1. Webbench
Webbench is a very simple website stress testing tool used under Linux. It uses fork() to simulate multiple clients accessing the specified URL simultaneously, testing the performance of the website under pressure, and can simulate up to 30,000 concurrent connections to test the website’s load capacity. Webbench is written in C, and the code is extremely concise, totaling less than 600 lines. Download link:http://home.tiscali.cz/~cz210552/webbench.html
2. Tinyhttpd
Tinyhttpd is a lightweight HTTP server developed in C, with only 502 lines of code (including comments), and comes with a simple client. Reading this code can help you understand the essence of an HTTP server. Download link:http://sourceforge.net/projects/tinyhttpd/
3. cJSON
cJSON is a JSON encoder/decoder in C, very lightweight, with only over 500 lines of C code, and offers very good speed. cJSON has a few weaknesses; although its functionality is not very powerful, its small size and speed are commendable. The code is well-maintained and easy to understand, making it a great C language project for learning. Project homepage:http://sourceforge.net/projects/cjson/
4. CMockery
CMockery is a lightweight framework for C unit testing released by Google. It is compact, has no dependencies on other open-source packages, and has low invasiveness to the code being tested. The source code of CMockery is less than 3K lines, and reading the source code for will_return and mock is quite enlightening.
Main features:
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Free and open-source, with technical support from Google;
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Lightweight framework that makes testing faster and simpler;
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Avoids complex compiler features, ensuring good compatibility with older compilers;
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Does not require the code under test to depend on the C99 standard, which is useful for many embedded system developments.
Download link:http://code.google.com/p/cmockery/downloads/list
5. Libev
Libev is an open-source event-driven library based on epoll, kqueue, and other OS-provided infrastructures. It is known for its efficiency, unifying IO events, timers, and signals under a single event handling framework. Based on the Reactor pattern, it is efficient and has concise code (over 8000 lines in version 4.15), making it a great resource for learning event-driven programming.Download link:http://software.schmorp.de/pkg/libev.html
6. Memcached
Memcached is a high-performance distributed memory object caching system used for dynamic web applications to reduce database load. It reduces the number of times the database is read by caching data and objects in memory, thus speeding up dynamic database-driven websites. Memcached is based on a hashmap that stores key/value pairs. The code size of Memcached-1.4.7 is acceptable, around 10K lines. Download link:http://memcached.org/
7. Lua
Lua is great; it was invented by Brazilians, which is somewhat annoying, but not enough to make me blush, just a bit envious. What makes me blush is Lua’s source code, which is 100% ANSI C, without any fluff. It can be easily compiled on any platform that supports an ANSI C compiler. I have tried it, and there is absolutely no nonsense. The code size is small enough, with version 5.1.4 having only 15,000 lines, and removing blank lines and comments probably brings it down to 10,000 lines. Download link:http://www.lua.org/
8. SQLite
SQLite is an open-source embedded relational database that implements a self-contained, zero-configuration, transactional SQL database engine. Its features include high portability, ease of use, compact structure, efficiency, and reliability. It is small enough, with approximately 30,000 lines of C code, totaling 250K. Download link:http://www.sqlite.org/.
9. UNIX v6
The source code of the UNIX V6 kernel, including device drivers, is about 10,000 lines, a quantity that beginners can fully understand. There is a saying that the maximum amount of code a person can understand is around 10,000 lines, and the UNIX V6 kernel source code fits right into that range. At this point, you might think, “If it’s only 10,000 lines, maybe I can learn it too.” On the other hand, recent operating systems, such as the latest Linux kernel, reportedly exceed 10 million lines of code. Even for experienced developers, fully understanding all the code is practically impossible. Download link:http://minnie.tuhs.org/cgi-bin/utree.pl?file=V6
10. NETBSD
NetBSD is a free, highly portable UNIX-like operating system, known for being the most portable operating system available, capable of running on many platforms, from 64-bit alpha servers to handheld devices and embedded systems. The slogan of the NetBSD project is: “Of course it runs NetBSD.” It is designed to be simple, with standardized code, and has many advanced features, making it well-regarded in both industry and academia. Due to its simple design and advanced features, it performs excellently in both production and research, and it also has complete source code supported by its users. Many programs can be easily obtained through the NetBSD Packages Collection. Download link:http://www.netbsd.org/