From ae49575bd9b9b0fed7b0138022081cb0a9601734 Mon Sep 17 00:00:00 2001 From: emad Date: Fri, 5 Jun 2026 21:14:39 +0430 Subject: [PATCH] implement TODOs exept bonus tasks --- README.md | 202 ----------------------------- Report.md | 39 ++++++ src/main/java/DownloadWorker.java | 20 ++- src/main/java/Main.java | 23 +++- src/main/java/ProgressMonitor.java | 6 + 5 files changed, 81 insertions(+), 209 deletions(-) delete mode 100644 README.md create mode 100644 Report.md diff --git a/README.md b/README.md deleted file mode 100644 index e5cc79c..0000000 --- a/README.md +++ /dev/null @@ -1,202 +0,0 @@ -# Eighth Assignment: Multithreading Basics - -## Table of contents -- [Introduction](#introduction) -- [Objectives 🎯](#objectives-) -- [Theoretical Questions πŸ“](#theoretical-questions-) -- [Practical Questions πŸ’»](#practical-questions-) -- [Evaluation βš–οΈ](#evaluation-) -- [Submission βŒ›](#submission-) -- [Additional Resources πŸ“š](#additional-resources-) - -## Important Note: -This project is configured as a **Maven project**. If you're opening this project in an IDE (like IntelliJ IDEA or VS Code), please ensure you import it as a Maven project so that dependencies and build settings are recognized automatically. - -To run the project from the command line, use: -```bash -mvn compile -mvn exec:java -Dexec.mainClass="Main" -``` - -## Introduction -Welcome to your Eighth Advanced Programming (AP) Assignment. This project is divided into two main sections: - -1. **Theoretical Questions**: Analyze key multithreading concepts (Start vs Run, Daemon threads, and Lambdas). -2. **Practical Questions**: Implement a **Simulated Download Manager**. You will use Java Threads to simulate downloading a file in multiple chunks concurrently. - -> **⚠️ Note:** This is a **local simulation only**. There is no actual network activity, URL connection, or socket programming involved. The goal is to practice thread management and state observation. - -## Objectives 🎯 - -By completing this assignment, you will: -- Apply **multithreading** basics using the `Thread` class and `Runnable` interface. -- Understand how to manage multiple worker threads performing independent tasks. -- Implement a monitor thread to observe the progress of other threads. -- Practice using `start()` and `join()` for thread lifecycle management. - -## Theoretical Questions πŸ“ -**Note: Please answer these questions in a Markdown file (Report.md) and place it in the root directory of your fork. Include code or screenshots where you see fit.** - -### 1. `start()` vs `run()` - -```java -public class StartVsRun { - static class MyRunnable implements Runnable { - public void run() { - System.out.println("Running in: " + Thread.currentThread().getName()); - } - } - public static void main(String[] args) throws InterruptedException { - Thread t1 = new Thread(new MyRunnable(), "Thread-1"); - System.out.println("Calling run()"); - t1.run(); - Thread.sleep(100); - - Thread t2 = new Thread(new MyRunnable(), "Thread-2"); - System.out.println("Calling start()"); - t2.start(); - } -} -``` - -**Questions:** - -- What output do you get from the program? Why? - -- What’s the difference in behavior between calling `start()` and `run()`? - ---- - -### 2. Daemon Threads - -```java -public class DaemonExample { - static class DaemonRunnable implements Runnable { - public void run() { - for(int i = 0; i < 20; i++) { - System.out.println("Daemon thread running..."); - try { - Thread.sleep(500); - } catch (InterruptedException e) { - //[Handling Exception...] - } - } - } - } - public static void main(String[] args) { - Thread thread = new Thread(new DaemonRunnable()); - thread.setDaemon(true); - thread.start(); - System.out.println("Main thread ends."); - } -} -``` - -**Questions:** -- What output do you get from the program? Why? - -- What happens if you remove `thread.setDaemon(true)`? - -- What are some real-life use cases of daemon threads? - - ---- - -### 3. A shorter way to create threads - -```java -public class ThreadDemo { - public static void main(String[] args) { - Thread thread = new Thread(() -> { - System.out.println("Thread is running using a ...!"); - }); - - thread.start(); - } -} -``` - -**Questions:** -- What output do you get from the program? - -- What is the `() -> { ... }` syntax called? - -- How is this code different from creating a class that extends `Thread` or implements `Runnable`? - - -## Practical Questions πŸ’» - -### Simulated Download Manager -You are tasked with completing a skeleton project for a download manager. The application reads a