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Redis challenge

This is a an attempt at a C++ implementation of the "Build Your Own Redis" Challenge.

Instructions

Installation/prerequisites

  • A pretty recent C++ compiler that supports C++23 is required (what worked for me was g++ version 13 or newer). You need to have your system's default compiler point to this newer compiler (usually /usr/bin/c++) if you want vscode or whatever setup you have to work out of the box.
  • cmake (3.29+) and make (4.2.1+)
  • gtest is pulled in from a zip file (see the CMakeLists.txt file).
  • CLI11 (header-only lib) is included as a git submodule in this repository.

codecrafters CLI

The codecrafters CLI is primarily how the program is tested. You can also use the spawn_redis_server.sh script to build and run the main executable called server.

Faster iteration

  • make test should run the unit tests I've written so far.
  • There's also a clean rule to clean the build directory (e.g. make clean or even make clean test).
  • make run -- <any args go here> if you want to run the server executable with flags.
  • NOTE: you can't combine multiple rules (like make clean run) if you also try to pass arguments.

Bugs / Missing Features / TODOs

  • set up consistent formatter/linter
  • the code that reads from the client socket can only handle 1024 bytes. (add tests for this)
  • can't handle client messages with newlines (I think this is fixed but tests wouldn't be a bad idea?)
  • need tests for network code (simple integration test will do just fine, since codecrafters doesn't let me test whatever I want)
  • GET commands don't support multiple args or wildcards.
  • set up *san builds and run them regularly.
  • use blacklists to get msan and tsan to shut up about CLI11
  • move all the flags from make to cmake
  • figure out a way to fix false-positives in msan (need to build and instrument my own libc, see here).
    • Can probably ditch msan and just use valgrind.
  • install and start using clang-tidy (part of clangd in vscode) as well as clang static analyzer and cppcheck (part of codechecker in vscode).
  • clean up all the warnings and errors from the above static analysis tools.
  • write out RDB file

Progress Log

Basic Parser Finished

I finished the base set of challenges using a really hacky/dirty parser

Parser rehaul

I'm doing a rehaul of the parser.

  • basic unit tests for parser (can't rely on codecrafters test suite since it doesn't allow testing efactors). Start with roundtripping Messages.
  • hook up the new refactored parser parts to the Server and see if it works.
  • get IDE autocomplete to work in tests (having trouble with gtest)
  • fix roundtripping tests
  • turn on compiler warning flags
  • consider using istringstream instead of using iterators on the chars (also fix the bugs where we dereference end iterators).
  • consider using the visitor pattern on the variant of Message data field (right now I use a bunch of switch statements).
  • clean up the header/source files. Lots of redundant stuff, stale comments, etc. Throw out old parser logic once the new refactored parser is hooked up.
  • cleanly break apart the server logic from the Parser file. Also clean up all the namespacing mess I made.
  • remove unnecessary header includes
  • one last thing: need to run in all the sanitizer modes and fix issues

Rehaul is done.

RDB (persistence)

Just starting out on the RDB challenge. The goal is to have be able to save the db to disk (and read it when starting up).

Finished reading basic RDB. Things I skipped:

  • All encodings except for length-prefixed string and IntAsString.
  • Actually checking the CRC against the data I'm reading.
  • Parsing wildcard in GET and CONFIG GET commands.

I'm surprised it didnt ask me to implement writing out an RDB file. I should probably implement that.

Replication

Will work on replication to allow for a master and replicas to work together.