UniFr-OS-Project-SP18

Authors

Michaël Papinutto Sami Veillard Sylvain Julmy

Instructions to build this project

Use the following commands in a terminal in order to build project

cmake */UniFr-OS-Project-SP18
make

In case the project do not compile do not hesitate to contact us we would be glad to provie you with the executable files.

Server launch

TCP Port	5000 (Can be set in server main file)
.\server	start server

Client launch

.\client	Client start
.\client -option	Client start with options

-? or -h or --help	Client help option
-f or --file	Client start and execute command in file
-F or --files	Client start and execute command in files

Database operations

• ls display the content of the database

• add <key> <value> add the specified value, related to the specified key, to the database

• add <value> add the specified value to the database and return the associated key

• read_v <key> return the value of the associated key

• read_k <value> return a key for the associated value

• rm_k <key> delete the database entry specified by key

• rm_v <value> delete a database entry specified by value

• update_kv <key> <value> update the value specified by key, if key don't exist, the behavior is similar to add <key> <value>

• q terminate the server process

Project specifications

The goal of the Mini-Project Lab is to implement a simple In-Memory Key-Value store with simultaneous access via TCP in Linux.

“Key-value (KV) stores use the associative array (also known as a map or dictionary) as their fundamental data model. In this model, data is represented as a collection of key-value pairs, such that each possible key appears at most once in the collection.” Wik 15

Race conditions e.g. due to badly synchronized database accesses are still an issue in real use cases as of today. Fra 15

Deliverables

A runnable code with a makefile and testing scripts. A short two pages documentation per group. Preparation of a final presentation per group (3minPerson). One page report per participant (Approach chosen, Problems encountered, Lessons learned.).

Minimal feature set

Ability to write keys with values through TCP sockets. Ability to read values through TCP sockets by providing a key. Graceful fallback (error message) if key is nonexistent. Use multiple threads. Simultaneous safe access of the readers and the writers. Provide an automated testing in form of another program or script. (Showing all the mentioned functionalities including simultaneous and mixed readwrite requests.)

Implementation decision

Read or Write priority: Which requests have priority, writes or reads? Data structure Size: How many entries can the KV store have? Can the size grow? Simultaneous access: How many connections to allow simultaneously? Synchronization: How to synchronize the threads?

Hints

Semaphores Fork with Semaphores