Add chunk coordinator

Bukkit/build.gradle

@@ -28,7 +28,7 @@ dependencies {
         exclude(module: "bukkit")
 
     }
-    compile("io.papermc:paperlib:1.0.2")
+    compile("io.papermc:paperlib:1.0.4")
     implementation("net.kyori:text-adapter-bukkit:3.0.3")
     compile("com.github.MilkBowl:VaultAPI:1.7") {
         exclude(module: "bukkit")
@@ -94,7 +94,7 @@ task copyFiles {
 shadowJar {
     dependencies {
         include(dependency(":PlotSquared-Core"))
-        include(dependency("io.papermc:paperlib:1.0.2"))
+        include(dependency("io.papermc:paperlib:1.0.4"))
         include(dependency("net.kyori:text-adapter-bukkit:3.0.3"))
         include(dependency("org.bstats:bstats-bukkit:1.7"))
         include(dependency("org.khelekore:prtree:1.7.0-SNAPSHOT"))

Bukkit/src/main/java/com/plotsquared/bukkit/queue/ChunkCoordinator.java

@@ -0,0 +1,326 @@
+/*
+ *       _____  _       _    _____                                _
+ *      |  __ \| |     | |  / ____|                              | |
+ *      | |__) | | ___ | |_| (___   __ _ _   _  __ _ _ __ ___  __| |
+ *      |  ___/| |/ _ \| __|\___ \ / _` | | | |/ _` | '__/ _ \/ _` |
+ *      | |    | | (_) | |_ ____) | (_| | |_| | (_| | | |  __/ (_| |
+ *      |_|    |_|\___/ \__|_____/ \__, |\__,_|\__,_|_|  \___|\__,_|
+ *                                    | |
+ *                                    |_|
+ *            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.bukkit.queue;
+
+import com.google.common.base.Preconditions;
+import com.plotsquared.bukkit.BukkitMain;
+import com.sk89q.worldedit.math.BlockVector2;
+import io.papermc.lib.PaperLib;
+import org.bukkit.Chunk;
+import org.bukkit.World;
+import org.bukkit.plugin.Plugin;
+import org.bukkit.plugin.java.JavaPlugin;
+import org.bukkit.scheduler.BukkitRunnable;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Consumer;
+
+/**
+ * Utility that allows for the loading and coordination of chunk actions
+ * <p>
+ * The coordinator takes in collection of chunk coordinates, loads them
+ * and allows the caller to specify a sink for the loaded chunks. The
+ * coordinator will prevent the chunks from being unloaded until the sink
+ * has fully consumed the chunk
+ * <p>
+ * Usage:
+ * <pre>{@code
+ * final ChunkCoordinator chunkCoordinator = ChunkCoordinator.builder()
+ *     .inWorld(Objects.requireNonNull(Bukkit.getWorld("world"))).withChunk(BlockVector2.at(0, 0))
+ *     .withConsumer(chunk -> System.out.printf("Got chunk %d;%d", chunk.getX(), chunk.getZ()))
+ *     .withFinalAction(() -> System.out.println("All chunks have been loaded"))
+ *     .withThrowableConsumer(throwable -> System.err.println("Something went wrong... =("))
+ *     .withMaxIterationTime(25L)
+ *     .build();
+ * chunkCoordinator.subscribeToProgress((coordinator, progress) ->
+ *     System.out.printf("Progress: %.1f", progress * 100.0f));
+ * chunkCoordinator.start();
+ * }</pre>
+ *
+ * @author Alexander Söderberg
+ * @see #builder() To create a new coordinator instance
+ */
+public final class ChunkCoordinator extends BukkitRunnable {
+
+    private final List<ProgressSubscriber> progressSubscribers = new LinkedList<>();
+
+    private final Queue<BlockVector2> requestedChunks;
+    private final Queue<Chunk> availableChunks;
+    private final long maxIterationTime;
+    private final Plugin plugin;
+    private final Consumer<Chunk> chunkConsumer;
+    private final World world;
+    private final Runnable whenDone;
+    private final Consumer<Throwable> throwableConsumer;
+    private final int totalSize;
+
+    private AtomicInteger expectedSize;
+    private int batchSize;
+
+    private ChunkCoordinator(final long maxIterationTime, final int initialBatchSize,
+        @NotNull final Consumer<Chunk> chunkConsumer, @NotNull final World world,
+        @NotNull final Collection<BlockVector2> requestedChunks, @NotNull final Runnable whenDone,
+        @NotNull final Consumer<Throwable> throwableConsumer) {
+        this.requestedChunks = new LinkedBlockingQueue<>(requestedChunks);
+        this.availableChunks = new LinkedBlockingQueue<>();
+        this.totalSize = requestedChunks.size();
+        this.expectedSize = new AtomicInteger(this.totalSize);
+        this.world = world;
