Fix a race condition in EventWaiterListener

8 files changed, 66 insertions, 39 deletions

diff --git a/src/main/java/libot/Main.java b/src/main/java/libot/Main.java
index a65c7c6..bb43869 100644
--- a/src/main/java/libot/Main.java
+++ b/src/main/java/libot/Main.java
@@ -4,6 +4,7 @@ import static java.lang.Integer.parseInt;
 import static java.lang.Runtime.getRuntime;
 import static java.lang.System.getenv;
 import static java.util.concurrent.TimeUnit.MINUTES;
+import static java.util.stream.Stream.concat;
 import static libot.core.Constants.*;
 import static libot.core.processes.ProcessManager.getProcesses;
 import static libot.utils.ReflectionUtils.scanClasspath;
@@ -14,6 +15,7 @@ import static org.slf4j.LoggerFactory.getLogger;
 
 import java.io.IOException;
 import java.util.*;
+import java.util.stream.Stream;
 
 import javax.annotation.Nonnull;
 import javax.security.auth.login.LoginException;
@@ -25,6 +27,7 @@ import libot.core.commands.CommandManager;
 import libot.core.data.DataManagerFactory;
 import libot.core.data.providers.ProviderManager;
 import libot.core.entities.BotContext;
+import libot.core.listeners.*;
 import libot.core.processes.ProcessManager;
 import libot.core.shred.Shredder;
 import libot.core.shred.Shredder.Shred;
@@ -51,11 +54,14 @@ public class Main {
                         System.exit(1);
                 });
                 LOG.info("Creating shreds");
+                var ewl = new EventWaiterListener();
+
                 var builder =
                         JDABuilder.create(GUILD_MEMBERS, GUILD_EMOJIS, GUILD_VOICE_STATES, GUILD_MESSAGES, GUILD_MESSAGE_REACTIONS)
                                 .enableCache(VOICE_STATE, EMOTE, MEMBER_OVERRIDES)
                                 .disableCache(ACTIVITY, CLIENT_STATUS, ONLINE_STATUS)
                                 .setChunkingFilter(ChunkingFilter.ALL)
+                                .addEventListeners(ewl)
                                 .setStatus(IDLE);
 
                 var shreds = startShreds(builder);
@@ -68,7 +74,7 @@ public class Main {
                 var providers = ProviderManager.fromClasspath(shredder, data);
                 var config = BotConfiguration.fromEnvironment();
                 var commands = CommandManager.fromClasspath();
-                var bot = new BotContext(config, commands, data, shredder, providers);
+                var bot = new BotContext(config, commands, data, shredder, providers, ewl);
 
                 bot.cron().scheduleWithFixedDelay(providers::storeAll, 2, 2, MINUTES);
                 getRuntime().addShutdownHook(new Thread(() -> stop(bot), "libot-shutdown"));
@@ -147,13 +153,15 @@ public class Main {
 
         @SuppressWarnings("null")
         private static void loadEventListeners(@Nonnull Shredder shredder, @Nonnull BotContext bot) {
-                var listeners = scanClasspath(EventListener.class, libot.listeners.Anchor.class, c -> {
-                        try {
-                                return c.getDeclaredConstructor(BotContext.class).newInstance(bot);
-                        } catch (NoSuchMethodException e) {
-                                return c.getDeclaredConstructor().newInstance();
-                        }
-                }).toArray();
+
+                var listeners = concat(Stream.of(new MessageListener(bot), new ShredClashListener(bot), new EventLogListener()),
+                                                           scanClasspath(EventListener.class, libot.listeners.Anchor.class, c -> {
+                                                                   try {
+                                                                           return c.getDeclaredConstructor(BotContext.class).newInstance(bot);
+                                                                   } catch (NoSuchMethodException e) {
+                                                                           return c.getDeclaredConstructor().newInstance();
+                                                                   }
+                                                           }).stream()).toArray();
                 shredder.getShreds().stream().map(Shred::jda).forEach(j -> j.addEventListener(listeners));
         }
 
diff --git a/src/main/java/libot/core/entities/BotContext.java b/src/main/java/libot/core/entities/BotContext.java
index 25c526b..b211d2e 100644
--- a/src/main/java/libot/core/entities/BotContext.java
+++ b/src/main/java/libot/core/entities/BotContext.java
@@ -10,6 +10,7 @@ import libot.core.BotConfiguration;
 import libot.core.commands.CommandManager;
 import libot.core.data.DataManager;
 import libot.core.data.providers.*;
+import libot.core.listeners.EventWaiterListener;
 import libot.core.shred.Shredder;
 
 public class BotContext {
@@ -26,14 +27,18 @@ public class BotContext {
         private final Shredder shredder;
         @Nonnull
         private final ProviderManager providers;
+        @Nonnull
+        private final EventWaiterListener ewl;
 
         public BotContext(@Nonnull BotConfiguration config, @Nonnull CommandManager commands, @Nonnull DataManager data,
-                                          @Nonnull Shredder shredder, @Nonnull ProviderManager providers) {
+                                          @Nonnull Shredder shredder, @Nonnull ProviderManager providers,
+                                          @Nonnull EventWaiterListener ewl) {
                 this.config = config;
                 this.commands = commands;
                 this.data = data;
                 this.shredder = shredder;
                 this.providers = providers;
+                this.ewl = ewl;
         }
 
