Experimental ZooKeeper based implementation

Author: hiranya911

core/pom.xml

@@ -28,6 +28,10 @@
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-api</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.apache.zookeeper</groupId>
+            <artifactId>zookeeper</artifactId>
+        </dependency>
     </dependencies>
 
 </project>

core/src/main/java/edu/ucsb/cs/wrench/GradesDataServer.java

@@ -3,8 +3,9 @@
 import edu.ucsb.cs.wrench.commands.Command;
 import edu.ucsb.cs.wrench.config.WrenchConfiguration;
 import edu.ucsb.cs.wrench.paxos.PaxosAgent;
+import edu.ucsb.cs.wrench.paxos.ZKPaxosAgent;
 
-public class GradesDataServer extends PaxosAgent {
+public class GradesDataServer extends ZKPaxosAgent {
 
     public static void main(String[] args) {
         final GradesDataServer server = new GradesDataServer();

core/src/main/java/edu/ucsb/cs/wrench/client/WrenchClient.java

@@ -11,8 +11,11 @@
 
 public class WrenchClient {
 
+    private static final int THREADS = 1;
+    private static final int REQUESTS = 1;
+
     public static void main(String[] args) throws Exception {
-        ClientThread[] threads = new ClientThread[1];
+        ClientThread[] threads = new ClientThread[THREADS];
         for (int i = 0; i < threads.length; i++) {
             threads[i] = new ClientThread();
         }
@@ -29,7 +32,7 @@ public void run() {
                 transport.open();
                 TProtocol protocol = new TBinaryProtocol(transport);
                 WrenchManagementService.Client client = new WrenchManagementService.Client(protocol);
-                for (int i = 0; i < 100; i++) {
+                for (int i = 0; i < REQUESTS; i++) {
                     System.out.println(client.append(UUID.randomUUID().toString(), getName()));
                     Thread.sleep(100);
                 }

core/src/main/java/edu/ucsb/cs/wrench/config/WrenchConfiguration.java

@@ -4,6 +4,7 @@
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.util.HashMap;
@@ -149,13 +150,14 @@ public static WrenchConfiguration getConfiguration() {
         if (config == null) {
             synchronized (WrenchConfiguration.class) {
                 if (config == null) {
-                    String configPath = System.getProperty("wrench.config.file", "wrench.properties");
+                    String configPath = System.getProperty("wrench.config.dir", "conf");
                     Properties props = new Properties();
+                    File configFile = new File(configPath, "wrench.properties");
                     try {
-                        props.load(new FileInputStream(configPath));
+                        props.load(new FileInputStream(configFile));
                         config = new WrenchConfiguration(props);
                     } catch (IOException e) {
-                        String msg = "Error loading Wrench configuration from: " + configPath;
+                        String msg = "Error loading Wrench configuration from: " + configFile.getPath();
                         log.error(msg, e);
                         throw new WrenchException(msg, e);
                     }

core/src/main/java/edu/ucsb/cs/wrench/messaging/WrenchManagementServiceHandler.java

@@ -7,14 +7,14 @@
 import edu.ucsb.cs.wrench.paxos.*;
 import org.apache.thrift.TException;
 
-import java.util.HashMap;
 import java.util.Map;
+import java.util.TreeMap;
 
 public class WrenchManagementServiceHandler implements WrenchManagementService.Iface {
 
-    private PaxosAgent agent;
+    private AgentService agent;
 
-    public WrenchManagementServiceHandler(PaxosAgent agent) {
+    public WrenchManagementServiceHandler(AgentService agent) {
         this.agent = agent;
     }
 
@@ -98,7 +98,7 @@ public void notifyAppend(String transactionId) throws TException {
     @Override
     public Map<Long,String> getPastOutcomes(long lastRequest) throws TException {
         Map<Long,Command> commands = agent.getPastOutcomes(lastRequest);
-        Map<Long,String> pastOutcomes = new HashMap<Long, String>();
+        Map<Long,String> pastOutcomes = new TreeMap<Long, String>();
         for (Map.Entry<Long,Command> entry : commands.entrySet()) {
             pastOutcomes.put(entry.getKey(), entry.getValue().toString());
         }

core/src/main/java/edu/ucsb/cs/wrench/paxos/AgentService.java

@@ -0,0 +1,24 @@
+package edu.ucsb.cs.wrench.paxos;
+
+import edu.ucsb.cs.wrench.commands.Command;
+import edu.ucsb.cs.wrench.config.Member;
+
+import java.util.Map;
+
+public interface AgentService {
+
+    public void onElection();
+
+    public void onVictory(Member member);
+
+    public boolean onLeaderQuery();
+
+    public void enqueue(PaxosEvent event);
+
+    public boolean executeClientRequest(Command command);
+
+    public Map<Long,Command> getPastOutcomes(long request);
+
+    public BallotNumber getNextBallotNumber();
+
+}

core/src/main/java/edu/ucsb/cs/wrench/paxos/PaxosAgent.java

@@ -24,7 +24,7 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
 
-public abstract class PaxosAgent {
+public abstract class PaxosAgent implements AgentService {
 
     private static final Log log = LogFactory.getLog(PaxosAgent.class);