Articles
android

BIO select poll epoll

BIO int main () { int sk = socket(AF_INET, SOCK_STREAM, 0 ); connect(sk, ...) recv(sk, ...) } Copy code In the development of high-concurrency servers, the performance of this network IO is extremely poor. because 1. The process is likely to be blocked when recv, resulting in a process switch ( data has not yet arrived ) 2. When the connection data is ready, the process will be awakened again, another process switch ( waking up when the data is copied to the socket receiving buffer ) 3. A proces

... Isaac
schedule 16 min read
android

Elasticsearch: enrich processor (new feature in 7.5 release)

We use an enrich processor to simplify data ingestion. Simply put: you can use the enrich processor to add data from the existing index to the incoming document during ingest. For example, you can use it in the following scenarios: Identify web services or providers based on known IP addresses Add product information to retail orders based on product ID Supplement contact information based on email address Add zip code based on user coordinates In my previous article " Logstash: Use jdbc_streami

... Henry
schedule 12 min read
android

Webpack

Webpack Webpack Javascript Webpack Loader Plugin Webpack Webpack Webpack (webpack : 4.41.4) : webpack.config.js const path = require('path'); module.exports = { mode: 'development', devtool: 'none', entry: './src/index.js', output: { path: path.resolve(__dirname, 'dist'), filename: '[name].js' } } : ./src/index.js let title = require('./title'); console.log(title); : ./src/title.js module.exports = ' '; : main.js (function (modules) { // var installedModules = {}; function __webpack_require__(m

... Kai
schedule 6 min read
android

JetPack-Compose ink painting effect

The likes of big guys are my motivation for writing The first four chapters Jetpack-Compose basic layout JetPack-Compose-custom drawing JetPack-Compose-Flutter dynamic UI? JetPack-Compose UI end article 1. Ink painting effect       I watched the Nuggets two days ago and found that the ink and wash color changes written by a front-end boss are very good. Today, let's use Compose to achieve the effect. The effect is as follows, the effect is the effect made by the fr

... Grayson
schedule 13 min read
android

A SAP consultant in the United States these years

Today's article comes from my fellow villager Song Hao, who worked in the United States as an SAP consultant for many years. Now he is about to join the S4CRM development team of SAP Chengdu Research Institute. We are all Dayi people. Dayi County is part of Chengdu City in Sichuan Province and is located in the western part of the Chengdu Plain, bordering the Qionglai Mountains. It borders Chongzhou City to the east, Xinjin County to the southeast, Qionglai City to the southwest, Lushan County a

... Wesley
schedule 22 min read
coder_life

STM32 entry development: LWIP network protocol stack transplantation (network card adopts DM9000)

1. Environmental introduction MCU: STM32F103ZET6 Code development tool: Keil5 TCP/IP protocol stack: LWIP Network card: DM9000 This article mainly explains how to add and transplant the LWIP protocol in the STM32F103 project, and finally complete the communication test of the TCP server and TCP client. The network card uses DM9000. In the engineering code, the FSMC interface of STM32 is used to drive the DM900 network card. DM9000 is a parallel port network card with many pins but high speed. Ot

... Logan
schedule 34 min read
coder_life

[Reproduced] A quick list of common new features of C++11

Reprinted with the permission of the original blog, the original link: A quick overview of C++ 11 common new features In recent work, I encountered some problems, it would be more convenient to use C++11 to realize it, and the online production environment does not support C++11, so I decided to promote C++11 in the group after the New Year s work started. Come, organize the following documents so that they can be consulted by yourself and colleagues can get started quickly. (Future/Promise and

... Alan
schedule 36 min read
coder_life

LeetCode Problem Solution No. 199. Binary Tree Right Side View

Question link English website: 199. Binary Tree Right Side View Chinese website: 199. Right view of binary tree Problem Description Given the rootof a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom . Example 1: Input: root = [1,2,3,null,5,null,4] Output: [1,3,4] Copy code Example 2: Input: root = [1,null,3] Output: [1,3] Copy code Example 3: Input: root = [] Output: [] Copy code Constraints: The number of node

... Matthew
schedule 5 min read
coder_life

SSM+ActiveMQ message retransmission mechanism and message confirmation mechanism Ack

Background: I changed a new company and took on an old project of ssm architecture. The mq used was ActiveMQ. Looking at the code, I found that ActiveMQ did not see retry and message confirmation operations when processing messages. Previously, RabbitMQ and RocketMQ were used. I thought that ActiveMQ did not have a message retransmission and ACK mechanism. The interface of the project is added and recorded here. Learn the first principles of new things, see the official documentation. Official d

... Alejandro
schedule 7 min read
coder_life

JD T7 architect painstakingly compiled the Java thread pool complete solution manual, I hope it can help you

Hello, today I will share the Java thread pool with all children's shoes, please take out a small book and write it down! 1. Write in front 1.1 What is a thread pool Thread Pool (Thread Pool) is a tool for thread pool management, which often appears in multi-threaded servers, such as MySQL. Too many threads will bring additional overhead, including the overhead of creating and destroying threads, the overhead of scheduling threads by the operating system, and so on. It also reduces the overall p

