usage and applicable scenarios of errGroup, which is often used. Why is it useful? Generally, when we use goroutine, we cannot return a value. If you want to pass out the result of the goroutine execution, you usually have to use the channel. The errGroup package is suitable if you want to know when the goroutine you opened encounters an error during execution and stop working, and I need to know the error value. errGroup usage The package needs to be downloaded and i...

   GOLANG,ERRGROUP,WAITHROUP,CONCURRENCY     2023-05-27 23:58:20

  Python internals: adding a new statement to Python

This article is an attempt to better understand how the front-end of Python works. Just reading documentation and source code may be a bit boring, so I’m taking a hands-on approach here: I’m going to add an until statement to Python. All the coding for this article was done against the cutting-edge Py3k branch in the Python Mercurial repository mirror. The until statement Some languages, like Ruby, have an until statement, which is the complement to while (until num == 0 is equi...

   Python,New statement,Research,Addition     2012-03-12 07:32:24

  If PHP Were British

When Rasmus Lerdorf first put PHP together, he - quite sensibly, despite his heritage - chose not to write it in Greenlandic or Danish. Good job too - that would have been rather unpleasant to work with. He opted instead, being in Canada at the time, for the local tongue. No, not French - that bastard dialect of the Queen's English commonly referred to as "US English"1. PHP developers in Britain have been grumpy about this ever since. What was he thinking? And more importantly, how do we ...

   PHP,British,Class,Statement,Engilish like     2011-12-01 02:36:55

  Understanding the "this" keyword in JavaScript

Many people get tripped up by the this keyword in JavaScript. I think the confusion comes from people reasonably expecting this to work like “this” does in Java or the way people use “self” in Python. Although this is sometimes used to similar effect, it’s nothing like “this” in Java or other languages. And while it’s a little harder to understand, its behavior isn’t magic. In fact, this follows a relatively small set of simple rules. This...

   JavaScript,this,understanding     2012-03-29 13:48:59

  HeartBleed: Should C be blamed for the HeartBleed bug?

There is a discussion about the security of applications written in C on Hacker News recently after the report of HeartBleed bug in OpenSSL. In this discussion, some people are saying that the applications written in C are unsafe. It seems all or most of the faults should be laid on C. I think this is biased. The language itself should not be blamed.Safety is a relative term for programming languages. No language is absolutely safe. We claim some languages like Java and C# are safer than C/C++ b...

   C,HeartBleed,Analysis,Code review     2014-04-14 03:52:55

  What is the use of empty struct in GoLang

In Go, an empty struct struct{} is a struct with no fields that may appear to be of little use, but in reality, it can be useful in certain situations and become a simple and efficient solution in code. As a semaphore or lock Because the empty struct has no fields, it can be conveniently used to implement some concurrency control functions, such as mutex locks, read-write locks. We can use chan struct{} to implement an unbuffered channel for controlling concurrent access. package main import ( ...

   GOLANG,EMPTY STRUCT     2024-04-05 23:54:03

  Launch Java process programmatically in Java

In some cases while working on some automation testcase, developers would like to launch Java process programmatically so that the tests can be ran without manual intervention. Java provides such methods to achieve this. ProcessBuilder can be used to build a Java process which can be launched when everything is ready. Basically it can take a list of parameters which are similar to the command line options/arguments.  For example, if you want to launch a Java process, you can do followi...

   JAVA,PROCESSBUILDER,COMMAND LINE     2016-04-27 04:03:30

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