configuration file, splits a "file" into several chunks, and assigns each chunk to a dedicated worker thread. - -#### πŸ— Project Structure -- `src/main/resources/download_config.txt`: Contains simulation parameters (file size, chunk count, delays). -- `DownloadWorker.java`: The logic for simulating a chunk download (needs implementation). -- `ProgressMonitor.java`: A thread that periodically prints the total progress (needs implementation). -- `Main.java`: The entry point that initializes chunks, starts threads, and waits for completion. -- `ChunkStatus.java`: Data class holding the state of individual chunks. - -#### πŸ›  What You Need to Do -In the provided source code, look for **`// TODO`** comments. You must: - -1. **Implement `DownloadWorker`**: - - Record start/end times for each chunk. - - Use a loop to simulate progress based on the random delays and step sizes provided in the config. - - Update the shared `ChunkStatus` object so the monitor can see progress. -2. **Implement `ProgressMonitor`**: - - Periodically calculate the total downloaded megabytes across all chunks. - - Exit gracefully once all chunks are marked as completed. -3. **Complete `Main`**: - - Properly instantiate and `start()` the worker threads and the monitor thread. - - Use `join()` to ensure the main thread waits for all workers to finish before printing the final report. - -#### βš™οΈ Configuration -The simulation behavior is controlled by `src/main/resources/download_config.txt`. You can modify these values to test different scenarios (e.g., more chunks or faster/slower speeds). - ---- - -## Bonus Tasks 🌟 -- Download Speed and ETA: - - Calculate and display the current overall download speed during the simulation. - - Estimate and show the remaining time (ETA) based on the current progress and speed. - -- User Interface (UI): - - Improve the console output or design a simple UI that presents download progress in a cleaner and more intuitive way. - - Make the simulation easier to follow by showing chunk activity, total progress, and final results in a user-friendly format. - -- Real-Time Progress Bar: - - Implement a real-time progress bar that updates in place instead of printing a new line each time. - - Show smooth progress growth in the console so the output looks more like a real download manager. - -- Sequential vs Multithreaded Comparison: - - Add a mode to simulate downloading chunks sequentially (one after another) and compare it with the multithreaded version. - - Measure and report the total execution time of both approaches, and briefly analyze the difference in performance. - -## Evaluation βš–οΈ - -Your work will be evaluated based on: - -- **Thread Management**: Correct use of `start()` and `join()`. -- **Simulation Logic**: Correct implementation of the loops and random delays in the worker threads. -- **Thread Safety**: Following the constraint of each worker only writing to its own assigned object. -- **Code Quality**: Readable code and proper use of Java conventions. - -**Total: 500 points** -- 🧠 Theoretical Questions – 150 points -- πŸ’» Practical Task (Download Manager) – 350 points - -## Submission βŒ› - -1. Add your mentor as a contributor to the project. -2. Create a `develop` branch for implementing features. -3. Use Git for regular code commits. -4. Push your code and the answers file (Report.md) to the remote repository. -5. Submit a pull request to merge the `develop` branch with `main`. - -**Deadline:** **Friday, June 5** (15th of Khordad) - -## Additional Resources πŸ“š - -- [Java Concurrency and Multithreading](https://jenkov.com/tutorials/java-concurrency/index.html) -- [Creating and Starting Java Threads](https://jenkov.com/tutorials/java-concurrency/creating-and-starting-threads.html) -- [Thread.join() explained](https://docs.oracle.com/javase/8/docs/api/java/lang/Thread.html#join--) \ No newline at end of file diff --git a/Report.md b/Report.md new file mode 100644 index 0000000..2c42543 --- /dev/null +++ b/Report.md @@ -0,0 +1,39 @@ +# Answers of theoretical questions + +## 1: + +**outputs:** + + Calling run() + Running in: main + Calling start() + Running in: Thread-2 + +this is because of the difference between run() and start() method. +when you call run method, it only calls the run function of StartVsRun class and it runs on the main thread; +but when you call **start** method it runs on new thread(here we name it Thread-2) +--- +## 2: + +**outputs:** + + Main thread ends. + Daemon thread running... + +if we set daemon true The **JVM** terminates the thread right after the main thread