-
Notifications
You must be signed in to change notification settings - Fork 4.2k
/
ShareReplayScope.swift
458 lines (358 loc) · 13.5 KB
/
ShareReplayScope.swift
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
//
// ShareReplayScope.swift
// RxSwift
//
// Created by Krunoslav Zaher on 5/28/17.
// Copyright © 2017 Krunoslav Zaher. All rights reserved.
//
/// Subject lifetime scope
public enum SubjectLifetimeScope {
/**
**Each connection will have it's own subject instance to store replay events.**
**Connections will be isolated from each another.**
Configures the underlying implementation to behave equivalent to.
```
source.multicast(makeSubject: { MySubject() }).refCount()
```
**This is the recommended default.**
This has the following consequences:
* `retry` or `concat` operators will function as expected because terminating the sequence will clear internal state.
* Each connection to source observable sequence will use it's own subject.
* When the number of subscribers drops from 1 to 0 and connection to source sequence is disposed, subject will be cleared.
```
let xs = Observable.deferred { () -> Observable<TimeInterval> in
print("Performing work ...")
return Observable.just(Date().timeIntervalSince1970)
}
.share(replay: 1, scope: .whileConnected)
_ = xs.subscribe(onNext: { print("next \($0)") }, onCompleted: { print("completed\n") })
_ = xs.subscribe(onNext: { print("next \($0)") }, onCompleted: { print("completed\n") })
_ = xs.subscribe(onNext: { print("next \($0)") }, onCompleted: { print("completed\n") })
```
Notice how time interval is different and `Performing work ...` is printed each time)
```
Performing work ...
next 1495998900.82141
completed
Performing work ...
next 1495998900.82359
completed
Performing work ...
next 1495998900.82444
completed
```
*/
case whileConnected
/**
**One subject will store replay events for all connections to source.**
**Connections won't be isolated from each another.**
Configures the underlying implementation behave equivalent to.
```
source.multicast(MySubject()).refCount()
```
This has the following consequences:
* Using `retry` or `concat` operators after this operator usually isn't advised.
* Each connection to source observable sequence will share the same subject.
* After number of subscribers drops from 1 to 0 and connection to source observable sequence is dispose, this operator will
continue holding a reference to the same subject.
If at some later moment a new observer initiates a new connection to source it can potentially receive
some of the stale events received during previous connection.
* After source sequence terminates any new observer will always immediatelly receive replayed elements and terminal event.
No new subscriptions to source observable sequence will be attempted.
```
let xs = Observable.deferred { () -> Observable<TimeInterval> in
print("Performing work ...")
return Observable.just(Date().timeIntervalSince1970)
}
.share(replay: 1, scope: .forever)
_ = xs.subscribe(onNext: { print("next \($0)") }, onCompleted: { print("completed\n") })
_ = xs.subscribe(onNext: { print("next \($0)") }, onCompleted: { print("completed\n") })
_ = xs.subscribe(onNext: { print("next \($0)") }, onCompleted: { print("completed\n") })
```
Notice how time interval is the same, replayed, and `Performing work ...` is printed only once
```
Performing work ...
next 1495999013.76356
completed
next 1495999013.76356
completed
next 1495999013.76356
completed
```
*/
case forever
}
extension ObservableType {
/**
Returns an observable sequence that **shares a single subscription to the underlying sequence**, and immediately upon subscription replays elements in buffer.
This operator is equivalent to:
* `.whileConnected`
```
// Each connection will have it's own subject instance to store replay events.
// Connections will be isolated from each another.
source.multicast(makeSubject: { Replay.create(bufferSize: replay) }).refCount()
```
* `.forever`
```
// One subject will store replay events for all connections to source.
// Connections won't be isolated from each another.
source.multicast(Replay.create(bufferSize: replay)).refCount()
```
It uses optimized versions of the operators for most common operations.
- parameter replay: Maximum element count of the replay buffer.
- parameter scope: Lifetime scope of sharing subject. For more information see `SubjectLifetimeScope` enum.
- seealso: [shareReplay operator on reactivex.io](http://reactivex.io/documentation/operators/replay.html)
- returns: An observable sequence that contains the elements of a sequence produced by multicasting the source sequence.
*/
public func share(replay: Int = 0, scope: SubjectLifetimeScope = .whileConnected)
-> Observable<E> {
switch scope {
case .forever:
switch replay {
case 0: return self.multicast(PublishSubject()).refCount()
default: return self.multicast(ReplaySubject.create(bufferSize: replay)).refCount()
}
case .whileConnected:
switch replay {
case 0: return ShareWhileConnected(source: self.asObservable())
case 1: return ShareReplay1WhileConnected(source: self.asObservable())
default: return self.multicast(makeSubject: { ReplaySubject.create(bufferSize: replay) }).refCount()
}
}
}
}
fileprivate final class ShareReplay1WhileConnectedConnection<Element>
: ObserverType
, SynchronizedUnsubscribeType {
typealias E = Element
typealias Observers = AnyObserver<Element>.s
typealias DisposeKey = Observers.KeyType
typealias Parent = ShareReplay1WhileConnected<Element>
private let _parent: Parent
private let _subscription = SingleAssignmentDisposable()
private let _lock: RecursiveLock
private var _disposed: Bool = false
fileprivate var _observers = Observers()
fileprivate var _element: Element?
