Multithreaded Key-Value Server

A lightweight, concurrent key-value database built from scratch in C.
Implements low-level file persistence, interprocess communication, multithreading, and networked client access using Unix domain sockets and POSIX system calls.

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Features

• Concurrent Request Handling — spawns worker threads per connection using pthread for parallel client servicing.
• Interprocess Communication — utilizes Unix domain sockets for local multi-client connectivity.
• Persistent Storage — appends key-value pairs to a data file with atomic writes and locking (flock).
• Compaction via Signals — triggers on SIGUSR1 to reclaim unused disk space.
• Custom Commands
  • set <key> <value> — insert or overwrite a key
  • get <key> — retrieve a value
  • size — return file size using a forked wc process
  • compact — operates behind scenes with signaling, optimizes datastore file size on reassignment.
  • quit — close client connection

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Core Components

• kvstore.c — data operations (set, get, size, compact)
• kvstore_server.c — network listener, connection handler, signal setup
• kvstore_client.c — interactive user interface and command sender

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How to Run

1. Compile

gcc kvstore.c -c
gcc kvstore_server.c -pthread kvstore.o -o kvstore_server
gcc kvstore_client.c -o kvstore_client

2. Run the Server

Copy code
./kvstore_server

3. Run the Client

./kvstore_client

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Example Session

MIT License