Cleanup work for Adapter#get_multi

[jnunemaker]

get_multi was recently added, but only made efficient for the redis adapter. I need to finish making the other adapters do bulk loads for get multi instead of n+1's.

• add get_multi to active record
• add get_multi to dalli
• add get_multi to mongo
• add get_multi to sequel
• return value for get_multi? currently array, should it be hash
• ensure get_multi is doc'd (Adapters.md)
• ensure preload and preload_all are doc's (Optimizations.md)

[gshutler]

get_multi returning a Hash is probably preferable. I know it would reduce the complexity in Memoizable for example, and if you only want the Array you can always call values on the Hash so I don't think there's any loss.

Let me know if I can help in any way.

[jnunemaker]

@gshutler cool. Changed to hash. I think I have everything ready but the docs. If you want to take a crack at those, feel free (just let me know so we don't both work on them), but I'll try to get to them soon and push out a new release afterwards.

[jnunemaker]

@gshutler it would be helpful if you wanted to double check some of my recent changes for get_multi in the various adapters for sanity, but don't feel like you have to. I should have done a PR...

[gshutler]

I had a look through them all (using fc6b58d...master) and didn't notice anything unexpected. All following a similar pattern to the Redis one which only changed slightly to return a Hash.

I'm not going to have time to look at docs for a few days so unlikely to get to it before you do.

[jnunemaker]

@gshutler thanks! No problem about the docs. I'll try to get to it tonight or tomorrow night.

[mscoutermarsh]

Hey @jnunemaker. Running this in production now.

Nice. THANK YOU for your work on this.

This is an endpoint doing 10-15 flag checks with postgres. Now uses preload with redis.

❤️

[jnunemaker]

Finished up docs this morning quick. Going to do a release.

@mscoutermarsh awesome! Really appreciate you sharing that.