concatMapEager and maxConcurrent

[adipascu]

How should I limit the maximum number of concurrently subscribed observables ?

I think a parameter like the one in flatMap (maxConcurrent) could be very useful.
concatMapEage currently has an optional parameter, capacityHint.

I think this is not very useful, I expected to find something like maxConcurrent
This operator might be confusing for some people, similar with #3498

[akarnokd]

The operator was designed to be eager on the input side and bounded on the mapped inner Observables.

I agree that adding a parameter would be confusing to concatMapEager but you can name the maxConcurrent+capacityHint version like orderedMerge or something like it.

Would you like to post a PR for this?

[adipascu]

Are you proposing to renameconcatMapEager(Func1 mapper, int capacityHint) into orderedMerge ?

I am proposing to add extra functionality to manage the number of concurrent observables and change the docs/rename some operators to make the functionality more obvious.

I can try to provide a PR.

[akarnokd]

Don't rename concatMapEager, just add an overload concatMapEager(Func1 mapper, int capacityHint, int maxConcurrency) and modify the OperatorConcatMapEager to support the maxConcurrency mode.

[adipascu]

I am not sure how to write a proper test case for this change, I tested various scenarios manually and ran the existing test case

[akarnokd]

Add a doOnRequested before the operator and capture the long values in a List. Then compare it against the expected pattern, i.e., 5, 1, 1, 1, 1, 1, 1.

[akarnokd]

Closing via #3714