Improve Suggestion Indexing Strategy

[kand617]

Revisit indexing strategy of the suggestion service.
Currently it executes periodically regardless of change.

[sudhirtumati]

As API spec updates are controlled by the application, it would be better run indexing as and when API(s) change. To avoid re-indexing in a quick succession, due to spike in user activity, indexing task could be deferred by few seconds. See below link for details

https://stackoverflow.com/a/2258082

[sudhirtumati]

Few indexing improvements have been done as part of #42

Other possible improvements:

• Index new changes when an API is created or updated
• Rebuild entire index when an API is deleted
• Stop indexing on fixed schedule

@kand617 what do you think?

[kand617]

That makes sense. Perhaps it might be worth looking at some event driven architecture.
https://github.com/ReactiveX/RxJava