Implemented chat client simulation

src/Main.java

@@ -2,25 +2,40 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 import java.util.stream.IntStream;
 import model.BlockChain;
+import model.ChatClient;
 import model.Miner;
 
 public final class Main {
 
     public static void main(final String[] args) throws InterruptedException {
+        final var nThreads = Runtime.getRuntime().availableProcessors();
         final var blockChain = new BlockChain();
         blockChain.load();
 
-        final var nThreads = Runtime.getRuntime().availableProcessors();
-        final var executor = Executors.newFixedThreadPool(nThreads);
+        final var chatExecutor = Executors.newScheduledThreadPool(nThreads);
 
+        // Mocks 3 chat clients who send messages to the blockchain
+        IntStream.range(0, 3)
+                .mapToObj(chatClientId -> new ChatClient(chatClientId, blockChain))
+                .forEach(e -> chatExecutor.scheduleAtFixedRate(e, 0, 100, TimeUnit.MILLISECONDS));
+
+        final var minerExecutor = Executors.newFixedThreadPool(nThreads);
+
+        // Creation of 5 miners
         IntStream.range(0, 5)
-            .mapToObj(minerId -> new Miner(minerId, blockChain))
-            .forEach(executor::submit);
+                .mapToObj(minerId -> new Miner(minerId, blockChain))
+                .forEach(minerExecutor::submit);
 
-        executor.shutdown();
+        minerExecutor.shutdown();
 
-        if (!executor.awaitTermination(60, TimeUnit.SECONDS)) {
-            executor.shutdownNow();
+        if (!minerExecutor.awaitTermination(60, TimeUnit.SECONDS)) {
+            minerExecutor.shutdownNow();
+        }
+
+        chatExecutor.shutdown();
+
+        if (!chatExecutor.awaitTermination(60, TimeUnit.SECONDS)) {
+            chatExecutor.shutdownNow();
         }
 
         blockChain.save();

src/model/Block.java

@@ -1,32 +1,39 @@
 package model;
 
-import static java.lang.String.valueOf;
-
-import util.HashFunction;
 import java.io.Serializable;
 import java.util.Date;
-import java.util.Random;
+import java.util.List;
+import java.util.stream.Collectors;
 
 public class Block implements Serializable {
 
   private static final long serialVersionUID = 1L;
   private final String previousBlockHash;
+  private final String blockHash;
   private final int minerId;
   private final int id;
-  private final int hashZeroes;
+  private final int magicNumber;
+  private final float generationSecs;
+  private final List<String> chatMessages;
   private final long timeStamp;
-  private final String blockHash;
-  private final transient Random random = new Random();
-  private int magicNumber;
-  private float generationSecs = 0;
 
-  public Block(final String previousBlockHash,final int minerId, final int id, final int hashZeroes) {
+  public Block(
+          final String previousBlockHash,
+          final String blockHash,
+          final int minerId,
+          final int id,
+          final int magicNumber,
+          final float generationSecs,
+          final List<String> chatMessages
+  ) {
     this.previousBlockHash = previousBlockHash;
+    this.blockHash = blockHash;
     this.minerId = minerId;
     this.id = id;
-    this.hashZeroes = hashZeroes;
+    this.magicNumber = magicNumber;
+    this.generationSecs = generationSecs;
+    this.chatMessages = chatMessages;
     this.timeStamp = new Date().getTime();
-    this.blockHash = calculateBlockHash();
   }
 
   public String getBlockHash() {
@@ -37,35 +44,23 @@ public class Block implements Serializable {
     return previousBlockHash;
   }
 
-  public float getGenerationSecs() {
-    return generationSecs;
-  }
-
-  private String calculateBlockHash() {
-    final long start = System.currentTimeMillis();
-    var hash = "";
-    do {
-      hash = HashFunction.applySha256(this.id + valueOf(this.timeStamp) + calculateMagicNumber());
-    } while (!hash.matches("(?s)0{" + hashZeroes + "}([^0].*)?"));
-    final long end = System.currentTimeMillis();
-    generationSecs = (end - start) / 1000F;
-    return hash;
-  }
-
-  private int calculateMagicNumber() {
-    magicNumber = random.nextInt();
-    return magicNumber;
-  }
-
   public String toString() {
     return "Block: " + "\n"
-        + "Created by miner #" + this.minerId + "\n"
-        + "Id: " + this.id + "\n"
-        + "Timestamp: " + this.timeStamp + "\n"
-        + "Magic number: " + this.magicNumber + "\n"
-        + "Hash of the previous block: " + "\n" + this.previousBlockHash + "\n"
-        + "Hash of the block: \n" + this.blockHash + "\n"
-        + "Block was generating for " + this.generationSecs + " seconds";
+            + "Created by miner #" + this.minerId + "\n"
+            + "Id: " + this.id + "\n"
+            + "Timestamp: " + this.timeStamp + "\n"
+            + "Magic number: " + this.magicNumber + "\n"
+            + "Hash of the previous block: " + "\n" + this.previousBlockHash + "\n"
+            + "Hash of the block: \n" + this.blockHash + "\n"
+            + "Block data: \n"
+            + getMessages()
+            + "Block was generating for " + this.generationSecs + " seconds";
+  }
+
+  public String getMessages() {
+    return chatMessages.stream()
+            .map(m -> m.concat("\n"))
+            .collect(Collectors.joining());
   }
 
