Remove shared prepared statement cache (Refs #76)

tests/unit/db-statements.test.ts

@@ -8,9 +8,10 @@ beforeEach(async () => {
 });
 afterEach(async () => {
     await fixture.cleanup();
+    vi.unstubAllEnvs();
 });
 
-describe('prepared statement caching', () => {
+describe('database statements', () => {
     it('tunes the controller connection and stops periodic optimization when closed', async () => {
         const { db, closeDb } = await import('../../src/lib/server/db/index.js');
         vi.useFakeTimers({ toFake: ['setInterval', 'clearInterval'] });
@@ -30,7 +31,7 @@ describe('prepared statement caching', () => {
             vi.useRealTimers();
         }
     });
-    it('reuses statements with fresh parameters and remains usable after rollback', async () => {
+    it('keeps caller-owned statements reusable with fresh parameters 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 = ?';
@@ -45,8 +46,8 @@ describe('prepared statement caching', () => {
         ).toThrow('rollback');
         db().prepare(insertSql).run('cache-second', 'two');
 
-        expect(db().prepare(insertSql)).toBe(insert);
-        expect(db().prepare(selectSql)).toBe(select);
+        expect(db().prepare(insertSql)).not.toBe(insert);
+        expect(db().prepare(selectSql)).not.toBe(select);
         expect(select.get('cache-first')).toEqual({ value: 'one' });
         expect(select.get('cache-second')).toEqual({ value: 'two' });
         expect(select.get('cache-rollback')).toBeUndefined();
@@ -65,6 +66,56 @@ describe('prepared statement caching', () => {
         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);
+        expect(db().prepare(sql)).not.toBe(statement);
+    });
+
+    describe.each([0, 20])('statement isolation with EC_SLOW_SQL_MS=%i', (slowMs) => {
+        beforeEach(() => vi.stubEnv('EC_SLOW_SQL_MS', String(slowMs)));
+
+        it.each([
+            ['raw', [1]],
+            ['pluck', 1],
+            ['expand', { $: { value: 1 } }],
+            ['safeIntegers', { value: 1n }]
+        ] as const)('keeps %s mode local to its statement', async (mode, expected) => {
+            const { db } = await import('../../src/lib/server/db/index.js');
+            const sql = 'SELECT 1 AS value';
+            const customized = db().prepare(sql)[mode]();
+            const standard = db().prepare(sql);
+
+            expect(standard.get()).toEqual({ value: 1 });
+            expect(customized.get()).toEqual(expected);
+            customized[mode](false);
+            standard[mode]();
+            expect(customized.get()).toEqual({ value: 1 });
+            expect(standard.get()).toEqual(expected);
+            expect(db().prepare(sql).get()).toEqual({ value: 1 });
+        });
+
+        it('keeps permanent bindings local to their statement', async () => {
+            const { db } = await import('../../src/lib/server/db/index.js');
+            const sql = 'SELECT ? AS value';
+            const bound = db().prepare(sql).bind('first');
+
+            expect(db().prepare(sql).get('second')).toEqual({ value: 'second' });
+            expect(bound.get()).toEqual({ value: 'first' });
+            expect(db().prepare(sql).bind('third').get()).toEqual({ value: 'third' });
+            expect(bound.get()).toEqual({ value: 'first' });
+        });
+
+        it('allows identical queries while another statement is being iterated', async () => {
+            const { db } = await import('../../src/lib/server/db/index.js');
+            const sql = 'SELECT 1 AS value UNION ALL SELECT 2 AS value';
+            const iterator = db().prepare(sql).iterate();
+            try {
+                expect(iterator.next()).toEqual({ value: { value: 1 }, done: false });
+                expect(db().prepare(sql).get()).toEqual({ value: 1 });
+                expect([...db().prepare(sql).iterate()]).toEqual([{ value: 1 }, { value: 2 }]);
+                expect(iterator.next()).toEqual({ value: { value: 2 }, done: false });
+                expect(iterator.next().done).toBe(true);
+            } finally {
+                iterator.return?.();
+            }
+        });
     });
 });