Dynamic attribute optimizations

[danbernier]

I was profiling some code that handles json_api_client results, and makes a lot of use of the dynamic attribute methods. I noticed that if I just implemented my own getter methods:

class Article
  def title
    attributes[:title]
  end
end

...then it got surprisingly faster.

I looked at the source, and spotted a few optimizations I could make. Here are 4, each with before/after benchmark times (the benchmark code is committed here as a unit test, which we can yank or move before this is merged).

The only commit without benchmark times is the change to use end_with?('=') instead of =~ /^(.*)=$/, because it didn't actually speed it up. I committed it here as a curiosity; because I think ends_with?('=') is clearer than the regex; and because I've seen people say that it's faster, so this heads off the conversation.

Probably the most controversial optimization is the last one: to auto-define getter methods for attributes from DynamicAttributes#method_missing. This is a significant speed-up: basically, we'll never have to run that method_missing logic again for that method name. Since the classes already respond to those methods, and handle those messages in an equivalent (but slower) way, this seems OK to me. Also, I don't think we have to worry about overwriting client code, because by definition, if #method_missing is running, then they didn't define this one.

Here's the overall benchmark difference, from the first commit (which only adds the benchmark unit test), to the last (with the 4 optimizations):

Before:

       user     system      total        real
read:   1.090000   0.010000   1.100000 (  1.091464)
write:  1.130000   0.000000   1.130000 (  1.136750)

After:

       user     system      total        real
read:   0.020000   0.000000   0.020000 (  0.016366)
write:  0.690000   0.000000   0.690000 (  0.687914)

[jsmestad]

@danbernier great work on this! I've pulled this into a released fork of this gem jsonapi-consumer along with some other outstanding bug fixes.

[danbernier]

@chingor13, thanks for merging this! Glad to see this project is still alive.

And @jsmestad thank you, too, glad you found it helpful!