bounded caches

[facebook]

bounded caches

[simonmar]

I can understand the need to limit the cache size in certain use cases. However, as soon as we stop caching everything, we lose the nice replayability property that Haxl has now: the cache is a complete record of the execution, and the request can be replayed without fetching any data.

So I'm open to doing this so long as we can make it non-invasive, and make it clear that it breaks replayability.

[kantp]

I agree, caching everything should stay the default, since that is the typical use case.

I'll add a default implementation that chooses an unbounded cache and make it explicit in the docs that changing the default sacrifices replayability, before opening a pull request.