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author | schneems <richard.schneeman+foo@gmail.com> | 2018-10-11 17:07:28 -0500 |
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committer | schneems <richard.schneeman+foo@gmail.com> | 2018-10-15 15:31:32 -0500 |
commit | f45267bc423017109e442e5c35a5765dc482b12b (patch) | |
tree | b20711429044a4221710ade1561cabc7bb82f1f9 /activesupport/lib/active_support/core_ext/date | |
parent | 134dab46e4e94d7e6e37cec43dca8183fe72aea6 (diff) | |
download | rails-f45267bc423017109e442e5c35a5765dc482b12b.tar.gz rails-f45267bc423017109e442e5c35a5765dc482b12b.tar.bz2 rails-f45267bc423017109e442e5c35a5765dc482b12b.zip |
ActiveRecord#respond_to? No longer allocates strings
This is an alternative to https://github.com/rails/rails/pull/34195
The active record `respond_to?` method needs to do two things if `super` does not say that the method exists. It has to see if the "name" being passed in represents a column in the table. If it does then it needs to pass it to `has_attribute?` to see if the key exists in the current object. The reason why this is slow is that `has_attribute?` needs a string and most (almost all) objects passed in are symbols.
The only time we need to allocate a string in this method is if the column does exist in the database, and since these are a limited number of strings (since column names are a finite set) then we can pre-generate all of them and use the same string.
We generate a list hash of column names and convert them to symbols, and store the value as the string name. This allows us to both check if the "name" exists as a column, but also provides us with a string object we can use for the `has_attribute?` call.
I then ran the test suite and found there was only one case where we're intentionally passing in a string and changed it to a symbol. (However there are tests where we are using a string key, but they don't ship with rails).
As re-written this method should never allocate unless the user passes in a string key, which is fairly uncommon with `respond_to?`.
This also eliminates the need to special case every common item that might come through the method via the `case` that was originally added in https://github.com/rails/rails/commit/f80aa5994603e684e3fecd3f53bfbf242c73a107 (by me) and then with an attempt to extend in https://github.com/rails/rails/pull/34195.
As a bonus this reduces 6,300 comparisons (in the CodeTriage app homepage) to 450 as we also no longer need to loop through the column array to check for an `include?`.
Diffstat (limited to 'activesupport/lib/active_support/core_ext/date')
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