mempubsub

Documentation

Overview

Package mempubsub provides an in-memory pubsub implementation. Use NewTopic to construct a *pubsub.Topic, and/or NewSubscription to construct a *pubsub.Subscription.

mempubsub should not be used for production: it is intended for local development and testing.

URLs

For pubsub.OpenTopic and pubsub.OpenSubscription, mempubsub registers for the scheme "mem". To customize the URL opener, or for more details on the URL format, see URLOpener. See https://godoc.org/gocloud.dev#hdr-URLs for background information.

As

mempubsub does not support any types for As.

Example

package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"gocloud.dev/pubsub"
	"gocloud.dev/pubsub/mempubsub"
)

func main() {
	// Construct a *pubsub.Topic.
	ctx := context.Background()
	t := mempubsub.NewTopic()
	defer t.Shutdown(ctx)

	// Construct a *pubsub.Subscription for the topic.
	s := mempubsub.NewSubscription(t, 1*time.Minute /* ack deadline */)
	defer s.Shutdown(ctx)

	// Now we can use t to send messages and s will receive them.
	err := t.Send(ctx, &pubsub.Message{Body: []byte("Hello World")})
	if err != nil {
		log.Fatal(err)
	}

	msg, err := s.Receive(ctx)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(string(msg.Body))
	msg.Ack()

}

Output:

Hello World

Example (OpenfromURL)

package main

import (
	"context"

	"gocloud.dev/pubsub"
)

func main() {
	ctx := context.Background()

	// OpenTopic creates a *pubsub.Topic from a URL.
	// This URL will open the topic "mytopic".
	t, err := pubsub.OpenTopic(ctx, "mem://mytopic")

	// Similarly, OpenSubscription creates a *pubsub.Subscription from a URL.
	// This URL will open a subscription to the topic "mytopic", which must
	// have been previously opened using OpenTopic.
	s, err := pubsub.OpenSubscription(ctx, "mem://mytopic")
	_, _, _ = t, s, err
}

Index

• Constants
• func NewSubscription(top *pubsub.Topic, ackDeadline time.Duration) *pubsub.Subscription
• func NewTopic() *pubsub.Topic
• type URLOpener
  • func (o *URLOpener) OpenSubscriptionURL(ctx context.Context, u *url.URL) (*pubsub.Subscription, error)
  • func (o *URLOpener) OpenTopicURL(ctx context.Context, u *url.URL) (*pubsub.Topic, error)

Examples

• Package
• Package (OpenfromURL)

Constants

const Scheme = "mem"

Scheme is the URL scheme mempubsub registers its URLOpeners under on pubsub.DefaultMux.

Functions

func NewSubscription

func NewSubscription(top *pubsub.Topic, ackDeadline time.Duration) *pubsub.Subscription

NewSubscription creates a new subscription for the given topic. It panics if the given topic did not come from mempubsub.

func NewTopic

func NewTopic() *pubsub.Topic

NewTopic creates a new in-memory topic.

Types

type URLOpener

type URLOpener struct {
	// contains filtered or unexported fields
}

URLOpener opens mempubsub URLs like "mem://topic".

The URL's host+path is used as the topic to create or subscribe to.

Query parameters:

• ackdeadline: The ack deadline for OpenSubscription, in time.ParseDuration formats. Defaults to 1m.

func (*URLOpener) OpenSubscriptionURL

func (o *URLOpener) OpenSubscriptionURL(ctx context.Context, u *url.URL) (*pubsub.Subscription, error)

OpenSubscriptionURL opens a pubsub.Subscription based on u.

func (*URLOpener) OpenTopicURL

func (o *URLOpener) OpenTopicURL(ctx context.Context, u *url.URL) (*pubsub.Topic, error)

OpenTopicURL opens a pubsub.Topic based on u.