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
|
package watch
import (
"fmt"
"time"
events "github.com/docker/go-events"
)
// ErrSinkTimeout is returned from the Write method when a sink times out.
var ErrSinkTimeout = fmt.Errorf("timeout exceeded, tearing down sink")
// timeoutSink is a sink that wraps another sink with a timeout. If the
// embedded sink fails to complete a Write operation within the specified
// timeout, the Write operation of the timeoutSink fails.
type timeoutSink struct {
timeout time.Duration
sink events.Sink
}
func (s timeoutSink) Write(event events.Event) error {
errChan := make(chan error)
go func(c chan<- error) {
c <- s.sink.Write(event)
}(errChan)
timer := time.NewTimer(s.timeout)
select {
case err := <-errChan:
timer.Stop()
return err
case <-timer.C:
s.sink.Close()
return ErrSinkTimeout
}
}
func (s timeoutSink) Close() error {
return s.sink.Close()
}
// dropErrClosed is a sink that suppresses ErrSinkClosed from Write, to avoid
// debug log messages that may be confusing. It is possible that the queue
// will try to write an event to its destination channel while the queue is
// being removed from the broadcaster. Since the channel is closed before the
// queue, there is a narrow window when this is possible. In some event-based
// dropping events when a sink is removed from a broadcaster is a problem, but
// for the usage in this watch package that's the expected behavior.
type dropErrClosed struct {
sink events.Sink
}
func (s dropErrClosed) Write(event events.Event) error {
err := s.sink.Write(event)
if err == events.ErrSinkClosed {
return nil
}
return err
}
func (s dropErrClosed) Close() error {
return s.sink.Close()
}
// dropErrClosedChanGen is a ChannelSinkGenerator for dropErrClosed sinks wrapping
// unbuffered channels.
type dropErrClosedChanGen struct{}
func (s *dropErrClosedChanGen) NewChannelSink() (events.Sink, *events.Channel) {
ch := events.NewChannel(0)
return dropErrClosed{sink: ch}, ch
}
// TimeoutDropErrChanGen is a ChannelSinkGenerator that creates a channel,
// wrapped by the dropErrClosed sink and a timeout.
type TimeoutDropErrChanGen struct {
timeout time.Duration
}
// NewChannelSink creates a new sink chain of timeoutSink->dropErrClosed->Channel
func (s *TimeoutDropErrChanGen) NewChannelSink() (events.Sink, *events.Channel) {
ch := events.NewChannel(0)
return timeoutSink{
timeout: s.timeout,
sink: dropErrClosed{
sink: ch,
},
}, ch
}
// NewTimeoutDropErrSinkGen returns a generator of timeoutSinks wrapping dropErrClosed
// sinks, wrapping unbuffered channel sinks.
func NewTimeoutDropErrSinkGen(timeout time.Duration) ChannelSinkGenerator {
return &TimeoutDropErrChanGen{timeout: timeout}
}
|
