fix(grouper): delete cache if event saved to db (#383)

* fix(grouper): delete cache if event saved to db

* imp(grouper): move event cache creation to the separate method

* chore(grouper): add comments

Author: e11sy

workers/grouper/src/index.ts

@@ -82,9 +82,7 @@ export default class GrouperWorker extends Worker {
     /**
      * Find event by group hash.
      */
-    let existedEvent = await this.getEvent(task.projectId, {
-      groupHash: uniqueEventHash,
-    });
+    let existedEvent = await this.getEvent(task.projectId, uniqueEventHash);
 
     /**
      * If we couldn't group by group hash (title), try grouping by Levenshtein distance with last N events
@@ -131,6 +129,13 @@ export default class GrouperWorker extends Worker {
           usersAffected: incrementAffectedUsers ? 1 : 0,
         } as GroupedEventDBScheme);
 
+        const eventCacheKey = await this.getEventCacheKey(task.projectId, uniqueEventHash);
+
+        /**
+         * If event is saved, then cached event state is no longer actual, so we should remove it
+         */
+        this.cache.del(eventCacheKey);
+
         /**
          * Increment daily affected users for the first event
          */
@@ -372,25 +377,37 @@ export default class GrouperWorker extends Worker {
    * Returns finds event by query from project with passed ID
    *
    * @param projectId - project's identifier
-   * @param query - mongo query string
+   * @param groupHash - group hash of the event   
    */
-  private async getEvent(projectId: string, query: Record<string, unknown>): Promise<GroupedEventDBScheme> {
+  private async getEvent(projectId: string, groupHash: string): Promise<GroupedEventDBScheme> {
     if (!mongodb.ObjectID.isValid(projectId)) {
       throw new ValidationError('Controller.saveEvent: Project ID is invalid or missed');
     }
 
-    const eventCacheKey = `${projectId}:${JSON.stringify(query)}`;
+    const eventCacheKey = await this.getEventCacheKey(projectId, groupHash);
 
     return this.cache.get(eventCacheKey, async () => {
       return this.db.getConnection()
         .collection(`events:${projectId}`)
-        .findOne(query)
+        .findOne({
+          groupHash,
+        })
         .catch((err) => {
           throw new DatabaseReadWriteError(err);
         });
     });
   }
 
+  /**
+   * Method that returns event cache key based on projectId and groupHash
+   * @param projectId - used for cache key creation
+   * @param groupHash - used for cache key creation
+   * @returns cache key
+   */
+  private async getEventCacheKey(projectId: string, groupHash: string): Promise<string> {
+    return `${projectId}:${JSON.stringify({groupHash: groupHash})}`
+  }
+
   /**
    * Save event to database
    *

workers/grouper/tests/index.test.ts

@@ -24,6 +24,9 @@ jest.mock('../../../lib/cache/controller', () => {
 
     // eslint-disable-next-line @typescript-eslint/no-empty-function, jsdoc/require-jsdoc
     public set(): void { }
+    
+    // eslint-disable-next-line @typescript-eslint/no-empty-function, jsdoc/require-jsdoc
+    public del(): void { }
   };
 });