Go - Queue.Receive()
Receive tasks from a queue.
import (
"context"
"fmt"
"github.com/nitrictech/go-sdk/nitric"
)
func main() {
queue, err := nitric.NewQueue("queue-name").With(nitric.QueueReceiving)
if err != nil {
return
}
ctx := context.TODO()
// Receive up to 10 tasks from the queue
tasks, err := queue.Receive(ctx, 10)
if err != nil {
return
}
for _, t := range tasks {
fmt.Println(t.Task().ID)
t.Complete(ctx)
}
if err := nitric.Run(); err != nil {
fmt.Println(err)
}
}
Parameters
- Name
ctx- Required
- Required
- Type
- context
- Description
The context of the call, used for tracing.
- Name
depth- Required
- Required
- Type
- int
- Description
The maximum number of tasks to receive from the queue.
Notes
Completing tasks
Since the process is async, the queue doesn't know when a task has been completed. So failed function/containers don't result in lost tasks, tasks are not removed from a queue when they're received.
Instead, tasks are hidden and receivers are granted a temporary lease for each task they receive.
When complete, the receiver 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 task before the lease expires will result in it being re-queued.
To notify the queue that a task was completed call the Complete() method on the task reference.
Receive depth
When calling Receive() a depth parameter can be provided, e.g. Receive(ctx, 5). This will attempt to receive up to 5 tasks from the queue.
However, if the queue is empty or less than 5 tasks are available on the queue, then the max available will be returned.
This means calls to receive will return between 0 and depth tasks.
Examples
Receive tasks from a queue
import (
"context"
"fmt"
"github.com/nitrictech/go-sdk/nitric"
)
func main() {
queue, err := nitric.NewQueue("queue-name").With(nitric.QueueReceiving)
if err != nil {
return
}
ctx := context.TODO()
// Receive up to 10 tasks from the queue
tasks, err := queue.Receive(ctx, 10)
if err != nil {
return
}
for _, t := range tasks {
fmt.Println(t.Task().ID)
t.Complete(ctx)
}
if err := nitric.Run(); err != nil {
fmt.Println(err)
}
}