async-a-sync

async-a-sync is an innovative compiler and runtime system designed to provide asynchronous functionality in C programming while maintaining a synchronous coding style. Built on top of Fil-C, this project allows developers to write code that appears blocking, yet runs asynchronously under the hood, eliminating the need for complex asynchronous coding patterns.

Key Features:

• Immediate Return on Function Calls: Functions annotated for asynchrony return immediately, passing the call to an asynchronous runtime without blocking.
• Pending Buffers: Buffers produced by function calls remain pending until they are fulfilled, optimizing resource handling and execution flow. Use filc_async_wait_all(tags, count) to manage completion of multiple operations efficiently.
• Automatic Waiting on First Access: The Fil-C's InvisiCaps mechanism associates every pointer with its object's header, ensuring that the first access to a pending buffer automatically waits for completion, promoting simplified programming.
• Flexible Runtime Integration: The system does not mandate a specific runtime, allowing the developer to specify the runtime required for each annotated function with runtime=<name>. This repository includes two runtimes; one that sends calls as io_uring requests to the kernel in batches and another that handles calls to a TCP server for demonstration purposes.

Example Code:

FILC_ASYNC(io_uring, FILC_OP(pread), FILC_BOUT(buf))
void* read_at(int fd, void* buf, size_t len, unsigned long offset);

// Asynchronous file read requests without blocking
for (int i = 0; i < n; i++)
    read_at(fd[i], buf[i], len, 0);

// Addressing completion through first access
for (int i = 0; i < n; i++)
    if (count_words(buf[i]) != expect[i])
        return 1;

When compiled conventionally, the first example would result in blocking reads. However, with async-a-sync, multiple reads complete roughly 3.5 times faster than traditional approaches.

Demos and Documentation:

Explore practical demonstrations such as the wait-all demo, which showcases how to efficiently handle multiple asynchronous reads. Documentation is available in the wiki/ folder, covering troubleshooting, annotations, runtimes, and performance evaluations.

async-a-sync streamlines the asynchronous programming process in C by allowing developers to focus on straightforward coding principles while leveraging powerful asynchronous capabilities underneath. For those looking to enhance their C projects with modern asynchronous practices without sacrificing readability or maintainability, this tool provides a high-level approach to effective coding.