common/messaging/interface.go

// Copyright (c) 2017 Uber Technologies, Inc.
//
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// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// THE SOFTWARE.

package messaging

import "context"

type (
	// Client is the interface used to abstract out interaction with messaging system for replication
	Client interface {
		NewConsumer(appName, consumerName string) (Consumer, error)
		NewProducer(appName string) (Producer, error)
	}

	// Consumer is the unified interface for both internal and external kafka clients
	Consumer interface {
		// Start starts the consumer
		Start() error
		// Stop stops the consumer
		Stop()
		// Messages return the message channel for this consumer
		Messages() <-chan Message
	}

	// Message is the unified interface for a Kafka message
	Message interface {
		// Value is a mutable reference to the message's value
		Value() []byte
		// Partition is the ID of the partition from which the message was read.
		Partition() int32
		// Offset is the message's offset.
		Offset() int64
		// Ack marks the message as successfully processed.
		Ack() error
		// Nack marks the message processing as failed and the message will be retried or sent to DLQ.
		Nack() error
	}

	// Producer is the interface used to send replication tasks to other clusters through replicator
	Producer interface {
		Publish(ctx context.Context, message interface{}) error
	}

	// CloseableProducer is a Producer that can be closed
	CloseableProducer interface {
		Producer
		Close() error
	}

	// AckManager convert out of order acks into ackLevel movement.
	AckManager interface {
		// Read an item into backlog for processing for ack
		ReadItem(id int64) error
		// Get current max ID from read items
		GetReadLevel() int64
		// Set current max ID from read items
		SetReadLevel(readLevel int64)
		// Mark an item as done processing, and remove from backlog
		AckItem(id int64) (ackLevel int64)
		// Get current max level that can safely ack
		GetAckLevel() int64
		// Set current max level that can safely ack
		SetAckLevel(ackLevel int64)
		// GetBacklogCount return the of items that are waiting for ack
		GetBacklogCount() int64
	}
)