Refactor handshake out for data request

network/src/main/java/io/bitsquare/p2p/network/Connection.java

@@ -286,7 +286,7 @@ public class Connection implements MessageListener {
         shutDown(true, null);
     }
 
-    private void shutDown(boolean sendCloseConnectionMessage) {
+    public void shutDown(boolean sendCloseConnectionMessage) {
         shutDown(sendCloseConnectionMessage, null);
     }
 
@@ -557,6 +557,11 @@ public class Connection implements MessageListener {
         public void stop() {
             Log.traceCall();
             stopped = true;
+            try {
+                objectInputStream.close();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
         }
 
         @Override

network/src/main/java/io/bitsquare/p2p/peers/PeerExchangeManager.java

@@ -32,7 +32,7 @@ public class PeerExchangeManager implements MessageListener, ConnectionListener
     private final PeerManager peerManager;
     private final Set<NodeAddress> seedNodeAddresses;
     private final ScheduledThreadPoolExecutor executor;
-    private Timer continueWithMorePeersTimer, timeoutTimer, maintainConnectionsTimer;
+    private Timer connectToMorePeersTimer, timeoutTimer, maintainConnectionsTimer;
 
 
     ///////////////////////////////////////////////////////////////////////////////////////////
@@ -42,6 +42,7 @@ public class PeerExchangeManager implements MessageListener, ConnectionListener
     public PeerExchangeManager(NetworkNode networkNode, PeerManager peerManager, Set<NodeAddress> seedNodeAddresses) {
         this.networkNode = networkNode;
         this.peerManager = peerManager;
+        checkArgument(!seedNodeAddresses.isEmpty(), "seedNodeAddresses must not be empty");
         this.seedNodeAddresses = new HashSet<>(seedNodeAddresses);
 
         executor = Utilities.getScheduledThreadPoolExecutor("PeerExchangeManager", 1, 10, 5);
@@ -52,7 +53,7 @@ public class PeerExchangeManager implements MessageListener, ConnectionListener
         Log.traceCall();
 
         networkNode.removeMessageListener(this);
-        stopContinueWithMorePeersTimer();
+        stopConnectToMorePeersTimer();
         stopMaintainConnectionsTimer();
         stopTimeoutTimer();
         MoreExecutors.shutdownAndAwaitTermination(executor, 500, TimeUnit.MILLISECONDS);
@@ -64,7 +65,9 @@ public class PeerExchangeManager implements MessageListener, ConnectionListener
     ///////////////////////////////////////////////////////////////////////////////////////////
 
     public void requestReportedPeers(NodeAddress nodeAddress) {
-        requestReportedPeers(nodeAddress, new ArrayList<>(seedNodeAddresses));
+        ArrayList<NodeAddress> remainingNodeAddresses = new ArrayList<>(seedNodeAddresses);
+        remainingNodeAddresses.remove(nodeAddress);
+        requestReportedPeers(nodeAddress, remainingNodeAddresses);
 
         long delay = new Random().nextInt(60) + 60 * 3; // 3-4 min. 
         executor.scheduleAtFixedRate(() -> UserThread.execute(this::maintainConnections),
@@ -106,7 +109,11 @@ public class PeerExchangeManager implements MessageListener, ConnectionListener
             Log.traceCall(message.toString());
             if (message instanceof GetPeersRequest) {
                 HashSet<ReportedPeer> reportedPeers = ((GetPeersRequest) message).reportedPeers;
-                log.trace("Received reported peers: " + reportedPeers);
+
+                StringBuilder result = new StringBuilder("Received peers:");
+                reportedPeers.stream().forEach(e -> result.append("\n").append(e));
+                log.trace(result.toString());
+                
                 checkArgument(connection.getPeersNodeAddressOptional().isPresent(),
                         "The peers address must have been already set at the moment");
                 SettableFuture<Connection> future = networkNode.sendMessage(connection,
@@ -126,11 +133,16 @@ public class PeerExchangeManager implements MessageListener, ConnectionListener
                 peerManager.addToReportedPeers(reportedPeers, connection);
             } else if (message instanceof GetPeersResponse) {
                 stopTimeoutTimer();
+
                 HashSet<ReportedPeer> reportedPeers = ((GetPeersResponse) message).reportedPeers;
-                log.trace("Received reported peers: " + reportedPeers);
+
+                StringBuilder result = new StringBuilder("Received peers:");
+                reportedPeers.stream().forEach(e -> result.append("\n").append(e));
+                log.trace(result.toString());
+
                 peerManager.addToReportedPeers(reportedPeers, connection);
 
-                continueWithMorePeers();
+                connectToMorePeers();
             }
         }
     }
@@ -144,14 +156,14 @@ public class PeerExchangeManager implements MessageListener, ConnectionListener
         Log.traceCall("nodeAddress=" + nodeAddress + " /  remainingNodeAddresses=" + remainingNodeAddresses);
         checkNotNull(networkNode.getNodeAddress(), "My node address must not be null at requestReportedPeers");
 
