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[Feature #13884] Reduce number of memory allocations for "and", "or" and "diff" operations on small arrays Very often, arrays are used to filter parameters and to select interesting items from 2 collections and very often these collections are small enough, for example: ```ruby SAFE_COLUMNS = [:id, :title, :created_at] def columns @all_columns & SAFE_COLUMNS end ``` In this patch, I got rid of unnecessary memory allocations for small arrays when "and", "or" and "diff" operations are performed. name | HEAD | PATCH -----------------+------:+------: array_small_and | 0.615 | 0.263 array_small_diff | 0.676 | 0.282 array_small_or | 0.953 | 0.463 name | PATCH -----------------+------: array_small_and | 2.343 array_small_diff | 2.392 array_small_or | 2.056 name | HEAD | PATCH -----------------+------:+------: array_small_and | 1.429 | 1.005 array_small_diff | 1.493 | 0.878 array_small_or | 1.672 | 1.152 name | PATCH -----------------+------: array_small_and | 1.422 array_small_diff | 1.700 array_small_or | 1.452 Author: Dmitry Bochkarev <dimabochkarev@gmail.com> git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60057 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
87 lines
2.7 KiB
Ruby
87 lines
2.7 KiB
Ruby
require File.expand_path('../../../spec_helper', __FILE__)
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require File.expand_path('../fixtures/classes', __FILE__)
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describe "Array#-" do
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it "creates an array minus any items from other array" do
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([] - [ 1, 2, 4 ]).should == []
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([1, 2, 4] - []).should == [1, 2, 4]
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([ 1, 2, 3, 4, 5 ] - [ 1, 2, 4 ]).should == [3, 5]
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end
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it "removes multiple items on the lhs equal to one on the rhs" do
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([1, 1, 2, 2, 3, 3, 4, 5] - [1, 2, 4]).should == [3, 3, 5]
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end
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it "properly handles recursive arrays" do
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empty = ArraySpecs.empty_recursive_array
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(empty - empty).should == []
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([] - ArraySpecs.recursive_array).should == []
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array = ArraySpecs.recursive_array
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(array - array).should == []
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end
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it "tries to convert the passed arguments to Arrays using #to_ary" do
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obj = mock('[2,3,3,4]')
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obj.should_receive(:to_ary).and_return([2, 3, 3, 4])
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([1, 1, 2, 2, 3, 4] - obj).should == [1, 1]
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end
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it "raises a TypeError if the argument cannot be coerced to an Array by calling #to_ary" do
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obj = mock('not an array')
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lambda { [1, 2, 3] - obj }.should raise_error(TypeError)
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end
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it "does not return subclass instance for Array subclasses" do
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(ArraySpecs::MyArray[1, 2, 3] - []).should be_an_instance_of(Array)
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(ArraySpecs::MyArray[1, 2, 3] - ArraySpecs::MyArray[]).should be_an_instance_of(Array)
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([1, 2, 3] - ArraySpecs::MyArray[]).should be_an_instance_of(Array)
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end
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it "does not call to_ary on array subclasses" do
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([5, 6, 7] - ArraySpecs::ToAryArray[7]).should == [5, 6]
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end
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it "removes an item identified as equivalent via #hash and #eql?" do
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obj1 = mock('1')
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obj2 = mock('2')
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obj1.stub!(:hash).and_return(0)
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obj2.stub!(:hash).and_return(0)
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obj1.should_receive(:eql?).at_least(1).and_return(true)
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([obj1] - [obj2]).should == []
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([obj1, obj1, obj2, obj2] - [obj2]).should == []
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end
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it "doesn't remove an item with the same hash but not #eql?" do
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obj1 = mock('1')
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obj2 = mock('2')
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obj1.stub!(:hash).and_return(0)
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obj2.stub!(:hash).and_return(0)
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obj1.should_receive(:eql?).at_least(1).and_return(false)
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([obj1] - [obj2]).should == [obj1]
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([obj1, obj1, obj2, obj2] - [obj2]).should == [obj1, obj1]
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end
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it "removes an identical item even when its #eql? isn't reflexive" do
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x = mock('x')
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x.stub!(:hash).and_return(42)
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x.stub!(:eql?).and_return(false) # Stubbed for clarity and latitude in implementation; not actually sent by MRI.
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([x] - [x]).should == []
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end
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it "is not destructive" do
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a = [1, 2, 3]
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a - []
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a.should == [1, 2, 3]
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a - [1]
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a.should == [1, 2, 3]
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a - [1,2,3]
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a.should == [1, 2, 3]
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a - [:a, :b, :c]
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a.should == [1, 2, 3]
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end
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end
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