I am developing a cross-platform system (Windows and Ubuntu) that needs signal and slot communication between two QObjects living in different threads. When both QObjects live in the same thread, the performance difference between Windows and Ubuntu is negligible, but when I move one the QObjects to another thread I notice the performance on. The signal slot mechanism of the thread needs to turn on the event loop mechanism of the thread, that is to call the qthread:: exec function to start the event. The QThread::run method only spins (exec in Qt parlance) an event loop (of course it won't do it anymore if your reimplementation doesn't). An event loop waits for events to arrive in the queue, and then notifies the target QObjects of their reception. The cross-thread (queued) signal-slot connections are implemented by leveraging events.
Qt Signal Slot
Qt provides several ways to implement Inter-Process Communication (IPC) in Qt applications.
TCP/IP
The cross-platform Qt Network module provides classes that make network programming portable and easy. It offers high-level classes (e.g. QNetworkAccessManager) that communicate using specific application-level protocols, and lower-level classes (e.g., QTcpSocket, QTcpServer, QSslSocket) for implementing protocols.
Local Server/Socket
The cross-platform Qt Network module provides classes that make local network programming portable and easy. It offers the QLocalServer and QLocalSocket classes that allow for network-like communication in a local setup. Their TCP counterparts can be used as drop-in replacement to make the communication work across networks.
Shared Memory
The cross-platform shared memory class, QSharedMemory, provides access to the operating system's shared memory implementation. It allows safe access to shared memory segments by multiple threads and processes. Additionally, QSystemSemaphore can be used to control access to resources shared by the system, as well as to communicate between processes.
D-Bus protocol
The Qt D-Bus module is a Unix-only library you can use to implement IPC using the D-Bus protocol. It extends Qt's Signals and Slots mechanism to the IPC level, allowing a signal emitted by one process to be connected to a slot in another process. The Qt D-Bus documentation has detailed information on how to use the Qt D-Bus module.
QProcess Class
The cross-platform class QProcess can be used to start external programs as child processes, and to communicate with them. It provides an API for monitoring and controlling the state of the child process. QProcess gives access to the input/output channels of child process by inheriting from QIODevice.
Session Management
On Linux/X11, Windows and macOS, Qt provides support for session management. Sessions allow events to be propagated to processes, for example, to notify when a shutdown occurs. The process and applications can then perform any necessary operations such as save open documents.
Qt Signal Slot Performance
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QT implementation of text editor (automatic completion, syntax highlight)
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1. What is the difference between a stack and a queue? Eat too much pull is the queue; eat too much spit is the stack 2. The furthest distance in the world is not between life and death, but the bug you made by yourself is right in front of you, but how can […]The < < operator of C + +
I program a small white, if there are errors, please point out, thank youToday, when I was writing a question, I came across the solution< You can see, a<When B = 2, with the increase of a, the value always increases by 4 timesWhen B = 3, with the increase of a, the value always […]Why do university teachers like to write constants to the left of = = operator
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This blog will elaborate and discuss the following contents: ●int The range of int varies between 16 bits or 32 bits according to different computers. Take 16 bits for example. The maximum value is 1111111111111, that is 65535. If 65536 occurs, it will overflow. ●Signed int Taking a 16 bit system as an example, […]Data structure section 4 (tree (middle))
tree This time, we will continue to talk about trees. Last time, we talked about the basic properties of trees and the four ways to traverse a tree. This time, we will talk about several “useful” binary trees Binary search tree For a binary tree, how to achieve its dynamic search (there will be new […]C / C + + learning diary: C + + Basics – structure, union and enumeration
This article introduces C + + basic knowledge, structure, union and enumeration, mainly using examples, application skills, summary of basic knowledge points and matters needing attention. It has certain reference value, and friends in need can refer to it. 1. Structure 1.0 structure An array is a collection of elements of the same […]Vs2019 login white page problem
The first step is to open the account option in his pop-up interface The second step is to open the embedded web browser in the view environment account option The third step is to change this into a system web browser Finally, click finish, and then click login to jump out of the browser interface. […]Sorting out the basic knowledge points of C / C + +
What is the identifier principle in C + + language? Answer: the identifier can only be composed of letters, numbers and underscores; the identifier can only start with letters and underscores; the identifier cannot be a keyword. What is the difference between global variables and local variables in memory storage? A: 1. Global variables are […]Expose the true face of C + +! Netizen: This is the real programming language boss “C + +”!
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preface 1. This paper focuses on how to make a snow that only you can see on the console 2. It is a simple cross platform, mainly c language 3. The animation adopts 1s 40 frames, and the snowflake has X-axis speed and y-axis speed 4. Relatively simple, you can give students as C language […]