GitLite

A lightweight Git-inspired version control system built in Java to understand the core concepts behind Git. GitLite implements repository initialization, content-addressable storage, staging, commits, branching, checkout, and status using Java and the Java NIO API.

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Features

• Initialize a GitLite repository
• Stage files using SHA-1 hashing
• Store blobs in an object database
• Create commits with parent tracking
• View commit history
• Display repository status
• Create and list branches
• Switch between branches (checkout)
• Automated unit testing with JUnit 5

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Project Structure

.gitlite/
├── objects/      # Blob storage
├── commits/      # Commit objects
├── refs/         # Branch references
├── HEAD          # Current branch
└── index         # Staging area

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Commands

Initialize a repository

.\gradlew.bat run --args="init"

Add a file

.\gradlew.bat run --args="add hello.txt"

Create a commit

.\gradlew.bat run --args="commit -m Initial"

View commit history

.\gradlew.bat run --args="log"

View repository status

.\gradlew.bat run --args="status"

Create a branch

.\gradlew.bat run --args="branch feature"

List branches

.\gradlew.bat run --args="branch"

Switch branches

.\gradlew.bat run --args="checkout feature"

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How GitLite Works

Blob Storage

When a file is added:

1. The file contents are read.
2. A SHA-1 hash is generated.
3. The contents are stored inside .gitlite/objects.
4. The staging area (index) stores:

filename=sha1hash

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Commit

Each commit stores:

• Commit message
• Timestamp
• Parent commit ID
• List of tracked files

Commits are stored inside:

.gitlite/commits/

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Branches

Each branch is represented by a file inside:

.gitlite/refs/

The HEAD file stores the currently checked-out branch.

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Technologies Used

• Java 21
• Gradle
• Java NIO
• SHA-1 Hashing
• JUnit 5

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Testing

Run all unit tests:

.\gradlew.bat test

The project includes automated tests for:

• Repository initialization
• File staging
• Commit creation
• Branch creation
• Branch checkout

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Future Improvements

Potential enhancements include:

• Merge
• Reset
• Restore
• Diff
• Tags
• Remote repositories
• Push/Pull support

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Repository Layout

GitLite
├── app/
├── gradle/
├── src/
├── .gitignore
├── README.md
├── build.gradle.kts
├── settings.gradle.kts
├── gradlew
└── gradlew.bat

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Author

Aryaa Agarwal

Built as a learning project to understand how modern version control systems work internally.