-
-
Notifications
You must be signed in to change notification settings - Fork 16
/
client.ts
727 lines (652 loc) · 21.7 KB
/
client.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
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
/**
*
* client
*
*/
import { createParser } from './parser';
import { isObject } from './utils';
import {
RequestParams,
Sink,
StreamMessage,
ExecutionResult,
ExecutionPatchResult,
TOKEN_HEADER_KEY,
} from './common';
/** This file is the entry point for browsers, re-export common elements. */
export * from './common';
/** @category Client */
export interface ClientOptions {
/**
* Reuses a single SSE connection for all GraphQL operations.
*
* When instantiating with `false` (default), the client will run
* in a "distinct connections mode" mode. Meaning, a new SSE
* connection will be established on each subscribe.
*
* On the other hand, when instantiating with `true`, the client
* will run in a "single connection mode" mode. Meaning, a single SSE
* connection will be used to transmit all operation results while
* separate HTTP requests will be issued to dictate the behaviour.
*
* @default false
*/
singleConnection?: boolean;
/**
* Controls when should the connection be established while using the
* client in "single connection mode" (see `singleConnection ` option).
*
* - `false`: Establish a connection immediately.
* - `true`: Establish a connection on first subscribe and close on last unsubscribe.
*
* Note that the `lazy` option has NO EFFECT when using the client
* in "distinct connection mode" (`singleConnection = false`).
*
* @default true
*/
lazy?: boolean;
/**
* Used ONLY when the client is in non-lazy mode (`lazy = false`). When
* using this mode, errors might have no sinks to report to; however,
* to avoid swallowing errors, `onNonLazyError` will be called when either:
* - An unrecoverable error/close event occurs
* - Silent retry attempts have been exceeded
*
* After a client has errored out, it will NOT perform any automatic actions.
*
* @default console.error
*/
onNonLazyError?: (error: unknown) => void;
/**
* URL of the GraphQL over SSE server to connect.
*
* If the option is a function, it will be called on each connection attempt.
* Returning a Promise is supported too and the connection phase will stall until it
* resolves with the URL.
*
* A good use-case for having a function is when using the URL for authentication,
* where subsequent reconnects (due to auth) may have a refreshed identity token in
* the URL.
*/
url: string | (() => Promise<string> | string);
/**
* HTTP headers to pass along the request.
*
* If the option is a function, it will be called on each connection attempt.
* Returning a Promise is supported too and the connection phase will stall until it
* resolves with the headers.
*
* A good use-case for having a function is when using the headers for authentication,
* where subsequent reconnects (due to auth) may have a refreshed identity token in
* the header.
*/
headers?:
| Record<string, string>
| (() => Promise<Record<string, string>> | Record<string, string>);
/**
* The Fetch function to use.
*
* For NodeJS environments consider using [`node-fetch`](https://github.com/node-fetch/node-fetch).
*
* @default global.fetch
*/
fetchFn?: unknown;
/**
* The AbortController implementation to use.
*
* For NodeJS environments before v15 consider using [`node-abort-controller`](https://github.com/southpolesteve/node-abort-controller).
*
* @default global.AbortController
*/
abortControllerImpl?: unknown;
/**
* A custom ID generator for identifying subscriptions.
*
* The default generates a v4 UUID to be used as the ID using `Math`
* as the random number generator. Supply your own generator
* in case you need more uniqueness.
*
* Reference: https://gist.github.com/jed/982883
*/
generateID?: () => string;
/**
* How many times should the client try to reconnect before it errors out?
*
* @default 5
*/
retryAttempts?: number;
/**
* Control the wait time between retries. You may implement your own strategy
* by timing the resolution of the returned promise with the retries count.
*
* `retries` argument counts actual reconnection attempts, so it will begin with
* 0 after the first retryable disconnect.
*
* @default 'Randomised exponential backoff, 5 times'
*/
retry?: (retries: number) => Promise<void>;
}
/** @category Client */
export interface Client {
/**
* Subscribes to receive through a SSE connection.
*
* It uses the `sink` to emit received data or errors. Returns a _dispose_
* function used for dropping the subscription and cleaning up.
*/
subscribe<Data = Record<string, unknown>, Extensions = unknown>(
request: RequestParams,
sink: Sink<ExecutionResult<Data, Extensions>>,
): () => void;
/**
* Dispose of the client, destroy connections and clean up resources.
