Inconsistent batch request components

[revett]

Problem

Scenario:

• A batch request for 5 components.
• 4 of the components are retrieved from the cache, however 1 component's cache has expired/not exist.
• Broker requests content for the expired component, and updates the cache before returning it.

In this situation, one of the components may have more recent data which could contradict the other 4 components (e.g. stock price).

Solution

• If 1+ of many components in a batch request is required to fetch new content, then all components must follow suit.
• This can be given as an option with the JSON body of the batch POST request (defaults to false).

  Implementation

• Before the point where the components are loaded in parallel, the broker must evaluate if all requested components exist in the cache.
• This boolean value is then handed to the LoadStrategy, which uses it to determine if it is necessary to check the cache.
• Make sure that we aren't checking the cache twice.