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
|
// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
using System.Reactive.Disposables;
using System.Reactive.Linq;
namespace System.Reactive.Subjects
{
/// <summary>
/// Represents an observable wrapper that can be connected and disconnected from its underlying observable sequence.
/// </summary>
/// <typeparam name="TSource">The type of the elements in the source sequence.</typeparam>
/// <typeparam name="TResult">The type of the elements in the resulting sequence, after transformation through the subject.</typeparam>
internal class ConnectableObservable<TSource, TResult> : IConnectableObservable<TResult>
{
private readonly ISubject<TSource, TResult> _subject;
private readonly IObservable<TSource> _source;
private readonly object _gate;
private Connection _connection;
/// <summary>
/// Creates an observable that can be connected and disconnected from its source.
/// </summary>
/// <param name="source">Underlying observable source sequence that can be connected and disconnected from the wrapper.</param>
/// <param name="subject">Subject exposed by the connectable observable, receiving data from the underlying source sequence upon connection.</param>
public ConnectableObservable(IObservable<TSource> source, ISubject<TSource, TResult> subject)
{
_subject = subject;
_source = source.AsObservable(); // This gets us auto-detach behavior; otherwise, we'd have to roll our own, including trampoline installation.
_gate = new object();
}
/// <summary>
/// Connects the observable wrapper to its source. All subscribed observers will receive values from the underlying observable sequence as long as the connection is established.
/// </summary>
/// <returns>Disposable object used to disconnect the observable wrapper from its source, causing subscribed observer to stop receiving values from the underlying observable sequence.</returns>
public IDisposable Connect()
{
lock (_gate)
{
if (_connection == null)
{
var subscription = _source.SubscribeSafe(_subject);
_connection = new Connection(this, subscription);
}
return _connection;
}
}
class Connection : IDisposable
{
private readonly ConnectableObservable<TSource, TResult> _parent;
private IDisposable _subscription;
public Connection(ConnectableObservable<TSource, TResult> parent, IDisposable subscription)
{
_parent = parent;
_subscription = subscription;
}
public void Dispose()
{
lock (_parent._gate)
{
if (_subscription != null)
{
_subscription.Dispose();
_subscription = null;
_parent._connection = null;
}
}
}
}
/// <summary>
/// Subscribes an observer to the observable sequence. No values from the underlying observable source will be received unless a connection was established through the Connect method.
/// </summary>
/// <param name="observer">Observer that will receive values from the underlying observable source when the current ConnectableObservable instance is connected through a call to Connect.</param>
/// <returns>Disposable used to unsubscribe from the observable sequence.</returns>
public IDisposable Subscribe(IObserver<TResult> observer)
{
if (observer == null)
throw new ArgumentNullException("observer");
return _subject.SubscribeSafe(observer);
}
}
}
|
