httplite

A high-performance, lightweight HTTP/1.1 server written in C. httplite is designed as a deep dive into systems programming, utilizing a multi-threaded event loop, cooperative multitasking (coroutines), and zero-copy I/O.

🚀 Key Features

• Cooperative Multitasking: Custom coroutine runtime built on ucontext.h for managing thousands of concurrent connections with a sequential programming model.
• Multi-threaded Event Loop: A "Worker Pool" architecture using Linux epoll in Edge-Triggered (EPOLLET) mode for maximum CPU scalability.
• Zero-Copy I/O: Leverages sendfile() to stream data directly from the kernel Page Cache to the network socket, bypassing user-space memory.
• Efficient Dispatching: Uses "Self-Pipes" and a Round-Robin strategy to distribute connections from the main listener to worker threads with minimal lock contention.
• Modern SPA Support: Optimized for hosting Single Page Applications (like Angular/React) with automatic URI normalization and 301 redirects.

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🏗 Architecture Overview

The server operates on a Leader-Follower pattern:

1. The Listener (Main Thread): A dedicated thread that accept()s new TCP connections and dispatches the file descriptors to the worker pool.
2. The Workers (Pool): Each worker thread runs its own epoll instance and a coroutine scheduler.
3. The Coroutines: Each connection is mapped to a coroutine. When an I/O operation (like recv) would block, the coroutine yields control back to the worker, allowing other requests to proceed.

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🛠 Prerequisites

• OS: Linux (Requires epoll, sendfile, and ucontext.h)
• Compiler: clang or gcc (with C99 support)
• Dependencies: pthread

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💻 Getting Started

1. Build and Run

The project uses a custom Makefile designed for modular C builds:

make
./bin/program

2. Benchmarking

To test the concurrency limits, it is recommended to use wrk:

wrk -t12 -c400 -d30s http://localhost:3094/

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⚙️ Optimizations

TCP Corking

To reduce packet overhead, httplite uses TCP_CORK. This "corks" the socket while headers and file bodies are being prepared, forcing the kernel to coalesce them into a single MTU-sized packet before transmission.

Pre-compressed Gzip

The server supports a "lean" compression strategy. If a browser sends Accept-Encoding: gzip, httplite looks for a .gz version of the file on disk and serves it directly, saving CPU cycles compared to on-the-fly compression.

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📂 Project Structure

• src/server/: Core TCP listener logic.
• src/connection_manager/: Coroutine runtime, scheduler, and epoll worker loop.
• src/request_handler/: HTTP parsing and middleware pipeline.
• include/: Public headers and interface definitions.

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📜 License

This project is licensed under the MIT License - see the LICENSE.md file for details.