From 45c3e4dd8ff8cdd1a227025e5f33b68fd348ffa5 Mon Sep 17 00:00:00 2001 From: Amir Ali Amiri Date: Sat, 27 Jun 2026 13:24:03 +0330 Subject: [PATCH] Implement simulated core download manager multithreading logic --- README.md | 221 +++++------------------------ src/main/java/DownloadWorker.java | 41 ++++-- src/main/java/Main.java | 49 +++---- src/main/java/ProgressMonitor.java | 21 +-- 4 files changed, 88 insertions(+), 244 deletions(-) diff --git a/README.md b/README.md index e5cc79c..506c3f4 100644 --- a/README.md +++ b/README.md @@ -1,202 +1,53 @@ -# Eighth Assignment: Multithreading Basics +
-## Table of contents -- [Introduction](#introduction) -- [Objectives 🎯](#objectives-) -- [Theoretical Questions 📝](#theoretical-questions-) -- [Practical Questions 💻](#practical-questions-) -- [Evaluation ⚖️](#evaluation-) -- [Submission ⌛](#submission-) -- [Additional Resources 📚](#additional-resources-) +# گزارش پروژه هشتم - برنامه‌نویسی پیشرفته -## 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 📝 -**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 💻 - -### 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. - -#### 🏗 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. - -#### 🛠 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. - -#### ⚙️ 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). +**نام دانشجو:** امیرعلی امیری +**درس:** برنامه‌نویسی پیشرفته (AP) --- -## 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. +## بخش اول: مقایسه `start()` و `run()` -- 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. +### ۱. خروجی برنامه و دلیل آن +* **خروجی فراخوانی `t1.run()`:** عبارت `Running in: main` +* **خروجی فراخوانی `t2.start()`:** عبارت `Running in: Thread-2` -- 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. +**دلیل:** هنگام فراخوانی مستقیم متد `t1.run()`، نخ (Thread) جدیدی ساخته نمی‌شود؛ به همین دلیل کدهای درون این متد مانند یک متد معمولی و به صورت خط‌به‌خط، داخل همان نخ فعلی (یعنی نخ `main`) اجرا می‌شوند. +اما با فراخوانی متد `t2.start()`، به ماشین مجازی جاوا (JVM) درخواست داده می‌شود تا یک نخ کاملاً جدید و مستقل ایجاد کند. پس از ایجاد این نخ، متد `run()` درون آن و به صورت موازی با نخ اصلی اجرا خواهد شد. -- 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. +### ۲. تفاوت رفتاری +* **متد `start()`:** به صورت غیرهمگام (Asynchronous) عمل می‌کند. این متد با ایجاد یک Call Stack مجزا برای نخ جدید، امکان اجرای هم‌زمان وظایف مختلف را فراهم می‌سازد. +* **متد `run()`:** به صورت همگام (Synchronous) عمل می‌کند و رفتار آن کاملاً مشابه یک متد عادی است؛ در نتیجه، نخ فعلی را تا زمان اتمام اجرای کدهای خود متوقف (Block) می‌کند. -## Evaluation ⚖️ +--- -Your work will be evaluated based on: +## بخش دوم: نخ‌های پس‌زمینه (Daemon Threads) -- **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. +### ۱. خروجی برنامه و دلیل آن +* **خروجی:** معمولاً برنامه تنها با چاپ خط `Main thread ends.` پایان می‌یابد. -**Total: 500 points** -- 🧠 Theoretical Questions – 150 points -- 💻 Practical Task (Download Manager) – 350 points +**دلیل:** در جاوا، به محض اتمام کار تمامی نخ‌های کاربر (User Threads یا همان نخ‌های غیر دیمن)، ماشین مجازی جاوا (JVM) به طور خودکار بسته می‌شود. از آنجا که نخ `main` بلافاصله پس از فعال‌سازی نخ دیمن به پایان می‌رسد، JVM نیز کار برنامه را خاتمه می‌دهد و منتظر کامل شدن حلقه نخ دیمن نمی‌ماند. -## Submission ⌛ +### ۲. حذف خط `thread.setDaemon(true)` +در صورت حذف این خط، نخ به یک نخ کاربر معمولی تبدیل می‌شود. در این حالت، حتی پس از اتمام کار نخ `main`، ماشین مجازی جاوا روشن باقی می‌ماند و منتظر می‌شود تا این نخ تمام ۲۰ دور حلقه خود را (که حدود ۱۰ ثانیه زمان می‌برد) به طور کامل اجرا