fix(kv): stop multi-key commands spanning cluster slots (#2310)

fluxer_api/pkgs/cache/src/__tests__/CacheClusterSlots.test.ts

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {KVCacheProvider} from '@pkgs/cache/src/providers/KVCacheProvider';
+import type {IKVPipeline, IKVProvider} from '@pkgs/kv_client/src/IKVProvider';
+import {describe, expect, it} from 'vitest';
+
+function hashSlot(key: string): number {
+	let hashed = key;
+	const start = key.indexOf('{');
+	if (start !== -1) {
+		const end = key.indexOf('}', start + 1);
+		if (end > start + 1) {
+			hashed = key.slice(start + 1, end);
+		}
+	}
+	let crc = 0;
+	for (let index = 0; index < hashed.length; index += 1) {
+		crc ^= (hashed.charCodeAt(index) & 0xff) << 8;
+		for (let bit = 0; bit < 8; bit += 1) {
+			crc = (crc & 0x8000) === 0 ? (crc << 1) & 0xffff : ((crc << 1) ^ 0x1021) & 0xffff;
+		}
+	}
+	return crc % 16384;
+}
+
+function createRecordingProvider(): {
+	client: IKVProvider;
+	commands: Array<Array<string>>;
+} {
+	const commands: Array<Array<string>> = [];
+	const client = {
+		set: async (key: string) => {
+			commands.push([key]);
+			return 'OK';
+		},
+		setex: async (key: string) => {
+			commands.push([key]);
+		},
+		pipeline: () => {
+			const keys: Array<string> = [];
+			commands.push(keys);
+			const batch = {
+				set: (key: string) => {
+					keys.push(key);
+					return batch;
+				},
+				setex: (key: string) => {
+					keys.push(key);
+					return batch;
+				},
+				exec: async () => [],
+			} as unknown as IKVPipeline;
+			return batch;
+		},
+	} as unknown as IKVProvider;
+	return {client, commands};
+}
+
+describe('KVCacheProvider cluster hash slots', () => {
+	it('keeps a multi entry write off batched commands that span hash slots', async () => {
+		const {client, commands} = createRecordingProvider();
+		const provider = new KVCacheProvider({client});
+
+		expect(hashSlot('cache:alpha')).not.toBe(hashSlot('cache:beta'));
+
+		await provider.mset([
+			{key: 'cache:alpha', value: 1, ttlSeconds: 60},
+			{key: 'cache:beta', value: 2},
+		]);
+
+		expect(commands.flat().sort()).toEqual(['cache:alpha', 'cache:beta']);
+		expect(commands.filter((keys) => new Set(keys.map(hashSlot)).size > 1)).toEqual([]);
+	});
+});