/
chan.go
91 lines (72 loc) · 2.38 KB
/
chan.go
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/*
* Copyright 2021 Comcast Cable Communications Management, LLC
*
* 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.
*
* SPDX-License-Identifier: Apache-2.0
*/
package dsl
import "time"
var (
// DefaultChanBufferSize is a default buffer size any Chan can
// choose to consider.
DefaultChanBufferSize = 1024
)
type Msg struct {
Topic string `json:"topic"`
Payload string `json:"payload"`
ReceivedAt time.Time `json:"receivedAt"`
}
// ChanOpts represents generic data that is give to a Chan constructor.
type ChanOpts interface{}
// ChanKind is something like 'mqtt', 'kds', etc.
//
// Support for a Chan registers itself in ChanRegistry.
type ChanKind string
// ChanMaker is the signature for a Chan constructor.
type ChanMaker func(ctx *Ctx, def interface{}) (Chan, error)
// ChanRegistry maps a ChanKind to a constructor for that type of
// Chan.
type ChanRegistry map[ChanKind]ChanMaker
func (r ChanRegistry) Register(ctx *Ctx, kind ChanKind, maker ChanMaker) {
r[kind] = maker
}
// TheChanRegistry is the global, well-known registry of supported
// Chan types.
var TheChanRegistry = make(ChanRegistry)
// Chan can send and receive messages.
type Chan interface {
// Open starts up the Chan.
Open(ctx *Ctx) error
// Chose shuts down this Chan.
Close(ctx *Ctx) error
// Kill ungracefully closes an underlying connection (if any).
//
// Useful for testing MQTT LWT.
Kill(ctx *Ctx) error
// Kind returns this Chan's type.
Kind() ChanKind
// Sub, when required, initials a subscription.
//
// Use the Recv method to obtain messages that arrive via any
// subscription.
Sub(ctx *Ctx, topic string) error
// Recv returns a channel of messages.
Recv(ctx *Ctx) chan Msg
// Pub, when supported, publishes a message on this Chan.
Pub(ctx *Ctx, m Msg) error
// To is a utility to send a message to the channel returned
// by Recv.
To(ctx *Ctx, m Msg) error
DocSpec() *DocSpec
}