Fix race conditions and duplicate stars in starboard

backend/src/data/GuildStarboardReactions.ts

@@ -19,10 +19,22 @@ export class GuildStarboardReactions extends BaseGuildRepository {
   }
 
   async createStarboardReaction(messageId: string, reactorId: string) {
+    const existingReaction = await this.allStarboardReactions.findOne({
+      where: {
+        guild_id: this.guildId,
+        message_id: messageId,
+        reactor_id: reactorId,
+      },
+    });
+
+    if (existingReaction) {
+      return;
+    }
+
     await this.allStarboardReactions.insert({
+      guild_id: this.guildId,
       message_id: messageId,
       reactor_id: reactorId,
-      guild_id: this.guildId,
     });
   }
 

backend/src/migrations/1608692857722-FixStarboardReactionsIndices.ts

@@ -0,0 +1,26 @@
+import { MigrationInterface, QueryRunner, TableIndex, TableUnique } from "typeorm";
+
+export class FixStarboardReactionsIndices1608692857722 implements MigrationInterface {
+  public async up(queryRunner: QueryRunner): Promise<any> {
+    // Remove previously-added duplicate stars
+    await queryRunner.query(`
+        DELETE r1.* FROM starboard_reactions AS r1
+        INNER JOIN starboard_reactions AS r2
+          ON r2.guild_id = r1.guild_id AND r2.message_id = r1.message_id AND r2.reactor_id = r1.reactor_id AND r2.id < r1.id
+      `);
+
+    await queryRunner.dropIndex("starboard_reactions", "IDX_dd871a4ef459dd294aa368e736");
+    await queryRunner.createIndex(
+      "starboard_reactions",
+      new TableIndex({
+        isUnique: true,
+        columnNames: ["guild_id", "message_id", "reactor_id"],
+      }),
+    );
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<any> {
+    await queryRunner.dropIndex("starboard_reactions", "IDX_d08ee47552c92ec8afd1a5bd1b");
+    await queryRunner.createIndex("starboard_reactions", new TableIndex({ columnNames: ["reactor_id", "message_id"] }));
+  }
+}

backend/src/plugins/Starboard/events/StarboardReactionAddEvt.ts

@@ -36,6 +36,8 @@ export const StarboardReactionAddEvt = starboardEvt({
       categoryId: (msg.channel as TextChannel).parentID,
     });
 
+    const boardLock = await pluginData.locks.acquire(`starboards`);
+
     const applicableStarboards = Object.values(config.boards)
       .filter(board => board.enabled)
       // Can't star messages in the starboard channel itself
@@ -59,8 +61,6 @@ export const StarboardReactionAddEvt = starboardEvt({
       });
 
     for (const starboard of applicableStarboards) {
-      const boardLock = await pluginData.locks.acquire(`starboards-channel-${starboard.channel_id}`);
-
       // Save reaction into the database
       await pluginData.state.starboardReactions.createStarboardReaction(msg.id, userId).catch(noop);
 
@@ -92,8 +92,8 @@ export const StarboardReactionAddEvt = starboardEvt({
         // Otherwise, if the star count exceeds the required star count, save the message to the starboard
         await saveMessageToStarboard(pluginData, msg, starboard);
       }
-
-      boardLock.unlock();
     }
+
+    boardLock.unlock();
   },
 });

backend/src/plugins/Starboard/events/StarboardReactionRemoveEvts.ts

@@ -4,7 +4,9 @@ export const StarboardReactionRemoveEvt = starboardEvt({
   event: "messageReactionRemove",
 
   async listener(meta) {
+    const boardLock = await meta.pluginData.locks.acquire(`starboards`);
     await meta.pluginData.state.starboardReactions.deleteStarboardReaction(meta.args.message.id, meta.args.member.id);
+    boardLock.unlock();
   },
 });
 
@@ -12,6 +14,8 @@ export const StarboardReactionRemoveAllEvt = starboardEvt({
   event: "messageReactionRemoveAll",
 
   async listener(meta) {
+    const boardLock = await meta.pluginData.locks.acquire(`starboards`);
     await meta.pluginData.state.starboardReactions.deleteAllStarboardReactionsForMessageId(meta.args.message.id);
+    boardLock.unlock();
   },
 });

backend/src/plugins/Starboard/util/updateStarboardMessageStarCount.ts

@@ -2,6 +2,10 @@ import { Client, GuildTextableChannel, Message } from "eris";
 import { noop } from "../../../utils";
 import { createStarboardPseudoFooterForMessage } from "./createStarboardPseudoFooterForMessage";
 import { TStarboardOpts } from "../types";
+import Timeout = NodeJS.Timeout;
+
+const DEBOUNCE_DELAY = 1000;
+const debouncedUpdates: Record<string, Timeout> = {};
 
 export async function updateStarboardMessageStarCount(
   starboard: TStarboardOpts,
@@ -10,8 +14,16 @@ export async function updateStarboardMessageStarCount(
   starEmoji: string,
   starCount: number,
 ) {
-  const embed = starboardMessage.embeds[0]!;
-  embed.fields!.shift(); // Remove pseudo footer
-  embed.fields!.push(createStarboardPseudoFooterForMessage(starboard, originalMessage, starEmoji, starCount)); // Create new pseudo footer
-  await starboardMessage.edit({ embed });
+  const key = `${originalMessage.id}-${starboardMessage.id}`;
+  if (debouncedUpdates[key]) {
+    clearTimeout(debouncedUpdates[key]);
+  }
+
+  debouncedUpdates[key] = setTimeout(() => {
+    delete debouncedUpdates[key];
+    const embed = starboardMessage.embeds[0]!;
+    embed.fields!.shift(); // Remove pseudo footer
+    embed.fields!.push(createStarboardPseudoFooterForMessage(starboard, originalMessage, starEmoji, starCount)); // Create new pseudo footer
+    starboardMessage.edit({ embed });
+  }, DEBOUNCE_DELAY);
 }