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| author | Sean Griffin <sean@seantheprogrammer.com> | 2015-09-28 10:37:28 -0400 |
|---|---|---|
| committer | Sean Griffin <sean@seantheprogrammer.com> | 2015-09-28 10:42:09 -0400 |
| commit | 3e408a2654727b49ee0e054e27a4f4ca199f72a7 (patch) | |
| tree | 38a478f44d0a1b44e5165db50644702d0859afba | |
| parent | 58750422c57e0cdc7f0a4ab4030fb9a98ec0b9db (diff) | |
| download | rails-3e408a2654727b49ee0e054e27a4f4ca199f72a7.tar.gz rails-3e408a2654727b49ee0e054e27a4f4ca199f72a7.tar.bz2 rails-3e408a2654727b49ee0e054e27a4f4ca199f72a7.zip | |
Speed up `Hash#transform_values` when empty
We're calling this function on an empty hash as part of copying the
attribute set during dirty checking initialization. The new structure
caused a performance regression on loading records from the database.
This causes `User.all.to_a` to perform about 10% faster w/ 10k records.
Calculating -------------------------------------
User.all - master 9.000 i/100ms
User.all - sg-fix-ar-regression
8.000 i/100ms
-------------------------------------------------
User.all - master 81.236 (± 7.4%) i/s - 405.000
User.all - sg-fix-ar-regression
89.716 (± 7.8%) i/s - 448.000
| -rw-r--r-- | activesupport/lib/active_support/core_ext/hash/transform_values.rb | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/hash/transform_values.rb b/activesupport/lib/active_support/core_ext/hash/transform_values.rb index e9bcce761f..6b3402b2c9 100644 --- a/activesupport/lib/active_support/core_ext/hash/transform_values.rb +++ b/activesupport/lib/active_support/core_ext/hash/transform_values.rb @@ -6,6 +6,7 @@ class Hash # # => { a: 2, b: 4, c: 6 } def transform_values return enum_for(:transform_values) unless block_given? + return {} if empty? result = self.class.new each do |key, value| result[key] = yield(value) |