init(parent: Parent, lock: RecursiveLock) {
_parent = parent
_lock = lock
#if TRACE_RESOURCES
_ = Resources.incrementTotal()
#endif
}
final func on(_ event: Event<E>) {
_lock.lock()
let observers = _synchronized_on(event)
_lock.unlock()
dispatch(observers, event)
}
final private func _synchronized_on(_ event: Event<E>) -> Observers {
if _disposed {
return Observers()
}
switch event {
case .next(let element):
_element = element
return _observers
case .error, .completed:
let observers = _observers
self._synchronized_dispose()
return observers
}
}
final func connect() {
_subscription.setDisposable(_parent._source.subscribe(self))
}
final func _synchronized_subscribe<O : ObserverType>(_ observer: O) -> Disposable where O.E == Element {
_lock.lock(); defer { _lock.unlock() }
if let element = _element {
observer.on(.next(element))
}
let disposeKey = _observers.insert(observer.on)
return SubscriptionDisposable(owner: self, key: disposeKey)
}
final private func _synchronized_dispose() {
_disposed = true
if _parent._connection === self {
_parent._connection = nil
}
_observers = Observers()
}
final func synchronizedUnsubscribe(_ disposeKey: DisposeKey) {
_lock.lock()
let shouldDisconnect = _synchronized_unsubscribe(disposeKey)
_lock.unlock()
if shouldDisconnect {
_subscription.dispose()
}
}
@inline(__always)
final private func _synchronized_unsubscribe(_ disposeKey: DisposeKey) -> Bool {
// if already unsubscribed, just return
if self._observers.removeKey(disposeKey) == nil {
return false
}
if _observers.count == 0 {
_synchronized_dispose()
return true
}
return false
}
#if TRACE_RESOURCES
deinit {
_ = Resources.decrementTotal()
}
#endif
}
// optimized version of share replay for most common case
final fileprivate class ShareReplay1WhileConnected<Element>
: Observable<Element> {
fileprivate typealias Connection = ShareReplay1WhileConnectedConnection<Element>
fileprivate let _source: Observable<Element>
fileprivate let _lock = RecursiveLock()
fileprivate var _connection: Connection?
init(source: Observable<Element>) {
self._source = source
}
override func subscribe<O : ObserverType>(_ observer: O) -> Disposable where O.E == E {
_lock.lock()
let connection = _synchronized_subscribe(observer)
let count = connection._observers.count
let disposable = connection._synchronized_subscribe(observer)
_lock.unlock()
if count == 0 {
connection.connect()
}
return disposable
}
@inline(__always)
private func _synchronized_subscribe<O : ObserverType>(_ observer: O) -> Connection where O.E == E {
let connection: Connection
if let existingConnection = _connection {
connection = existingConnection
}
else {
connection = ShareReplay1WhileConnectedConnection<Element>(
parent: self,
lock: _lock)
_connection = connection
}
return connection
}
}
fileprivate final class ShareWhileConnectedConnection<Element>
: ObserverType
, SynchronizedUnsubscribeType {
typealias E = Element
typealias Observers = AnyObserver<Element>.s
typealias DisposeKey = Observers.KeyType
typealias Parent = ShareWhileConnected<Element>
private let _parent: Parent
private let _subscription = SingleAssignmentDisposable()
private let _lock: RecursiveLock
private var _disposed: Bool = false
fileprivate var _observers = Observers()
init(parent: Parent, lock: RecursiveLock) {
_parent = parent
_lock = lock
#if TRACE_RESOURCES
_ = Resources.incrementTotal()
#endif
}
final func on(_ event: Event<E>) {
_lock.lock()
let observers = _synchronized_on(event)
_lock.unlock()
dispatch(observers, event)
}
final private func _synchronized_on(_ event: Event<E>) -> Observers {
if _disposed {
return Observers()
}
switch event {
case .next:
return _observers
case .error, .completed:
let observers = _observers
self._synchronized_dispose()
return observers
}
}
final func connect() {
_subscription.setDisposable(_parent._source.subscribe(self))
}
final func _synchronized_subscribe<O : ObserverType>(_ observer: O) -> Disposable where O.E == Element {
_lock.lock(); defer { _lock.unlock() }
let disposeKey = _observers.insert(observer.on)
return SubscriptionDisposable(owner: self, key: disposeKey)
}
final private func _synchronized_dispose() {
_disposed = true
if _parent._connection === self {
_parent._connection = nil
}
_observers = Observers()
}
final func synchronizedUnsubscribe(_ disposeKey: DisposeKey) {
_lock.lock()
let shouldDisconnect = _synchronized_unsubscribe(disposeKey)
_lock.unlock()
if shouldDisconnect {
_subscription.dispose()
}
}
@inline(__always)
final private func _synchronized_unsubscribe(_ disposeKey: DisposeKey) -> Bool {
// if already unsubscribed, just return
if self._observers.removeKey(disposeKey) == nil {
return false
}
if _observers.count == 0 {
_synchronized_dispose()
return true
}
return false
}
#if TRACE_RESOURCES
deinit {
_ = Resources.decrementTotal()
}
#endif
}
// optimized version of share replay for most common case
final fileprivate class ShareWhileConnected<Element>
: Observable<Element> {
fileprivate typealias Connection = ShareWhileConnectedConnection<Element>
fileprivate let _source: Observable<Element>
fileprivate let _lock = RecursiveLock()
fileprivate var _connection: Connection?
init(source: Observable<Element>) {
self._source = source
}
override func subscribe<O : ObserverType>(_ observer: O) -> Disposable where O.E == E {
_lock.lock()
let connection = _synchronized_subscribe(observer)
let count = connection._observers.count
let disposable = connection._synchronized_subscribe(observer)
_lock.unlock()
if count == 0 {
connection.connect()
}
return disposable
}
@inline(__always)
private func _synchronized_subscribe<O : ObserverType>(_ observer: O) -> Connection where O.E == E {
let connection: Connection
if let existingConnection = _connection {
connection = existingConnection
}
else {
connection = ShareWhileConnectedConnection<Element>(
parent: self,
lock: _lock)
_connection = connection
}
return connection
}
}