📢 echo-server

This project is a simple implementation of a TCP echo server using BSD sockets that I put together to explore different methods of synchronous I/O multiplexing in a Linux environment. It allows for the selection of a multiplexing method using an application argument. Available methods are select, poll, and epoll, and each method has performance and cross-platform compatibility trade-offs.

Note: this program uses epoll, a Linux kernel system call, so it can only be compiled in a Linux environment.

Usage

echo_server 8080 epoll

• arg[1] the port you want the server to bind to.
• arg[2] the multiplexing method you want to use (select, poll, or epoll).

Both arguments are required.

The simplest way to test the server is using telnet.

Synchronous I/O multiplexing methods

Method	Summary
select()	The primary advantage is portability. BSD sockets and WINSOCK interfaces fully support it. It can only monitor up to 1024 file descriptors. Unix man recommends that modern applications use poll() or epoll(). It isn't very efficient. The kernel has to iterate through the max file descriptor value, even when a single file descriptor is watched. File descriptor sets are reconstructed on return, so each subsequent call must reinitialize them.
poll()	It improves on the select() method, but it's only available in UNIX. It stores file descriptors in an array, so it doesn't need to iterate through the max file descriptor value. The poll() system call separates input and output events, allowing the array to be reused without having to reinitialize it. The time complexity of poll(), like select() is O(n), and it's still a slow solution when a large number of file descriptors is used.
epoll()	It performs better than select() and poll(), but it's only available on Linux and not standardized by POSIX. The time complexity of epoll() is O(1). epoll_wait() only returns file descriptors ready for IO operations, so there's no need to iterate through the entire set. It allows adding and removing file descriptors while waiting. It can be used either as an edge-triggered or a level-triggered interface.

Licence

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Copyright (c) 2023 Shlomi Nissan
https://betamark.com

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