-        stopContinueWithMorePeersTimer();
+        stopConnectToMorePeersTimer();
         stopTimeoutTimer();
 
         timeoutTimer = UserThread.runAfter(() -> {
                     log.info("timeoutTimer called");
                     handleError(nodeAddress, remainingNodeAddresses);
                 },
-                10, TimeUnit.SECONDS);
+                20, TimeUnit.SECONDS);
 
         SettableFuture<Connection> future = networkNode.sendMessage(nodeAddress,
                 new GetPeersRequest(networkNode.getNodeAddress(), getReportedPeersHashSet(nodeAddress)));
@@ -171,35 +183,11 @@ public class PeerExchangeManager implements MessageListener, ConnectionListener
         });
     }
 
-    private void handleError(NodeAddress nodeAddress, List<NodeAddress> remainingNodeAddresses) {
+    private void connectToMorePeers() {
-        Log.traceCall("nodeAddress=" + nodeAddress + " /  remainingNodeAddresses=" + remainingNodeAddresses);
-
-        stopTimeoutTimer();
-
-        if (!remainingNodeAddresses.isEmpty()) {
-            log.info("There are remaining nodes available for requesting peers. " +
-                    "We will try getReportedPeers again.");
-            requestReportedPeersFromList(remainingNodeAddresses);
-        } else {
-            log.info("There is no remaining node available for requesting peers. " +
-                    "That is expected if no other node is online.\n" +
-                    "We will try to use reported peers (if no available we use persisted peers) " +
-                    "and try again to request peers from our seed nodes after a random pause.");
-            if (continueWithMorePeersTimer == null)
-                continueWithMorePeersTimer = UserThread.runAfter(this::continueWithMorePeers,
-                        30, TimeUnit.SECONDS);
-        }
-    }
-
-    private void requestReportedPeersFromList(List<NodeAddress> remainingNodeAddresses) {
-        NodeAddress nextCandidate = remainingNodeAddresses.get(new Random().nextInt(remainingNodeAddresses.size()));
-        remainingNodeAddresses.remove(nextCandidate);
-        requestReportedPeers(nextCandidate, remainingNodeAddresses);
-    }
-
-    private void continueWithMorePeers() {
         Log.traceCall();
-        stopContinueWithMorePeersTimer();
+
+        stopConnectToMorePeersTimer();
+
         if (!peerManager.hasSufficientConnections()) {
             // We want to keep it sorted but avoid duplicates
             List<NodeAddress> list = new ArrayList<>(getFilteredAndSortedList(peerManager.getReportedPeers(), new ArrayList<>()));
@@ -222,6 +210,67 @@ public class PeerExchangeManager implements MessageListener, ConnectionListener
         }
     }
 
+    private void handleError(NodeAddress peersNodeAddress, List<NodeAddress> remainingNodeAddresses) {
+        Log.traceCall("peersNodeAddress=" + peersNodeAddress + " /  remainingNodeAddresses=" + remainingNodeAddresses);
+
+        stopTimeoutTimer();
+
+        // In case a shutdown was not triggered already by the error we close that connection 
+        // if it is not a DIRECT_MSG_PEER
+        peerManager.shutDownConnection(peersNodeAddress);
+
+        if (!remainingNodeAddresses.isEmpty()) {
+            log.info("There are remaining nodes available for requesting peers. " +
+                    "We will try getReportedPeers again.");
+            requestReportedPeersFromRandomPeer(remainingNodeAddresses);
+        } else {
+            log.info("There is no remaining node available for requesting peers. " +
+                    "That is expected if no other node is online.\n" +
+                    "We will try to use reported peers (if no available we use persisted peers) " +
+                    "and try again to request peers from our seed nodes after a random pause.");
+            if (connectToMorePeersTimer == null)
+                connectToMorePeersTimer = UserThread.runAfterRandomDelay(this::connectToMorePeers, 20, 30);
+        }
+    }
+
+    // we check if we have at least one seed node connected
+    private void maintainConnections() {
+        Log.traceCall();
+
+        stopMaintainConnectionsTimer();
+
+        // we want at least 1 seed node connected
+        Set<Connection> confirmedConnections = networkNode.getConfirmedConnections();
+        long numberOfConnectedSeedNodes = confirmedConnections.stream()
+                .filter(peerManager::isSeedNode)
+                .count();
+        if (numberOfConnectedSeedNodes == 0)
+            requestReportedPeersFromRandomPeer(new ArrayList<>(seedNodeAddresses));
+
+        // We try to get sufficient connections by connecting to reported and persisted peers
+        if (numberOfConnectedSeedNodes == 0) {
+            // If we requested a seed node we delay a bit to not have too many requests simultaneously
+            if (connectToMorePeersTimer == null)
+                connectToMorePeersTimer = UserThread.runAfter(this::connectToMorePeers, 10);
+        } else {
+            connectToMorePeers();
+        }
+
+        // Use all outbound connections for updating reported peers and make sure we keep the connection alive
+        // Inbound connections should be maintained be the requesting peer
+        confirmedConnections.stream()
+                .filter(c -> c.getPeersNodeAddressOptional().isPresent() &&
+                        c instanceof OutboundConnection).
+                forEach(c -> UserThread.runAfterRandomDelay(() ->
+                        requestReportedPeers(c.getPeersNodeAddressOptional().get(), new ArrayList<>())
+                        , 3, 5));
+    }
+
+
+    ///////////////////////////////////////////////////////////////////////////////////////////
+    // Utils
+    ///////////////////////////////////////////////////////////////////////////////////////////
+
     // sorted by most recent lastActivityDate
     private List<NodeAddress> getFilteredAndSortedList(Set<ReportedPeer> set, List<NodeAddress> list) {
         return set.stream()
@@ -236,34 +285,10 @@ public class PeerExchangeManager implements MessageListener, ConnectionListener
                 .collect(Collectors.toList());
     }
 