ends. +if we don't set the thread as a daemon, after the main thread ended it will continue it's work until it will be done(print Daemon thread running 20 times). + + +### Real-Life use case of daemon threads: + +- Memory and Resource Management(like java's garbage collector) +- Infrastructure & Telemetry Monitoring(like send a ping to a central server every 5 seconds) +- Spell Checkers + +## 3: + +**output:** + + Thread is running using a ...! + +it calls **Lambda Expression** and it is shorter and faster way than making a class which extend thread or implement runnable to have another thread for our works. \ No newline at end of file diff --git a/src/main/java/DownloadWorker.java b/src/main/java/DownloadWorker.java index 546de2d..b30bd39 100644 --- a/src/main/java/DownloadWorker.java +++ b/src/main/java/DownloadWorker.java @@ -23,21 +23,37 @@ public class DownloadWorker implements Runnable { public void run() { // TODO: Record the chunk start time in chunkStatus. double downloaded = 0.0; - + chunkStatus.setStartTimeMs(System.currentTimeMillis()); // TODO: Print a message that this chunk has started downloading. + System.out.println("Chunk " + chunkStatus.getChunkId() + " has started downloading."); while (downloaded < chunkStatus.getChunkSizeMB()) { // TODO: Generate a random sleep delay between min and max delay. // TODO: Sleep for that delay. + try { + Thread.sleep(random.nextInt(config.getMinStepDelayMs(), config.getMaxStepDelayMs())); + } catch (InterruptedException e) { + throw new RuntimeException(e); + } // TODO: Generate a random download amount for this step. // TODO: Increase downloaded, but do not go beyond chunk size. + downloaded += random.nextDouble(config.getMinStepDownloadMB(), config.getMaxStepDownloadMB()); + if(downloaded > chunkStatus.getChunkSizeMB()) + { + downloaded = chunkStatus.getChunkSizeMB(); + } // TODO: Save the updated downloaded value into chunkStatus. + chunkStatus.setDownloadedMB(downloaded); // TODO: Optionally print step-by-step progress. + System.out.println(chunkStatus); } - // TODO: Mark the chunk as completed. + chunkStatus.setCompleted(true); + // TODO: Record the chunk end time in chunkStatus. + chunkStatus.setEndTimeMs(System.currentTimeMillis()); // TODO: Print a message that this chunk has finished downloading. + System.out.println("Chunk " + chunkStatus.getChunkId() + " has finished downloading."); } } diff --git a/src/main/java/Main.java b/src/main/java/Main.java index 82bd239..79e4ab5 100644 --- a/src/main/java/Main.java +++ b/src/main/java/Main.java @@ -37,6 +37,7 @@ public class Main { // TODO: // Students may print helpful debug information here, // for example which chunk is assigned to which worker thread. + System.out.println("Chunk " + chunk.getChunkId() + " assigned to " + workerThread.getName()); } // 4. Create and start monitor thread @@ -48,12 +49,16 @@ public class Main { // so that progress can be displayed while downloading happens. // // Example idea: - // monitorThread.start(); + monitorThread.start(); // 5. Start worker threads // TODO: // Start each worker thread in workerThreads. // Use a loop and call start() on each thread. + for(Thread worker: workerThreads) + { + worker.start(); + } // 6. Wait for workers to finish // TODO: @@ -61,9 +66,13 @@ public class Main { // This should be done inside a try-catch block for InterruptedException. // // Hint: - // for (Thread thread : workerThreads) { - // thread.join(); - // } + try { + for (Thread thread : workerThreads) { + thread.join(); + } + } catch (InterruptedException e) { + throw new RuntimeException(e); + } // TODO: // After all workers finish, the monitor thread may also need to stop. @@ -72,7 +81,11 @@ public class Main { // - add a stopping mechanism in ProgressMonitor later. // // If your monitor finishes automatically, you may join it here. - + try { + monitorThread.join(); + } catch (InterruptedException e) { + throw new RuntimeException(e); + } // NOTE: // this final report may show 0 progress because no worker has actually run yet. // Until students complete the thread start/join TODOs above, diff --git a/src/main/java/ProgressMonitor.java b/src/main/java/ProgressMonitor.java index 475c0e0..b5018c5 100644 --- a/src/main/java/ProgressMonitor.java +++ b/src/main/java/ProgressMonitor.java @@ -57,6 +57,12 @@ public class ProgressMonitor implements Runnable { // TODO: // If all chunks are completed, print a final message and exit the loop + if(completedChunks == chunks.size()) + { + System.out.println("file has finished downloading"); + break; + } + try { Thread.sleep(monitorDelayMs);