Undis

A persistent key-value store supporting aspects of the Memcached protocol.

Features:

safe and performant concurrent reading/writing
a cross-platform TCP server to serve clients
unlimited concurrent connections with a thread pool that grows and shrinks dynamically according to demand
ability to specify an expiration time and flags to accompany a string value, like Memcached
optional persistence to disk via a compact serialization algorithm

This project also makes use of modern metaprogramming techniques to avoid unnecessary copies and allocations while using concepts to maintain semantics.

Building and Testing

This project builds with CMake and requires the C++20 standard. There are no dependencies other than the standard C++ library and system headers. Unit tests depend on GoogleTest.

$ git clone https://github.com/ianzhao05/undis.git && cd undis
$ cmake -B ./build
$ cmake --build ./build
$ ctest --test-dir ./build

Once built and ran, clients can connect on port 8080 by default, for instance with telnet. Data will be read from and written to undis.db at startup and shutdown, respectively. The port can be changed with the -p flag, and the persistence file can be changed with the -f flag.

Sample Usage

From the Memcached protocol, the get, delete, set, add, replace, prepend, append, and quit commands are supported.

$ telnet localhost 8080
undis > set key 42 0 5
value
STORED
undis > get key
VALUE key 42 5
value
END
undis > add key2 64 0 6
value2
STORED
undis > replace key2 65 0 9
value two
STORED
undis > append key2 0 0 7
_suffix
STORED
undis > get key key2
VALUE key 42 5
value
VALUE key2 65 16
value two_suffix
END
undis > delete key
DELETED
undis > delete key
NOT_FOUND
undis > quit
Connection closed by foreign host.