HW2 Simple Key-value Store

Overview

This code implements a simple key-value store server that can handle SET, GET, and DELETE operations through a client-server architecture using sockets. The server is multithreaded, allowing it to handle multiple client connections simultaneously.

Directories

• /server -> server program related sources
• /client -> client program related sources
• /common -> common inclusions
• /util -> common utilization
• /build -> target build directory

Building the Project

Code out your /server/server.c and /client/client.c, then

$ make

Test your /build/server and build/client.

Implementations

Please briefly describe your multi-threading design pattern

Key-Value Storage:

• The key-value pairs are stored in a linked list structure. There are 26 possible linked lists (one for each letter of the alphabet) to handle different keys.
• Each linked list node (KeyValue) holds a key and a pointer to a Value structure that contains the associated value.

Please briefly describe your data structure implementation

1.Server Functions:

• open_serverfd(char *port): This function sets up the server to listen on the specified port. It creates a socket, binds it to the port, and starts listening for incoming connections.
• response(void *socket_desc): This function is the entry point for a new thread handling a client request. It reads commands from the client, processes them, and sends the appropriate response back.
• processing(char operation[], char firstLetter, char key[], char *value): This function determines which operation (SET, GET, DELETE) the client requested and calls the appropriate processing function.

2. Client Functions:

   • open_clientfd(char *hostname, char *port): This function connects the client to the server at the specified hostname and port. It handles reading and writing data to the server.
   • The client interacts with the server by sending commands like SET key value, GET key, or DELETE key.

3. Command Processing:

   • SET Operation: setProcessing adds a new key-value pair to the linked list or returns an error if the key already exists.
   • GET Operation: getProcessing searches for a key in the linked list and retrieves its value.
   • DELETE Operation: deleteProcessing removes a key-value pair from the linked list.

4. Multithreading:

   • The server uses the pthread_create function to create a new thread for each client connection. This allows the server to handle multiple clients concurrently.

5. Error Handling:

   • The server and client functions include basic error handling, such as checking if a socket was created successfully or if the connection to the server was successful.

6. Command Parsing:

   • The client and server use strtok to parse incoming command strings, splitting them into command, key, and value components.

References

• POSIX thread man pages
• socket man pages

Summary

This code demonstrates a basic client-server model using sockets to implement a simple key-value store. The server can handle multiple clients concurrently using threads and supports basic operations like setting, getting, and deleting key-value pairs. The implementation includes error handling and command parsing to ensure smooth operation.