使用 Java 客户端库配置 PubSub 的消息保留持续时间 [关闭]

Question

我在我的桌面应用程序中使用google cloud pubsub java library。我为特定主题创建订阅并从中接收数据。我想知道是否可以配置订阅的消息保留时间。我在任何地方都找不到它。谢谢。

为了让问题更清楚，我粘贴了我用来创建订阅的代码块：

String topicName = "some-topic";
String subscriptionName = "some-subscription";
ProjectTopicName topic = ProjectTopicName.of(PROJECT_ID, topicName);
ProjectSubscriptionName subscription = ProjectSubscriptionName.of(PROJECT_ID, subscriptionName);
SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create(); // I reuse this object so I create it in advance
try {
   subscriptionAdminClient.createSubscription(subscription,
        topic,
        PushConfig.getDefaultInstance(),
        0
   );
} catch (ApiException e) {
   if (e.getStatusCode().getCode() != StatusCode.Code.ALREADY_EXISTS) {
        subscriptionAdminClient.close();
   }
}

Answer 1

您可以在 Java 中配置订阅的消息保留期限。创建Subscription 对象时，您可以在创建请求中提供message_retention_duration field。要在 Java 中执行此操作，请使用 setMessageRetentionDuration method on Subscription.Builder 对象，如本例所示（使用 com.google.cloud:google-cloud-pubsub:1.86.0 依赖项）：

package com.example;

import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
import com.google.pubsub.v1.Subscription;
import com.google.pubsub.v1.TopicName;

import com.google.protobuf.util.Durations;

import java.io.IOException;

public class PubSubCreateSubscription {

    static Subscription createSubscriptionWithMessageRetentionDuration(
        String topicName,
        String subscriptionName,
        long messageRetentionDurationInMillis
    ) throws IOException {
        try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {
            Subscription request = Subscription.newBuilder()
                .setName(subscriptionName)
                .setTopic(topicName)
                .setMessageRetentionDuration(Durations
                    .fromMillis(messageRetentionDurationInMillis))
                .build();

            return subscriptionAdminClient
                .createSubscription(request);
        }
    }

    public static void main(String[] args)
    {
        String topicName = "projects/[PROJECT]/topics/[TOPIC_NAME]";
        String subscriptionName = "projects/[PROJECT]/subscriptions/[SUBSCRIPTION_NAME]";

        try {
            Subscription mySubscription = createSubscriptionWithMessageRetentionDuration(
                topicName,
                subscriptionName,
                600000 // 600 000 ms = 10 minutes
            );
            // [...]
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

注意setMessageRetentionDuration 将Duration 作为参数，因此您可能需要使用Durations helper class（例如fromMillis 方法）将毫秒转换为protobuf Duration。还要注意from the REST resource documentation，这个字段：

不能超过 7 天或少于 10 分钟。