Improve log performance when forking

[benjamincburns]

@tcoulter commented on Thu Mar 09 2017

See the way logs are done here: ConsenSys-archive/ganache-cli-archive#179

i.e., instead of making n requests to the forked chain, make 1.

[benjamincburns]

The way logs are fetched for forking is very inefficient. There are likely other performance improvements to be made in the forking fallback requests as well.

[area]

We needed this at Colony, so I've made a set of changes that do this here, which will hopefully prove helpful for whoever picks this issue up in the future. I'm a little frustrated that I had to make statemanager aware of forked chains, but I couldn't see a clean way of doing it otherwise.

Note that this memoizeFork branch this commit is on (though not the linked commit) has my changes related to #471, so don't just go pulling it in, helpful-person-in-the-future!

I might see if I have time to write tests for this (and, indeed, the other) issue in the future to make these in to PR's that could be merged but I'm not holding my breath - I hope this is useful anyway.