Enable recording where an interaction was acknowledged first

src/main/java/net/dv8tion/jda/api/exceptions/FirstAcknowledgementException.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2015 Austin Keener, Michael Ritter, Florian Spieß, and the JDA contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.dv8tion.jda.api.exceptions;
+
+/**
+ * Used to indicate where an interaction was first acknowledged at, for debugging purposes.
+ */
+public class FirstAcknowledgementException extends RuntimeException
+{
+    public FirstAcknowledgementException()
+    {
+        super("This is where the interaction was first acknowledged at");
+    }
+}

src/main/java/net/dv8tion/jda/internal/interactions/InteractionHookImpl.java

@@ -74,11 +74,6 @@ public InteractionHookImpl(@Nonnull JDA api, @Nonnull String token)
         this.isReady = true;
     }
 
-    public boolean ack()
-    {
-        return interaction == null || interaction.ack();
-    }
-
     public boolean isAck()
     {
         return interaction == null || interaction.isAcknowledged();

src/main/java/net/dv8tion/jda/internal/interactions/InteractionImpl.java

@@ -25,22 +25,32 @@
 import net.dv8tion.jda.api.entities.channel.ChannelType;
 import net.dv8tion.jda.api.entities.channel.concrete.PrivateChannel;
 import net.dv8tion.jda.api.entities.channel.middleman.GuildChannel;
+import net.dv8tion.jda.api.exceptions.FirstAcknowledgementException;
 import net.dv8tion.jda.api.interactions.DiscordLocale;
 import net.dv8tion.jda.api.interactions.Interaction;
 import net.dv8tion.jda.api.utils.data.DataArray;
 import net.dv8tion.jda.api.utils.data.DataObject;
 import net.dv8tion.jda.internal.JDAImpl;
-import net.dv8tion.jda.internal.entities.*;
+import net.dv8tion.jda.internal.entities.GuildImpl;
+import net.dv8tion.jda.internal.entities.MemberImpl;
+import net.dv8tion.jda.internal.entities.UserImpl;
 import net.dv8tion.jda.internal.entities.channel.concrete.PrivateChannelImpl;
 import net.dv8tion.jda.internal.utils.Helpers;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.List;
-import java.util.stream.Collectors;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
 
 public class InteractionImpl implements Interaction
 {
+    // Enables recording where the first ack is done,
+    // to help with debugging when an interaction is acknowledged twice
+    private static boolean recordAckTraces = false;
+    private static ScheduledFuture<?> scheduledRecordDeactivation;
+    private Throwable firstAckTrace = null;
+
     protected final long id;
     protected final long channelId;
     protected final int type;
@@ -120,11 +130,41 @@ public InteractionImpl(JDAImpl jda, DataObject data)
     public synchronized void releaseHook(boolean success) {}
 
     // Ensures that one cannot acknowledge an interaction twice
-    public synchronized boolean ack()
+    @Nullable
+    public synchronized IllegalStateException tryAck()
     {
-        boolean wasAck = isAck;
-        this.isAck = true;
-        return wasAck;
+        // If not already acknowledged => no exception
+        if (!isAck)
+        {
+            // Store where the first ack was made, so we can use show it on the 2nd ack
+            if (recordAckTraces)
+                firstAckTrace = new FirstAcknowledgementException();
+            isAck = true;
+            return null;
+        }
+
+        // Enable saving stack traces of acknowledgements.
+        // On future acknowledgements, the stack trace of the first ack will be kept, and added to the second ack,
+        // so the user doesn't have to figure out where the first ack was at.
+        if (firstAckTrace == null)
+        {
+            recordAckTraces = true;
+
+            // Stop recording after 15 minutes if the issue was not reproduced
+            if (scheduledRecordDeactivation != null)
+                scheduledRecordDeactivation.cancel(false);
+            scheduledRecordDeactivation = api.getGatewayPool().schedule(() ->
+            {
+                recordAckTraces = false;
+            }, 15, TimeUnit.MINUTES);
+            return new IllegalStateException("This interaction has already been acknowledged or replied to. You can only reply or acknowledge an interaction once! Retry using this interaction for more details.");
+        }
+        else
+        {
+            recordAckTraces = false;
+            scheduledRecordDeactivation.cancel(false);
+            return new IllegalStateException("This interaction has already been acknowledged or replied to. You can only reply or acknowledge an interaction once!", firstAckTrace);
+        }
     }
 
     @Override

src/main/java/net/dv8tion/jda/internal/requests/restaction/interactions/InteractionCallbackImpl.java

@@ -49,19 +49,10 @@ public InteractionCallbackAction<T> closeResources()
     // Here we intercept calls to queue/submit/complete to prevent double ack/reply scenarios with a better error message than discord provides //
     //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
-    // This is an exception factory method that only returns an exception if we would have to throw it or fail in another way.
-    protected final IllegalStateException tryAck() // note that interaction.ack() is already synchronized so this is actually thread-safe!
-    {
-        // true => we already called this before => this will never succeed!
-        return interaction.ack()
-                ? new IllegalStateException("This interaction has already been acknowledged or replied to. You can only reply or acknowledge an interaction once!")
-                : null; // null indicates we were successful, no exception means we can't fail :)
-    }
-
     @Override
     public final void queue(Consumer<? super T> success, Consumer<? super Throwable> failure)
     {
-        IllegalStateException exception = tryAck();
+        IllegalStateException exception = interaction.tryAck();
         if (exception != null)
         {
             if (failure != null)
@@ -78,7 +69,7 @@ public final void queue(Consumer<? super T> success, Consumer<? super Throwable>
     @Override
     public final CompletableFuture<T> submit(boolean shouldQueue)
     {
-        IllegalStateException exception = tryAck();
+        IllegalStateException exception = interaction.tryAck();
         if (exception != null)
         {
             CompletableFuture<T> future = new CompletableFuture<>();