🚢 Ferry Transport Simulation

Multithreaded Operating Systems Project — Java concurrency simulation demonstrating deadlock avoidance, starvation prevention, and centralized monitor synchronization.

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📋 Table of Contents

• Overview
• Features
• Architecture
• Technologies
• Getting Started
• Configuration
• Results
• Team
• License

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🎯 Overview

This project simulates a concurrent ferry transportation system where 30 independent vehicle threads (12 Cars, 10 Minibuses, 8 Trucks) and a single Ferry thread operate between Side A and Side B. The simulation demonstrates robust solutions to classic Operating System challenges including:

• 🔄 Race Conditions
• ⛔ Deadlock Avoidance
• ⏳ Starvation Prevention
• 📊 Fair Scheduling (FIFO)
• 🔒 Mutual Exclusion

The system follows a strict lifecycle: vehicles are generated, pass through toll booths, join a waiting queue, board the ferry without exceeding maximum capacity (20 units), travel to the opposite side, conduct business, and finally return to their original side to terminate.

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✨ Features

Feature	Description
Centralized Monitor Pattern	All synchronization operations managed by a single SimulationManager to eliminate nested locks and circular waits
Mesa Monitor Pattern	Uses Condition.await() / signalAll() for efficient thread coordination without busy-waiting
FIFO Discipline	Strict First-In-First-Out ordering via LinkedList queues; prevents overtaking
Bounded Wait (Timeout)	Ferry departs after timeout to prevent indefinite waiting
Consecutive Trip Limiter	Forces side switch after consecutive trips to prevent starvation of opposite side
No-Sleep-Under-Lock	All simulated delays executed outside critical sections to maximize liveness
Dynamic Configuration	Runtime-adjustable parameters via config.txt without recompilation
Fair Locking	ReentrantLock(true) with fairness policy to reduce starvation risk
State Machine	Each vehicle tracks its exact lifecycle via VehicleState enum
Comprehensive Logging	Real-time console logging with timestamps and statistics

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🏗️ Architecture

High-Level System Design

┌─────────────────┐     ┌──────────────────────────────┐     ┌─────────────────┐
│   Car Threads   │────▶│                              │◀────│                 │
├─────────────────┤     │    SimulationManager         │     │   Ferry Thread  │
│ Minibus Threads │────▶│    (Centralized Monitor)     │────▶│                 │
├─────────────────┤     │                              │     │                 │
│  Truck Threads  │────▶│  • ReentrantLock (fair)      │     │                 │
└─────────────────┘     │  • Condition Variables       │     └─────────────────┘
                        │  • FIFO Queues (Side A/B)    │
                        │  • Semaphore (Toll Booths)   │
                        └──────────────────────────────┘

Vehicle Boarding Flow

START
  │
  ▼
Acquire Lock
  │
  ▼
Is Head of Queue? ──NO──▶ await()
  │YES
  ▼
Fit in Capacity? ───NO──▶ await()
  │YES
  ▼
Board Ferry & signalAll()
  │
  ▼
Release Lock
  │
  ▼
 END

Core Components

Component	Responsibility
SimulationManager	Centralized monitor: manages all shared resources, queues, locks, and conditions
Ferry	Worker thread: manages boarding, travel, and unloading phases
Vehicle	Client thread: state machine lifecycle, invokes blocking requests to manager
Config	Dynamic configuration loader from config.txt
TimeManager	Simulation time tracking
Logger	Thread-safe console output

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🛠️ Technologies

• Language: Java 17+
• Concurrency: java.util.concurrent (ReentrantLock, Condition, Semaphore)
• Collections: LinkedList (FIFO queues), ArrayList
• Build: Platform-independent (no external dependencies)
• OS Concepts: Monitor pattern, deadlock avoidance, starvation prevention, bounded waiting

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🚀 Getting Started

Prerequisites

• Java JDK 17 or higher
• Terminal / Command Line

Compilation & Execution

# Clone the repository
git clone https://github.com/yourusername/ferry-transport-simulation.git
cd ferry-transport-simulation

# Compile all source files
javac -d . Main.java model/*.java manager/*.java enums/*.java config/*.java

# Run the simulation
java Main

Windows (Batch)

compile.bat
run.bat

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⚙️ Configuration

All simulation parameters can be adjusted in config.txt without recompiling:

# Vehicle Counts
TOTAL_CARS=12
TOTAL_MINIBUSES=10
TOTAL_TRUCKS=8

# System & Vehicle Settings
TOLL_BOOTHS_PER_SIDE=2
CAR_CAPACITY=1
MINIBUS_CAPACITY=2
TRUCK_CAPACITY=3

# Ferry Settings
FERRY_CAPACITY=20
BOARDING_TIMEOUT_SEC=3

# Delays (milliseconds)
TOLL_DELAY_MIN=200
TOLL_DELAY_MAX=600
BOARDING_DELAY_MIN=100
BOARDING_DELAY_MAX=300
TRAVEL_DELAY_MIN=1500
TRAVEL_DELAY_MAX=2500
RETURN_DELAY_MIN=2000
RETURN_DELAY_MAX=4000
TURNAROUND_DELAY=500

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📊 Results

Sample Output

Initializing Ferry Transport Simulation...

=====================================
[SYSTEM] Configuration loaded from config.txt
 -> Cars: 12, Minibuses: 10, Trucks: 8
 -> Ferry Capacity: 20
 -> Boarding Timeout: 3 sec
 -> Toll Delay Range: 200ms - 600ms
=====================================

[Time 2] Ferry is BOARDING on SIDE_A
[Time 5] CAR-1 created on SIDE_B
...

=== SIMULATION STATISTICS ===
Total Simulation Time: 19528 ms
Total Ferry Trips    : 8
Average Waiting Time : 2729 ms
Maximum Waiting Time : 7684 ms
Ferry Utilization    : 70.00%
=============================

Simulation completed safely. No deadlocks detected!

Key Metrics

Metric	Value
Total Vehicles	30
Ferry Capacity	20 units
Threads	31 (30 vehicles + 1 ferry)
Deadlocks	0
Average Utilization	~70%
Scheduling	Strict FIFO with starvation prevention

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👥 Team

Name	Student ID
Hasan ÇELİK	220315024
Emine ÇETİN	220315040
Mustafa Furkan YILMAZ	220315082

Institution: Manisa Celal Bayar University — Computer Engineering
Course: Operating Systems

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📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

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🙏 Acknowledgments

• Manisa Celal Bayar University, Computer Engineering Department
• Operating Systems course instructors