From f8a6fbd7197a44b0dc8752d1fe8fda438373db81 Mon Sep 17 00:00:00 2001
From: Ashcon Partovi <ashcon@partovi.net>
Date: Thu, 16 Apr 2020 09:38:18 -0700
Subject: [PATCH] Execute commands on the same thread they were submitted on *
 This fixes an issue where Bukkit commands would unexpectedly run off the main
 thread

Signed-off-by: Ashcon Partovi <ashcon@partovi.net>
---
 .../parametric/CommandExecutorWrapper.java    | 34 +++++++++++++++----
 .../intake/parametric/ParametricBuilder.java  |  4 +--
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/core/src/main/java/app/ashcon/intake/parametric/CommandExecutorWrapper.java b/core/src/main/java/app/ashcon/intake/parametric/CommandExecutorWrapper.java
index 8e78073..723538d 100644
--- a/core/src/main/java/app/ashcon/intake/parametric/CommandExecutorWrapper.java
+++ b/core/src/main/java/app/ashcon/intake/parametric/CommandExecutorWrapper.java
@@ -22,21 +22,41 @@
 
 import app.ashcon.intake.argument.CommandArgs;
 import java.util.concurrent.Callable;
-import java.util.concurrent.ExecutorService;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.Executor;
 import java.util.concurrent.Future;
 
 /** Wraps an ExecutorService into a CommandExecutor. */
 public class CommandExecutorWrapper implements CommandExecutor {
 
-  private final ExecutorService executorService;
+  private final Executor executor;
 
-  public CommandExecutorWrapper(ExecutorService executorService) {
-    checkNotNull(executorService, "executorService");
-    this.executorService = executorService;
+  public CommandExecutorWrapper(Executor executor) {
+    checkNotNull(executor, "executor");
+    this.executor = executor;
   }
 
   @Override
-  public <T> Future<T> submit(Callable<T> task, CommandArgs args) {
-    return executorService.submit(task);
+  public <T> Future<T> submit(Callable<T> callable, CommandArgs args) {
+    Task<T> task = new Task<>(callable);
+    executor.execute(task);
+    return task;
+  }
+
+  private static class Task<V> extends CompletableFuture<V> implements Runnable {
+    private final Callable<V> task;
+
+    private Task(Callable<V> task) {
+      this.task = checkNotNull(task, "task");
+    }
+
+    @Override
+    public void run() {
+      try {
+        complete(task.call());
+      } catch (Throwable t) {
+        completeExceptionally(t);
+      }
+    }
   }
 }
diff --git a/core/src/main/java/app/ashcon/intake/parametric/ParametricBuilder.java b/core/src/main/java/app/ashcon/intake/parametric/ParametricBuilder.java
index 6a7f645..ac07030 100644
--- a/core/src/main/java/app/ashcon/intake/parametric/ParametricBuilder.java
+++ b/core/src/main/java/app/ashcon/intake/parametric/ParametricBuilder.java
@@ -35,7 +35,6 @@
 import java.lang.reflect.Method;
 import java.util.List;
 import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 
 /**
  * Keeps a mapping of types to bindings and generates commands from classes with appropriate
@@ -49,7 +48,8 @@ public class ParametricBuilder {
   private Authorizer authorizer = new NullAuthorizer();
   private CommandCompleter defaultCompleter = new NullCompleter();
   private CommandExecutor commandExecutor =
-      new CommandExecutorWrapper(Executors.newSingleThreadExecutor());
+      new CommandExecutorWrapper(
+          Runnable::run); // Runs commands on the same thread they were submitted on
 
   public ParametricBuilder(Injector injector) {
     this.injector = injector;