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
|
// Package event implements an event multiplexer.
package event
import (
"errors"
"reflect"
"sync"
)
// Subscription is implemented by event subscriptions.
type Subscription interface {
// Chan returns a channel that carries events.
// Implementations should return the same channel
// for any subsequent calls to Chan.
Chan() <-chan interface{}
// Unsubscribe stops delivery of events to a subscription.
// The event channel is closed.
// Unsubscribe can be called more than once.
Unsubscribe()
}
// A TypeMux dispatches events to registered receivers. Receivers can be
// registered to handle events of certain type. Any operation
// called after mux is stopped will return ErrMuxClosed.
type TypeMux struct {
mutex sync.RWMutex
subm map[reflect.Type][]*muxsub
stopped bool
}
// ErrMuxClosed is returned when Posting on a closed TypeMux.
var ErrMuxClosed = errors.New("event: mux closed")
// NewTypeMux creates a running mux.
func NewTypeMux() *TypeMux {
return &TypeMux{subm: make(map[reflect.Type][]*muxsub)}
}
// Subscribe creates a subscription for events of the given types. The
// subscription's channel is closed when it is unsubscribed
// or the mux is closed.
func (mux *TypeMux) Subscribe(types ...interface{}) Subscription {
sub := newsub(mux)
mux.mutex.Lock()
if mux.stopped {
mux.mutex.Unlock()
close(sub.postC)
} else {
for _, t := range types {
rtyp := reflect.TypeOf(t)
oldsubs := mux.subm[rtyp]
subs := make([]*muxsub, len(oldsubs)+1)
copy(subs, oldsubs)
subs[len(oldsubs)] = sub
mux.subm[rtyp] = subs
}
mux.mutex.Unlock()
}
return sub
}
// Post sends an event to all receivers registered for the given type.
// It returns ErrMuxClosed if the mux has been stopped.
func (mux *TypeMux) Post(ev interface{}) error {
rtyp := reflect.TypeOf(ev)
mux.mutex.RLock()
if mux.stopped {
mux.mutex.RUnlock()
return ErrMuxClosed
}
subs := mux.subm[rtyp]
mux.mutex.RUnlock()
for _, sub := range subs {
sub.deliver(ev)
}
return nil
}
// Stop closes a mux. The mux can no longer be used.
// Future Post calls will fail with ErrMuxClosed.
// Stop blocks until all current deliveries have finished.
func (mux *TypeMux) Stop() {
mux.mutex.Lock()
for _, subs := range mux.subm {
for _, sub := range subs {
sub.closewait()
}
}
mux.subm = nil
mux.stopped = true
mux.mutex.Unlock()
}
func (mux *TypeMux) del(s *muxsub) {
mux.mutex.Lock()
for typ, subs := range mux.subm {
if pos := find(subs, s); pos >= 0 {
if len(subs) == 1 {
delete(mux.subm, typ)
} else {
mux.subm[typ] = posdelete(subs, pos)
}
}
}
s.mux.mutex.Unlock()
}
func find(slice []*muxsub, item *muxsub) int {
for i, v := range slice {
if v == item {
return i
}
}
return -1
}
func posdelete(slice []*muxsub, pos int) []*muxsub {
news := make([]*muxsub, len(slice)-1)
copy(news[:pos], slice[:pos])
copy(news[pos:], slice[pos+1:])
return news
}
type muxsub struct {
mux *TypeMux
closeMu sync.Mutex
closing chan struct{}
closed bool
// these two are the same channel. they are stored separately so
// postC can be set to nil without affecting the return value of
// Chan.
postMu sync.RWMutex
readC <-chan interface{}
postC chan<- interface{}
}
func newsub(mux *TypeMux) *muxsub {
c := make(chan interface{})
return &muxsub{
mux: mux,
readC: c,
postC: c,
closing: make(chan struct{}),
}
}
func (s *muxsub) Chan() <-chan interface{} {
return s.readC
}
func (s *muxsub) Unsubscribe() {
s.mux.del(s)
s.closewait()
}
func (s *muxsub) closewait() {
s.closeMu.Lock()
defer s.closeMu.Unlock()
if s.closed {
return
}
close(s.closing)
s.closed = true
s.postMu.Lock()
close(s.postC)
s.postC = nil
s.postMu.Unlock()
}
func (s *muxsub) deliver(ev interface{}) {
s.postMu.RLock()
select {
case s.postC <- ev:
case <-s.closing:
}
s.postMu.RUnlock()
}
|
