131 lines
3.6 KiB
Go
131 lines
3.6 KiB
Go
// Package broker is an interface used for asynchronous messaging
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package broker
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import (
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"context"
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"errors"
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"github.com/unistack-org/micro/v3/metadata"
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)
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// DefaultBroker default memory broker
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var DefaultBroker Broker = NewBroker()
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var (
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// ErrNotConnected returns when broker used but not connected yet
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ErrNotConnected = errors.New("broker not connected")
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// ErrDisconnected returns when broker disconnected
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ErrDisconnected = errors.New("broker disconnected")
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)
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// Broker is an interface used for asynchronous messaging.
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type Broker interface {
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// Name returns broker instance name
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Name() string
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// Init initilize broker
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Init(opts ...Option) error
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// Options returns broker options
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Options() Options
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// Address return configured address
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Address() string
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// Connect connects to broker
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Connect(ctx context.Context) error
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// Disconnect disconnect from broker
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Disconnect(ctx context.Context) error
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// Publish message to broker topic
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Publish(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error
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// Subscribe subscribes to topic message via handler
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Subscribe(ctx context.Context, topic string, h Handler, opts ...SubscribeOption) (Subscriber, error)
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// BatchPublish messages to broker with multiple topics
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BatchPublish(ctx context.Context, msgs []*Message, opts ...PublishOption) error
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// BatchSubscribe subscribes to topic messages via handler
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BatchSubscribe(ctx context.Context, topic string, h BatchHandler, opts ...SubscribeOption) (Subscriber, error)
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// String type of broker
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String() string
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}
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// Handler is used to process messages via a subscription of a topic.
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type Handler func(Event) error
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// Events contains multiple events
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type Events []Event
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func (evs Events) Ack() error {
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var err error
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for _, ev := range evs {
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if err = ev.Ack(); err != nil {
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return err
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}
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}
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return nil
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}
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func (evs Events) SetError(err error) {
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for _, ev := range evs {
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ev.SetError(err)
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}
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}
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// BatchHandler is used to process messages in batches via a subscription of a topic.
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type BatchHandler func(Events) error
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// Event is given to a subscription handler for processing
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type Event interface {
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// Topic returns event topic
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Topic() string
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// Message returns broker message
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Message() *Message
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// Ack acknowledge message
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Ack() error
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// Error returns message error (like decoding errors or some other)
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Error() error
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// SetError set event processing error
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SetError(err error)
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}
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// RawMessage is a raw encoded JSON value.
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// It implements Marshaler and Unmarshaler and can be used to delay decoding or precompute a encoding.
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type RawMessage []byte
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// MarshalJSON returns m as the JSON encoding of m.
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func (m *RawMessage) MarshalJSON() ([]byte, error) {
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if m == nil {
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return []byte("null"), nil
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}
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return *m, nil
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}
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// UnmarshalJSON sets *m to a copy of data.
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func (m *RawMessage) UnmarshalJSON(data []byte) error {
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if m == nil {
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return errors.New("RawMessage UnmarshalJSON on nil pointer")
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}
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*m = append((*m)[0:0], data...)
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return nil
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}
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// Message is used to transfer data
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type Message struct {
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// Header contains message metadata
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Header metadata.Metadata
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// Body contains message body
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Body RawMessage
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}
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// NewMessage create broker message with topic filled
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func NewMessage(topic string) *Message {
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m := &Message{Header: metadata.New(2)}
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m.Header.Set(metadata.HeaderTopic, topic)
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return m
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}
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// Subscriber is a convenience return type for the Subscribe method
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type Subscriber interface {
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// Options returns subscriber options
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Options() SubscribeOptions
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// Topic returns topic for subscription
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Topic() string
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// Unsubscribe from topic
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Unsubscribe(ctx context.Context) error
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}
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