[server]: cache the getUserCount on the requireEELicense calls

Author: Simon Emms

components/server/ee/src/container-module.ts

@@ -49,6 +49,7 @@ import { GitLabAppSupport } from "./gitlab/gitlab-app-support";
 import { Config } from "../../src/config";
 import { SnapshotService } from "./workspace/snapshot-service";
 import { BitbucketAppSupport } from "./bitbucket/bitbucket-app-support";
+import { UserCounter } from "./user/user-counter";
 
 export const productionEEContainerModule = new ContainerModule((bind, unbind, isBound, rebind) => {
     rebind(Server).to(ServerEE).inSingletonScope();
@@ -69,6 +70,8 @@ export const productionEEContainerModule = new ContainerModule((bind, unbind, is
     bind(BitbucketAppSupport).toSelf().inSingletonScope();
     bind(GitHubEnterpriseApp).toSelf().inSingletonScope();
 
+    bind(UserCounter).toSelf().inSingletonScope();
+
     bind(LicenseEvaluator).toSelf().inSingletonScope();
     bind(LicenseKeySource).to(DBLicenseKeySource).inSingletonScope();
 

components/server/ee/src/user/user-counter.ts

@@ -0,0 +1,31 @@
+/**
+ * Copyright (c) 2022 Gitpod GmbH. All rights reserved.
+ * Licensed under the GNU Affero General Public License (AGPL).
+ * See License-AGPL.txt in the project root for license information.
+ */
+
+import { injectable } from 'inversify';
+
+@injectable()
+export class UserCounter {
+    public expires: Date | null = null;
+
+    protected data: number | null = null;
+
+    protected readonly timeout: number = 60 * 1000; // Cache data for 1 minute
+
+    get count(): number | null {
+        if (this.expires !== null && Date.now() >= this.expires.getTime()) {
+            // The timestamp is in range - return the data
+            return this.data;
+        }
+        // Not in range - return null
+        return null;
+    }
+
+    set count(userCount: number | null) {
+        this.expires = new Date(Date.now() + this.timeout);
+
+        this.data = userCount;
+    }
+}

components/server/ee/src/workspace/gitpod-server-impl.ts

@@ -42,6 +42,7 @@ import { SnapshotService, WaitForSnapshotOptions } from "./snapshot-service";
 import { ClientMetadata, traceClientMetadata } from "../../../src/websocket/websocket-connection-manager";
 import { BitbucketAppSupport } from "../bitbucket/bitbucket-app-support";
 import { URL } from 'url';
+import { UserCounter } from "../user/user-counter";
 
 @injectable()
 export class GitpodServerEEImpl extends GitpodServerImpl {
@@ -75,6 +76,8 @@ export class GitpodServerEEImpl extends GitpodServerImpl {
 
     @inject(SnapshotService) protected readonly snapshotService: SnapshotService;
 
+    @inject(UserCounter) protected readonly userCounter: UserCounter;
+
     initialize(client: GitpodClient | undefined, user: User | undefined, accessGuard: ResourceAccessGuard, clientMetadata: ClientMetadata, connectionCtx: TraceContext | undefined, clientHeaderFields: ClientHeaderFields): void {
         super.initialize(client, user, accessGuard, clientMetadata, connectionCtx, clientHeaderFields);
 
@@ -153,7 +156,15 @@ export class GitpodServerEEImpl extends GitpodServerImpl {
     }
 
     protected async requireEELicense(feature: Feature) {
-        const userCount = await this.userDB.getUserCount(true);
+        const cachedUserCount = this.userCounter.count;
+
+        let userCount: number;
+        if (cachedUserCount === null) {
+            userCount = await this.userDB.getUserCount(true);
+            this.userCounter.count = userCount;
+        } else {
+            userCount = cachedUserCount;
+        }
 
         if (!this.licenseEvaluator.isEnabled(feature, userCount)) {
             throw new ResponseError(ErrorCodes.EE_LICENSE_REQUIRED, "enterprise license required");

components/server/ee/src/workspace/workspace-factory.ts

@@ -16,17 +16,27 @@ import { ResponseError } from 'vscode-jsonrpc';
 import { ErrorCodes } from '@gitpod/gitpod-protocol/lib/messaging/error';
 import { HostContextProvider } from '../../../src/auth/host-context-provider';
 import { UserDB } from '@gitpod/gitpod-db/lib';
+import { UserCounter } from '../user/user-counter';
 
 @injectable()
 export class WorkspaceFactoryEE extends WorkspaceFactory {
 
     @inject(LicenseEvaluator) protected readonly licenseEvaluator: LicenseEvaluator;
     @inject(HostContextProvider) protected readonly hostContextProvider: HostContextProvider;
+    @inject(UserCounter) protected readonly userCounter: UserCounter;
 
     @inject(UserDB) protected readonly userDB: UserDB;
 
     protected async requireEELicense(feature: Feature) {
-        const userCount = await this.userDB.getUserCount(true);
+        const cachedUserCount = this.userCounter.count;
+
+        let userCount: number;
+        if (cachedUserCount === null) {
+            userCount = await this.userDB.getUserCount(true);
+            this.userCounter.count = userCount;
+        } else {
+            userCount = cachedUserCount;
+        }
 
         if (!this.licenseEvaluator.isEnabled(feature, userCount)) {
             throw new ResponseError(ErrorCodes.EE_LICENSE_REQUIRED, "enterprise license required");