blob: d3d0f34c5d536d0a3450d9dacfdbf68dc8de9e01 (
plain)
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
|
// Copyright 2020 The gVisor Authors.
//
// 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 syncevent
// Source represents an event source.
type Source interface {
// SubscribeEvents causes the Source to notify the given Receiver of the
// given subset of events.
//
// Preconditions:
// * r != nil.
// * The ReceiverCallback for r must not take locks that are ordered
// prior to the Source; for example, it cannot call any Source
// methods.
SubscribeEvents(r *Receiver, filter Set) SubscriptionID
// UnsubscribeEvents causes the Source to stop notifying the Receiver
// subscribed by a previous call to SubscribeEvents that returned the given
// SubscriptionID.
//
// Preconditions: UnsubscribeEvents may be called at most once for any
// given SubscriptionID.
UnsubscribeEvents(id SubscriptionID)
}
// SubscriptionID identifies a call to Source.SubscribeEvents.
type SubscriptionID uint64
// UnsubscribeAndAck is a convenience function that unsubscribes r from the
// given events from src and also clears them from r.
func UnsubscribeAndAck(src Source, r *Receiver, filter Set, id SubscriptionID) {
src.UnsubscribeEvents(id)
r.Ack(filter)
}
// NoopSource implements Source by never sending events to subscribed
// Receivers.
type NoopSource struct{}
// SubscribeEvents implements Source.SubscribeEvents.
func (NoopSource) SubscribeEvents(*Receiver, Set) SubscriptionID {
return 0
}
// UnsubscribeEvents implements Source.UnsubscribeEvents.
func (NoopSource) UnsubscribeEvents(SubscriptionID) {
}
// See Broadcaster for a non-noop implementations of Source.
|
