108 lines
2.9 KiB
Go
108 lines
2.9 KiB
Go
// Package mq exposes the broker-agnostic messaging seam used by services.
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package mq
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import (
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"context"
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"encoding/json"
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"errors"
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"time"
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)
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var ErrUnavailable = errors.New("message broker unavailable")
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const (
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ProviderEMQX = "emqx"
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ProviderKafka = "kafka"
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ProviderRabbitMQ = "rabbitmq"
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)
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const (
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AtMostOnce byte = 0
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AtLeastOnce byte = 1
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ExactlyOnce byte = 2
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)
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type Message struct {
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Topic string
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Payload []byte
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QoS byte
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Retain bool
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}
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func (m Message) DecodeJSON(target any) error { return json.Unmarshal(m.Payload, target) }
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type Handler func(context.Context, Message)
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// TopicSubscription is one logical module subscription. The handler is kept
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// by the runtime and is replayed after a client reconnects or is rebuilt.
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type TopicSubscription struct {
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Topic string
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QoS byte
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Handler Handler
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}
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// SubscriptionSet is the complete subscription declaration for one module and
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// provider. Registering the same owner/provider replaces its previous set.
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// Owner must be a stable module name, not a request or goroutine identifier.
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type SubscriptionSet struct {
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Owner string
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Provider string
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Topics []TopicSubscription
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}
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// SubscriptionRegistrar is the module-facing seam for durable-in-process
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// subscription intent. Register does not require a live broker; the runtime
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// will bind the declared topics when the provider becomes available.
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type SubscriptionRegistrar interface {
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Register(SubscriptionSet) error
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Unregister(owner string) error
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}
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// SubscriptionContributor lets a module expose its broker subscriptions
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// without depending on the concrete integration implementation.
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type SubscriptionContributor interface {
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RegisterSubscriptions(SubscriptionRegistrar) error
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}
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type Client interface {
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Publish(context.Context, string, []byte, byte, bool) error
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Subscribe(context.Context, string, byte, Handler) error
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Unsubscribe(context.Context, ...string) error
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Connected() bool
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Close() error
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}
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// Registry exposes named broker clients while preserving Client as the
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// default EMQX/MQTT boundary for existing modules.
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type Registry interface {
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SubscriptionRegistrar
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Client(provider string) Client
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PublishTo(context.Context, string, string, []byte, byte, bool) error
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SubscribeTo(context.Context, string, string, byte, Handler) error
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UnsubscribeFrom(context.Context, string, ...string) error
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ConnectedTo(provider string) bool
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}
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type Config struct {
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Enabled bool
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Broker string
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ClientID string
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Username string
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Password string
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KeepAlive time.Duration
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CleanSession bool
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ConnectTimeout time.Duration
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ReconnectInterval time.Duration
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}
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func PublishJSON(ctx context.Context, client Client, topic string, value any, qos byte, retain bool) error {
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if client == nil {
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return ErrUnavailable
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}
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payload, err := json.Marshal(value)
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if err != nil {
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return err
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}
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return client.Publish(ctx, topic, payload, qos, retain)
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}
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