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20bafcb6 C |
1 | // Thanks: https://github.com/kwhitley/apicache |
2 | // We duplicated the library because it is unmaintened and prevent us to upgrade to recent NodeJS versions | |
3 | ||
4 | import * as express from 'express' | |
5 | import { OutgoingHttpHeaders } from 'http' | |
6 | import { isTestInstance, parseDurationToMs } from '@server/helpers/core-utils' | |
7 | import { logger } from '@server/helpers/logger' | |
8 | import { Redis } from '@server/lib/redis' | |
9 | import { HttpStatusCode } from '@shared/models' | |
10 | ||
11 | export interface APICacheOptions { | |
12 | headerBlacklist?: string[] | |
13 | excludeStatus?: HttpStatusCode[] | |
14 | } | |
15 | ||
16 | interface CacheObject { | |
17 | status: number | |
18 | headers: OutgoingHttpHeaders | |
19 | data: any | |
20 | encoding: BufferEncoding | |
21 | timestamp: number | |
22 | } | |
23 | ||
24 | export class ApiCache { | |
25 | ||
26 | private readonly options: APICacheOptions | |
27 | private readonly timers: { [ id: string ]: NodeJS.Timeout } = {} | |
28 | ||
29 | private index: { all: string[] } = { all: [] } | |
30 | ||
31 | constructor (options: APICacheOptions) { | |
32 | this.options = { | |
33 | headerBlacklist: [], | |
34 | excludeStatus: [], | |
35 | ||
36 | ...options | |
37 | } | |
38 | } | |
39 | ||
40 | buildMiddleware (strDuration: string) { | |
41 | const duration = parseDurationToMs(strDuration) | |
42 | ||
43 | return (req: express.Request, res: express.Response, next: express.NextFunction) => { | |
44 | const key = Redis.Instance.getPrefix() + 'api-cache-' + req.originalUrl | |
45 | const redis = Redis.Instance.getClient() | |
46 | ||
47 | if (!redis.connected) return this.makeResponseCacheable(res, next, key, duration) | |
48 | ||
49 | try { | |
50 | redis.hgetall(key, (err, obj) => { | |
51 | if (!err && obj && obj.response) { | |
52 | return this.sendCachedResponse(req, res, JSON.parse(obj.response), duration) | |
53 | } | |
54 | ||
55 | return this.makeResponseCacheable(res, next, key, duration) | |
56 | }) | |
57 | } catch (err) { | |
58 | return this.makeResponseCacheable(res, next, key, duration) | |
59 | } | |
60 | } | |
61 | } | |
62 | ||
63 | private shouldCacheResponse (response: express.Response) { | |
64 | if (!response) return false | |
65 | if (this.options.excludeStatus.includes(response.statusCode)) return false | |
66 | ||
67 | return true | |
68 | } | |
69 | ||
70 | private addIndexEntries (key: string) { | |
71 | this.index.all.unshift(key) | |
72 | } | |
73 | ||
74 | private filterBlacklistedHeaders (headers: OutgoingHttpHeaders) { | |
75 | return Object.keys(headers) | |
76 | .filter(key => !this.options.headerBlacklist.includes(key)) | |
77 | .reduce((acc, header) => { | |
78 | acc[header] = headers[header] | |
79 | ||
80 | return acc | |
81 | }, {}) | |
82 | } | |
83 | ||
84 | private createCacheObject (status: number, headers: OutgoingHttpHeaders, data: any, encoding: BufferEncoding) { | |
85 | return { | |
86 | status, | |
87 | headers: this.filterBlacklistedHeaders(headers), | |
88 | data, | |
89 | encoding, | |
90 | ||
91 | // Seconds since epoch, used to properly decrement max-age headers in cached responses. | |
92 | timestamp: new Date().getTime() / 1000 | |
93 | } as CacheObject | |
94 | } | |
95 | ||
96 | private cacheResponse (key: string, value: object, duration: number) { | |
97 | const redis = Redis.Instance.getClient() | |
98 | ||
99 | if (redis.connected) { | |
100 | try { | |
101 | redis.hset(key, 'response', JSON.stringify(value)) | |
102 | redis.hset(key, 'duration', duration + '') | |
103 | redis.expire(key, duration / 1000) | |
104 | } catch (err) { | |
105 | logger.error('Cannot set cache in redis.', { err }) | |
106 | } | |
107 | } | |
108 | ||
109 | // add automatic cache clearing from duration, includes max limit on setTimeout | |
110 | this.timers[key] = setTimeout(() => this.clear(key), Math.min(duration, 2147483647)) | |
111 | } | |
112 | ||
113 | private accumulateContent (res: express.Response, content: any) { | |
114 | if (!content) return | |
115 | ||
116 | if (typeof content === 'string') { | |
117 | res.locals.apicache.content = (res.locals.apicache.content || '') + content | |
118 | return | |
119 | } | |
120 | ||
121 | if (Buffer.isBuffer(content)) { | |
122 | let oldContent = res.locals.apicache.content | |
123 | ||
124 | if (typeof oldContent === 'string') { | |
125 | oldContent = Buffer.from(oldContent) | |
126 | } | |
127 | ||
128 | if (!oldContent) { | |
