Go - Queue.Dequeue()

Dequeue messages.

import (
"context"
"fmt"
"github.com/nitrictech/go-sdk/nitric"
"github.com/nitrictech/go-sdk/nitric/queues"
)
func main() {
queue := nitric.NewQueue("queue-name").Allow(queues.QueueDequeue)
ctx := context.TODO()
// dequeue up to 10 messages
messages, err := queue.Dequeue(ctx, 10)
if err != nil {
return
}
for _, message := range messages {
fmt.Println("Message: ", message.Message())
message.Complete(ctx)
}
nitric.Run()
}

Parameters

  • Name
    ctx
    Required
    Required
    Type
    context
    Description

    The context of the call, used for tracing.

  • Name
    depth
    Optional
    Optional
    Type
    int
    Description

    The maximum number of messages to dequeue. Defaults to 1.

Notes

Completing dequeued items

Since the process is asynchronous the queue doesn't know when a message has been processed. This ensures failed services/containers don't result in lost message, since messages are not removed from a queue when they're dequeued.

Instead, messages are hidden and requesters are granted a temporary lease for each message they request.

When processing is complete, the requester must tell the queue the task was completed successfully, which will remove it from the queue and stop it being reprocessed.

Failing to complete a dequeued message before the lease expires will result in it being re-queued.

To notify the queue that a message was completed call the Complete() method on the dequeued message reference.

Dequeue depth

When calling Dequeue() a depth parameter can be provided, e.g. Dequeue(ctx, 5). This will attempt to dequeue up to 5 messages from the queue.

However, if the queue is empty or less than 5 messages are available on the queue, then the maximum that are currently available will be returned.

This means calls to dequeue will return between 0 and depth tasks.

Examples

Dequeue and complete messages

import (
"context"
"fmt"
"github.com/nitrictech/go-sdk/nitric"
"github.com/nitrictech/go-sdk/nitric/queues"
)
func main() {
queue := nitric.NewQueue("queue-name").Allow(queues.QueueDequeue)
ctx := context.TODO()
// dequeue up to 10 messages
messages, err := queue.Dequeue(ctx, 10)
if err != nil {
return
}
for _, message := range messages {
fmt.Println("Message: ", message.Message())
message.Complete(ctx)
}
nitric.Run()
}
Last updated on Oct 15, 2024