*/
dispose: () => void;
}
/**
* Creates a disposable GraphQL over SSE client to transmit
* GraphQL operation results.
*
* If you have an HTTP/2 server, it is recommended to use the client
* in "distinct connections mode" (`singleConnection = false`) which will
* create a new SSE connection for each subscribe. This is the default.
*
* However, when dealing with HTTP/1 servers from a browser, consider using
* the "single connection mode" (`singleConnection = true`) which will
* use only one SSE connection.
*
* @category Client
*/
export function createClient(options: ClientOptions): Client {
const {
singleConnection = false,
lazy = true,
onNonLazyError = console.error,
/**
* Generates a v4 UUID to be used as the ID using `Math`
* as the random number generator. Supply your own generator
* in case you need more uniqueness.
*
* Reference: https://gist.github.com/jed/982883
*/
generateID = function generateUUID() {
return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, (c) => {
const r = (Math.random() * 16) | 0,
v = c == 'x' ? r : (r & 0x3) | 0x8;
return v.toString(16);
});
},
retryAttempts = 5,
retry = async function randomisedExponentialBackoff(retries) {
let retryDelay = 1000; // start with 1s delay
for (let i = 0; i < retries; i++) {
retryDelay *= 2;
}
await new Promise((resolve) =>
setTimeout(
resolve,
retryDelay +
// add random timeout from 300ms to 3s
Math.floor(Math.random() * (3000 - 300) + 300),
),
);
},
} = options;
const fetchFn = (options.fetchFn || fetch) as typeof fetch;
const AbortControllerImpl = (options.abortControllerImpl ||
AbortController) as typeof AbortController;
// we dont use yet another AbortController here because of
// node's max EventEmitters listeners being only 10
const client = (() => {
let disposed = false;
const listeners: (() => void)[] = [];
return {
get disposed() {
return disposed;
},
onDispose(cb: () => void) {
if (disposed) {
// empty the call stack and then call the cb
setTimeout(() => cb(), 0);
return () => {
// noop
};
}
listeners.push(cb);
return () => {
listeners.splice(listeners.indexOf(cb), 1);
};
},
dispose() {
if (disposed) return;
disposed = true;
// we copy the listeners so that onDispose unlistens dont "pull the rug under our feet"
for (const listener of [...listeners]) {
listener();
}
},
};
})();
let connCtrl: AbortController,
conn: Promise<Connection> | undefined,
locks = 0,
retryingErr = null as unknown,
retries = 0;
async function getOrConnect(): Promise<NonNullable<typeof conn>> {
try {
if (client.disposed) throw new Error('Client has been disposed');
return await (conn ??
(conn = (async () => {
if (retryingErr) {
await retry(retries);
// connection might've been aborted while waiting for retry
if (connCtrl.signal.aborted)
throw new Error('Connection aborted by the client');
retries++;
}
// we must create a new controller here because lazy mode aborts currently active ones
connCtrl = new AbortControllerImpl();
const unlistenDispose = client.onDispose(() => connCtrl.abort());
connCtrl.signal.addEventListener('abort', () => {
unlistenDispose();
conn = undefined;
});
const url =
typeof options.url === 'function'
? await options.url()
: options.url;
if (connCtrl.signal.aborted)
throw new Error('Connection aborted by the client');
const headers =
typeof options.headers === 'function'
? await options.headers()
: options.headers ?? {};
if (connCtrl.signal.aborted)
throw new Error('Connection aborted by the client');
let res;
try {
res = await fetchFn(url, {
signal: connCtrl.signal,
method: 'PUT',
headers,
});
} catch (err) {
throw new NetworkError(err);
}
if (res.status !== 201) throw new NetworkError(res);
const token = await res.text();
headers[TOKEN_HEADER_KEY] = token;
const connected = await connect({
signal: connCtrl.signal,
headers,
url,
fetchFn,
});
retryingErr = null; // future connects are not retries
retries = 0; // reset the retries on connect
connected.waitForThrow().catch(() => (conn = undefined));
return connected;
})()));
} catch (err) {
// whatever problem happens during connect means the connection was not established
conn = undefined;
throw err;
}
}
// non-lazy mode always holds one lock to persist the connection
if (singleConnection && !lazy) {
(async () => {
locks++;
for (;;) {
try {
const { waitForThrow } = await getOrConnect();
await waitForThrow();
} catch (err) {
if (client.disposed) return;
// all non-network errors are worth reporting immediately