+        this.batchSize = initialBatchSize;
+        this.chunkConsumer = chunkConsumer;
+        this.maxIterationTime = maxIterationTime;
+        this.whenDone = whenDone;
+        this.throwableConsumer = throwableConsumer;
+        this.plugin = JavaPlugin.getPlugin(BukkitMain.class);
+    }
+
+    /**
+     * Create a new {@link ChunkCoordinator} instance
+     *
+     * @return Coordinator builder instance
+     */
+    @NotNull public static ChunkCoordinatorBuilder builder() {
+        return new ChunkCoordinatorBuilder();
+    }
+
+    /**
+     * Start the coordinator instance
+     */
+    public void start() {
+        // Request initial batch
+        this.requestBatch();
+        // Wait until next tick to give the chunks a chance to be loaded
+        this.runTaskTimer(this.plugin, 1L, 1L);
+    }
+
+    @Override public void run() {
+        Chunk chunk = this.availableChunks.poll();
+        if (chunk == null) {
+            return;
+        }
+        long iterationTime;
+        int processedChunks = 0;
+        do {
+            final long start = System.currentTimeMillis();
+            try {
+                this.chunkConsumer.accept(chunk);
+            } catch (final Throwable throwable) {
+                this.throwableConsumer.accept(throwable);
+            }
+            this.freeChunk(chunk);
+            processedChunks++;
+            final long end = System.currentTimeMillis();
+            // Update iteration time
+            iterationTime = end - start;
+        } while (2 * iterationTime /* last chunk + next chunk */ < this.maxIterationTime
+            && (chunk = availableChunks.poll()) != null);
+        if (processedChunks < this.batchSize) {
+            // Adjust batch size based on the amount of processed chunks per tick
+            this.batchSize = processedChunks;
+        }
+
+        final int expected = this.expectedSize.addAndGet(-processedChunks);
+
+        final float progress = ((float) totalSize - (float) expected) / (float) totalSize;
+        for (final ProgressSubscriber subscriber : this.progressSubscribers) {
+            subscriber.notifyProgress(this, progress);
+        }
+
+        if (expected <= 0) {
+            try {
+                this.whenDone.run();
+            } catch (final Throwable throwable) {
+                this.throwableConsumer.accept(throwable);
+            }
+            this.cancel();
+        } else {
+            if (this.availableChunks.size() < processedChunks) {
+                this.requestBatch();
+            }
+        }
+    }
+
+    private void requestBatch() {
+        BlockVector2 chunk;
+        for (int i = 0; i < this.batchSize && (chunk = this.requestedChunks.poll()) != null; i++) {
+            // This required PaperLib to be bumped to version 1.0.4 to mark the request as urgent
+            PaperLib.getChunkAtAsync(this.world, chunk.getX(), chunk.getZ(), true, true)
+                .whenComplete((chunkObject, throwable) -> {
+                    if (throwable != null) {
+                        throwable.printStackTrace();
+                        // We want one less because this couldn't be processed
+                        this.expectedSize.decrementAndGet();
+                    } else {
+                        this.processChunk(chunkObject);
+                    }
+                });
+        }
+    }
+
+    private void processChunk(@NotNull final Chunk chunk) {
+        if (!chunk.isLoaded()) {
+            throw new IllegalArgumentException(
+                String.format("Chunk %d;%d is is not loaded", chunk.getX(), chunk.getZ()));
+        }
+        chunk.addPluginChunkTicket(this.plugin);
+        this.availableChunks.add(chunk);
+    }
+
+    private void freeChunk(@NotNull final Chunk chunk) {
+        if (!chunk.isLoaded()) {
+            throw new IllegalArgumentException(
+                String.format("Chunk %d;%d is is not loaded", chunk.getX(), chunk.getZ()));
+        }
+        chunk.removePluginChunkTicket(this.plugin);
+    }
+
+    /**
+     * Get the amount of remaining chunks (at the time of the method call)
+     *
+     * @return Snapshot view of remaining chunk count
+     */
+    public int getRemainingChunks() {
+        return this.expectedSize.get();
+    }
+
+    /**