-
+    private void requestReportedPeersFromRandomPeer(List<NodeAddress> remainingNodeAddresses) {
-    // we check if we have at least one seed node connected
+        NodeAddress nextCandidate = remainingNodeAddresses.get(new Random().nextInt(remainingNodeAddresses.size()));
-    private void maintainConnections() {
+        remainingNodeAddresses.remove(nextCandidate);
-        Log.traceCall();
+        requestReportedPeers(nextCandidate, remainingNodeAddresses);
-
-        stopMaintainConnectionsTimer();
-
-        // we want at least 1 seed node connected
-        Set<Connection> allConnections = networkNode.getConfirmedConnections();
-        List<Connection> connectedSeedNodes = allConnections.stream()
-                .filter(peerManager::isSeedNode)
-                .collect(Collectors.toList());
-        if (connectedSeedNodes.size() == 0 && !seedNodeAddresses.isEmpty())
-            requestReportedPeersFromList(new ArrayList<>(seedNodeAddresses));
-
-        // We try to get sufficient connections by using reported and persisted peers
-        if (continueWithMorePeersTimer == null)
-            continueWithMorePeersTimer = UserThread.runAfterRandomDelay(this::continueWithMorePeers, 10, 20);
-
-
-        // Use all outbound connections for updating reported peers and make sure we keep the connection alive
-        // Inbound connections should be maintained be the requesting peer
-        networkNode.getConfirmedConnections().stream()
-                .filter(c -> c.getPeersNodeAddressOptional().isPresent() &&
-                        c instanceof OutboundConnection).
-                forEach(c -> UserThread.runAfterRandomDelay(() ->
-                        requestReportedPeers(c.getPeersNodeAddressOptional().get(), new ArrayList<>())
-                        , 3, 5));
     }
 
     private HashSet<ReportedPeer> getReportedPeersHashSet(NodeAddress receiverNodeAddress) {
@@ -275,10 +300,10 @@ public class PeerExchangeManager implements MessageListener, ConnectionListener
                 .collect(Collectors.toSet()));
     }
 
-    private void stopContinueWithMorePeersTimer() {
+    private void stopConnectToMorePeersTimer() {
-        if (continueWithMorePeersTimer != null) {
+        if (connectToMorePeersTimer != null) {
-            continueWithMorePeersTimer.cancel();
+            connectToMorePeersTimer.cancel();
-            continueWithMorePeersTimer = null;
+            connectToMorePeersTimer = null;
         }
     }
 

network/src/main/java/io/bitsquare/p2p/peers/PeerManager.java

@@ -5,7 +5,7 @@ import io.bitsquare.common.UserThread;
 import io.bitsquare.p2p.Message;
 import io.bitsquare.p2p.NodeAddress;
 import io.bitsquare.p2p.network.*;
-import io.bitsquare.p2p.peers.messages.data.DataRequest;
+import io.bitsquare.p2p.peers.messages.data.UpdateDataRequest;
 import io.bitsquare.storage.Storage;
 import javafx.beans.value.ChangeListener;
 import org.jetbrains.annotations.Nullable;
@@ -135,7 +135,7 @@ public class PeerManager implements ConnectionListener, MessageListener {
     public void onMessage(Message message, Connection connection) {
         // In case a seed node connects to another seed node we get his address at the DataRequest triggered from
         // RequestDataManager.updateDataFromConnectedSeedNode 
-        if (message instanceof DataRequest) {
+        if (message instanceof UpdateDataRequest) {
             Optional<NodeAddress> peersNodeAddressOptional = connection.getPeersNodeAddressOptional();
             if (peersNodeAddressOptional.isPresent() &&
                     seedNodeAddresses.contains(peersNodeAddressOptional.get()))
@@ -251,8 +251,9 @@ public class PeerManager implements ConnectionListener, MessageListener {
                     .collect(Collectors.toMap(e -> e, Function.identity()));
             HashSet<ReportedPeer> adjustedReportedPeers = new HashSet<>();
             reportedPeersToAdd.stream()
-                    .filter(e -> !e.nodeAddress.equals(networkNode.getNodeAddress()))
+                    .filter(e -> e.nodeAddress != null &&
-                    .filter(e -> !getConnectedPeers().contains(e))
+                            !e.nodeAddress.equals(networkNode.getNodeAddress()) &&
+                            !getConnectedPeers().contains(e))
                     .forEach(e -> {
                         if (reportedPeersMap.containsKey(e)) {
                             if (e.lastActivityDate != null && reportedPeersMap.get(e).lastActivityDate != null) {
@@ -377,6 +378,19 @@ public class PeerManager implements ConnectionListener, MessageListener {
         return networkNode.getNodeAddressesOfConfirmedConnections().contains(nodeAddress);
     }
 
