Add dev caching toggle / server options

[ccallebs]

Taken extensively from @Sonopa's PR (#19091). Added ability to specify caching on server start.

Fixes #18875.

[ccallebs]

This could potentially cause some confusion, as there is already a -c option. I think it should be changed, I just didn't have a notion of what it should be.

[kaspth]

Would be easier to grasp as just --toggle-caching - maybe we don't even need a shorthand?

Though I'm still ¯_(ツ)_/¯ about the server options in general.

[ccallebs]

@kaspth I'm ambivalent about the whole thing as well, just added it as it seemed there was support in the previous PR. I'll go with the hivemind on it.

[kaspth]

If you change your pull request description to say "Fixes #18875" the original issue will be closed if this is merged 😄

[ccallebs]

@kaspth Thank you for the suggestions -- I'll implement them this evening!

[kaspth]

It seems like setting --perform-caching once never removes the file and leaves caching on all the time. Let's fix that 😄

[ccallebs]

@kaspth I implemented most of your suggestions. Instead of having a --toggle-cache option on the server, I chose to remove caching if the option wasn't specified. It made more sense to me that way, as a user will know when they start their server whether or not they would like to temporarily cache.

[dhh]

Awesome. Thanks for working on this!

[kaspth]

Break the lines at 80 chars 😄

[kaspth]

Alright, once the final comment has been addressed, ping me. Remember to keep it to one commit, then I'll gladly merge 😁

[kaspth]

I just realized there's a scenario we have to make sure doesn't happen. Maybe I'm misunderstanding something, but what happens when rake dev:cache reboots the server?

There's no --perform-caching flag provided, so won't the caching be turned off again?

I'd like a test that checks against this.

[ccallebs]

@kaspth That's a good point! I'll write the test and if it fails find a workaround.

[ccallebs]

@kaspth The easiest way to fix the above is just by defaulting the server to create the cache file if options are passed. Otherwise, default to the last rake dev:cache command. I've pushed the changes up.

Additionally, I couldn't find any concrete examples of tests that check the server start. Could you point me toward some (if they exist)?

[kaspth]

Honestly, that --perform-caching setting doesn't make sense anymore. If I passed an option on one server start and then removed it for the next server start I wouldn't expect it to still be in effect.

Looking back to @pixeltrix's original suggestion I see --perform-caching takes an argument, which is exactly how we should do it.

Perhaps --perform-caching=true to enable and --perform-caching=false to disable could do it. There's probably a separate issue with what values can be truthy and falsy on a command line interface, but we can deal with that later.

[kaspth]

@ccallebs Sorry, I'm not aware of any tests checking the server start.

[kaspth]

@ccallebs are you up for adding an argument to --perform-caching as mentioned here: #20961 (comment)?

[ccallebs]

@kaspth Absolutely! Sorry, I've been busy and haven't been able to sit down and do it. I'll try to tackle it this evening.

[kaspth]

Cool, glad to hear it 😄

[ccallebs]

@kaspth After looking at the OptionParser documentation, I ended up changing the name of the keyword. (http://docs.ruby-lang.org/en/2.2.0/OptionParser.html)

Now, it would be rails s --dev-caching or rails s --no-dev-caching. It seemed to be the way to define boolean arguments according to that class. If we want to change it to perform-caching=[true|false] I'm completely fine with that, but it looked like this followed OptionParser conventions more closely.

[kaspth]

@ccallebs Thanks ❤️

[sdhull]

Apologies for resurrecting an ancient PR thread but... wouldn't it make more sense to have the task called rails dev:toggle-cache or something like that? I was assuming rails dev:cache would turn on caching and I came looking for a way to turn it off (rails dev:nocache or something).