谷歌PubSub :带有拉功能的显式NACK？

from google.cloud import pubsub_v1

subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path("your-project-id", "your-subscription-id")

def callback(message):
    print(f"Received message: {message}")
    message.ack()

streaming_pull_future = subscriber.subscribe(subscription_path, callback=callback)
streaming_pull_future.result()

def callback(message):
    try:
        print(f"Received message: {message}")
        # 处理消息
        message.ack()
    except Exception as e:
        print(f"Error processing message: {e}")
        message.nack()  # 显式地拒绝并重新排队消息

from google.api_core.exceptions import NotFound
from google.cloud.pubsub_v1 import SubscriberClient
from google.cloud.pubsub_v1.subscriber.message import Message

subscriber = SubscriberClient()
subscription_path = subscriber.subscription_path("your-project-id", "your-subscription-id")

# 创建死信队列的订阅
try:
    dlq_subscription = subscriber.create_subscription(
        request={"name": "projects/your-project-id/subscriptions/your-dead-letter-subscription-id"}
    )
except NotFound:
    dlq_subscription = subscriber.get_subscription(request={"subscription": "projects/your-project-id/subscriptions/your-dead-letter-subscription-id"})

policy = {
    "dead_letter_policy": {
        "dead_letter_topic": dlq_subscription.name,
        "max_delivery_attempts": 5,
    }
}

subscriber.modify_subscription(request={"subscription": subscription_path, "dead_letter_policy": policy})