


How Can a 64-Bit Atomic Counter Be Implemented Using Only 32-Bit Atomics?
Dec 09, 2024 am 04:52 AMImplementing a 64-Bit Atomic Counter Using 32-Bit Atomics
This question delves into creating a 64-bit atomic counter from 32-bit atomic integers. The counter has a single writer and multiple readers, with the writer being a signal handler that must not block.
The proposed solution employs a generation count, using the low bit as a read lock. Readers retry until the generation count is stable across the read, and the low bit is unset.
Design and Memory Ordering
The code provided generally follows the correct design principles of a SeqLock, a known pattern for implementing lock-free atomic counters with sequence numbers. The use of memory ordering is sound, ensuring that the counter is updated atomically.
Potential Improvements
However, it's worth noting that using atomic RMW operations for the increment of the payload is unnecessary if the system supports cheaper 64-bit atomic addition or load. Instead, a simple load of both halves, followed by a non-atomic increment, and atomic storage of the result is sufficient.
Additionally, the sequence counter can also avoid atomic RMW operations unless it's used as a spinlock with multiple writers. With a single writer, it can use pure loads and pure stores with release ordering, which are more efficient than atomic RMW or stores with seq_cst ordering.
Optimizations and Alternatives
To bypass the limitations of atomic
Another alternative would be to implement a SeqLock template that dynamically checks if the target supports lock-free atomic operations on atomic
In conclusion, while the code provided presents a functional implementation of a 64-bit atomic counter using 32-bit atomics, there are potential optimizations and alternatives that could improve performance and simplify the code.
The above is the detailed content of How Can a 64-Bit Atomic Counter Be Implemented Using Only 32-Bit Atomics?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

Yes, function overloading is a polymorphic form in C, specifically compile-time polymorphism. 1. Function overload allows multiple functions with the same name but different parameter lists. 2. The compiler decides which function to call at compile time based on the provided parameters. 3. Unlike runtime polymorphism, function overloading has no extra overhead at runtime, and is simple to implement but less flexible.

C has two main polymorphic types: compile-time polymorphism and run-time polymorphism. 1. Compilation-time polymorphism is implemented through function overloading and templates, providing high efficiency but may lead to code bloating. 2. Runtime polymorphism is implemented through virtual functions and inheritance, providing flexibility but performance overhead.

Yes, polymorphisms in C are very useful. 1) It provides flexibility to allow easy addition of new types; 2) promotes code reuse and reduces duplication; 3) simplifies maintenance, making the code easier to expand and adapt to changes. Despite performance and memory management challenges, its advantages are particularly significant in complex systems.

Implementing polymorphism in C can be achieved through the following steps: 1) use inheritance and virtual functions, 2) define a base class containing virtual functions, 3) rewrite these virtual functions by derived classes, and 4) call these functions using base class pointers or references. Polymorphism allows different types of objects to be treated as objects of the same basis type, thereby improving code flexibility and maintainability.

C destructorscanleadtoseveralcommonerrors.Toavoidthem:1)Preventdoubledeletionbysettingpointerstonullptrorusingsmartpointers.2)Handleexceptionsindestructorsbycatchingandloggingthem.3)Usevirtualdestructorsinbaseclassesforproperpolymorphicdestruction.4

Polymorphisms in C are divided into runtime polymorphisms and compile-time polymorphisms. 1. Runtime polymorphism is implemented through virtual functions, allowing the correct method to be called dynamically at runtime. 2. Compilation-time polymorphism is implemented through function overloading and templates, providing higher performance and flexibility.

C polymorphismincludescompile-time,runtime,andtemplatepolymorphism.1)Compile-timepolymorphismusesfunctionandoperatoroverloadingforefficiency.2)Runtimepolymorphismemploysvirtualfunctionsforflexibility.3)Templatepolymorphismenablesgenericprogrammingfo

People who study Python transfer to C The most direct confusion is: Why can't you write like Python? Because C, although the syntax is more complex, provides underlying control capabilities and performance advantages. 1. In terms of syntax structure, C uses curly braces {} instead of indentation to organize code blocks, and variable types must be explicitly declared; 2. In terms of type system and memory management, C does not have an automatic garbage collection mechanism, and needs to manually manage memory and pay attention to releasing resources. RAII technology can assist resource management; 3. In functions and class definitions, C needs to explicitly access modifiers, constructors and destructors, and supports advanced functions such as operator overloading; 4. In terms of standard libraries, STL provides powerful containers and algorithms, but needs to adapt to generic programming ideas; 5