+    public void shutDownConnection(Connection connection) {
+        if (connection.getPeerType() != Connection.PeerType.DIRECT_MSG_PEER)
+            connection.shutDown();
+    }
+
+    public void shutDownConnection(NodeAddress peersNodeAddress) {
+        networkNode.getAllConnections().stream()
+                .filter(connection -> connection.getPeersNodeAddressOptional().isPresent() &&
+                        connection.getPeersNodeAddressOptional().get().equals(peersNodeAddress) &&
+                        connection.getPeerType() != Connection.PeerType.DIRECT_MSG_PEER)
+                .findFirst()
+                .ifPresent(connection -> connection.shutDown(true));
+    }
 
     ///////////////////////////////////////////////////////////////////////////////////////////
     //  Private

network/src/main/java/io/bitsquare/p2p/peers/RequestDataHandshake.java

@@ -0,0 +1,183 @@
+package io.bitsquare.p2p.peers;
+
+import com.google.common.util.concurrent.FutureCallback;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.SettableFuture;
+import io.bitsquare.app.Log;
+import io.bitsquare.common.UserThread;
+import io.bitsquare.p2p.Message;
+import io.bitsquare.p2p.NodeAddress;
+import io.bitsquare.p2p.network.Connection;
+import io.bitsquare.p2p.network.MessageListener;
+import io.bitsquare.p2p.network.NetworkNode;
+import io.bitsquare.p2p.peers.messages.data.DataRequest;
+import io.bitsquare.p2p.peers.messages.data.DataResponse;
+import io.bitsquare.p2p.peers.messages.data.PreliminaryDataRequest;
+import io.bitsquare.p2p.peers.messages.data.UpdateDataRequest;
+import io.bitsquare.p2p.storage.P2PDataStorage;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.HashSet;
+import java.util.Random;
+import java.util.Timer;
+import java.util.concurrent.TimeUnit;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+public class RequestDataHandshake implements MessageListener {
+    private static final Logger log = LoggerFactory.getLogger(RequestDataHandshake.class);
+
+    ///////////////////////////////////////////////////////////////////////////////////////////
+    // Listener
+    ///////////////////////////////////////////////////////////////////////////////////////////
+
+    public interface Listener {
+        void onComplete();
+
+        void onFault(String errorMessage);
+    }
+
+
+    ///////////////////////////////////////////////////////////////////////////////////////////
+    // Class fields
+    ///////////////////////////////////////////////////////////////////////////////////////////
+
+    private final NetworkNode networkNode;
+    private final P2PDataStorage dataStorage;
+    private final PeerManager peerManager;
+    private final Listener listener;
+    private Timer timeoutTimer;
+    private long requestNonce;
+
+
+    ///////////////////////////////////////////////////////////////////////////////////////////
+    // Constructor
+    ///////////////////////////////////////////////////////////////////////////////////////////
+
+    public RequestDataHandshake(NetworkNode networkNode, P2PDataStorage dataStorage, PeerManager peerManager,
+                                Listener listener) {
+        this.networkNode = networkNode;
+        this.dataStorage = dataStorage;
+        this.peerManager = peerManager;
+        this.listener = listener;
+
+        networkNode.addMessageListener(this);
+    }
+
+    public void shutDown() {
+        Log.traceCall();
+
+        networkNode.removeMessageListener(this);
+
+        stopTimeoutTimer();
+    }
+
+    ///////////////////////////////////////////////////////////////////////////////////////////
+    // API
+    ///////////////////////////////////////////////////////////////////////////////////////////
+
+    public void requestData(NodeAddress nodeAddress) {
+        Log.traceCall("nodeAddress=" + nodeAddress);
+
+        stopTimeoutTimer();
+
+        checkArgument(timeoutTimer == null, "requestData must not be called twice.");
+        timeoutTimer = UserThread.runAfter(() -> {
+                    log.info("timeoutTimer called");
+                    peerManager.shutDownConnection(nodeAddress);
+                    shutDown();
+                    listener.onFault("A timeout occurred");
+                },
+                10, TimeUnit.SECONDS);
+
+        Message dataRequest;
+        requestNonce = new Random().nextLong();
+        if (networkNode.getNodeAddress() == null)
+            dataRequest = new PreliminaryDataRequest(requestNonce);
+        else
+            dataRequest = new UpdateDataRequest(networkNode.getNodeAddress(), requestNonce);
+
+        log.info("We send a {} to peer {}. ", dataRequest.getClass().getSimpleName(), nodeAddress);
+
+        SettableFuture<Connection> future = networkNode.sendMessage(nodeAddress, dataRequest);
+        Futures.addCallback(future, new FutureCallback<Connection>() {
+            @Override
+            public void onSuccess(@Nullable Connection connection) {
+                log.trace("Send DataRequest to " + nodeAddress + " succeeded.");
+            }
+
+            @Override
+            public void onFailure(@NotNull Throwable throwable) {
+                String errorMessage = "Sending " + dataRequest.getClass().getSimpleName() + " to " + nodeAddress +
+                        " failed. That is expected if the peer is offline. " +
+                        "Exception:" + throwable.getMessage();
+                log.info(errorMessage);
+
+                peerManager.shutDownConnection(nodeAddress);
+                shutDown();
+                listener.onFault(errorMessage);
+            }
+        });
+    }
+
+    ///////////////////////////////////////////////////////////////////////////////////////////
+    // MessageListener implementation
+    ///////////////////////////////////////////////////////////////////////////////////////////
+
+    @Override
+    public void onMessage(Message message, Connection connection) {
+        if (message instanceof DataRequest) {
+            Log.traceCall(message.toString());
+            DataRequest dataRequest = (DataRequest) message;
+            DataResponse dataResponse = new DataResponse(new HashSet<>(dataStorage.getMap().values()), dataRequest.getNonce());
+            SettableFuture<Connection> future = networkNode.sendMessage(connection, dataResponse);
+            Futures.addCallback(future, new FutureCallback<Connection>() {
+                @Override
+                public void onSuccess(Connection connection) {
+                    log.trace("Send DataResponse to {} succeeded. dataResponse={}",
+                            connection.getPeersNodeAddressOptional(), dataResponse);
+                    shutDown();
+                    listener.onComplete();
+                }
+
+                @Override
+                public void onFailure(@NotNull Throwable throwable) {
+                    String errorMessage = "Send DataResponse to " + connection.getPeersNodeAddressOptional() + " failed. " +
+                            "That is expected if the peer went offline. " +
+                            "Exception:" + throwable.getMessage();
+                    log.info(errorMessage);
+
+                    peerManager.shutDownConnection(connection);
+                    shutDown();
+                    listener.onFault(errorMessage);
+                }
+            });
+        } else if (message instanceof DataResponse) {
+            DataResponse dataResponse = (DataResponse) message;
+            if (dataResponse.requestNonce == requestNonce) {
+                Log.traceCall(message.toString());
+
+                stopTimeoutTimer();
+
+                // connection.getPeersNodeAddressOptional() is not present at the first call
+                log.debug("connection.getPeersNodeAddressOptional() " + connection.getPeersNodeAddressOptional());
+                connection.getPeersNodeAddressOptional().ifPresent(peersNodeAddress -> {
+                    ((DataResponse) message).dataSet.stream()
+                            .forEach(e -> dataStorage.add(e, peersNodeAddress));
+                });
+                shutDown();
+                listener.onComplete();
+            }
+        }
+    }
+
+    private void stopTimeoutTimer() {
+        if (timeoutTimer != null) {
+            timeoutTimer.cancel();
+            timeoutTimer = null;
+        }
+    }
+}

