Improve design

Core/src/main/java/com/plotsquared/core/uuid/ServiceFailure.java

@@ -1,49 +0,0 @@
-/*
- *       _____  _       _    _____                                _
- *      |  __ \| |     | |  / ____|                              | |
- *      | |__) | | ___ | |_| (___   __ _ _   _  __ _ _ __ ___  __| |
- *      |  ___/| |/ _ \| __|\___ \ / _` | | | |/ _` | '__/ _ \/ _` |
- *      | |    | | (_) | |_ ____) | (_| | |_| | (_| | | |  __/ (_| |
- *      |_|    |_|\___/ \__|_____/ \__, |\__,_|\__,_|_|  \___|\__,_|
- *                                    | |
- *                                    |_|
- *            PlotSquared plot management system for Minecraft
- *                  Copyright (C) 2020 IntellectualSites
- *
- *     This program is free software: you can redistribute it and/or modify
- *     it under the terms of the GNU General Public License as published by
- *     the Free Software Foundation, either version 3 of the License, or
- *     (at your option) any later version.
- *
- *     This program is distributed in the hope that it will be useful,
- *     but WITHOUT ANY WARRANTY; without even the implied warranty of
- *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *     GNU General Public License for more details.
- *
- *     You should have received a copy of the GNU General Public License
- *     along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-package com.plotsquared.core.uuid;
-
-import java.util.concurrent.CompletableFuture;
-
-/**
- * Thrown by a {@link UUIDService} when it cannot
- * complete a request. This is not an error and
- * will be dealt with silently.
- */
-public class ServiceFailure extends Throwable {
-
-    private static final ServiceFailure instance = new ServiceFailure();
-
-    public static <T> CompletableFuture<T> getFuture() {
-        final CompletableFuture<T> completableFuture = new CompletableFuture<>();
-        completableFuture.completeExceptionally(instance);
-        return completableFuture;
-    }
-
-    @Override public Throwable fillInStackTrace() {
-        return this;
-    }
-
-}

Core/src/main/java/com/plotsquared/core/uuid/UUIDPipeline.java

@@ -28,8 +28,11 @@ package com.plotsquared.core.uuid;
 import com.google.common.collect.Lists;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
-import java.util.ListIterator;
+import java.util.Optional;
 import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
@@ -79,9 +82,7 @@ public class UUIDPipeline {
      * @return Copy of service list
      */
     public List<UUIDService> getServiceListInstance() {
-        final List<UUIDService> serviceList = Lists.newLinkedList(this.serviceList);
+        return Collections.unmodifiableList(this.serviceList);
-        serviceList.add(EndOfPipeline.instance);
-        return serviceList;
     }
 
     private void consume(@NotNull final UUIDMapping mapping) {
@@ -93,74 +94,34 @@ public class UUIDPipeline {
     /**
      * Asynchronously attempt to fetch the mapping from a given UUID or username
      *
-     * @param request UUID or username
+     * @param requests UUIDs or usernames
      * @return Future that may complete with the mapping
      */
-    public CompletableFuture<UUIDMapping> get(@NotNull final Object request) {
+    public CompletableFuture<Collection<UUIDMapping>> get(@NotNull final Collection<Object> requests) {
+        final List<UUIDService> serviceList = this.getServiceListInstance();
+        return CompletableFuture.supplyAsync(() -> {
+            final List<UUIDMapping> mappings = new ArrayList<>(requests.size());
+            outer: for (final Object request : requests) {
                 if (!(request instanceof String) && !(request instanceof UUID)) {
                     throw new IllegalArgumentException("Request has to be either a username or UUID");
                 }
-        final CompletableFuture<UUIDMapping> future = new CompletableFuture<>();
+                for (final UUIDService service : serviceList) {
-        final ListIterator<UUIDService> serviceListIterator
+                    final Optional<?> result = service.get(request);
-            = this.getServiceListInstance().listIterator();
+                    if (result.isPresent()) {
-        final Runnable[] runnable = new Runnable[1];
-        runnable[0] = () -> {
-            if (serviceListIterator.hasNext()) {
-                final UUIDService uuidService = serviceListIterator.next();
-                uuidService.get(request).whenCompleteAsync(((result, throwable) -> {
-                    if (throwable != null) {
-                        if (throwable instanceof ServiceFailure) {
-                            try {
-                                runnable[0].run();
-                            } catch (final Throwable inner) {
-                                future.completeExceptionally(inner);
-                            }
-                        } else {
-                            future.completeExceptionally(throwable);
-                        }
-                    } else {
                         final String username = request instanceof String ? (String) request
-                            : (String) result;
+                            : (String) result.get();
                         final UUID uuid = request instanceof UUID ? (UUID) request
-                            : (UUID) result;
+                            : (UUID) result.get();
                         final UUIDMapping mapping = new UUIDMapping(uuid, username);
-                        future.complete(mapping);
                         this.consume(mapping);
+                        mappings.add(mapping);
+                        continue outer;
                     }
-                }), this.executor);
-            } else {
-                throw new ServiceError("Pipeline is incomplete");
                 }
-        };
+                throw new ServiceError("End of pipeline");
-        try {
-            // Start the pipeline traversal
-            runnable[0].run();
-        } catch (final Throwable throwable) {
-            future.completeExceptionally(throwable);
-        }
-        return future;
-    }
-
-    /**
-     * Indicates that the end of the pipeline has been reached, this
-     * will cause the request to fail, as no service was able to
-     * fulfil the request
-     */
-    private static class EndOfPipeline implements UUIDService {
-
-        public static final EndOfPipeline instance = new EndOfPipeline();
-
-        @Override @NotNull public CompletableFuture<String> get(@NotNull final UUID uuid) {
-            final CompletableFuture<String> future = new CompletableFuture<>();
-            future.completeExceptionally(new ServiceError("End of pipeline"));
-            return future;
-        }
-
-        @Override @NotNull public CompletableFuture<UUID> get(@NotNull final String username) {
-            final CompletableFuture<UUID> future = new CompletableFuture<>();
-            future.completeExceptionally(new ServiceError("End of pipeline"));
-            return future;
             }
+            return mappings;
+        }, this.executor);
     }
 
