Stop using KV cache backend for now, but also improves it for higher performances (#2510)

Author: SamyPesse

.changeset/popular-toys-argue.md

@@ -0,0 +1,5 @@
+---
+'gitbook': patch
+---
+
+Stop using KV cache backend for now, but also improves it for higher performances

packages/gitbook/src/lib/cache/backends.ts

@@ -1,6 +1,5 @@
 import { cloudflareCache } from './cloudflare-cache';
 import { cloudflareDOCache } from './cloudflare-do';
-import { cloudflareKVCache } from './cloudflare-kv';
 import { memoryCache } from './memory';
 
 export const cacheBackends = [
@@ -10,7 +9,6 @@ export const cacheBackends = [
  // Cache local to the datacenter
  // It can't be purged globally but it's faster
  cloudflareCache,
- // Cache global, but with slow replication
- cloudflareKVCache,
+ // Global cache with slower performances
  cloudflareDOCache,
 ];

packages/gitbook/src/lib/cache/cloudflare-kv.ts

@@ -1,56 +1,23 @@
 import type { KVNamespace } from '@cloudflare/workers-types';
 
-import { CacheBackend, CacheEntry, CacheEntryMeta } from './types';
+import { CacheBackend, CacheEntry, CacheEntryLookup, CacheEntryMeta } from './types';
 import { getCacheMaxAge } from './utils';
 import { trace } from '../tracing';
 
-const cacheVersion = 1;
+const cacheVersion = 2;
 
 interface KVTagMetadata {
  meta: CacheEntryMeta;
 }
 
-/**
- * As we migrate off KV, we start disabling it for some tests content.
- */
-const noKVTags = new Set([
- // docs.gitbook.com
- 'url:docs.gitbook.com',
- 'site:site_p4Xo4',
- 'space:NkEGS7hzeqa35sMXQZ4X',
-]);
-
-function shouldUseKVForTag(tag: string): boolean {
- if (noKVTags.has(tag)) {
- return false;
- }
- if (tag.startsWith('change-request:')) {
- return false;
- }
-
- // Hash the tag and return true for 95% of the tags
- const hash = tag.split('').reduce((acc, char) => {
- return acc + char.charCodeAt(0);
- }, 0);
- if (hash % 100 <= 30) {
- return true;
- }
-
- return false;
-}
-
 /**
  * Cache implementation using the Cloudflare KV API.
  * https://developers.cloudflare.com/kv/
  */
 export const cloudflareKVCache: CacheBackend = {
  name: 'cloudflare-kv',
  replication: 'global',
- async get({ key, tag }, options) {
- if (tag && !shouldUseKVForTag(tag)) {
- return null;
- }
-
+ async get(entry, options) {
  const kv = await getKVNamespace();
  if (!kv) {
  return null;
@@ -59,19 +26,19 @@ export const cloudflareKVCache: CacheBackend = {
  return trace(
  {
  operation: `cloudflareKV.get`,
- name: key,
+ name: entry.key,
  },
  async (span) => {
- const kvKey = getValueKey(key);
+ const kvKey = getKey(entry);
 
- const entry = await kv.get<CacheEntry>(kvKey, {
+ const kvEntry = await kv.get<CacheEntry>(kvKey, {
  type: 'json',
  cacheTtl: 60,
  });
 
- span.setAttribute('hit', !!entry);
+ span.setAttribute('hit', !!kvEntry);
 
- return entry;
+ return kvEntry;
  },
  );
  },
@@ -94,23 +61,10 @@ export const cloudflareKVCache: CacheBackend = {
  return;
  }
 
- const kvKey = getValueKey(entry.meta.key);
+ const kvKey = getKey(entry.meta);
  await kv.put(kvKey, JSON.stringify(entry), {
  expirationTtl: secondsFromNow,
  });
-
- if (entry.meta.tag) {
- const metadata: KVTagMetadata = {
- meta: entry.meta,
- };
- const jsonMetadata = JSON.stringify(metadata);
- const tagKey = getTagKey(entry.meta.tag, entry.meta.key);
-
- await kv.put(tagKey, jsonMetadata, {
- metadata,
- expirationTtl: secondsFromNow,
- });
- }
  },
  );
  },
@@ -121,8 +75,8 @@ export const cloudflareKVCache: CacheBackend = {
  }
 
  await Promise.all(
- entries.map(async ({ key }) => {
- const kvKey = getValueKey(key);
+ entries.map(async (entry) => {
+ const kvKey = getKey(entry);
  await kv.delete(kvKey);
  }),
  );
@@ -147,12 +101,7 @@ export const cloudflareKVCache: CacheBackend = {
  for (const entry of entries.keys) {
  if (entry.metadata) {
  const metadata = entry.metadata;
- const key = metadata.meta.key;
-
  result.push(metadata.meta);
-
- // Delete the tag key and the value key
- pendingDeletions.push(kv.delete(getValueKey(key)));
  pendingDeletions.push(kv.delete(entry.name));
  }
  }
@@ -174,16 +123,12 @@ export const cloudflareKVCache: CacheBackend = {
  },
 };
 
-function getValueKey(key: string): string {
- return `${cacheVersion}.v.${key}`;
+function getKey(entry: CacheEntryLookup) {
+ return `${getTagPrefix(entry.tag || 'default')}.${entry.key}`;
 }
 
 function getTagPrefix(tag: string) {
- return `${cacheVersion}.tag.${tag}.`;
-}
-
-function getTagKey(tag: string, key: string) {
- return `${getTagPrefix(tag)}${key}`;
+ return `${cacheVersion}.${tag}.`;
 }
 
 async function getKVNamespace(): Promise<KVNamespace | null> {