network/src/main/java/io/bitsquare/p2p/peers/RequestDataManager.java

@@ -1,8 +1,5 @@
 package io.bitsquare.p2p.peers;
 
-import com.google.common.util.concurrent.FutureCallback;
-import com.google.common.util.concurrent.Futures;
-import com.google.common.util.concurrent.SettableFuture;
 import io.bitsquare.app.Log;
 import io.bitsquare.common.UserThread;
 import io.bitsquare.p2p.Message;
@@ -11,11 +8,7 @@ import io.bitsquare.p2p.network.Connection;
 import io.bitsquare.p2p.network.MessageListener;
 import io.bitsquare.p2p.network.NetworkNode;
 import io.bitsquare.p2p.peers.messages.data.DataRequest;
-import io.bitsquare.p2p.peers.messages.data.DataResponse;
-import io.bitsquare.p2p.peers.messages.data.PreliminaryDataRequest;
 import io.bitsquare.p2p.storage.P2PDataStorage;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -55,8 +48,10 @@ public class RequestDataManager implements MessageListener {
     private final Collection<NodeAddress> seedNodeAddresses;
     private final Listener listener;
 
+    private final Map<NodeAddress, RequestDataHandshake> requestDataHandshakeMap = new HashMap<>();
+
     private Optional<NodeAddress> nodeOfPreliminaryDataRequest = Optional.empty();
-    private Timer requestDataAfterDelayTimer, timeoutTimer;
+    private Timer requestDataTimer;
     private boolean dataUpdateRequested;
 
 
@@ -69,6 +64,7 @@ public class RequestDataManager implements MessageListener {
         this.networkNode = networkNode;
         this.dataStorage = dataStorage;
         this.peerManager = peerManager;
+        checkArgument(!seedNodeAddresses.isEmpty(), "seedNodeAddresses must not be empty.");
         this.seedNodeAddresses = new HashSet<>(seedNodeAddresses);
         this.listener = listener;
 
@@ -78,10 +74,11 @@ public class RequestDataManager implements MessageListener {
     public void shutDown() {
         Log.traceCall();
 
+        stopRequestDataTimer();
+
         networkNode.removeMessageListener(this);
 
