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  PHP advisory file lock : flock

When we process a file in PHP, we may often need to acquire a lock so that other scripts cannot edit the same file at the same time. There is a flock() function in PHP which can help us lock the file we want to process. But there is one issue we should take care. Recently, ffb encountered one issue while he was trying to lock a file handle. The codes are below: $filename = "/tmp/lock.txt";      $fp = fopen($filename, "r+");   if (!$fp...

   flock(),advisory locking,PHP     2013-04-23 11:42:48

  Use of log in programming

Usually, The purposes of log are for troubleshooting and displaying program running status. Good log will help us locate the error easier. Many programmers think log in programs is very simple, but it's not an easy task to write log codes to efficiently locate the error. Here we discuss about program log in three aspects: Where to log What to log Log styles to be avoided Where to log 1. When calling external functions When your program is calling some external functions which are not written b...

   Log, Programming,Debug     2012-11-28 11:42:23

  Python PLC Honeypot Project

Program Design Propose : This project aims to develop a sophisticated honeypot system that emulates an OT (Operational Technology) SCADA network environment, bridging Level 1 OT field controller devices (PLCs) with Level 2 control programs, including Human-Machine Interfaces (HMIs). This honeypot will simulate various PLC models from major vendors, such as Schneider and Siemens, while supporting the primary communication protocols Modbus-TCP and Siemens-S7Comm. The system will integrate essenti...

       2024-11-25 03:56:49

  Python and PLC Communication

This article provides detailed steps on how to use Python to communicate with Schneider M221 and Siemens S7-1200 PLCs via Ethernet. Additionally, we offer a packaged Python PLC client library, enabling you to easily build your own SCADA control programs, such as Human-Machine Interfaces (HMI). The system overview is shown below: To check the project detail please refer to Python Physical PLC Communication Clients # Created: 2024/06/29 # Version: v0.1.3 # Copyright: Copyright (c) 2024 ...

   PYTHON,PLC,COMMUNICATION     2024-06-30 02:21:17

  Introduction to the Application of eBPF in Golang

Most of the time, when we develop software or even use software, we play within the safe boundaries of the operating system. We might not know how the network interface welcomes that IP packet, nor how the filesystem handles the inodes when we save a file. This boundary is called user space, which is where we write applications, libraries, and tools. But there's another world, kernel space, where the operating system's kernel resides and is responsible for managing system resources such as memor...

   EBPF,GOLANG,GUIDE,APPLICATION     2024-10-02 08:46:37

  When and Where to Use Pointers in Go

When declaring variables in Go, we usually have two syntax options: In some scenarios, pointers; in others, reference; sometimes, either. It’s great to have choices, but it is also confusing sometimes as to which one in which scenario. To be more reasonable in choice-making, I started from pointers, walked through their natures, and summarized some rules in using them in Go. from unsplash, Jordan Ladikos Pointers Go has pointers. A pointer holds the memory address of a ...

   POINTER,GOLANG     2022-05-01 02:24:43

  How to make select in WinSock exceed the 64-socket limit

When doing cross-platform network programming, the only API available on Windows that corresponds to the epoll/kevent style reactor event model is select. However, it has a limitation: the number of sockets passed into select cannot exceed FD_SETSIZE, which is set to 64. Therefore, select in Java’s NIO on Windows also has the same limit. Many services ported to Windows that use the reactor model face this constraint, which often gives the impression that server programs on Windows hav...

   EXCEED,SELECT,JAVA,WINDOWS     2024-10-31 23:47:50

  Mock Solutions for GoLang Unit Test

In Go development, Unit Test is inevitable. And it is essential to use Mock when writing Unit Tests. Mock can help test isolate the business logic it depends on, enabling it to compile, link, and run independently. Mock needs Stub. Stub function replaces the real business logic function, returns the required result, and assists the test. I involved the related test code for Controllers while writing Kubernetes Operator recently, and there would be mocks for GRPC and HT...

   UNIT TEST,TESTIFY,GOSTUB,GOMOCK     2020-10-31 21:59:15

  A Sip of Go Log

Logging is indispensable in any code that we need its support both in debugging and in statistics. However, a package that filled withfmt.Println/fmt.Printf printing various messages can never be considered a read-to-be-adopted package, which can be optimized by a simple change, using Golang’s native log package to print information to standard output or to a file. Then, how to apply the log package? Are there any limitations? If so, can we seek open-source packages? Let&rsq...

   GOLANG,LOGGING     2022-06-16 05:43:24

  When and How to Use the Go Channel

Go’s concise structure and powerful native library enable us to hit the ground running easily. It is more efficient than Java or Python when implementing the same functions, especially its concurrent programming, which is very handy and widely admired due to its goroutine and channel. goroutine and channel has much to dig into, and let’s start with channel, which I used to consider narrowly as a message queue to transfer data between gorouti...

   GOLANG,CONTEXT,CHANNEL     2022-09-17 23:06:36

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