129 | oldContent = Buffer.alloc(0) | |
130 | } | |
131 | ||
132 | res.locals.apicache.content = Buffer.concat( | |
133 | [ oldContent, content ], | |
134 | oldContent.length + content.length | |
135 | ) | |
136 | ||
137 | return | |
138 | } | |
139 | ||
140 | res.locals.apicache.content = content | |
141 | } | |
142 | ||
143 | private makeResponseCacheable (res: express.Response, next: express.NextFunction, key: string, duration: number) { | |
144 | const self = this | |
145 | ||
146 | res.locals.apicache = { | |
147 | write: res.write, | |
148 | writeHead: res.writeHead, | |
149 | end: res.end, | |
150 | cacheable: true, | |
151 | content: undefined, | |
152 | headers: {} | |
153 | } | |
154 | ||
155 | // Patch express | |
156 | res.writeHead = function () { | |
157 | if (self.shouldCacheResponse(res)) { | |
158 | res.setHeader('cache-control', 'max-age=' + (duration / 1000).toFixed(0)) | |
159 | } else { | |
160 | res.setHeader('cache-control', 'no-cache, no-store, must-revalidate') | |
161 | } | |
162 | ||
163 | res.locals.apicache.headers = Object.assign({}, res.getHeaders()) | |
164 | return res.locals.apicache.writeHead.apply(this, arguments as any) | |
165 | } | |
166 | ||
167 | res.write = function (chunk: any) { | |
168 | self.accumulateContent(res, chunk) | |
169 | return res.locals.apicache.write.apply(this, arguments as any) | |
170 | } | |
171 | ||
172 | res.end = function (content: any, encoding: BufferEncoding) { | |
173 | if (self.shouldCacheResponse(res)) { | |
174 | self.accumulateContent(res, content) | |
175 | ||
176 | if (res.locals.apicache.cacheable && res.locals.apicache.content) { | |
177 | self.addIndexEntries(key) | |
178 | ||
179 | const headers = res.locals.apicache.headers || res.getHeaders() | |
180 | const cacheObject = self.createCacheObject( | |
181 | res.statusCode, | |
182 | headers, | |
183 | res.locals.apicache.content, | |
184 | encoding | |
185 | ) | |
186 | self.cacheResponse(key, cacheObject, duration) | |
187 | } | |
188 | } | |
189 | ||
190 | res.locals.apicache.end.apply(this, arguments as any) | |
191 | } as any | |
192 | ||
193 | next() | |
194 | } | |
195 | ||
196 | private sendCachedResponse (request: express.Request, response: express.Response, cacheObject: CacheObject, duration: number) { | |
197 | const headers = response.getHeaders() | |
198 | ||
199 | if (isTestInstance()) { | |
200 | Object.assign(headers, { | |
201 | 'x-api-cache-cached': 'true' | |
202 | }) | |
203 | } | |
204 | ||
205 | Object.assign(headers, this.filterBlacklistedHeaders(cacheObject.headers || {}), { | |
206 | // Set properly decremented max-age header | |
207 | // This ensures that max-age is in sync with the cache expiration | |
208 | 'cache-control': | |
209 | 'max-age=' + | |
210 | Math.max( | |
211 | 0, | |
212 | (duration / 1000 - (new Date().getTime() / 1000 - cacheObject.timestamp)) | |
213 | ).toFixed(0) | |
214 | }) | |
215 | ||
216 | // unstringify buffers | |
217 | let data = cacheObject.data | |
218 | if (data && data.type === 'Buffer') { | |
219 | data = typeof data.data === 'number' | |
220 | ? Buffer.alloc(data.data) | |
221 | : Buffer.from(data.data) | |
222 | } | |
223 | ||
224 | // Test Etag against If-None-Match for 304 | |
225 | const cachedEtag = cacheObject.headers.etag | |
226 | const requestEtag = request.headers['if-none-match'] | |
227 | ||
228 | if (requestEtag && cachedEtag === requestEtag) { | |
229 | response.writeHead(304, headers) | |
230 | return response.end() | |
231 | } | |
232 | ||
233 | response.writeHead(cacheObject.status || 200, headers) | |
234 | ||
235 | return response.end(data, cacheObject.encoding) | |
236 | } | |
237 | ||
238 | private clear (target: string) { | |
239 | const redis = Redis.Instance.getClient() | |
240 | ||
241 | if (target) { | |
242 | clearTimeout(this.timers[target]) | |
243 | delete this.timers[target] | |
244 | ||
245 | try { | |
246 | redis.del(target) | |
247 | } catch (err) { | |
248 | logger.error('Cannot delete %s in redis cache.', target, { err }) | |
249 | } | |
250 | ||
251 | this.index.all = this.index.all.filter(key => key !== target) | |
252 | } else { | |
253 | for (const key of this.index.all) { | |
254 | clearTimeout(this.timers[key]) | |
255 | delete this.timers[key] | |
256 | ||
257 | try { | |
258 | redis.del(key) | |
259 | } catch (err) { | |
260 | logger.error('Cannot delete %s in redis cache.', key, { err }) | |
261 | } | |
262 | } | |
263 | ||
264 | this.index.all = [] | |
265 | } | |
266 | ||
267 | return this.index | |
268 | } | |
269 | } |