New PRESENCE-related API websocket at /websockets/presence

src/main/java/org/qortal/api/ApiService.java

@@ -43,6 +43,7 @@ import org.qortal.api.websocket.ActiveChatsWebSocket;
 import org.qortal.api.websocket.AdminStatusWebSocket;
 import org.qortal.api.websocket.BlocksWebSocket;
 import org.qortal.api.websocket.ChatMessagesWebSocket;
+import org.qortal.api.websocket.PresenceWebSocket;
 import org.qortal.api.websocket.TradeBotWebSocket;
 import org.qortal.api.websocket.TradeOffersWebSocket;
 import org.qortal.settings.Settings;
@@ -200,6 +201,7 @@ public class ApiService {
 			context.addServlet(ChatMessagesWebSocket.class, "/websockets/chat/messages");
 			context.addServlet(TradeOffersWebSocket.class, "/websockets/crosschain/tradeoffers");
 			context.addServlet(TradeBotWebSocket.class, "/websockets/crosschain/tradebot");
+			context.addServlet(PresenceWebSocket.class, "/websockets/presence");
 
 			// Start server
 			this.server.start();

src/main/java/org/qortal/api/websocket/PresenceWebSocket.java

@@ -0,0 +1,190 @@
+package org.qortal.api.websocket;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.Collections;
+import java.util.EnumMap;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+
+import org.eclipse.jetty.websocket.api.Session;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketError;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketMessage;
+import org.eclipse.jetty.websocket.api.annotations.WebSocket;
+import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
+import org.qortal.controller.Controller;
+import org.qortal.data.transaction.PresenceTransactionData;
+import org.qortal.data.transaction.TransactionData;
+import org.qortal.event.Event;
+import org.qortal.event.EventBus;
+import org.qortal.event.Listener;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.repository.RepositoryManager;
+import org.qortal.transaction.PresenceTransaction.PresenceType;
+import org.qortal.transaction.Transaction.TransactionType;
+import org.qortal.utils.Base58;
+
+@WebSocket
+@SuppressWarnings("serial")
+public class PresenceWebSocket extends ApiWebSocket implements Listener {
+
+	@XmlAccessorType(XmlAccessType.FIELD)
+	@SuppressWarnings("unused")
+	private static class PresenceInfo {
+		public final PresenceType presenceType;
+		public final String publicKey;
+		public final long timestamp;
+
+		protected PresenceInfo() {
+			this.presenceType = null;
+			this.publicKey = null;
+			this.timestamp = 0L;
+		}
+
+		public PresenceInfo(PresenceType presenceType, String pubKey58, long timestamp) {
+			this.presenceType = presenceType;
+			this.publicKey = pubKey58;
+			this.timestamp = timestamp;
+		}
+
+		public PresenceType getPresenceType() {
+			return this.presenceType;
+		}
+
+		public String getPublicKey() {
+			return this.publicKey;
+		}
+
+		public long getTimestamp() {
+			return this.timestamp;
+		}
+	}
+
+	/** Outer map key is PresenceType (enum), inner map key is public key in base58, inner map value is timestamp */
+	private static final Map<PresenceType, Map<String, Long>> currentEntries = Collections.synchronizedMap(new EnumMap<>(PresenceType.class));
+
+	@Override
+	public void configure(WebSocketServletFactory factory) {
+		factory.register(PresenceWebSocket.class);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			populateCurrentInfo(repository);
+		} catch (DataException e) {
+			// How to fail properly?
+			return;
+		}
+
+		EventBus.INSTANCE.addListener(this::listen);
+	}
+
+	@Override
+	public void listen(Event event) {
+		if (!(event instanceof Controller.NewTransactionEvent))
+			return;
+
+		TransactionData transactionData = ((Controller.NewTransactionEvent) event).getTransactionData();
+
+		if (transactionData.getType() != TransactionType.PRESENCE)
+			return;
+
+		PresenceTransactionData presenceData = (PresenceTransactionData) transactionData;
+		PresenceType presenceType = presenceData.getPresenceType();
+
+		// Put/replace for this publickey making sure we keep newest timestamp
+		String pubKey58 = Base58.encode(presenceData.getCreatorPublicKey());
+		Long ourTimestamp = presenceData.getTimestamp();
+		Long computedTimestamp = mergePresence(presenceType, pubKey58, ourTimestamp);
+
+		if (!computedTimestamp.equals(ourTimestamp))
+			// nothing changed
+			return;
+
+		List<PresenceInfo> presenceInfo = Collections.singletonList(new PresenceInfo(presenceType, pubKey58, computedTimestamp));
+
+		// Notify sessions
+		for (Session session : getSessions())
+			sendPresenceInfo(session, presenceInfo);
+	}
+
+	@OnWebSocketConnect
+	@Override
+	public void onWebSocketConnect(Session session) {
+		List<PresenceInfo> presenceInfo;
+
+		synchronized (currentEntries) {
+			presenceInfo = currentEntries.entrySet().stream()
+					.flatMap(entry -> entry.getValue().entrySet().stream().map(innerEntry -> new PresenceInfo(entry.getKey(), innerEntry.getKey(), innerEntry.getValue())))
+					.collect(Collectors.toList());
+		}
+
+		if (!sendPresenceInfo(session, presenceInfo)) {
+			session.close(4002, "websocket issue");
+			return;
+		}
+
+		super.onWebSocketConnect(session);
+	}
+
+	@OnWebSocketClose
+	@Override
+	public void onWebSocketClose(Session session, int statusCode, String reason) {
+		super.onWebSocketClose(session, statusCode, reason);
+	}
+
+	@OnWebSocketError
+	public void onWebSocketError(Session session, Throwable throwable) {
+		/* ignored */
+	}
+
+	@OnWebSocketMessage
+	public void onWebSocketMessage(Session session, String message) {
+		/* ignored */
+	}
+
+	private boolean sendPresenceInfo(Session session, List<PresenceInfo> presenceInfo) {
+		try {
+			StringWriter stringWriter = new StringWriter();
+			marshall(stringWriter, presenceInfo);
+
+			String output = stringWriter.toString();
+			session.getRemote().sendStringByFuture(output);
+		} catch (IOException e) {
+			// No output this time?
+			return false;
+		}
+
+		return true;
+	}
+
+	private static void populateCurrentInfo(Repository repository) throws DataException {
+		// We want ALL PRESENCE transactions
+
+		List<TransactionData> presenceTransactionsData = repository.getTransactionRepository().getUnconfirmedTransactions(TransactionType.PRESENCE, null);
+
+		for (TransactionData transactionData : presenceTransactionsData) {
+			PresenceTransactionData presenceData = (PresenceTransactionData) transactionData;
+
+			PresenceType presenceType = presenceData.getPresenceType();
+
+			// Put/replace for this publickey making sure we keep newest timestamp
+			String pubKey58 = Base58.encode(presenceData.getCreatorPublicKey());
+			Long ourTimestamp = presenceData.getTimestamp();
+
+			mergePresence(presenceType, pubKey58, ourTimestamp);
+		}
+	}
+
+	private static Long mergePresence(PresenceType presenceType, String pubKey58, Long ourTimestamp) {
+		Map<String, Long> typedPubkeyTimestamps = currentEntries.computeIfAbsent(presenceType, someType -> Collections.synchronizedMap(new HashMap<>()));
+		return typedPubkeyTimestamps.compute(pubKey58, (somePubKey58, currentTimestamp) -> (currentTimestamp == null || currentTimestamp < ourTimestamp) ? ourTimestamp : currentTimestamp);
+	}
+
+}