Freshworks Backend Assignment

A Key-Value DataStore that supports CRD operations by creating a local database on the local machine.

Table of Contents

• About the Project
  • Built With
• Getting Started
  • Prerequisites
  • Installation
• Usage
• Testing

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About The Project

A file-based key-value data store that supports the basic CRD (create, read, and delete) operations. This data store is meant to be used as a local storage for one single process on one laptop. The data store must be exposed as a library to clients that can instantiate a class and work with the data store.

The data store supports the following functional requirements :

1. It can be initialized using an optional file path. If one is not provided, it will reliably create itself in a reasonable location on the laptop.

2. A new key-value pair can be added to the data store using the Create operation. The key is always a string - capped at 32chars. The value is always a JSON object - capped at 16KB.

3. If Create is invoked for an existing key, an appropriate error must be returned.

4. A Read operation on a key can be performed by providing the key, and receiving the value in response, as a JSON object.

5. A Delete operation can be performed by providing the key.

6. Every key supports setting a Time-To-Live property when it is created. This property is optional. If provided, it will be evaluated as an integer defining the number of seconds the key must be retained in the data store. Once the Time-To-Live for a key has expired, the key will no longer be available for Read or Delete operations.

7. Appropriate error responses must always be returned to a client if it uses the data store in unexpected ways or breaches any limits.

The data store will also support the following non-functional requirements :

1. The size of the file storing data must never exceed 1GB.

2. More than one client process cannot be allowed to use the same file as a data store at any given time.

3. A client process is allowed to access the data store using multiple threads, if it desires to. The data store must therefore be thread-safe.

4. The client will bear as little memory costs as possible to use this data store, while deriving maximum performance with respect to response times for accessing the data store.

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Built With

• Python
• Unittest

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Getting Started

To get a local copy up and running follow these simple example steps.

Prerequisites

1. Python

To check, if python is installed, type python in command line. If this opens python3 interpreter then you are good to go.

else, python3 follow this link to download the latest version.

2. Git

You can download the latest version of git here.

Installation

• Clone the repo

git clone https://github.com/A-lone-Contributer/File-based-Key-Value-Store.git

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Usage

Import the DataStore Class and json module

from ds.__init__ import DataStore
import json

Create DataStore Object

db = DataStore("C:\\Users\\acer\\Desktop\\data_store.json") # location is optional

Note: If location is provided then file desired json file must exist there

Creating a key value pair

db.create('Student', json.dumps({'Name': 'John Doe'}))

# Optional Time-To-Live (TTL) argument 
db.create('TempStudent', json.dumps({'Name': 'Steven'}), 2) # this {key:json obj} expires in 2 seconds

Reading the key

name = db.read('Student')

Deleting a key

db.delete('Student')

Testing

To run the unittests, follow the below written steps

1. Navigate to the test folder

cd tests

2. Run the tests file

python3 tests.py 

After running this file, all the 12 tests cases show run successfully indicating unittest coverage.

Output

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Roadmap

See the open issues for a list of proposed features (and known issues).

Contributing

Contributions are what make the open source community such an amazing place to be learn, inspire, and create. Any contributions you make are greatly appreciated.

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Commit your Changes (git commit -m 'Add some AmazingFeature')
4. Push to the Branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License

Distributed under the Apache-2.0 License. See LICENSE for more information.

Contact

Nishkarsh Tripathi : nishkarsh78@gmail.com

Project Link : File-based-Key-Value-Store