-
Notifications
You must be signed in to change notification settings - Fork 203
/
cache.ts
180 lines (156 loc) · 5.34 KB
/
cache.ts
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
import { Headers, Request, RequestInfo, Response } from "@mrbbot/node-fetch";
import CachePolicy from "http-cache-semantics";
import { KVClock, defaultClock } from "./helpers";
import { KVStorageNamespace } from "./namespace";
import { KVStorage } from "./storage";
export interface CacheMatchOptions {
// Consider the request's method GET, regardless of its actual value
ignoreMethod?: boolean;
}
export interface CachedResponse {
status: number;
headers: Record<string, string[]>;
body: string;
}
function normaliseRequest(req: RequestInfo): Request {
return req instanceof Request ? req : new Request(req);
}
// Normalises headers to object mapping lower-case names to single values.
// Single values are OK here as the headers we care about for determining
// cacheability are all single-valued, and we store the raw, multi-valued
// headers in KV once this has been determined.
function normaliseHeaders(headers: Headers): Record<string, string> {
const result: Record<string, string> = {};
for (const [key, value] of headers) {
result[key.toLowerCase()] = value;
}
return result;
}
function getKey(req: Request): string {
return `${req.url}.json`;
}
export interface CacheInterface {
put(req: string | Request, res: Response): Promise<undefined>;
match(
req: string | Request,
options?: CacheMatchOptions
): Promise<Response | undefined>;
delete(req: string | Request, options?: CacheMatchOptions): Promise<boolean>;
}
export class Cache implements CacheInterface {
readonly #storage: KVStorage;
readonly #clock: KVClock;
readonly #namespace: KVStorageNamespace;
constructor(storage: KVStorage, clock: KVClock = defaultClock) {
this.#storage = storage;
this.#clock = clock;
this.#namespace = new KVStorageNamespace(storage, clock);
}
async put(req: RequestInfo, res: Response): Promise<undefined> {
req = normaliseRequest(req);
// Cloudflare ignores request Cache-Control
const reqHeaders = normaliseHeaders(req.headers);
delete reqHeaders["cache-control"];
// Cloudflare never caches responses with Set-Cookie headers
// If Cache-Control contains private=set-cookie, Cloudflare will remove
// the Set-Cookie header automatically
const resHeaders = normaliseHeaders(res.headers);
if (
resHeaders["cache-control"]?.toLowerCase().includes("private=set-cookie")
) {
resHeaders["cache-control"] = resHeaders["cache-control"].replace(
/private=set-cookie/i,
""
);
delete resHeaders["set-cookie"];
}
// Build request and responses suitable for CachePolicy
const cacheReq: CachePolicy.Request = {
url: req.url,
method: req.method,
headers: reqHeaders,
};
const cacheRes: CachePolicy.Response = {
status: res.status,
headers: resHeaders,
};
// @ts-expect-error `now` isn't included in CachePolicy's type definitions
const originalNow = CachePolicy.prototype.now;
// @ts-expect-error `now` isn't included in CachePolicy's type definitions
CachePolicy.prototype.now = this.#clock;
let expirationTtl: number;
try {
const policy = new CachePolicy(cacheReq, cacheRes, { shared: true });
// Check if the request & response is cacheable, if not return undefined
if (
req.method !== "GET" ||
"set-cookie" in resHeaders ||
!policy.storable()
) {
return;
}
expirationTtl = policy.timeToLive() / 1000;
} finally {
// @ts-expect-error `now` isn't included in CachePolicy's type definitions
CachePolicy.prototype.now = originalNow;
}
// If it is cacheable, store it in KV
const key = getKey(req);
await this.#namespace.put(
key,
JSON.stringify({
status: res.status,
headers: res.headers.raw(),
body: Buffer.from(await res.arrayBuffer()).toString("base64"),
} as CachedResponse),
{ expirationTtl }
);
}
async match(
req: RequestInfo,
options?: CacheMatchOptions
): Promise<Response | undefined> {
req = normaliseRequest(req);
// Cloudflare only caches GET requests
if (req.method !== "GET" && !options?.ignoreMethod) return;
// Check if we have the response cached
const key = getKey(req);
const res = await this.#namespace.get<CachedResponse>(key, "json");
if (!res) return;
// Build Response from cache
res.headers["CF-Cache-Status"] = ["HIT"];
return new Response(Buffer.from(res.body, "base64"), {
status: res.status,
headers: res.headers,
});
}
async delete(
req: RequestInfo,
options?: CacheMatchOptions
): Promise<boolean> {
req = normaliseRequest(req);
// Cloudflare only caches GET requests
if (req.method !== "GET" && !options?.ignoreMethod) return false;
// Delete the cached response if it exists (we delete from this.storage not
// this.namespace since we need to know whether we deleted something)
const key = getKey(req);
return this.#storage.delete(key);
}
}
export class NoOpCache implements CacheInterface {
async put(_req: string | Request, _res: Response): Promise<undefined> {
return;
}
async match(
_req: string | Request,
_options?: CacheMatchOptions
): Promise<Response | undefined> {
return;
}
async delete(
_req: string | Request,
_options?: CacheMatchOptions
): Promise<boolean> {
return false;
}
}