         @Nonnull
@@ -67,6 +72,11 @@ public class BotContext {
         }
 
         @Nonnull
+        public EventWaiterListener ewl() {
+                return this.ewl;
+        }
+
+        @Nonnull
         public <T extends Provider<?>> T provider(@Nonnull Class<T> clazz) {
                 return this.providers.get(clazz);
         }
diff --git a/src/main/java/libot/core/entities/CommandContext.java b/src/main/java/libot/core/entities/CommandContext.java
index 4d286b9..042e9bb 100644
--- a/src/main/java/libot/core/entities/CommandContext.java
+++ b/src/main/java/libot/core/entities/CommandContext.java
@@ -787,7 +787,7 @@ public class CommandContext {
 
         public EventUtils getWaiter() {
                 if (!isWaiterInited())
-                        this.waiter = new EventUtils(getUser(), getChannel());
+                        this.waiter = new EventUtils(getBotContext().ewl(), getUser(), getChannel());
                 return this.waiter;
         }
 
diff --git a/src/main/java/libot/listeners/EventLogListener.java b/src/main/java/libot/core/listeners/EventLogListener.java
index dceb635..fa95138 100644
--- a/src/main/java/libot/listeners/EventLogListener.java
+++ b/src/main/java/libot/core/listeners/EventLogListener.java
@@ -1,4 +1,4 @@
-package libot.listeners;
+package libot.core.listeners;
 
 import static org.slf4j.LoggerFactory.getLogger;
 
diff --git a/src/main/java/libot/listeners/EventWaiterListener.java b/src/main/java/libot/core/listeners/EventWaiterListener.java
index a2e32e7..e4aad6c 100644
--- a/src/main/java/libot/listeners/EventWaiterListener.java
+++ b/src/main/java/libot/core/listeners/EventWaiterListener.java
@@ -1,4 +1,4 @@
-package libot.listeners;
+package libot.core.listeners;
 
 import static java.lang.String.format;
 import static java.lang.Thread.interrupted;
@@ -23,17 +23,18 @@ public class EventWaiterListener implements EventListener {
         private static final String FORMAT_WRONG_TYPE = "Something went wrong; onEvent() returned %s instead of %s";
 
         // @formatter:off 💀
-        private static final MutableIntObjectMap<
+        private final MutableIntObjectMap<
                                                         Triple<
                                                                 Predicate<GenericEvent>,
                                                                 MessageLock<GenericEvent>,
                                                                 Predicate<Void>
                                                         >
-                                                > EVENT_WAITERS =
+                                                > eventWaiters =
         // @formatter:on
-                IntObjectMaps.mutable.<Triple<Predicate<GenericEvent>, MessageLock<GenericEvent>, Predicate<Void>>>empty()
-                        .asSynchronized(); // death
-        private static final AtomicInteger COUNTER = new AtomicInteger();
+                IntObjectMaps.mutable.<Triple<Predicate<GenericEvent>, MessageLock<GenericEvent>, Predicate<Void>>>empty(); // death
+
+        private final AtomicInteger counter = new AtomicInteger();
+        private final Object mutex = new Object();
 
         /**
          * Pauses the current thread and awaits a certain event.<br>
@@ -63,21 +64,25 @@ public class EventWaiterListener implements EventListener {
          * @throws InterruptedException
          */
         @SuppressWarnings("unchecked")
-        public static <T extends GenericEvent> T awaitEvent(@Nonnull Predicate<GenericEvent> predicate,
-                                                                                                                @Nullable Predicate<Void> nullableCleanupPredicate, int timeout,
-                                                                                                                @Nullable TimeUnit timeoutUnit,
-                                                                                                                @Nonnull Class<T> eventClass) throws TimeoutException,
-                                                                                                                                                                          InterruptedException {
+        public <T extends GenericEvent> T awaitEvent(@Nonnull Predicate<GenericEvent> predicate,
+                                                                                                 @Nullable Predicate<Void> nullableCleanupPredicate, int timeout,
+                                                                                                 @Nullable TimeUnit timeoutUnit,
+                                                                                                 @Nonnull Class<T> eventClass) throws TimeoutException,
+                                                                                                                                                           InterruptedException {
                 var cleanupPredicate = nullableCleanupPredicate;
                 if (cleanupPredicate == null)
                         cleanupPredicate = p -> false;
 
                 var lock = new MessageLock<GenericEvent>();
-                int ticket = COUNTER.getAndIncrement();
+                int ticket = this.counter.getAndIncrement();
                 Predicate<GenericEvent> isInstance = eventClass::isInstance;
-                EVENT_WAITERS.put(ticket, new ImmutableTriple<>(isInstance.and(predicate), lock, cleanupPredicate));
+                synchronized (this.mutex) {
+                        this.eventWaiters.put(ticket, new ImmutableTriple<>(isInstance.and(predicate), lock, cleanupPredicate));
+                }
                 GenericEvent awaited = lock.receive(timeout, timeoutUnit);
-                EVENT_WAITERS.remove(ticket);
+                synchronized (this.mutex) {
+                        this.eventWaiters.remove(ticket);
+                }
                 sanityCheck(eventClass, awaited);
                 return (T) awaited;
         }
@@ -97,9 +102,11 @@ public class EventWaiterListener implements EventListener {
 
