http://blog.csdn.net/sparkliang/article/details/8567602
http://brg-liuwei.github.io/tech/2014/10/15/leveldb-0.html
https://segmentfault.com/a/1190000003061165
https://github.com/google/leveldb
此外,还有memcached, redis, nginx, tinyhttps/lighthttpd的源码。