From a6da7938017647dd6e19e23d3d47126cb7a3e1fe Mon Sep 17 00:00:00 2001
From: Sean Griffin <sean@seantheprogrammer.com>
Date: Mon, 26 Sep 2016 10:27:11 -0400
Subject: Use xor to avoid allocations in `AR::Core#hash`
This is not as good a solution as actually hashing both values, but Ruby
doesn't expose that capability other than allocating the array. Unless we were
to do something silly like have a thread local array that is re-used, I don't
see any other way to do this without allocation. This solution may not be
perfect, but it should reasonably avoid collisions to the extent that we need.
---
activerecord/lib/active_record/core.rb | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index 3465b68ac6..622df0cfc1 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -452,7 +452,7 @@ module ActiveRecord
# [ Person.find(1), Person.find(2), Person.find(3) ] & [ Person.find(1), Person.find(4) ] # => [ Person.find(1) ]
def hash
if id
- [self.class, id].hash
+ self.class.hash ^ self.id.hash
else
super
end
--
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