         @Override
         public void onEvent(GenericEvent event) {
-                for (var e : EVENT_WAITERS.values()) {
-                        if (e.getLeft().test(event))
-                                e.getMiddle().send(event);
+                synchronized (this.mutex) {
+                        for (var e : this.eventWaiters.values()) {
+                                if (e.getLeft().test(event))
+                                        e.getMiddle().send(event);
+                        }
                 }
         }
 
diff --git a/src/main/java/libot/listeners/MessageListener.java b/src/main/java/libot/core/listeners/MessageListener.java
index 00fa2e4..8bccece 100644
--- a/src/main/java/libot/listeners/MessageListener.java
+++ b/src/main/java/libot/core/listeners/MessageListener.java
@@ -1,4 +1,4 @@
-package libot.listeners;
+package libot.core.listeners;
 
 import static libot.utils.ParseUtils.parseCommandName;
 
diff --git a/src/main/java/libot/listeners/ShredClashListener.java b/src/main/java/libot/core/listeners/ShredClashListener.java
index 93b1c19..a54cbcb 100644
--- a/src/main/java/libot/listeners/ShredClashListener.java
+++ b/src/main/java/libot/core/listeners/ShredClashListener.java
@@ -1,4 +1,4 @@
-package libot.listeners;
+package libot.core.listeners;
 
 import javax.annotation.Nonnull;
 
diff --git a/src/main/java/libot/utils/EventUtils.java b/src/main/java/libot/utils/EventUtils.java
index a5b44a4..85687cb 100644
--- a/src/main/java/libot/utils/EventUtils.java
+++ b/src/main/java/libot/utils/EventUtils.java
@@ -5,7 +5,7 @@ import static libot.core.Constants.*;
 
 import javax.annotation.Nonnull;
 
-import libot.listeners.EventWaiterListener;
+import libot.core.listeners.EventWaiterListener;
 import net.dv8tion.jda.api.entities.*;
 import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
 import net.dv8tion.jda.api.events.message.react.*;
@@ -15,20 +15,22 @@ public class EventUtils {
         private int timeout;
         private final User user;
         private final MessageChannel channel;
+        private final EventWaiterListener ewl;
 
-        public EventUtils(User user, MessageChannel channel) {
+        public EventUtils(EventWaiterListener ewl, User user, MessageChannel channel) {
                 this.user = user;
                 this.channel = channel;
+                this.ewl = ewl;
         }
 
-        public EventUtils(User user, MessageChannel channel, int timeout) {
-                this(user, channel);
+        public EventUtils(EventWaiterListener ewl, User user, MessageChannel channel, int timeout) {
+                this(ewl, user, channel);
                 this.timeout = timeout;
         }
 
         @Nonnull
         public MessageReaction getReaction(Message message) throws InterruptedException {
-                return EventWaiterListener.awaitEvent(p -> {
+                return this.ewl.awaitEvent(p -> {
                         GenericMessageReactionEvent e = (GenericMessageReactionEvent) p;
                         return e.getUserIdLong() == this.user.getIdLong() && e.getMessageIdLong() == message.getIdLong();
                 }, p -> {
@@ -41,10 +43,10 @@ public class EventUtils {
                 }, this.timeout, SECONDS, GenericMessageReactionEvent.class).getReaction();
         }
 
-        @SuppressWarnings("null")
         @Nonnull
+        @SuppressWarnings("null")
         public Message getMessage(String emoji) throws InterruptedException {
-                GenericMessageReactionEvent event = EventWaiterListener.awaitEvent(p -> {
+                GenericMessageReactionEvent event = this.ewl.awaitEvent(p -> {
 
                         GenericMessageReactionEvent e = (GenericMessageReactionEvent) p;
 
@@ -58,7 +60,7 @@ public class EventUtils {
 
         @Nonnull
         public Message awaitMessage(boolean ignoreBlank) throws InterruptedException {
-                return EventWaiterListener.awaitEvent(p -> {
+                return this.ewl.awaitEvent(p -> {
 
                         var e = (MessageReceivedEvent) p;
 
@@ -70,7 +72,7 @@ public class EventUtils {
         }
 
         public boolean awaitBoolean(@Nonnull Message question) throws InterruptedException {
-                boolean result = ACCEPT_EMOJI.equals(EventWaiterListener.awaitEvent(p -> {
+                boolean result = ACCEPT_EMOJI.equals(this.ewl.awaitEvent(p -> {
                         MessageReactionAddEvent e = (MessageReactionAddEvent) p;
                         String emote = e.getReactionEmote().getName();