... Isaac
schedule 20 min read
dev_tools

AI foundation: sequence model based on natural language processing

This article mainly refers to the notes part of Wu Enda's deep learning course [1]. 0. Introduction The sequence model is the basis of natural language processing. This episode explains the cyclic sequence model. I am writing an AI basic series, which has been released so far: \ AI Basics: Introduction to Simple Mathematics AI basics: Python development environment settings and tips AI Basics: Getting Started with Python AI Basics: Getting Started with Numpy AI Basics: Simple Introduction to Pa

... Patrick
schedule 91 min read
dev_tools

100 basic Python interview questions part one (1-20) Python topic month

This article is participating in the "Python theme Month" view details about the active links 100 basic Python interview questions part one (1-20) Python topic month Q-1: What is Python, what are the benefits of using it, and what is your understanding of PEP 8? Q-2: What is the output of the following Python code snippet? Prove your answer. Q-3: If the program does not require actions but needs it grammatically, what statements can be used in Python? Q-4: What is the process of using "~" to get

... Richard
schedule 12 min read
dev_tools

"CSS Revealed" Intensive Reading Notes (2) Shape

Preface This article is the second part of "CSS Demystification"-shape notes. It introduces the implementation principles of adaptive ellipses, parallelograms, prismatic pictures, corner cutting effects, trapezoidal tabs, and simple pie charts. It is attached to each section. A personal code link. The article gives a variety of solutions for the realization of various shapes, and I have to feel the convenience that the emergence of new attributes (such as clip-path, conic-gradient) has brought u

... Daisy
schedule 23 min read
dev_tools

Java software design principles

In software development, in order to improve the maintainability and reusability of the software system, and increase the scalability and flexibility of the software, programmers should try their best to develop programs according to six principles, thereby improving software development efficiency and saving software development Costs and maintenance costs. 1. The principle of opening and closing Open for extension, closed for modification. When the program needs to be expanded, the original co

... Jayce
schedule 16 min read
dev_tools

Use WeChat QR code engine on web pages

background I have a tool project based on the Electron cross-platform framework, and I need to make a plug-in that recognizes and parses the QR code on the PC side. I just started using the webAssembly version of zxing. In the process of using it, I found that in some edge cases (the QR code is very small or very large, the picture is tilted, etc.), the recognition ability is very poor, and it takes a long time. One picture with multiple codes is not supported. From the perspective of daily use,

... Brady
schedule 16 min read
programming

SpringBoot global exception capture and processing (including custom exception capture processing)

When working on a project, you need to capture and handle custom exceptions. Now record the code for later reference. 1. Global exception capture processing @ControllerAdvice ( annotations = {RestController.class} ) public class ExceptionHandlerAdvice { private static final Logger LOGGER = LoggerFactory.getLogger( this .getCLass()); @ExceptionHandler(EntityTransException.class) public ResponseResult entityTransExceptionHandle (HttpServletRequest request,EntityTransException e) { LOGGER.error( "*

... Timothy
schedule 6 min read
programming

[Recurrence] Chrome's second 0Day within three days (combined with other vulnerabilities to bypass the sandbox)

Vulnerability description Google Chrome is a free web browser developed by Google. After testing, this 0day vulnerability affects the latest official version of Chrome (90.0.4430.72) and the official version of Microsoft Edge (89.0.774.77) based on the Chromium kernel. An attacker can use this vulnerability to gain remote code execution by constructing a specially crafted web page and inducing the victim to visit it. Sphere of influence Google Chrome <= 90.0.4430.72 Microsoft Edge based on C

... Silas
schedule 8 min read
programming

JDK HashMap ( )

JDK HashMap ( ) HashMap HashMap 5.HashMap 5.1 put(K key, V value) put hash key a b value size threshold public V put(K key, V value) { // hash(key) key hash return putVal(hash(key), key, value, false, true); } HashMap put putVal put putVal putVal key hash , hash static final int hash(Object key) { int h; // key null hash 0, // key hashCode() key h, // h 16 hash , // hash // return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16); } HashMap key HashTable Key hashCode key hash key k

... Mackenzie
schedule 11 min read
programming

React Native all-round abnormal monitoring

Recently, I am working on the need for online error monitoring of RN applications, and I will record the common solutions here. Starting address 0. Start React Native can be divided into three parts in architecture as a whole: Native, JavaScript and Bridge. Among them, Native manages UI updates and interactions, JavaScript calls Native capabilities to implement business functions, and Bridge is responsible for passing messages between the two. The top layer provides React-like support and runs

... Austin
schedule 16 min read
programming

Use Python to crawl Zhihu's god reply about programmers

Data Science Club Chinese data scientist community Author : Brother Qiang, once worked for Morgan Stanley and eBay. \ Crawling Zhihu's reply is very simple. In this article, we will reveal the principle behind it. Know what are the characteristics of God's reply? Let's take a look \ Do you see any pattern? Is it short and incisive? Do you agree with a lot? Therefore, crawling Zhihu God replies to us as long as we crawl the answers that are more agreeable and have a few words. It can be achieved

... Bradley
schedule 19 min read
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