 }

Core/src/main/java/com/plotsquared/core/uuid/UUIDService.java

@@ -27,15 +27,15 @@ package com.plotsquared.core.uuid;
 
 import org.jetbrains.annotations.NotNull;
 
+import java.util.Optional;
 import java.util.UUID;
-import java.util.concurrent.CompletableFuture;
 
 /**
  * Service used to provide usernames from player UUIDs
  */
 public interface UUIDService {
 
-    default CompletableFuture<?> get(@NotNull final Object request) {
+    default Optional<?> get(@NotNull final Object request) {
         if (request instanceof UUID) {
             return get((UUID) request);
         } else if (request instanceof String) {
@@ -54,9 +54,9 @@ public interface UUIDService {
      * this completes with an empty optional.
      *
      * @param uuid Player UUID
-     * @return Future that may contain the username if it exists
+     * @return Optional that may contain the username if it exists
      */
-    @NotNull CompletableFuture<String> get(@NotNull final UUID uuid);
+    @NotNull Optional<String> get(@NotNull final UUID uuid);
 
     /**
      * Get a stored UUID from the service if it exists.
@@ -67,8 +67,8 @@ public interface UUIDService {
      * this completes with an empty optional.
      *
      * @param username Player username
-     * @return Future that may contain the UUID if it exists
+     * @return Optional  that may contain the UUID if it exists
      */
-    @NotNull CompletableFuture<UUID> get(@NotNull final String username);
+    @NotNull Optional<UUID> get(@NotNull final String username);
 
 }

Core/src/main/java/com/plotsquared/core/uuid/offline/OfflineModeUUIDService.java

@@ -27,13 +27,12 @@ package com.plotsquared.core.uuid.offline;
 
 import com.google.common.base.Charsets;
 import com.plotsquared.core.configuration.Settings;
-import com.plotsquared.core.uuid.ServiceFailure;
 import com.plotsquared.core.uuid.UUIDService;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.Locale;
+import java.util.Optional;
 import java.util.UUID;
-import java.util.concurrent.CompletableFuture;
 
 /**
  * Name provider service that creates UUIDs from usernames
@@ -47,13 +46,12 @@ public class OfflineModeUUIDService implements UUIDService {
         return UUID.nameUUIDFromBytes(("OfflinePlayer:" + username).getBytes(Charsets.UTF_8));
     }
 
-    @Override @NotNull public CompletableFuture<String> get(@NotNull final UUID uuid) {
+    @Override @NotNull public Optional<String> get(@NotNull final UUID uuid) {
-        // This service can only get UUIDs from usernames
+        return Optional.empty();
-        return ServiceFailure.getFuture();
     }
 
-    @Override @NotNull public CompletableFuture<UUID> get(@NotNull final String username) {
+    @Override @NotNull public Optional<UUID> get(@NotNull final String username) {
-        return CompletableFuture.completedFuture(this.getFromUsername(username));
+        return Optional.of(this.getFromUsername(username));
     }
 
 }