lockfree

lockfree queue for C++20 and above

Requirements

vcpkg install doctest

SPSC optimization

Separate Head and Tail Indices:

• Producer only modifies head_ and reads tail_.
• Consumer only modifies tail_ and reads head_.
• This separation ensures that the producer and consumer do not contend over the same atomic variable, reducing cache coherence traffic.

Cache Line Padding:

• Aligning head_ and tail_ to separate cache lines (typically 64 bytes) prevents them from residing on the same cache line, which can cause false sharing and degrade performance.

Power-of-Two Buffer Size with Bitmasking:

• By ensuring that N is a power of two, we can replace the modulo operation with a bitmask (& mask_), which is significantly faster.
• The static_assert ensures at compile-time that N meets this requirement.

Avoiding std::optional in pop():

• While an optional return type provides a convenient interface, it introduces additional overhead.Instead, providing an output parameter version of pop can enhance performance.
• An additional pop() method returning std::optional is included for convenience, but its usage should be limited to scenarios where the slight overhead is acceptable.

Exception Safety:

• The class is marked noexcept where appropriate, ensuring that it doesn't throw exceptions, which is crucial for lock-free data structures.

lockfree threadpool

idea: 管理一个任务队列(lockfree)，一个线程队列(std::array<std::jthread, N>)，然后每次取一个任务分配给一个线程去做，循环往复。

graceful cleanup

Handling graceful cleanup of shared memory upon program termination

• Global Variables: Use global variables to make shared memory pointers and sizes accessible within signal handlers.
• Signal Handlers: Implement platform-specific signal handlers to catch termination signals.
• Registration of Handlers: Register these handlers at the beginning of your main function.
• Cleanup Logic: Ensure that the shared memory is properly destroyed within the handlers.