Merge pull request 'HW08' (#1) from develop into main

Reviewed-on: Arefe00/HW-08-Basic-Multithreading#1

Report.md

@@ -0,0 +1,71 @@
+Report
+
+1. start() vs run()
+
+What output do you get from the program? Why?
+
+The output is usually something like this:
+Calling run()
+Running in: main
+Calling start()
+Running in: Thread-2
+
+When we call "run()" directly, no new thread is created and the code runs in the main thread. That's why "main" is printed.
+
+However, when we call "start()", Java creates a new thread and then executes the "run()" method inside that thread, so the thread name becomes "Thread-2".
+
+What's the difference between calling "start()" and "run()"?
+
+The "run()" method behaves like a normal method call and does not create a new thread.
+
+The "start()" method creates a new thread and allows concurrent execution. Internally, it automatically calls the "run()" method.
+
+---
+
+2. Daemon Threads
+
+What output do you get from the program? Why?
+
+The output is usually:
+
+Main thread ends.
+
+Sometimes a few lines of
+
+Daemon thread running...
+
+may also appear.
+
+This happens because daemon threads run in the background. As soon as the main thread finishes, the JVM stops all daemon threads, even if they have not completed their work.
+
+What happens if you remove "thread.setDaemon(true)"?
+
+If we remove this line, the thread becomes a normal user thread. In this case, the JVM waits until the thread finishes all 20 iterations before terminating the program.
+
+What are some real-life use cases of daemon threads?
+
+Examples include:
+
+- Garbage collection
+- Background logging
+- Cache cleanup
+- Monitoring system resources
+- Periodic maintenance tasks
+
+---
+
+3. A shorter way to create threads
+
+What output do you get from the program?
+
+Thread is running using a ...!
+
+What is the "() -> { ... }" syntax called?
+
+This syntax is called a Lambda Expression.
+
+How is this code different from creating a class that extends "Thread" or implements "Runnable"?
+
+Using lambda expressions makes the code shorter and easier to read. Instead of creating a separate class for "Runnable", we can write the thread's behavior directly where we create the thread.
+
+This reduces extra code and makes the program cleaner.

src/main/java/DownloadWorker.java

@@ -22,22 +22,50 @@ 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("Chunk #" + chunkStatus.getChunkId() + " started downloading.");
 
         while (downloaded < chunkStatus.getChunkSizeMB()) {
             // TODO: Generate a random sleep delay between min and max delay.
+            int delay = random.nextInt(
+                    config.getMaxStepDelayMs() - config.getMinStepDelayMs() + 1)
+                    + config.getMinStepDelayMs();
             // TODO: Sleep for that delay.
+            try {
+                Thread.sleep(delay);
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+
             // TODO: Generate a random download amount for this step.
+            double stepDownload =
+                    config.getMinStepDownloadMB() +
+                            (config.getMaxStepDownloadMB() - config.getMinStepDownloadMB()) * random.nextDouble();
+
             // TODO: Increase downloaded, but do not go beyond chunk size.
+            downloaded += stepDownload;
+            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() + " finished downloading.");
+
     }
 
 }

src/main/java/Main.java

@@ -35,8 +35,9 @@ public class Main {
             workerThreads.add(workerThread);
 
             // 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
@@ -44,64 +45,52 @@ public class Main {
         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();
-
-        // 5. Start worker threads
-        // TODO:
-        // Start each worker thread in workerThreads.
-        // Use a loop and call start() on each thread.
-
-        // 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();
-        // }
+        monitorThread.start();
 
         // 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,
-
-        // 7. Print final report
-        System.out.println();
-        System.out.println("=== Final Report ===");
-
-        int completedChunks = 0;
-        double downloadedMB = 0.0;
-
-        for (ChunkStatus chunk : chunks) {
-            downloadedMB += chunk.getDownloadedMB();
-
-            if (chunk.isCompleted()) {
-                completedChunks++;
+        for (Thread thread : workerThreads){
+            thread.start();
+        }
+        // TODO:
+        try{
+            for (Thread thread : workerThreads) {
+                thread.join();
             }
-
-            System.out.println(
-                    "Chunk " + chunk.getChunkId()
-                            + ": " + chunk.getDownloadedMB()
-                            + "/" + chunk.getChunkSizeMB()
-                            + " MB"
-            );
+        }
+        catch (InterruptedException e) {
+            System.out.println("Main thread interrupted.");
         }
 
-        System.out.println();
-        System.out.println("Completed chunks: " + completedChunks + "/" + chunks.size());
-        System.out.println("Downloaded total: " + downloadedMB + "/" + config.getTotalSizeMB() + " MB");
-        System.out.println("Simulation finished.");
-    }
-}
+                // TODO:
+                try {
+                    monitorThread.join();
+                }catch (InterruptedException e) {
+                    System.out.println("Monitor thread interrupted.");
+                }
+                System.out.println();
+                System.out.println("=== Final Report ===");
+
+                int completedChunks = 0;
+                double downloadedMB = 0.0;
+
+                for (ChunkStatus chunk : chunks) {
+                    downloadedMB += chunk.getDownloadedMB();
+
+                    if (chunk.isCompleted()) {
+                        completedChunks++;
+                    }
+
+                    System.out.println(
+                            "Chunk " + chunk.getChunkId()
+                                    + ": " + chunk.getDownloadedMB()
+                                    + "/" + chunk.getChunkSizeMB()
+                                    + " MB"
+                    );
+                }
+
+                System.out.println();
+                System.out.println("Completed chunks: " + completedChunks + "/" + chunks.size());
+                System.out.println("Downloaded total: " + downloadedMB + "/" + config.getTotalSizeMB() + " MB");
+                System.out.println("Simulation finished.");
+            }
+        }

src/main/java/ProgressMonitor.java

@@ -57,6 +57,10 @@ 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("All cchunks have been downloadeed.Monitor stopped.");
+                break;
+            }
 
             try {
                 Thread.sleep(monitorDelayMs);