1. RabbitMQ 1.1 Core Components RabbitMQ is an open source message middleware that implements the Advanced Message Queuing Protocol (AMQP) and provides various important components to support the production, transmission and consumption of messages. Producer: The producer is the sender of messages and is responsible for publishing messages to the RabbitMQ server. Messages can contain […]
Tag: letter
QT captures keyboard input and displays the input shortcut key combinations, and solves the problem that some key combinations (such as Ctrl+Shift+letters) cannot be recognized in the Linux environment
Recently I am working on a QT project, which requires identifying keyboard input keys to generate shortcut keys. There is a class QKeySequenceEdit in QT. Using this, you can directly obtain keyboard input. However, if you want to filter out the keys you do not want to recognize, you must rewrite it. ThekeyPressEvent(QKeyEvent *e) function. […]
RabbitMQ delayed messages: dead letter exchange
Table of Contents 1. Dead letter switch 2. Delay message plug-in Declare delay switch Send delayed message Usage scenarios In the payment business of e-commerce, for some products with limited inventory, for a better user experience, the inventory of the product is usually deducted immediately when the user places an order. For example, when purchasing […]
Sharing jupyter between python and R is not successful at the moment–The letter makes me miserable, I will stay with you forever
conda creates an R environment: conda create -n lry_R4.2.2 conda activate lry_R4.2.2 conda install -c conda-forge r-base=4.2.2 After installation, enter R to run R. Exit and enter q(); In the R environment, you can install the corresponding R package. The corresponding R package can be installed in the R environment. Or use conda to install, […]
Device driver letter Bind file descriptor
K1.c #include <linux/init.h> #include <linux/module.h> #include <linux/io.h> #include <linux/fs.h> #include <linux/types.h> #include <linux/gpio.h> #include <linux/cdev.h> #include <linux/device.h> #include “head.h” char kbuf[128] = {}; //Define three pointers pointing to mapped virtual memory unsigned int *vir_rcc; unsigned int *vir_moder_led1; unsigned int *vir_odr_led1; unsigned int *vir_moder_led2; unsigned int *vir_odr_led2; unsigned int *vir_moder_led3; unsigned int *vir_odr_led3; struct cdev *cdev; […]
[RocketMQ Series 13] RocketMQ’s cluster core concept of consumption retry & dead letter queue & emergence and processing of idempotent messages
Hello, I am Fei Ge (wei158556), a coder. Thank you for reading this article. Welcome to connect three times with one click. 1. Python basics column, covering all basic knowledge in one place. If you buy it for 9.9 yuan, you will not suffer a loss or be cheated. Python from beginner to proficient 2. […]
RabbitMq uses TTL + dead letter queue to implement delayed message queue, pure annotation style
Table of Contents 1 Introduction 2. Overview of TTL 3. Introduction to the dead letter queue 4. Why do we need to delay the message queue? 5. Introduction to RabbitMQ annotations 6. Implement delayed message queue using pure annotations 7. Sample code Define a normal business switch and queue, but do not enable this consumer […]
814 – The Letter Carrier’s Rounds (UVA)
The question link is as follows: Online Judge My code is as follows: #include <cstdio> #include <set> #include <string> #include <algorithm> #include <vector> #include <iostream> #include <map> // #define debug struct MTA{ std::string city; std::set<std::string> name; }; struct rcpt{ std::string city; std::vector<std::string> name; }; char city[16], name[16], s[32]; int n, loc, cnt; std::string str, s1, […]
RabbitMQ dead letter queue principle and project code examples
1. Reasons for generating dead letter messages When consuming a message, if the message in the queue occurs in the following situations, the message will become a dead letter message: When a message is nacked using the channel.basicNack method or the channel.basicReject method, and the requeue attribute is set to false. The survival time of […]
Lombok + Swagger2 +Jackson The second letter of the attribute is uppercase, and the second letter of the field after serialization is lowercase
Article directory 1. Problem Overview 2. Cause analysis: 1. Overview of the problem The original FastJson converter used in the SpringBoot project, with Swagger2 + lombok serialization, the field case is normal, but when it is replaced with fastJson, if the second letter in the original entity is capitalized, the fields returned in the swagger […]