82 lines
2.0 KiB
Go
82 lines
2.0 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package events
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import (
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"context"
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"time"
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"github.com/containerd/typeurl"
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"github.com/gogo/protobuf/types"
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)
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// Envelope provides the packaging for an event.
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type Envelope struct {
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Timestamp time.Time
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Namespace string
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Topic string
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Event *types.Any
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}
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// Field returns the value for the given fieldpath as a string, if defined.
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// If the value is not defined, the second value will be false.
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func (e *Envelope) Field(fieldpath []string) (string, bool) {
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if len(fieldpath) == 0 {
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return "", false
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}
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switch fieldpath[0] {
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// unhandled: timestamp
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case "namespace":
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return e.Namespace, len(e.Namespace) > 0
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case "topic":
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return e.Topic, len(e.Topic) > 0
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case "event":
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decoded, err := typeurl.UnmarshalAny(e.Event)
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if err != nil {
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return "", false
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}
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adaptor, ok := decoded.(interface {
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Field([]string) (string, bool)
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})
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if !ok {
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return "", false
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}
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return adaptor.Field(fieldpath[1:])
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}
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return "", false
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}
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// Event is a generic interface for any type of event
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type Event interface{}
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// Publisher posts the event.
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type Publisher interface {
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Publish(ctx context.Context, topic string, event Event) error
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}
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// Forwarder forwards an event to the underlying event bus
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type Forwarder interface {
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Forward(ctx context.Context, envelope *Envelope) error
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}
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// Subscriber allows callers to subscribe to events
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type Subscriber interface {
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Subscribe(ctx context.Context, filters ...string) (ch <-chan *Envelope, errs <-chan error)
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}
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