Review the return types used for operations in the admin ns

[cddr]

Many of the operations in the admin namespace block on some upstream result before transforming the result into something a bit more idiomatic for Clojure programs. If the operation is unable to complete (e.g. it is unable to connect to the configured broker), the operation will never return, potentially blocking your REPL.

Returning a manifold deferred instead allows jackdaw to asynchronously perform the same transformation but instead of returning the transformed object after blocking, immediately return a deferred that eventually resolves to the transformed result.

In addition, functions like create-topics! currently return a boolean indicating whether all operations were completed. The underlying kafka operations allow us to infer which operations failed and provide representation of this to the caller.

Current jackdaw.admin

Operation	Blocking Operation	Returns
list-topics	ListTopicsResult.names	[Str]
topic-exists?	ListTopicsResult.names	boolean
retry-exists?	specified by caller	boolean
create-topics!	CreateTopicsResult.all	boolean
describe-topics	DescribeTopicsResult.all	{Str topic-metadata?}
describe-topics-configs	DescribeConfigsResult.all	{Str topic-config?}
topics-ready?	DescribeTopicsResult.all	boolean
alter-topic-config!	AlterConfigsResult.all	boolean
delete-topics!	DeleteTopicsResult.all	boolean
partition-ids-of-topics	DescribeTopicsResult.all	{Str partition-info?}
describe-cluster	DescribeClusterResult.all	cluster-result?
get-broker-config	DescribeConfigsResult.all	config-result?

Proposed jackdaw.admin

Operation	Blocking Operation	Deferred?	Returns	Comments
list-topics	ListTopicsResult.names	Yes	[Str]
topic-exists?	ListTopicsResult.names	Yes	boolean
retry-exists?	specified by caller	No	boolean	Unchanged
create-topics!	CreateTopicsResult.all	Yes	{Str boolean}	boolean -> {Str boolean}
describe-topics	DescribeTopicsResult.all	Yes	{Str topic-metadata?}
describe-topics-configs	DescribeConfigsResult.all	Yes	{Str topic-config?}
topics-ready?	DescribeTopicsResult.all	No	boolean	Unchanged
alter-topic-config!	AlterConfigsResult.all	Yes	{Str boolean}	boolean -> {Str boolean}
delete-topics!	DeleteTopicsResult.all	Yes	{Str boolean}	boolean -> {Str boolean}
partition-ids-of-topics	DescribeTopicsResult.all	Yes	{Str partition-info?}
describe-cluster	DescribeClusterResult.all	Yes	cluster-result?
get-broker-config	DescribeConfigsResult.all	Yes	config-result?