کند. -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`. +### ۳. کاربردهای واقعی نخ‌های Daemon +* **سیستم زباله‌روبی جاوا (Garbage Collection):** مدیریت و آزاد‌سازی حافظه بلااستفاده در پس‌زمینه برنامه. +* **نخ‌های مانیتورینگ:** بررسی مداوم وضعیت سلامت و میزان مصرف منابع سیستم در پس‌زمینه. +* **سیستم ذخیره خودکار (Auto-Save):** ذخیره‌سازی دوره‌ای اطلاعات در بازی‌ها یا نرم‌افزارهای ویرایشگر، بدون ایجاد وقفه در جریان اصلی برنامه. -**Deadline:** **Friday, June 5** (15th of Khordad) +--- -## Additional Resources 📚 +## بخش سوم: روش کوتاه‌تر برای ساخت نخ‌ها (Lambda Expression) -- [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 +### ۱. خروجی برنامه +* **خروجی:** عبارت `Thread is running using a ...!` در کنسول چاپ می‌شود. + +### ۲. نام این سینتکس +به سینتکس `() -> { ... }` اصطلاحاً **Lambda Expression** (عبارت لمبدا) می‌گویند. + +### ۳. تفاوت با روش‌های سنتی +در روش‌های سنتی باید یک کلاس مجزا به صورت مشتق‌شده از `Thread` ایجاد می‌کردیم یا اینترفیس `Runnable` را از طریق یک کلاس جداگانه یا بی‌نام (Anonymous Class) پیاده‌سازی می‌نمودیم. اما با استفاده از عبارت لمبدا، نیازی به نوشتن این کدهای تکراری و اضافی نیست و می‌توان پیاده‌سازی تنها متد انتزاعی اینترفیس (یعنی متد `run`) را به صورت مستقیم و خلاصه به سازنده کلاس `Thread` پاس داد. این کار خوانایی کد را افزایش می‌دهد، در حالی که عملکرد آن در پشت صحنه هیچ تفاوتی با روش‌های گذشته ندارد. + +
\ No newline at end of file diff --git a/src/main/java/DownloadWorker.java b/src/main/java/DownloadWorker.java index 546de2d..6be56e3 100644 --- a/src/main/java/DownloadWorker.java +++ b/src/main/java/DownloadWorker.java @@ -21,23 +21,40 @@ public class DownloadWorker implements Runnable { @Override public void run() { - // TODO: Record the chunk start time in chunkStatus. + chunkStatus.setStartTimeMs(System.currentTimeMillis()); double downloaded = 0.0; - // TODO: Print a message that this chunk has started downloading. + System.out.println("Worker for Chunk #" + chunkStatus.getChunkId() + " has started."); while (downloaded < chunkStatus.getChunkSizeMB()) { - // TODO: Generate a random sleep delay between min and max delay. - // TODO: Sleep for that delay. - // TODO: Generate a random download amount for this step. - // TODO: Increase downloaded, but do not go beyond chunk size. - // TODO: Save the updated downloaded value into chunkStatus. - // TODO: Optionally print step-by-step progress. + // محاسبه زمان تاخیر تصادفی در محدوده مجاز کانفیگ + int delayRange = config.getMaxStepDelayMs() - config.getMinStepDelayMs(); + int sleepDelay = config.getMinStepDelayMs() + (delayRange > 0 ? random.nextInt(delayRange + 1) : 0); + + try { + Thread.sleep(sleepDelay); + } catch (InterruptedException e) { + System.out.println("Worker for Chunk #" + chunkStatus.getChunkId() + " was interrupted."); + return; + } + + // محاسبه حجم دانلود تصادفی در این گام + double sizeRange = config.getMaxStepDownloadMB() - config.getMinStepDownloadMB(); + double stepDownload = config.getMinStepDownloadMB() + (sizeRange > 0 ? random.nextDouble() * sizeRange : 0); + + // اضافه کردن حجم دانلود شده بدون تجاوز از حجم کل چانک + downloaded += stepDownload; + if (downloaded > chunkStatus.getChunkSizeMB()) { + downloaded = chunkStatus.getChunkSizeMB(); + } + + chunkStatus.setDownloadedMB(downloaded); } - // TODO: Mark the chunk as completed. - // TODO: Record the chunk end time in chunkStatus. - // TODO: Print a message that this chunk has finished downloading. + chunkStatus.setCompleted(true); + chunkStatus.setEndTimeMs(System.currentTimeMillis()); + + System.out.println("Worker for Chunk #" + chunkStatus.getChunkId() + " has finished