HW8

src/main/java/DownloadWorker.java

@@ -1,12 +1,5 @@
 import java.util.Random;
 
-/**
- * Simulates downloading a single chunk of a file.
- *
- * <p>This class is intentionally provided as a skeleton for students.
- * The main multithreading and simulation logic should be completed
- * in the run() method.</p>
- */
 public class DownloadWorker implements Runnable {
 
     private final ChunkStatus chunkStatus;
@@ -21,23 +14,36 @@ public class DownloadWorker implements Runnable {
 
     @Override
     public void run() {
-        // TODO: Record the chunk start time in chunkStatus.
+        chunkStatus.setStartTimeMs(System.currentTimeMillis());
+        System.out.println(Thread.currentThread().getName() + " started downloading.");
+
         double downloaded = 0.0;
+        double chunkSize = chunkStatus.getChunkSizeMB();
 
-        // TODO: Print a message that this chunk has started downloading.
+        while (downloaded < chunkSize) {
+            int delayMs = config.getMinStepDelayMs() + random.nextInt(config.getMaxStepDelayMs() - config.getMinStepDelayMs() + 1);
 
-        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.
+            try {
+                Thread.sleep(delayMs);
+            } catch (InterruptedException e) {
+                System.out.println(Thread.currentThread().getName() + " was interrupted.");
+                return;
+            }
+
+            double stepDownload = config.getMinStepDownloadMB() + (config.getMaxStepDownloadMB() - config.getMinStepDownloadMB()) * random.nextDouble();
+            downloaded += stepDownload;
+
+            if (downloaded > chunkSize) {
+                downloaded = chunkSize;
+            }
+
+            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(Thread.currentThread().getName() + " finished downloading.");
     }
 
-}
+}

src/main/java/Main.java

@@ -5,7 +5,6 @@ public class Main {
     public static void main(String[] args) {
         System.out.println("=== Simulated Download Manager ===");
 
-        // 1. Read config
         DownloadConfig config;
         try {
             config = ConfigReader.readConfig("download_config.txt");
@@ -19,13 +18,11 @@ public class Main {
         System.out.println("Chunk count: " + config.getChunkCount());
         System.out.println();
 
-        // 2. Create chunks
         List<ChunkStatus> chunks = ChunkUtils.createChunks(
                 config.getTotalSizeMB(),
                 config.getChunkCount()
         );
 
-        // 3. Create worker threads
         List<Thread> workerThreads = new ArrayList<>();
 
         for (ChunkStatus chunk : chunks) {
@@ -33,51 +30,32 @@ public class Main {
             Thread workerThread = new Thread(worker, "Worker-" + chunk.getChunkId());
 
             workerThreads.add(workerThread);
-
-            // TODO:
-            // Students may print helpful debug information here,
-            // for example which chunk is assigned to which worker thread.
+            System.out.println("Assigned Chunk " + chunk.getChunkId() + " 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();
-        // }
+        for (Thread thread : workerThreads) {
+            try {
+                thread.join();
+            } catch (InterruptedException e) {
+                System.out.println("Main thread interrupted while waiting for " + thread.getName());
+            }
+        }
 
-        // 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.
+        try {
+            monitorThread.join();
+        } catch (InterruptedException e) {
+            System.out.println("Main thread interrupted while waiting for progress monitor.");
+        }
 
-        // 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 ===");
 
@@ -104,4 +82,4 @@ public class Main {
         System.out.println("Downloaded total: " + downloadedMB + "/" + config.getTotalSizeMB() + " MB");
         System.out.println("Simulation finished.");
     }
-}
+}

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 +43,10 @@ public class ProgressMonitor implements Runnable {
                     chunks.size()
             );
 
-
-            // TODO:
-            // If all chunks are completed, print a final message and exit the loop
+            if (completedChunks == chunks.size()) {
+                System.out.println("Progress monitor: All chunks completed.");
+                break;
+            }
 
             try {
                 Thread.sleep(monitorDelayMs);
@@ -66,4 +56,4 @@ public class ProgressMonitor implements Runnable {
             }
         }
     }
-}
+}