(core) move home server into core

Summary: This moves enough server material into core to run a home server.  The data engine is not yet incorporated (though in manual testing it works when ported).

Test Plan: existing tests pass

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2552

app/gen-server/lib/Usage.ts

@@ -0,0 +1,62 @@
+import {Document} from 'app/gen-server/entity/Document';
+import {Organization} from 'app/gen-server/entity/Organization';
+import {User} from 'app/gen-server/entity/User';
+import {HomeDBManager} from 'app/gen-server/lib/HomeDBManager';
+import * as log from 'app/server/lib/log';
+
+// Frequency of logging usage information.  Not something we need
+// to track with much granularity.
+const USAGE_PERIOD_MS = 1 * 60 * 60 * 1000;   // log every 1 hour
+
+/**
+ * Occasionally log usage information - number of users, orgs,
+ * docs, etc.
+ */
+export class Usage {
+  private _interval: NodeJS.Timeout;
+
+  public constructor(private _dbManager: HomeDBManager) {
+    this._interval = setInterval(() => this.apply().catch(log.warn.bind(log)), USAGE_PERIOD_MS);
+    // Log once at beginning, in case we roll over servers faster than
+    // the logging period for an extended length of time,
+    // and to raise the visibility of this logging step so if it gets
+    // slow devs notice.
+    this.apply().catch(log.warn.bind(log));
+  }
+
+  public close() {
+    clearInterval(this._interval);
+  }
+
+  public async apply() {
+    const manager = this._dbManager.connection.manager;
+    // raw count of users
+    const userCount = await manager.count(User);
+    // users who have logged in at least once
+    const userWithLoginCount = await manager.createQueryBuilder()
+      .from(User, 'users')
+      .where('first_login_at is not null')
+      .getCount();
+    // raw count of organizations (excluding personal orgs)
+    const orgCount = await manager.createQueryBuilder()
+      .from(Organization, 'orgs')
+      .where('owner_id is null')
+      .getCount();
+    // organizations with subscriptions that are in a non-terminated state
+    const orgInGoodStandingCount = await manager.createQueryBuilder()
+      .from(Organization, 'orgs')
+      .leftJoin('orgs.billingAccount', 'billing_accounts')
+      .where('owner_id is null')
+      .andWhere('billing_accounts.in_good_standing = true')
+      .getCount();
+    // raw count of documents
+    const docCount = await manager.count(Document);
+    log.rawInfo('activity', {
+      docCount,
+      orgCount,
+      orgInGoodStandingCount,
+      userCount,
+      userWithLoginCount,
+    });
+  }
+}