downloading."); } -} +} \ No newline at end of file diff --git a/src/main/java/Main.java b/src/main/java/Main.java index 82bd239..8aca790 100644 --- a/src/main/java/Main.java +++ b/src/main/java/Main.java @@ -34,48 +34,33 @@ public class Main { workerThreads.add(workerThread); - // TODO: - // Students may print helpful debug information here, - // for example which chunk is assigned to which worker thread. + // چاپ جزییات تخصیص چانک به نخ‌ها جهت دیباگ کردن برنامه + System.out.println("Assigned Chunk #" + chunk.getChunkId() + " (" + chunk.getChunkSizeMB() + " MB) to " + workerThread.getName()); } // 4. Create and start monitor thread ProgressMonitor monitor = new ProgressMonitor(config, chunks); Thread monitorThread = new Thread(monitor, "Progress-Monitor"); - // TODO: - // Start the monitor thread before starting the workers - // 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 thread : workerThreads) { + thread.start(); + } // 6. Wait for workers to finish - // TODO: - // Wait for all worker threads to complete by calling join(). - // This should be done inside a try-catch block for InterruptedException. - // - // Hint: - // for (Thread thread : workerThreads) { - // thread.join(); - // } + try { + // انتظار برای به پایان رسیدن تک تک ورکرهای دانلود چانک‌ها + for (Thread thread : workerThreads) { + thread.join(); + } - // TODO: - // After all workers finish, the monitor thread may also need to stop. - // Depending on how ProgressMonitor is implemented, students may: - // - wait for it to finish on its own, or - // - add a stopping mechanism in ProgressMonitor later. - // - // If your monitor finishes automatically, you may join it here. - - // NOTE: - // this final report may show 0 progress because no worker has actually run yet. - // Until students complete the thread start/join TODOs above, + // انتظار برای اتمام کار نخ مانیتور + monitorThread.join(); + } catch (InterruptedException e) { + System.out.println("Main thread was interrupted while waiting for threads."); + } // 7. Print final report System.out.println(); @@ -104,4 +89,4 @@ public class Main { System.out.println("Downloaded total: " + downloadedMB + "/" + config.getTotalSizeMB() + " MB"); System.out.println("Simulation finished."); } -} +} \ No newline at end of file diff --git a/src/main/java/ProgressMonitor.java b/src/main/java/ProgressMonitor.java index 475c0e0..8930d5a 100644 --- a/src/main/java/ProgressMonitor.java +++ b/src/main/java/ProgressMonitor.java @@ -16,17 +16,6 @@ public class ProgressMonitor implements Runnable { @Override public void run() { - // TODO: - // Repeatedly check chunk progress until all chunks are completed. - // In each loop: - // 1. Read the downloaded size from every chunk - // 2. Add all downloaded amounts to totalDownloadedMB - // 3. Count completed chunks - // 4. Print a progress message - // 5. If completedChunks == chunks.size(), print a final monitor message and stop - // 6. Otherwise sleep for monitorDelayMs and continue - - while (true) { double totalDownloadedMB = 0.0; int completedChunks = 0; @@ -54,9 +43,11 @@ public class ProgressMonitor implements Runnable { chunks.size() ); - - // TODO: - // If all chunks are completed, print a final message and exit the loop + // بررسی پایان دانلود تمام چانک‌ها برای خروج از حلقه مانیتور + if (completedChunks == chunks.size()) { + System.out.println("Progress Monitor: All chunks completed successfully. Exiting monitor thread."); + break; + } try { Thread.sleep(monitorDelayMs); @@ -66,4 +57,4 @@ public class ProgressMonitor implements Runnable { } } } -} +} \ No newline at end of file