Make task executor lifecycled to platform readiness.

Closes #2459.

Author: wizjany

worldedit-core/src/main/java/com/sk89q/worldedit/WorldEdit.java

@@ -26,7 +26,6 @@
 import com.google.common.collect.Lists;
 import com.google.common.collect.SetMultimap;
 import com.google.common.util.concurrent.ListeningExecutorService;
-import com.google.common.util.concurrent.MoreExecutors;
 import com.sk89q.worldedit.blocks.BaseItem;
 import com.sk89q.worldedit.entity.Player;
 import com.sk89q.worldedit.event.platform.BlockInteractEvent;
@@ -55,7 +54,6 @@
 import com.sk89q.worldedit.util.Direction;
 import com.sk89q.worldedit.util.Location;
 import com.sk89q.worldedit.util.asset.AssetLoaders;
-import com.sk89q.worldedit.util.concurrency.EvenMoreExecutors;
 import com.sk89q.worldedit.util.eventbus.EventBus;
 import com.sk89q.worldedit.util.formatting.text.TextComponent;
 import com.sk89q.worldedit.util.formatting.text.TranslatableComponent;
@@ -124,8 +122,6 @@ public final class WorldEdit {
     @Deprecated
     private final EditSessionFactory editSessionFactory = new EditSessionFactory.EditSessionFactoryImpl();
     private final SessionManager sessions = new SessionManager(this);
-    private final ListeningExecutorService executorService = MoreExecutors.listeningDecorator(
-            EvenMoreExecutors.newBoundedCachedThreadPool(0, 1, 20, "WorldEdit Task Executor - %s"));
     private final Supervisor supervisor = new SimpleSupervisor();
     private final AssetLoaders assetLoaders = new AssetLoaders(this);
 
@@ -192,7 +188,7 @@ public Supervisor getSupervisor() {
      * @return the executor service
      */
     public ListeningExecutorService getExecutorService() {
-        return executorService;
+        return platformManager.getExecutorService();
     }
 
     /**

worldedit-core/src/main/java/com/sk89q/worldedit/event/platform/PlatformInitializeEvent.java

@@ -23,7 +23,7 @@
 
 /**
  * Fired when configuration has been loaded and the platform is in the
- * intialization stage.
+ * initialization stage.
  *
  * <p>This event is fired once.</p>
  */

worldedit-core/src/main/java/com/sk89q/worldedit/extension/platform/PlatformManager.java

@@ -19,6 +19,9 @@
 
 package com.sk89q.worldedit.extension.platform;
 
+import com.google.common.collect.Maps;
+import com.google.common.util.concurrent.ListeningExecutorService;
+import com.google.common.util.concurrent.MoreExecutors;
 import com.sk89q.worldedit.LocalConfiguration;
 import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.WorldEdit;
@@ -41,7 +44,9 @@
 import com.sk89q.worldedit.util.HandSide;
 import com.sk89q.worldedit.util.Location;
 import com.sk89q.worldedit.util.SideEffect;
+import com.sk89q.worldedit.util.concurrency.EvenMoreExecutors;
 import com.sk89q.worldedit.util.eventbus.Subscribe;
+import com.sk89q.worldedit.util.lifecycle.SimpleLifecycled;
 import com.sk89q.worldedit.world.World;
 import org.apache.logging.log4j.Logger;
 
@@ -69,7 +74,8 @@ public class PlatformManager {
 
     private final WorldEdit worldEdit;
     private final PlatformCommandManager platformCommandManager;
-    private final List<Platform> platforms = new ArrayList<>();
+    private final SimpleLifecycled<ListeningExecutorService> executorService;
+    private final Map<Platform, Boolean> platforms = Maps.newHashMap();
     private final Map<Capability, Platform> preferences = new EnumMap<>(Capability.class);
     private @Nullable String firstSeenVersion;
     private final AtomicBoolean initialized = new AtomicBoolean();
@@ -84,6 +90,7 @@ public PlatformManager(WorldEdit worldEdit) {
         checkNotNull(worldEdit);
         this.worldEdit = worldEdit;
         this.platformCommandManager = new PlatformCommandManager(worldEdit, this);
+        this.executorService = SimpleLifecycled.invalid();
 
         // Register this instance for events
         worldEdit.getEventBus().register(this);
@@ -101,7 +108,7 @@ public synchronized void register(Platform platform) {
 
         // Just add the platform to the list of platforms: we'll pick favorites
         // once all the platforms have been loaded
-        platforms.add(platform);
+        platforms.put(platform, false);
 
         // Make sure that versions are in sync
         if (firstSeenVersion != null) {
@@ -126,7 +133,7 @@ public synchronized void register(Platform platform) {
     public synchronized boolean unregister(Platform platform) {
         checkNotNull(platform);
 
-        boolean removed = platforms.remove(platform);
+        boolean removed = platforms.remove(platform) != null;
 
         if (removed) {
             LOGGER.info("Unregistering " + platform.getClass().getCanonicalName() + " from WorldEdit");
@@ -212,7 +219,7 @@ private synchronized void choosePreferred() {
         Platform preferred = null;
         Preference highest = null;
 
-        for (Platform platform : platforms) {
+        for (Platform platform : platforms.keySet()) {
             Preference preference = platform.getCapabilities().get(capability);
             if (preference != null && (highest == null || preference.isPreferredOver(highest))) {
                 preferred = platform;
@@ -231,7 +238,7 @@ private synchronized void choosePreferred() {
      * @return a list of platforms
      */
     public synchronized List<Platform> getPlatforms() {
-        return new ArrayList<>(platforms);
+        return new ArrayList<>(platforms.keySet());
     }
 
     /**
@@ -284,6 +291,21 @@ public PlatformCommandManager getPlatformCommandManager() {
         return platformCommandManager;
     }
 
+    /**
+     * Get the executor service. Internal, not for API use.
+     *
+     * @return the executor service
+     */
+    public ListeningExecutorService getExecutorService() {
+        return executorService.valueOrThrow();
+    }
+
+    private static ListeningExecutorService createExecutor() {
+        return MoreExecutors.listeningDecorator(
+                EvenMoreExecutors.newBoundedCachedThreadPool(
+                        0, 1, 20, "WorldEdit Task Executor - %s"));
+    }
+
     /**
      * Get the current configuration.
      *
@@ -340,6 +362,10 @@ public void handlePlatformsRegistered(PlatformsRegisteredEvent event) {
     @Subscribe
     public void handleNewPlatformReady(PlatformReadyEvent event) {
         preferences.forEach((cap, platform) -> cap.ready(this, platform));
+        platforms.put(event.getPlatform(), true);
+        if (!executorService.isValid()) {
+            executorService.newValue(createExecutor());
+        }
     }
 
     /**
@@ -348,6 +374,11 @@ public void handleNewPlatformReady(PlatformReadyEvent event) {
     @Subscribe
     public void handleNewPlatformUnready(PlatformUnreadyEvent event) {
         preferences.forEach((cap, platform) -> cap.unready(this, platform));
+        platforms.put(event.getPlatform(), false);
+        if (!platforms.containsValue(true)) {
+            executorService.value().ifPresent(ListeningExecutorService::shutdownNow);
+            executorService.invalidate();
+        }
     }
 
     @Subscribe