-        stopRequestDataTimer();
+        requestDataHandshakeMap.values().stream().forEach(RequestDataHandshake::shutDown);
-        stopTimeoutTimer();
     }
 
 
@@ -91,8 +88,7 @@ public class RequestDataManager implements MessageListener {
 
     public void requestPreliminaryData() {
         Log.traceCall();
-        checkArgument(!seedNodeAddresses.isEmpty(), "seedNodeAddresses must not be empty.");
+        requestDataFromRandomPeer(new ArrayList<>(seedNodeAddresses));
-        requestDataFromList(new ArrayList<>(seedNodeAddresses));
     }
 
     public void requestUpdatesData() {
@@ -116,19 +112,55 @@ public class RequestDataManager implements MessageListener {
 
     @Override
     public void onMessage(Message message, Connection connection) {
-        if (message instanceof PreliminaryDataRequest || message instanceof DataRequest) {
+        if (message instanceof DataRequest) {
             Log.traceCall(message.toString());
-            networkNode.sendMessage(connection, new DataResponse(new HashSet<>(dataStorage.getMap().values())));
+            log.trace("Received {} at {}", message.getClass().getSimpleName(), connection);
-        } else if (message instanceof DataResponse) {
+            RequestDataHandshake requestDataHandshake = new RequestDataHandshake(networkNode, dataStorage, peerManager,
-            Log.traceCall(message.toString());
+                    new RequestDataHandshake.Listener() {
-            stopTimeoutTimer();
+                        @Override
-            connection.getPeersNodeAddressOptional().ifPresent(peersNodeAddress -> {
+                        public void onComplete() {
-                ((DataResponse) message).dataSet.stream()
+                            log.trace("RequestDataHandshake of inbound connection complete. Connection= {}",
-                        .forEach(e -> dataStorage.add(e, peersNodeAddress));
+                                    connection);
+                        }
+
+                        @Override
+                        public void onFault(String errorMessage) {
+                            log.info("RequestDataHandshake of inbound connection failed. Connection= {}",
+                                    errorMessage, connection);
+                        }
+                    });
+            requestDataHandshake.onMessage(message, connection);
+        }
+    }
+
+
+    ///////////////////////////////////////////////////////////////////////////////////////////
+    // Private
+    ///////////////////////////////////////////////////////////////////////////////////////////
+
+    private void requestDataFromRandomPeer(List<NodeAddress> nodeAddresses) {
+        Log.traceCall("remainingNodeAddresses=" + nodeAddresses);
+        NodeAddress nextCandidate = nodeAddresses.get(new Random().nextInt(nodeAddresses.size()));
+        nodeAddresses.remove(nextCandidate);
+        requestData(nextCandidate, nodeAddresses);
+    }
+
+    private void requestData(NodeAddress nodeAddress, List<NodeAddress> remainingNodeAddresses) {
+        Log.traceCall("nodeAddress=" + nodeAddress + " /  remainingNodeAddresses=" + remainingNodeAddresses);
+
+        if (!requestDataHandshakeMap.containsKey(nodeAddress)) {
+            RequestDataHandshake requestDataHandshake = new RequestDataHandshake(networkNode, dataStorage, peerManager,
+                    new RequestDataHandshake.Listener() {
+                        @Override
+                        public void onComplete() {
+                            stopRequestDataTimer();
+
+                            // need to remove before listeners are notified as they cause the update call
+                            requestDataHandshakeMap.remove(nodeAddress);
 
                             // 1. We get a response from requestPreliminaryData
                             if (!nodeOfPreliminaryDataRequest.isPresent()) {
-                    nodeOfPreliminaryDataRequest = Optional.of(peersNodeAddress);
+                                nodeOfPreliminaryDataRequest = Optional.of(nodeAddress);
                                 listener.onPreliminaryDataReceived();
                             }
 
@@ -139,82 +171,24 @@ public class RequestDataManager implements MessageListener {
                             }
 
                             listener.onDataReceived();
-            });
-        }
-    }
-
-
-    ///////////////////////////////////////////////////////////////////////////////////////////
-    // Private
-    ///////////////////////////////////////////////////////////////////////////////////////////
-
-    private void requestDataFromList(List<NodeAddress> nodeAddresses) {
-        Log.traceCall("remainingNodeAddresses=" + nodeAddresses);
-        NodeAddress nextCandidate = nodeAddresses.get(new Random().nextInt(nodeAddresses.size()));
-        nodeAddresses.remove(nextCandidate);
-        requestData(nextCandidate, nodeAddresses);
-    }
-
-    private void requestData(NodeAddress nodeAddress, List<NodeAddress> remainingNodeAddresses) {
-        Log.traceCall("nodeAddress=" + nodeAddress + " /  remainingNodeAddresses=" + remainingNodeAddresses);
-        log.info("We try to send a DataRequest request to peer. " + nodeAddress);
-
-        stopTimeoutTimer();
-        stopRequestDataTimer();
-
-        timeoutTimer = UserThread.runAfter(() -> {
-                    log.info("timeoutTimer called");
-                    handleError(nodeAddress, remainingNodeAddresses);
-                },
-                10, TimeUnit.SECONDS);
-
-        Message dataRequest;
-        if (networkNode.getNodeAddress() == null)
-            dataRequest = new PreliminaryDataRequest();
-        else
-            dataRequest = new DataRequest(networkNode.getNodeAddress());
-
-        SettableFuture<Connection> future = networkNode.sendMessage(nodeAddress, dataRequest);
-        Futures.addCallback(future, new FutureCallback<Connection>() {
-            @Override
-            public void onSuccess(@Nullable Connection connection) {
-                log.trace("Send DataRequest to " + nodeAddress + " succeeded.");
                         }
 
