Cache prepared statements per database connection

src/lib/server/db/index.ts

@@ -391,6 +391,21 @@ export function db(): Database.Database {
         throw err;
     }
 
+    // Cache only runtime queries, after migrations have finished. Statements
+    // belong to this connection, so reopening the DB starts with an empty cache.
+    // Callers share statement options (e.g. raw()); use consistent options for
+    // identical SQL and pass values to run/get/all rather than binding permanently.
+    const statements = new Map<string, Database.Statement>();
+    const prepare = handle.prepare.bind(handle);
+    handle.prepare = ((sql: string) => {
+        let statement = statements.get(sql);
+        if (!statement) {
+            statement = prepare(sql);
+            statements.set(sql, statement);
+        }
+        return statement;
+    }) as typeof handle.prepare;
+
     _db = handle;
     return _db;
 }

tests/unit/creation-queue.test.ts

@@ -48,7 +48,11 @@ beforeEach(async () => {
     vi.mocked(komodo.komodoUpdateTagsOnResource).mockResolvedValue({ ok: true });
     const rcon = await import('../../src/lib/server/integrations/rcon.js');
     vi.mocked(rcon.rconGetPlayerCount).mockResolvedValue(0);
-    vi.mocked(rcon.rconPlutoniumVersion).mockResolvedValue({ revision: 5354, error: null });
+    vi.mocked(rcon.rconPlutoniumVersion).mockImplementation(async () => {
+        // Version evidence must be observed strictly after the launch timestamp.
+        await new Promise(resolve => setTimeout(resolve, 2));
+        return { revision: 5354, error: null };
+    });
     vi.mocked(rcon.rconStatusResult).mockImplementation(async server => status(server));
     const { kick } = await import('../../src/lib/server/pipeline/worker.js');
     vi.mocked(kick).mockResolvedValue(undefined);

tests/unit/db-statements.test.ts

@@ -0,0 +1,45 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { newFixture, type Fixture } from '../helpers/fixture.js';
+
+let fixture: Fixture;
+beforeEach(async () => {
+    vi.resetModules();
+    fixture = await newFixture([]);
+});
+afterEach(async () => { await fixture.cleanup(); });
+
+describe('prepared statement caching', () => {
+    it('reuses statements with fresh parameters and remains usable after rollback', async () => {
+        const { db } = await import('../../src/lib/server/db/index.js');
+        const insertSql = 'INSERT INTO settings (key, value) VALUES (?, ?)';
+        const selectSql = 'SELECT value FROM settings WHERE key = ?';
+        const insert = db().prepare(insertSql);
+        const select = db().prepare(selectSql);
+        insert.run('cache-first', 'one');
+        expect(() => db().transaction(() => {
+            db().prepare(insertSql).run('cache-rollback', 'discarded');
+            throw new Error('rollback');
+        })()).toThrow('rollback');
+        db().prepare(insertSql).run('cache-second', 'two');
+
+        expect(db().prepare(insertSql)).toBe(insert);
+        expect(db().prepare(selectSql)).toBe(select);
+        expect(select.get('cache-first')).toEqual({ value: 'one' });
+        expect(select.get('cache-second')).toEqual({ value: 'two' });
+        expect(select.get('cache-rollback')).toBeUndefined();
+    });
+
+    it('prepares fresh statements when the connection is reopened', async () => {
+        const { db, closeDb } = await import('../../src/lib/server/db/index.js');
+        const sql = 'SELECT value FROM settings WHERE key = ?';
+        const oldStatement = db().prepare(sql);
+        db().prepare('INSERT INTO settings (key, value) VALUES (?, ?)').run('cache-persisted', 'saved');
+        closeDb();
+
+        const statement = db().prepare(sql);
+        expect(statement).not.toBe(oldStatement);
+        expect(statement.database).not.toBe(oldStatement.database);
+        expect(statement.get('cache-persisted')).toEqual({ value: 'saved' });
+        expect(db().prepare(sql)).toBe(statement);
+    });
+});

tests/unit/deployment-collections.test.ts

@@ -15,7 +15,11 @@ vi.mock('../../src/lib/server/integrations/komodo.js', () => ({
 }));
 vi.mock('../../src/lib/server/integrations/rcon.js', () => ({
     rconGetPlayerCount: vi.fn(async () => 0),
-    rconPlutoniumVersion: vi.fn(async () => ({ revision: 5354, error: null })),
+    rconPlutoniumVersion: vi.fn(async () => {
+        // Version evidence must be observed strictly after the launch timestamp.
+        await new Promise(resolve => setTimeout(resolve, 2));
+        return { revision: 5354, error: null };
+    }),
     rconStatusResult: vi.fn(async (server: string) => ({ ok: true, endpoint: { host: 'localhost', port: 28960 }, rawReply: '',
         status: { players: 0, map: server.startsWith('t6_') ? 'zm_transit' : server.includes('_moon_') ? 'zombie_moon' : 'zombie_theater', gametype: null, roster: [] } }))
 }));