65 lines
3.3 KiB
Markdown
65 lines
3.3 KiB
Markdown
+++
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title = "Redis Stream"
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description = "A fast, open source, in-memory, key-value data store"
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date = 2023-02-01T22:30:00+08:00
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bref = "A fast, open source, in-memory, key-value data store"
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weight = 110
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Redis is the open source, in-memory data store used by millions of developers. Redis stream is a data structure that acts like an append-only log in Redis. We are providing Pub/Sub implementation based on [redis/go-redis](https://github.com/redis/go-redis).
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You can find a fully functional example with Redis Stream in the [Watermill examples](https://github.com/ThreeDotsLabs/watermill/tree/master/_examples/pubsubs/redisstream).
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## Installation
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```bash
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go get github.com/ThreeDotsLabs/watermill-redisstream
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```
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### Characteristics
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| Feature | Implements | Note |
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| ------- | ---------- | ---- |
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| ConsumerGroups | yes | |
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| ExactlyOnceDelivery | no | |
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| GuaranteedOrder | no | |
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| Persistent | yes | |
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| FanOut | yes | use XREAD to fan out messages when there is no consumer group |
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### Configuration
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{{% load-snippet-partial file="src-link/watermill-redisstream/pkg/redisstream/publisher.go" first_line_contains="type PublisherConfig struct" last_line_contains="// Publish publishes message to redis stream" %}}
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{{% load-snippet-partial file="src-link/watermill-redisstream/pkg/redisstream/subscriber.go" first_line_contains="type SubscriberConfig struct" last_line_contains="func (s *Subscriber) Subscribe" %}}
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#### Passing `redis.UniversalClient`
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You need to configure and pass your own go-redis client via `Client redis.UniversalClient` in `NewSubscriber` and `NewPublisher`. The client can be either `redis.Client` or `redis.ClusterClient`.
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#### Publisher
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{{% load-snippet-partial file="src-link/watermill-redisstream/pkg/redisstream/publisher.go" first_line_contains="// NewPublisher" last_line_contains="(*Publisher, error)" padding_after="0" %}}
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Example:
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{{% load-snippet-partial file="src-link/_examples/pubsubs/redisstream/main.go" first_line_contains="pubClient := redis.NewClient" last_line_contains="panic(err)" padding_after="1" %}}
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#### Subscriber
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{{% load-snippet-partial file="src-link/watermill-redisstream/pkg/redisstream/subscriber.go" first_line_contains="// NewSubscriber" last_line_contains="(*Subscriber, error)" padding_after="0" %}}
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Example:
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{{% load-snippet-partial file="src-link/_examples/pubsubs/redisstream/main.go" first_line_contains="subClient := redis.NewClient" last_line_contains="panic(err)" padding_after="1" %}}
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### Publishing
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{{% load-snippet-partial file="src-link/watermill-redisstream/pkg/redisstream/publisher.go" first_line_contains="// Publish" last_line_contains="func (p *Publisher) Publish" %}}
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### Subscribing
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{{% load-snippet-partial file="src-link/watermill-redisstream/pkg/redisstream/subscriber.go" first_line_contains="func (s *Subscriber) Subscribe" last_line_contains="func (s *Subscriber) Subscribe" %}}
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### Marshaler
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Watermill's messages cannot be directly sent to Redis - they need to be marshaled. You can implement your marshaler or use default implementation. The default implementation uses [MessagePack](https://msgpack.org/index.html) for efficient serialization.
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{{% load-snippet-partial file="src-link/watermill-redisstream/pkg/redisstream/marshaller.go" first_line_contains="const UUIDHeaderKey" last_line_contains="type DefaultMarshallerUnmarshaller" padding_after="0" %}}
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