Better exception for AdminClient

[anguillanneuf]

The exception that needs handling from the autocloseable try(AdminClient adminClient = AdminClient.create(adminClientSettings) is java.lang.Exception, which is very generic.

Pub/Sub uses java.io.IOException for TopicAdminClient and SubscriptionAdminClient (samples).

See original comment by @kurtisvg.

[lesv]

Does pubsub just throw IOException? That is better than just Exception. Better still is a more specific exception

[lesv]

Looking at the code, I see io.grpc.StatusException which is more specific and the user can actually check it's contents to figure out what's going on.

[lesv]

io.grpc.StatusException has a getStatus method which returns an io.grpc.status which has lots of additional info as well as metadata trailers. Much better for the user.

[anguillanneuf]

io.grpc.StatusException is indeed thrown by AdminClient creation (AdminClient.create(adminClientSettings)). And java.lang.InterruptedException and java.util.concurrent.ExecutionException are thrown by the .get() method.
But the try with resources block throws java.lang.Exception.

[kurtisvg]

@anguillanneuf A try-with-resources doesn't throw any exception, only the functions used within it do. Is this actually a client bug or do we just need to update the samples?

[anguillanneuf]

@kurtisvg It is the client. Without throwing java.lang.Exception, I get:

[ERROR] /Users/.../Projects/java-pubsublite/samples/snippets/src/main/java/pubsublite/CreateTopicExample.java:[83,22] unreported exception java.lang.Exception; must be caught or declared to be thrown
  exception thrown from implicit call to close() on resource variable 'adminClient'

With this function signature:

  public static void createTopicExample(
      String cloudRegion, char zoneId, long projectNumber, String topicId, int partitions)
      throws StatusException, ExecutionException, InterruptedException {
  // ...
  }

[kurtisvg]

@anguillanneuf My apologies you are correct - I was looking at the java-pubsub samples linked above not realizing they weren't java-pubsublite.

Digging deeper, it looks like this issue may be bigger than just an over-generic exception. The AutoClosable interface provides a close() method which is scoped to Exception. In Java/pubsub the AdminClient overrides this: https://github.com/googleapis/java-pubsub/blob/9c750c8e4899ae994a788c5323fc456ac5d7aa38/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/v1/TopicAdminClient.java#L1471-L1474

Looking at the pubsub-lite AdminClient interface, it looks like not only is the close() operation not overrode, but checking out AdminClientImpl it doesn't even look implemented: https://github.com/googleapis/java-pubsublite/blob/master/google-cloud-pubsublite/src/main/java/com/google/cloud/pubsublite/internal/AdminClientImpl.java