if (!(err instanceof NetworkError)) return onNonLazyError?.(err);
// retries are not allowed or we tried to many times, report error
if (!retryAttempts || retries >= retryAttempts)
return onNonLazyError?.(err);
// try again
retryingErr = err;
}
}
})();
}
return {
subscribe(request, sink) {
if (!singleConnection) {
// distinct connections mode
const control = new AbortControllerImpl();
const unlisten = client.onDispose(() => {
unlisten();
control.abort();
});
(async () => {
let retryingErr = null as unknown,
retries = 0;
for (;;) {
try {
if (retryingErr) {
await retry(retries);
// connection might've been aborted while waiting for retry
if (control.signal.aborted)
throw new Error('Connection aborted by the client');
retries++;
}
const url =
typeof options.url === 'function'
? await options.url()
: options.url;
if (control.signal.aborted)
throw new Error('Connection aborted by the client');
const headers =
typeof options.headers === 'function'
? await options.headers()
: options.headers ?? {};
if (control.signal.aborted)
throw new Error('Connection aborted by the client');
const { getResults } = await connect({
signal: control.signal,
headers,
url,
body: JSON.stringify(request),
fetchFn,
});
retryingErr = null; // future connects are not retries
retries = 0; // reset the retries on connect
for await (const result of getResults()) {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
sink.next(result as any);
}
return control.abort();
} catch (err) {
if (control.signal.aborted) return;
// all non-network errors are worth reporting immediately
if (!(err instanceof NetworkError)) throw err;
// retries are not allowed or we tried to many times, report error
if (!retryAttempts || retries >= retryAttempts) throw err;
// try again
retryingErr = err;
}
}
})()
.then(() => sink.complete())
.catch((err) => sink.error(err));
return () => control.abort();
}
// single connection mode
locks++;
const control = new AbortControllerImpl();
const unlisten = client.onDispose(() => {
unlisten();
control.abort();
});
(async () => {
const operationId = generateID();
request = {
...request,
extensions: { ...request.extensions, operationId },
};
let complete: (() => Promise<void>) | null = null;
for (;;) {
complete = null;
try {
const { url, headers, getResults } = await getOrConnect();
let res;
try {
res = await fetchFn(url, {
signal: control.signal,
method: 'POST',
headers,
body: JSON.stringify(request),
});
} catch (err) {
throw new NetworkError(err);
}
if (res.status !== 202) throw new NetworkError(res);
complete = async () => {
let res;
try {
const control = new AbortControllerImpl();
const unlisten = client.onDispose(() => {
unlisten();
control.abort();
});
res = await fetchFn(url + '?operationId=' + operationId, {
signal: control.signal,
method: 'DELETE',
headers,
});
} catch (err) {
throw new NetworkError(err);
}
if (res.status !== 200) throw new NetworkError(res);
};
for await (const result of getResults({
signal: control.signal,
operationId,
})) {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
sink.next(result as any);
}
complete = null; // completed by the server
return control.abort();
} catch (err) {
if (control.signal.aborted) return await complete?.();
// all non-network errors are worth reporting immediately
if (!(err instanceof NetworkError)) throw err;
// retries are not allowed or we tried to many times, report error
if (!retryAttempts || retries >= retryAttempts) throw err;
// try again
retryingErr = err;
} finally {
// release lock if aborted, and disconnect if no more locks
if (control.signal.aborted && --locks === 0) connCtrl.abort();
}
}
})()
.then(() => sink.complete())
.catch((err) => sink.error(err));
return () => control.abort();
},
dispose() {
client.dispose();
},
};
}
/**
* A network error caused by the client or an unexpected response from the server.
*
* Network errors are considered retryable, all others error types will be reported
* immediately.
*
* To avoid bundling DOM typings (because the client can run in Node env too),
* you should supply the `Response` generic depending on your Fetch implementation.
*
* @category Client
*/
export class NetworkError<
Response extends ResponseLike = ResponseLike,
> extends Error {
/**
* The underlyig response thats considered an error.
*
* Will be undefined when no response is received,
* instead an unexpected network error.
