Add UserProfilesStore, LruCache and cache for user permalink profiles (#10425)

src/stores/UserProfilesStore.ts

@@ -0,0 +1,150 @@
+/*
+Copyright 2023 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+import { logger } from "matrix-js-sdk/src/logger";
+import { IMatrixProfile, MatrixClient, MatrixEvent, RoomMember, RoomMemberEvent } from "matrix-js-sdk/src/matrix";
+
+import { LruCache } from "../utils/LruCache";
+
+const cacheSize = 500;
+
+type StoreProfileValue = IMatrixProfile | undefined | null;
+
+/**
+ * This store provides cached access to user profiles.
+ * Listens for membership events and invalidates the cache for a profile on update with different profile values.
+ */
+export class UserProfilesStore {
+    private profiles = new LruCache<string, IMatrixProfile | null>(cacheSize);
+    private knownProfiles = new LruCache<string, IMatrixProfile | null>(cacheSize);
+
+    public constructor(private client: MatrixClient) {
+        client.on(RoomMemberEvent.Membership, this.onRoomMembershipEvent);
+    }
+
+    /**
+     * Synchronously get a profile from the store cache.
+     *
+     * @param userId - User Id of the profile to fetch
+     * @returns The profile, if cached by the store.
+     *          Null if the profile does not exist.
+     *          Undefined if the profile is not cached by the store.
+     *          In this case a profile can be fetched from the API via {@link fetchProfile}.
+     */
+    public getProfile(userId: string): StoreProfileValue {
+        return this.profiles.get(userId);
+    }
+
+    /**
+     * Synchronously get a profile from known users from the store cache.
+     * Known user means that at least one shared room with the user exists.
+     *
+     * @param userId - User Id of the profile to fetch
+     * @returns The profile, if cached by the store.
+     *          Null if the profile does not exist.
+     *          Undefined if the profile is not cached by the store.
+     *          In this case a profile can be fetched from the API via {@link fetchOnlyKnownProfile}.
+     */
+    public getOnlyKnownProfile(userId: string): StoreProfileValue {
+        return this.knownProfiles.get(userId);
+    }
+
+    /**
+     * Asynchronousely fetches a profile from the API.
+     * Stores the result in the cache, so that next time {@link getProfile} returns this value.
+     *
+     * @param userId - User Id for which the profile should be fetched for
+     * @returns The profile, if found.
+     *          Null if the profile does not exist or there was an error fetching it.
+     */
+    public async fetchProfile(userId: string): Promise<IMatrixProfile | null> {
+        const profile = await this.fetchProfileFromApi(userId);
+        this.profiles.set(userId, profile);
+        return profile;
+    }
+
+    /**
+     * Asynchronousely fetches a profile from a known user from the API.
+     * Known user means that at least one shared room with the user exists.
+     * Stores the result in the cache, so that next time {@link getOnlyKnownProfile} returns this value.
+     *
+     * @param userId - User Id for which the profile should be fetched for
+     * @returns The profile, if found.
+     *          Undefined if the user is unknown.
+     *          Null if the profile does not exist or there was an error fetching it.
+     */
+    public async fetchOnlyKnownProfile(userId: string): Promise<StoreProfileValue> {
+        // Do not look up unknown users. The test for existence in knownProfiles is a performance optimisation.
+        // If the user Id exists in knownProfiles we know them.
+        if (!this.knownProfiles.has(userId) && !this.isUserIdKnown(userId)) return undefined;
+
+        const profile = await this.fetchProfileFromApi(userId);
+        this.knownProfiles.set(userId, profile);
+        return profile;
+    }
+
+    /**
+     * Looks up a user profile via API.
+     *
+     * @param userId - User Id for which the profile should be fetched for
+     * @returns The profile information or null on errors
+     */
+    private async fetchProfileFromApi(userId: string): Promise<IMatrixProfile | null> {
+        try {
+            return (await this.client.getProfileInfo(userId)) ?? null;
+        } catch (e) {
+            logger.warn(`Error retrieving profile for userId ${userId}`, e);
+        }
+
+        return null;
+    }
+
+    /**
+     * Whether at least one shared room with the userId exists.
+     *
+     * @param userId
+     * @returns true: at least one room shared with user identified by its Id, else false.
+     */
+    private isUserIdKnown(userId: string): boolean {
+        return this.client.getRooms().some((room) => {
+            return !!room.getMember(userId);
+        });
+    }
+
+    /**
+     * Simple cache invalidation if a room membership event is received and
+     * at least one profile value differs from the cached one.
+     */
+    private onRoomMembershipEvent = (event: MatrixEvent, member: RoomMember): void => {
+        const profile = this.profiles.get(member.userId);
+
+        if (
+            profile &&
+            (profile.displayname !== member.rawDisplayName || profile.avatar_url !== member.getMxcAvatarUrl())
+        ) {
+            this.profiles.delete(member.userId);
+        }
+
+        const knownProfile = this.knownProfiles.get(member.userId);
+
+        if (
+            knownProfile &&
+            (knownProfile.displayname !== member.rawDisplayName || knownProfile.avatar_url !== member.getMxcAvatarUrl())
+        ) {
+            this.knownProfiles.delete(member.userId);
+        }
+    };
+}