A transactional key-value store Sample written with Jetpack Compose with Room database to store commits.

• Jetpack Compose
• Dagger Hilt
• Room Database for persisting COMMIT transactions
• MVVM and clean architecture
• Unit and Database Tests(More tests to be written)

The assignment is to build an interactive command line interface to a transactional key value store. A user should be able to compile and run this program and get an interactive shell with a prompt where they can type commands. The user can enter commands to set/get/delete key/value pairs and count values. All values can be treated as strings, no need to differentiate by type. The key/value data only needs to exist in memory for the session, it does not need to be written to disk.

The interface should also allow the user to perform operations in transactions, which allows the user to commit or roll back their changes to the key value store. That includes the ability to nest transactions and roll back and commit within nested transactions. The solution shouldn’t depend on any third party libraries. The interface should support the following commands:

SET <key1> <value1> <key2> <value2> // store the value for key GET <key> // return the current value for key DELETE <key1> <key2> // remove the entry for key COUNT <value> // return the number of keys that have the given value BEGIN // start a new transaction COMMIT // complete the current transaction ROLLBACK // revert to state prior to BEGIN call 

> SET foo 123 > GET foo 123 

> DELETE foo > GET foo key not set 

> SET foo 123 > SET bar 456 > SET baz 123 > COUNT 123 2 > COUNT 456 1 

> BEGIN > SET foo 456 > COMMIT > ROLLBACK no transaction > GET foo 456 

> SET foo 123 > SET bar abc > BEGIN > SET foo 456 > GET foo 456 > SET bar def > GET bar def > ROLLBACK > GET foo 123 > GET bar abc > COMMIT no transaction 

> SET foo 123 > SET bar 456 > BEGIN > SET foo 456 > BEGIN > COUNT 456 2 > GET foo 456 > SET foo 789 > GET foo 789 > ROLLBACK > GET foo 456 > DELETE foo > GET foo key not set > ROLLBACK > GET foo 123