From c879649a733d982fba9e70f5a280d13636b67c37 Mon Sep 17 00:00:00 2001
From: Eugene Kenny <elkenny@gmail.com>
Date: Sun, 18 Jun 2017 15:37:06 +0100
Subject: Improve the performance of writing attributes
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Using a similar approach to 08576b94ad4f19dfc368619d7751e211d23dcad8,
this change adds a new internal `_write_attribute` method which bypasses
the code that checks for attribute aliases and custom primary keys.

We can use this method instead of `write_attribute` when we know that we
have the name of the actual column to be updated and not an alias.

This makes writing an attribute with `attribute=` about 18% faster.

Benchmark:

```
begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

gemfile(true) do
  source "https://rubygems.org"
  gem "rails", github: "rails/rails"
  gem "arel", github: "rails/arel"
  gem "sqlite3"
  gem "benchmark-ips"
end

require "active_record"

ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")

ActiveRecord::Schema.define do
  create_table :posts, force: true do |t|
  end
end

class Post < ActiveRecord::Base
end

post = Post.new(id: 1)

Benchmark.ips do |x|
  x.report("attribute=") { post.id = post.id + 1 }
end
```

Before:

    Warming up --------------------------------------
              attribute=    25.889k i/100ms
    Calculating -------------------------------------
              attribute=    290.946k (± 3.1%) i/s -      1.476M in   5.077036s

After:

    Warming up --------------------------------------
              attribute=    30.056k i/100ms
    Calculating -------------------------------------
              attribute=    345.088k (± 4.8%) i/s -      1.743M in   5.064264s
---
 activerecord/lib/active_record/timestamp.rb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'activerecord/lib/active_record/timestamp.rb')

diff --git a/activerecord/lib/active_record/timestamp.rb b/activerecord/lib/active_record/timestamp.rb
index 55f3a194a9..ae50bc6bc1 100644
--- a/activerecord/lib/active_record/timestamp.rb
+++ b/activerecord/lib/active_record/timestamp.rb
@@ -86,7 +86,7 @@ module ActiveRecord
 
         all_timestamp_attributes_in_model.each do |column|
           if !attribute_present?(column)
-            write_attribute(column, current_time)
+            _write_attribute(column, current_time)
           end
         end
       end
@@ -100,7 +100,7 @@ module ActiveRecord
 
         timestamp_attributes_for_update_in_model.each do |column|
           next if will_save_change_to_attribute?(column)
-          write_attribute(column, current_time)
+          _write_attribute(column, current_time)
         end
       end
       super(*args)
-- 
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