+     * Get the amount of requested chunks
+     *
+     * @return Requested chunk count
+     */
+    public int getTotalChunks() {
+        return this.totalSize;
+    }
+
+    /**
+     * Subscribe to coordinator progress updates
+     *
+     * @param subscriber Subscriber
+     */
+    public void subscribeToProgress(@NotNull final ChunkCoordinator.ProgressSubscriber subscriber) {
+        this.progressSubscribers.add(subscriber);
+    }
+
+
+    @FunctionalInterface
+    public interface ProgressSubscriber {
+
+        /**
+         * Notify about a progress update in the coordinator
+         *
+         * @param coordinator Coordinator instance that triggered the notification
+         * @param progress    Progress in the range [0, 1]
+         */
+        void notifyProgress(@NotNull final ChunkCoordinator coordinator, final float progress);
+
+    }
+
+
+    public static final class ChunkCoordinatorBuilder {
+
+        private final List<BlockVector2> requestedChunks = new LinkedList<>();
+        private Consumer<Throwable> throwableConsumer = Throwable::printStackTrace;
+        private World world;
+        private Consumer<Chunk> chunkConsumer;
+        private Runnable whenDone = () -> {
+        };
+        private long maxIterationTime = 60; // A little over 1 tick;
+        private int initialBatchSize = 4;
+
+        private ChunkCoordinatorBuilder() {
+        }
+
+        @NotNull public ChunkCoordinatorBuilder inWorld(@NotNull final World world) {
+            this.world = Preconditions.checkNotNull(world, "World may not be null");
+            return this;
+        }
+
+        @NotNull
+        public ChunkCoordinatorBuilder withChunk(@NotNull final BlockVector2 chunkLocation) {
+            this.requestedChunks
+                .add(Preconditions.checkNotNull(chunkLocation, "Chunk location may not be null"));
+            return this;
+        }
+
+        @NotNull public ChunkCoordinatorBuilder withChunks(
+            @NotNull final Collection<BlockVector2> chunkLocations) {
+            chunkLocations.forEach(this::withChunk);
+            return this;
+        }
+
+        @NotNull
+        public ChunkCoordinatorBuilder withConsumer(@NotNull final Consumer<Chunk> chunkConsumer) {
+            this.chunkConsumer =
+                Preconditions.checkNotNull(chunkConsumer, "Chunk consumer may not be null");
+            return this;
+        }
+
+        @NotNull public ChunkCoordinatorBuilder withFinalAction(@NotNull final Runnable whenDone) {
+            this.whenDone = Preconditions.checkNotNull(whenDone, "Final action may not be null");
+            return this;
+        }
+
+        @NotNull public ChunkCoordinatorBuilder withMaxIterationTime(final long maxIterationTime) {
+            Preconditions
+                .checkArgument(maxIterationTime > 0, "Max iteration time must be positive");
+            this.maxIterationTime = maxIterationTime;
+            return this;
+        }
+
+        @NotNull public ChunkCoordinatorBuilder withInitialBatchSize(final int initialBatchSize) {
+            Preconditions
+                .checkArgument(initialBatchSize > 0, "Initial batch size must be positive");
+            this.initialBatchSize = initialBatchSize;
+            return this;
+        }
+
+        @NotNull public ChunkCoordinatorBuilder withThrowableConsumer(
+            @NotNull final Consumer<Throwable> throwableConsumer) {
+            this.throwableConsumer =
+                Preconditions.checkNotNull(throwableConsumer, "Throwable consumer may not be null");
+            return this;
+        }
+
+        @NotNull public ChunkCoordinator build() {
+            Preconditions.checkNotNull(this.world, "No world was supplied");
+            Preconditions.checkNotNull(this.chunkConsumer, "No chunk consumer was supplied");
+            Preconditions.checkNotNull(this.whenDone, "No final action was supplied");
+            Preconditions
+                .checkNotNull(this.throwableConsumer, "No throwable consumer was supplied");
+            return new ChunkCoordinator(this.maxIterationTime, this.initialBatchSize,
+                this.chunkConsumer, this.world, this.requestedChunks, this.whenDone,
+                this.throwableConsumer);
+        }
+
+    }
+
+}