forked from looplab/eventhorizon
-
Notifications
You must be signed in to change notification settings - Fork 0
/
eventbus.go
54 lines (46 loc) · 1.86 KB
/
eventbus.go
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
// Copyright (c) 2014 - The Event Horizon 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 eventhorizon
import (
"context"
"fmt"
)
// EventBusError is an async error containing the error returned from a handler
// or observer and the event that it happened on.
type EventBusError struct {
Err error
Ctx context.Context
Event Event
}
// Error implements the Error method of the error interface.
func (e EventBusError) Error() string {
return fmt.Sprintf("%s: (%s)", e.Err, e.Event)
}
// EventBus sends published events to one of each handler type and all observers.
// That means that if the same handler is registered on multiple nodes only one
// of them will receive the event. In contrast all observers registered on multiple
// nodes will receive the event. Events are not garantued to be handeled or observed
// in order.
type EventBus interface {
// PublishEvent publishes the event on the bus.
PublishEvent(context.Context, Event) error
// AddHandler adds a handler for an event. Panics if either the matcher
// or handler is nil or the handler is already added.
AddHandler(EventMatcher, EventHandler)
// AddObserver adds an observer. Panics if the observer is nil or the observer
// is already added.
AddObserver(EventMatcher, EventHandler)
// Errors returns an error channel where async handling errors are sent.
Errors() <-chan EventBusError
}