Opencv4 C++ Compilation

1. Download https://github.com/opencv/opencv/releases https://github.com/opencv/opencv_contrib/releases Download the two zip packages and unzip them. 2. Cmake 1 2 cd opencv-4.2.0 mkdir build && cd build If you are simply using the C++ version of opencv for cpu, you can use the following cmake command 1 2 3 4 5 6 7 8 9 10 11 12 13 cmake -D CMAKE_BUILD_TYPE=RELEASE \ -D CMAKE_INSTALL_PREFIX=/home/test/opt/opencv \ -D WITH_CUDA=OFF \ -D WITH_IPP=OFF \ -D OPENCV_EXTRA_MODULES_PATH=/home/test/opencv/opencv_contrib-4.2.0/modules \ -D OPENCV_GENERATE_PKGCONFIG=ON \ -D BUILD_opencv_python3=OFF \ -D BUILD_opencv_python2=OFF \ -D BUILD_opencv_hdf=OFF \ -D BUILD_EXAMPLES=ON .

How to Implement Two Way Binding With Vuejs Prop

I recently encountered a problem, that is, how to implement two-way binding prop in Vue.js is better. Previously I was passing the prop to the child component, and then the child component directly changed the prop directly, this can reflect the result to the parent component, but it is not a good solution. For example, I often encounter this Warning. Avoid mutating a prop directly since the value will be overwritten…

Tcp Network Programming Best Practices

This article is based on years of TCP network programming experience of youzan middleware team. The purpose of this article is to avoid various unintended behaviors of applications due to various network anomalies, which can cause unintended effects and affect system stability and reliability. This document does not cover the basics of TCP, but mainly summarizes some of the problems that may be encountered in TCP network programming practice, as

Several Cases of Goroutine Leaks in Golang

Goroutine 1 2 3 for { go func() {}() } The threshold for using Goroutine is really low, and there are a lot of abuses. Goroutine Leak The causes of Goroutine leaks are usually: Read/write operations such as channel/mutex are being performed inside Goroutine, but due to logic problems, they are blocked all the time in some cases. The business logic within the Goroutine enters a dead loop and resources are never released.

Const in Golang

Constants are arguably present in every code file, and there are many benefits to using them. Avoid magic literals, i.e. numbers, strings, etc. that appear directly in the code. It is not possible to read the code and see what it means at a glance. It also avoids the inconsistencies that can occur when using literals. When their values need to be modified, constants only need to be modified in one place, while literals need to be modified in multiple places, making it easy to miss inconsistencies.

Jdbc Batch Insert Mybatis Postgresql

When inserting a lot of data at once, using bulk inserts can significantly improve performance. JDBC batch execute When using JDBC, you can use Statement#addBatch(String sql) or PreparedStatement#addBatch method to add SQL statements to the batch list, and then execute them in batch with the executeBatch method. When inserting a lot of data at once, using bulk inserts can significantly improve performance. reWriteBatchedInserts=true The PostgreSQL JDBC driver supports the reWriteBatchedInserts=true join parameter to modify multiple insert/update statements into a single statement, for example: insert into test(name) values ('n'); insert into test(name) values ('m'); is modified to insert into test(name) values ('n'), ('m'); .

Angular or Ionic Exception Handling ErrorHandler

Exception handling is very important in front-end, including client-side and server-side exceptions. Previously, exception handling was to add err handling for each asynchronous function, which not only increased the workload, but also easily missed some exceptions. Fortunately, Angular6 provides ErrorHandler to handle exceptions (Ionic4 for IonicErrorHandler), the default ErrorHandler handling exceptions is to output it on the console, which obviously can not meet the demand, so you need to implement

Exploring the React Native Startup Version Checking Mechanism

Colleague’s feedback React Native project startup reported an error indicating version mismatch, the error screenshot is as follows. After some troubleshooting, we finally found that the old version of js file was packed locally, and the project itself depends on a different version, so we can delete the old version of the local file. We can find out that RN has a version check at startup through this error, how is the specific mechanism, let’s follow the source code together.

Clipboard Operations Clipboard Api Tutorial

1, Introduction Browsers allow JavaScript scripts to read and write to the clipboard to automatically copy or paste content. In general, scripts should not alter the user’s clipboard in a way that does not meet the user’s expectations. However, there are times when this is convenient, such as the “one-click copy” feature, where the user clicks a button and the specified content automatically goes to the clipboard. Currently, there are three ways to implement clipboard operations.

Redis Expired Key Removal Policy

Redis stores key-value pairs, where the keys are strings and the values are of various types, such as string, list, hash, set, sorted set, and so on. When setting a key-value pair, we should also set the expiration time for it, which can be set by expire and pexpire commands, or by setnx command. So, after setting the expiration time, how exactly do you delete the expired key-value pairs? To find out, let’s take a look at Redis’ expired key deletion policy.

Implementing Unlimited Cached Channels in Golang

There are two types of channels in Go language, a channel without cache and a buffer with cache, both of which we are familiar with. Why am I suddenly talking about this infinite cache channel? The main reason is that I was recently reviewing a colleague’s code and I had a problem with a certain design idea that would have been solved by using an infinite cache channel. A dispatcher contains a channel, which holds the URLs to be processed A bunch of workers read tasks from the channel, download and parse the page, extract the links, and put the links into the dispatcher.