 }

src/model/BlockChain.java

@@ -1,46 +1,80 @@
 package model;
 
 import util.FileManagement;
-import java.util.LinkedList;
-import java.util.List;
+import util.HashFunction;
+
+import java.util.*;
 import java.util.stream.Collectors;
 
+import static java.lang.String.valueOf;
+
 public class BlockChain {
 
+  private final Random random = new Random();
+  private final List<Block> blockList = new LinkedList<>();
+  private final List<String> chatMessages = new ArrayList<>();
   private int hashZeroes;
-  private static final List<Block> blockList = new LinkedList<>();
+  private int magicNumber;
+  private float generationSecs = 0;
 
   public synchronized void addBlock(final int minerId) {
     final int nextId = blockList.size();
     final String previousBlockHash = (nextId > 0) ? blockList.get(nextId - 1).getBlockHash() : "0";
+    final String blockHash = calculateBlockHash(minerId);
 
-    final var block = new Block(previousBlockHash, minerId, nextId, hashZeroes);
+    final var block = new Block(
+            previousBlockHash,
+            blockHash,
+            minerId,
+            nextId,
+            magicNumber,
+            generationSecs,
+            chatMessages
+    );
     blockList.add(block);
+    System.out.println(block);
+    this.chatMessages.clear();
 
-    final float generationTime = blockList.get(nextId).getGenerationSecs();
-    final String CASE;
-
-    if (generationTime < 10) {
+    if (generationSecs < 1) {
       hashZeroes += 1;
-      CASE = "N was increased to " + hashZeroes + "\n";
-    } else if (generationTime > 60) {
+      System.out.println("N was increased to " + hashZeroes +"\n");
+    } else if (generationSecs > 10) {
       hashZeroes -= 1;
-      CASE = "N was decreased by 1" + "\n";
+      System.out.println("N was decreased by 1\n");
     } else {
-      CASE = "N stays the same";
+      System.out.println("N stays the same\n");
     }
 
-    System.out.println(block);
-    System.out.println(CASE);
   }
 
-  public boolean validateBlockchain() {
+  public void acceptMessage(String message) {
+    if (!blockList.isEmpty()) {
+      chatMessages.add(message);
+    }
+  }
+
+  public void load() {
+    FileManagement.loadBlockchain(blockList);
+  }
+
+  public void save() {
+    FileManagement.saveBlockchain(blockList);
+  }
+
+  public String toString() {
+    if (!validateBlockchain()) {
+      System.out.println("Blockchain invalid!");
+    }
+    return blockList.stream().map(Block::toString).collect(Collectors.joining("\n"));
+  }
+
+  private boolean validateBlockchain() {
     if (blockList.isEmpty()) {
       return true;
     }
 
     final List<String> previousHashes = blockList.stream().map(Block::getPreviousBlockHash).collect(
-        Collectors.toList());
+            Collectors.toList());
     final List<String> hashes = blockList.stream().map(Block::getBlockHash).collect(Collectors.toList());
 
     for (var index = 1; index < hashes.size(); index++) {
@@ -52,19 +86,23 @@ public class BlockChain {
     return true;
   }
 
-  public String toString() {
-    if (!validateBlockchain()) {
-      System.out.println("Blockchain invalid!");
-    }
-    return blockList.stream().map(Block::toString).collect(Collectors.joining("\n"));
+  private String calculateBlockHash(final int minerId) {
+    final long start = System.currentTimeMillis();
+    var hash = "";
+    do {
+      hash = HashFunction.applySha256(minerId
+              + valueOf(new Date().getTime())
+              + calculateMagicNumber()
+      );
+    } while (!hash.matches("(?s)0{" + hashZeroes + "}([^0].*)?"));
+    final long end = System.currentTimeMillis();
+    generationSecs = (end - start) / 1000F;
+    return hash;
   }
 
-  public void load() {
-    FileManagement.loadBlockchain(blockList);
-  }
-
-  public void save() {
-    FileManagement.saveBlockchain(blockList);
+  private int calculateMagicNumber() {
+    magicNumber = random.nextInt();
+    return magicNumber;
   }
 
 }

src/model/ChatClient.java

@@ -0,0 +1,31 @@
+package model;
+
+import java.util.Random;
+
+public class ChatClient implements Runnable {
+
+    private final int clientId;
+    private final BlockChain blockChain;
+    private static final Random random = new Random();
+
+    public ChatClient(int chatClientId, BlockChain blockChain) {
+        this.clientId = chatClientId;
+        this.blockChain = blockChain;
+    }
+
+    @Override
+    public void run() {
+        blockChain.acceptMessage(generateRandomAlphabeticString());
+    }
+
+    private String generateRandomAlphabeticString() {
+        int leftLimit = 97; // letter 'a'
+        int rightLimit = 122; // letter 'z'
+        int targetStringLength = 10;
+
+        return "Client " + clientId + " says: " + random.ints(leftLimit, rightLimit + 1)
+                .limit(targetStringLength)
+                .collect(StringBuilder::new, StringBuilder::appendCodePoint, StringBuilder::append)
+                .toString();
+    }
+}