62 lines
2.1 KiB
Go
62 lines
2.1 KiB
Go
// 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.
|