Uni-Project

Resource Allocation Graph Simulator with Deadlock detection

Version: 2.2 Authors: Amit, Anurag, Himanshu

A simple, interactive, browser-based graphical simulation tool for visualizing Resource Allocation Graphs (RAGs) and identifying potential deadlock scenarios (cycles). Built with HTML, CSS (Tailwind), and JavaScript Canvas, it serves as a visual aid for learning Operating Systems concepts.

Overview

Goal: To develop a graphical tool using web technologies for visualizing RAGs and analyzing potential deadlock cycles interactively.

Key Outcomes & Features:

• Graphical RAG Visualization: Represents processes (circles) and resources (squares).
• Interactive Graph Building:
  • Add Processes (P) and Resources (R).
  • Create Request edges (P->R, Q).
  • Create Assignment edges (R->P, A).
  • Remove selected nodes (Delete/Backspace/X) or edges (button).
• Drag-and-Drop: Reposition nodes easily on the canvas.
• On-Demand Deadlock Detection: Identifies and highlights cycles in the graph (D).
• Visual Indicators:
  • Color-coding for node types and edge types.
  • Selection highlighting (yellow).
  • Deadlock highlighting (purple).
  • Basic node creation animation.
• User Feedback: Status bar provides messages about actions and detection results.
• Keyboard Shortcuts: Speed up interactions (see below).
• Clear Options: Clear current selection (Escape) or the entire canvas (C).
• About Modal: Provides quick help and shortcut reference.

Scope:

• Primarily designed as an educational tool for OS students.
• Focuses on single-instance resource scenarios for cycle detection.
• Does not implement step-by-step deadlock analysis or resolution algorithms (like Banker's) in this version.

How to Use

1. Clone or Download: Get the project files from this repository.

   git clone https://github.com/JhaAnurag/OSproject
   cd OSproject

2. Open in Browser: Simply open the index.html file (or the main HTML file) in your web browser (like Chrome, Firefox, Edge).

• Live Demo

Keyboard Shortcuts

• P: Add Process node
• R: Add Resource node
• Q: Make Request edge (P->R) - Requires one Process and one Resource selected
• A: Make Assignment edge (R->P) - Requires one Process and one Resource selected
• Delete / Backspace / X: Remove the currently selected single node
• D: Detect Deadlock (cycles)
• Escape: Clear current node selection(s)
• C: Clear All nodes and edges (requires confirmation)

Deadlock Detection

• The simulator uses a Depth-First Search (DFS) algorithm to detect cycles within the graph structure.
• A cycle in a Resource Allocation Graph indicates a potential deadlock condition (assuming single-instance resources).
• When a deadlock is detected by pressing D or clicking the "Detect Deadlock" button:
  • A message appears in the status bar indicating the detected cycle.
  • The nodes involved in the cycle are highlighted with a distinct border color (purple).

Technology Stack

• Languages: JavaScript (ES6+)
• Web: HTML5, CSS3 (using Tailwind CSS via CDN)
• Graphics: HTML5 Canvas API (2D Context)
• Version Control: Git / GitHub

Conclusion

This simulator provides a basic but functional tool for interactively learning about Resource Allocation Graphs and the concept of deadlock detection through cycle identification in a visual manner.

Future Scope

• Enhance GUI and add more sophisticated animations.
• Add support for multiple resource instances.
• Implement deadlock prevention/avoidance algorithms (e.g., Banker's Algorithm).
• Implement save/load functionality for graph states (e.g., using JSON).
• Add step-by-step simulation controls to observe allocation/request sequences.
• Deploy the tool as a persistent web application.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request or open an Issue to discuss potential improvements or report bugs.

References

• Operating System Concepts – Abraham Silberschatz, Peter Baer Galvin, Greg Gagne.
• MDN Web Docs: Canvas API - https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API
• Tailwind CSS - https://tailwindcss.com/

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