*/
public response: Response | undefined;
constructor(msgOrErrOrResponse: string | Error | Response) {
let message, response: Response | undefined;
if (isResponseLike(msgOrErrOrResponse)) {
response = msgOrErrOrResponse;
message =
'Server responded with ' +
msgOrErrOrResponse.status +
': ' +
msgOrErrOrResponse.statusText;
} else if (msgOrErrOrResponse instanceof Error)
message = msgOrErrOrResponse.message;
else message = String(msgOrErrOrResponse);
super(message);
this.name = this.constructor.name;
this.response = response;
}
}
interface ResponseLike {
readonly ok: boolean;
readonly status: number;
readonly statusText: string;
}
function isResponseLike(val: unknown): val is ResponseLike {
return (
isObject(val) &&
typeof val['ok'] === 'boolean' &&
typeof val['status'] === 'number' &&
typeof val['statusText'] === 'string'
);
}
interface Connection {
url: string;
headers: Record<string, string> | undefined;
waitForThrow: () => Promise<void>;
getResults: (options?: {
signal: AbortSignal;
operationId: string;
}) => AsyncIterable<ExecutionResult | ExecutionPatchResult>;
}
interface ConnectOptions {
signal: AbortSignal;
url: string;
headers?: Record<string, string> | undefined;
body?: string;
fetchFn: typeof fetch;
}
async function connect(options: ConnectOptions): Promise<Connection> {
const { signal, url, headers, body, fetchFn } = options;
const waiting: {
[id: string]: { proceed: () => void };
} = {};
const queue: {
[id: string]: (ExecutionResult | ExecutionPatchResult | 'complete')[];
} = {};
let res;
try {
res = await fetchFn(url, {
signal,
method: body ? 'POST' : 'GET',
headers: {
...headers,
accept: 'text/event-stream',
},
body,
});
} catch (err) {
throw new NetworkError(err);
}
if (!res.ok) throw new NetworkError(res);
if (!res.body) throw new Error('Missing response body');
let error: unknown = null;
let waitingForThrow: ((error: unknown) => void) | null = null;
(async () => {
try {
const parse = createParser();
// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
for await (const chunk of toAsyncIterator(res.body!)) {
if (typeof chunk === 'string')
throw new Error(`Unexpected string chunk "${chunk}"`);
// read chunk and if messages are ready, yield them
const msgs = parse(chunk);
if (!msgs) continue;
for (const msg of msgs) {
const operationId =
msg.data && 'id' in msg.data
? msg.data.id // StreamDataForID
: ''; // StreamData
if (!(operationId in queue)) queue[operationId] = [];
switch (msg.event) {
case 'next':
if (operationId)
queue[operationId].push(
(msg as StreamMessage<true, 'next'>).data.payload,
);
else
queue[operationId].push(
(msg as StreamMessage<false, 'next'>).data,
);
break;
case 'complete':
queue[operationId].push('complete');
break;
default:
throw new Error(`Unexpected message event "${msg.event}"`);
}
waiting[operationId]?.proceed();
}
}
} catch (err) {
error = err;
if (waitingForThrow) waitingForThrow(err);
} finally {
Object.values(waiting).forEach(({ proceed }) => proceed());
}
})();
return {
url,
headers,
waitForThrow: () =>
new Promise((_, reject) => {
if (error) return reject(error);
waitingForThrow = reject;
}),
async *getResults(options) {
const { signal, operationId = '' } = options ?? {};
// operationId === '' ? StreamData : StreamDataForID
try {
for (;;) {
while (queue[operationId]?.length) {
// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
const result = queue[operationId].shift()!;
if (result === 'complete') return;
yield result;
}
if (error) throw error;
if (signal?.aborted)
throw new Error('Getting results aborted by the client');
await new Promise<void>((resolve) => {
const proceed = () => {
signal?.removeEventListener('abort', proceed);
delete waiting[operationId];
resolve();
};
signal?.addEventListener('abort', proceed);
waiting[operationId] = { proceed };
});
}
} finally {
delete queue[operationId];
}
},
};
}
/** Isomorphic ReadableStream to AsyncIterator converter. */
function toAsyncIterator(
val: ReadableStream | NodeJS.ReadableStream,
): AsyncIterable<string | Buffer | Uint8Array> {
// node stream is already async iterable
if (typeof Object(val)[Symbol.asyncIterator] === 'function') {
val = val as NodeJS.ReadableStream;
return val[Symbol.asyncIterator]();
}
// convert web stream to async iterable
return (async function* () {
val = val as ReadableStream;
const reader = val.getReader();
for (;;) {
const { value, done } = await reader.read();
if (done) return value;
yield value;
}
})();
}