FilesExpand file tree

 1.x

/

RefCountSubscription.java

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

145 lines (128 loc) · 4.24 KB

 1.x

/

RefCountSubscription.java

Copy path

Top

File metadata and controls

• Code
• Blame

145 lines (128 loc) · 4.24 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

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

/**

* Copyright 2014 Netflix, Inc.

*

* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

*

* http://www.apache.org/licenses/LICENSE-2.0

*

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

*/

package rx.subscriptions;

import java.util.concurrent.atomic.AtomicInteger;

import java.util.concurrent.atomic.AtomicReference;

import rx.Subscription;

/**

* Keeps track of the sub-subscriptions and unsubscribes the underlying subscription once all sub-subscriptions

* have unsubscribed.

*/

public final class RefCountSubscription implements Subscription {

private final Subscription actual;

static final State EMPTY_STATE = new State(false, 0);

final AtomicReference<State> state = new AtomicReference<State>(EMPTY_STATE);

private static final class State {

final boolean isUnsubscribed;

final int children;

State(boolean u, int c) {

this.isUnsubscribed = u;

this.children = c;

}

State addChild() {

return new State(isUnsubscribed, children + 1);

}

State removeChild() {

return new State(isUnsubscribed, children - 1);

}

State unsubscribe() {

return new State(true, children);

}

}

/**

* Creates a {@code RefCountSubscription} by wrapping the given non-null {@code Subscription}.

*

* @param s

* the {@link Subscription} to wrap

* @throws IllegalArgumentException

* if {@code s} is {@code null}

*/

public RefCountSubscription(Subscription s) {

if (s == null) {

throw new IllegalArgumentException("s");

}

this.actual = s;

}

/**

* Returns a new sub-subscription

*

* @return a new sub-subscription.

*/

public Subscription get() {

State oldState;

State newState;

final AtomicReference<State> localState = this.state;

do {

oldState = localState.get();

if (oldState.isUnsubscribed) {

return Subscriptions.unsubscribed();

} else {

newState = oldState.addChild();

}

} while (!localState.compareAndSet(oldState, newState));

return new InnerSubscription(this);

}

@Override

public boolean isUnsubscribed() {

return state.get().isUnsubscribed;

}

@Override

public void unsubscribe() {

State oldState;

State newState;

final AtomicReference<State> localState = this.state;

do {

oldState = localState.get();

if (oldState.isUnsubscribed) {

return;

}

newState = oldState.unsubscribe();

} while (!localState.compareAndSet(oldState, newState));

unsubscribeActualIfApplicable(newState);

}

private void unsubscribeActualIfApplicable(State state) {

if (state.isUnsubscribed && state.children == 0) {

actual.unsubscribe();

}

}

void unsubscribeAChild() {

State oldState;

State newState;

final AtomicReference<State> localState = this.state;

do {

oldState = localState.get();

newState = oldState.removeChild();

} while (!localState.compareAndSet(oldState, newState));

unsubscribeActualIfApplicable(newState);

}

/** The individual sub-subscriptions. */

private static final class InnerSubscription extends AtomicInteger implements Subscription {

final RefCountSubscription parent;

public InnerSubscription(RefCountSubscription parent) {

this.parent = parent;

}

@Override

public void unsubscribe() {

if (compareAndSet(0, 1)) {

parent.unsubscribeAChild();

}

}

@Override

public boolean isUnsubscribed() {

return get() != 0;

}

}

}