                         @Override
-            public void onFailure(@NotNull Throwable throwable) {
+                        public void onFault(String errorMessage) {
-                log.info("Send DataRequest to " + nodeAddress + " failed. " +
-                        "That is expected if the peer is offline. " +
-                        "Exception:" + throwable.getMessage());
-
-                handleError(nodeAddress, remainingNodeAddresses);
-            }
-        });
-    }
-
-    private void handleError(NodeAddress nodeAddress, List<NodeAddress> remainingNodeAddresses) {
-        Log.traceCall("nodeAddress=" + nodeAddress + " /  remainingNodeAddresses=" + remainingNodeAddresses);
-        stopTimeoutTimer();
-
                             if (!remainingNodeAddresses.isEmpty()) {
                                 log.info("There are remaining nodes available for requesting data. " +
                                         "We will try requestDataFromPeers again.");
-            requestDataFromList(remainingNodeAddresses);
+                                requestDataFromRandomPeer(remainingNodeAddresses);
                             } else {
                                 log.info("There is no remaining node available for requesting data. " +
                                         "That is expected if no other node is online.\n" +
                                         "We will try to use reported peers (if no available we use persisted peers) " +
                                         "and try again to request data from our seed nodes after a random pause.");
 
-            if (peerManager.isSeedNode(nodeAddress))
+                                // try again after a pause
-                listener.onNoSeedNodeAvailable();
+                                stopRequestDataTimer();
-            else
+                                requestDataTimer = UserThread.runAfterRandomDelay(() -> {
-                listener.onNoPeersAvailable();
-
-            requestDataAfterDelayTimer = UserThread.runAfterRandomDelay(() -> {
                                             log.trace("requestDataAfterDelayTimer called");
-                        if (!seedNodeAddresses.isEmpty()) {
-                            Set<NodeAddress> nodeAddressesOfConfirmedConnections = networkNode.getNodeAddressesOfConfirmedConnections();
                                             // We want to keep it sorted but avoid duplicates
                                             // We don't filter out already established connections for seed nodes as it might be that
                                             // we got from the other seed node contacted but we still have not requested the initial 
@@ -223,18 +197,30 @@ public class RequestDataManager implements MessageListener {
                                             list.addAll(getFilteredAndSortedList(peerManager.getReportedPeers(), list));
                                             list.addAll(getFilteredAndSortedList(peerManager.getPersistedPeers(), list));
                                             log.trace("Sorted and filtered list: list=" + list);
-                            if (!list.isEmpty()) {
+                                            checkArgument(!list.isEmpty(), "seedNodeAddresses must not be empty.");
                                             NodeAddress nextCandidate = list.get(0);
                                             list.remove(nextCandidate);
                                             requestData(nextCandidate, list);
-                            } else {
-                                log.info("Neither seed nodes, reported peers nor persisted peers are available. " +
-                                        "At least seed nodes should be always available.");
-                            }
-                        }
                                         },
                                         10, 15, TimeUnit.SECONDS);
                             }
+
+                            requestDataHandshakeMap.remove(nodeAddress);
+
+                            // Notify listeners
+                            if (!nodeOfPreliminaryDataRequest.isPresent()) {
+                                if (peerManager.isSeedNode(nodeAddress))
+                                    listener.onNoSeedNodeAvailable();
+                                else
+                                    listener.onNoPeersAvailable();
+                            }
+                        }
+                    });
+            requestDataHandshakeMap.put(nodeAddress, requestDataHandshake);
+            requestDataHandshake.requestData(nodeAddress);
+        } else {
+            log.warn("We have started already a DataRequest request to peer. " + nodeAddress);
+        }
     }
 
     // sorted by most recent lastActivityDate
@@ -242,7 +228,7 @@ public class RequestDataManager implements MessageListener {
         return set.stream()
                 .filter(e -> !list.contains(e.nodeAddress) &&
                         !peerManager.isSeedNode(e) &&
-                        !peerManager.isSelf(e.nodeAddress))
+                        !peerManager.isSelf(e))
                 .collect(Collectors.toList())
                 .stream()
                 .sorted((o1, o2) -> o2.lastActivityDate.compareTo(o1.lastActivityDate))
@@ -251,16 +237,9 @@ public class RequestDataManager implements MessageListener {
     }
 
     private void stopRequestDataTimer() {
-        if (requestDataAfterDelayTimer != null) {
+        if (requestDataTimer != null) {
-            requestDataAfterDelayTimer.cancel();
+            requestDataTimer.cancel();
-            requestDataAfterDelayTimer = null;
+            requestDataTimer = null;
-        }
-    }
-
-    private void stopTimeoutTimer() {
-        if (timeoutTimer != null) {
-            timeoutTimer.cancel();
-            timeoutTimer = null;
         }
     }
 }

network/src/main/java/io/bitsquare/p2p/peers/messages/data/DataRequest.java

@@ -1,36 +1,5 @@
 package io.bitsquare.p2p.peers.messages.data;
 
-import io.bitsquare.app.Version;
+public interface DataRequest {
-import io.bitsquare.p2p.NodeAddress;
+    long getNonce();
-import io.bitsquare.p2p.network.messages.SendersNodeAddressMessage;
-
-public final class DataRequest implements SendersNodeAddressMessage {
-    // That object is sent over the wire, so we need to take care of version compatibility.
-    private static final long serialVersionUID = Version.NETWORK_PROTOCOL_VERSION;
-
-    private final int networkId = Version.getNetworkId();
-    private final NodeAddress senderNodeAddress;
-
-    public DataRequest(NodeAddress senderNodeAddress) {
-        this.senderNodeAddress = senderNodeAddress;
-    }
-
-    @Override
-    public NodeAddress getSenderNodeAddress() {
-        return senderNodeAddress;
-    }
-
-    @Override
-    public int networkId() {
-        return networkId;
-    }
-
-    @Override
-    public String toString() {
-        return "DataRequest{" +
-                "senderNodeAddress=" + senderNodeAddress +
-                ", networkId=" + networkId +
-                '}';
-    }
-
 }

network/src/main/java/io/bitsquare/p2p/peers/messages/data/DataResponse.java

@@ -12,9 +12,11 @@ public final class DataResponse implements Message {
     private final int networkId = Version.getNetworkId();
 
     public final HashSet<ProtectedData> dataSet;
+    public final long requestNonce;
 
-    public DataResponse(HashSet<ProtectedData> dataSet) {
+    public DataResponse(HashSet<ProtectedData> dataSet, long requestNonce) {
         this.dataSet = dataSet;
+        this.requestNonce = requestNonce;
     }
 
     @Override
@@ -43,6 +45,7 @@ public final class DataResponse implements Message {
         return "DataResponse{" +
                 "networkId=" + networkId +
                 ", dataSet=" + dataSet +
+                ", requestNonce=" + requestNonce +
                 '}';
     }
 }

network/src/main/java/io/bitsquare/p2p/peers/messages/data/PreliminaryDataRequest.java

@@ -3,13 +3,20 @@ package io.bitsquare.p2p.peers.messages.data;
 import io.bitsquare.app.Version;
 import io.bitsquare.p2p.network.messages.AnonymousMessage;
 
-public final class PreliminaryDataRequest implements AnonymousMessage {
+public final class PreliminaryDataRequest implements AnonymousMessage, DataRequest {
     // That object is sent over the wire, so we need to take care of version compatibility.
     private static final long serialVersionUID = Version.NETWORK_PROTOCOL_VERSION;
 
     private final int networkId = Version.getNetworkId();
+    private final long nonce;
 
-    public PreliminaryDataRequest() {
+    public PreliminaryDataRequest(long nonce) {
+        this.nonce = nonce;
+    }
+
+    @Override
+    public long getNonce() {
+        return nonce;
     }
 
     @Override
@@ -21,6 +28,7 @@ public final class PreliminaryDataRequest implements AnonymousMessage {
     public String toString() {
         return "PreliminaryDataRequest{" +
                 "networkId=" + networkId +
+                ", nonce=" + nonce +
                 '}';
     }
 }

network/src/main/java/io/bitsquare/p2p/peers/messages/data/UpdateDataRequest.java

@@ -0,0 +1,44 @@
+package io.bitsquare.p2p.peers.messages.data;
+
+import io.bitsquare.app.Version;
+import io.bitsquare.p2p.NodeAddress;
+import io.bitsquare.p2p.network.messages.SendersNodeAddressMessage;
+
+public final class UpdateDataRequest implements SendersNodeAddressMessage, DataRequest {
+    // That object is sent over the wire, so we need to take care of version compatibility.
+    private static final long serialVersionUID = Version.NETWORK_PROTOCOL_VERSION;
+
+    private final int networkId = Version.getNetworkId();
+    private final NodeAddress senderNodeAddress;
+    private final long nonce;
+
+    public UpdateDataRequest(NodeAddress senderNodeAddress, long nonce) {
+        this.senderNodeAddress = senderNodeAddress;
+        this.nonce = nonce;
+    }
+
+    @Override
+    public long getNonce() {
+        return nonce;
+    }
+
+    @Override
+    public NodeAddress getSenderNodeAddress() {
+        return senderNodeAddress;
+    }
+
+    @Override
+    public int networkId() {
+        return networkId;
+    }
+
+    @Override
+    public String toString() {
+        return "DataRequest{" +
+                "senderNodeAddress=" + senderNodeAddress +
+                ", networkId=" + networkId +
+                ", nonce=" + nonce +
+                '}';
+    }
+
+}