hsbt	2015-01-03 11:27:50 +0900 (Sat, 03 Jan 2015)

  New Revision: 49114

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=49114

  Log:
    * array.c: Improve performance of Array#shift. use shared instead of
      MEMMOVE if with arguments. Patch by @ksss [fix GH-537]
    * test/ruby/test_array.rb: ditto.
    * benchmark/bm_array_shift.rb: Added benchmark of GH-537 issue.

  Added files:
    trunk/benchmark/bm_array_shift.rb
  Modified files:
    trunk/ChangeLog
    trunk/array.c
    trunk/test/ruby/test_array.rb
Index: array.c
===================================================================
--- array.c	(revision 49113)
+++ array.c	(revision 49114)
@@ -1066,14 +1066,21 @@ rb_ary_shift_m(int argc, VALUE *argv, VA https://github.com/ruby/ruby/blob/trunk/array.c#L1066
     n = RARRAY_LEN(result);
     if (ARY_SHARED_P(ary)) {
 	if (ARY_SHARED_OCCUPIED(ARY_SHARED(ary))) {
+	  setup_occupied_shared:
 	    ary_mem_clear(ary, 0, n);
 	}
         ARY_INCREASE_PTR(ary, n);
     }
     else {
-	RARRAY_PTR_USE(ary, ptr, {
-	    MEMMOVE(ptr, ptr + n, VALUE, RARRAY_LEN(ary)-n);
-	}); /* WB: no new reference */
+	if (RARRAY_LEN(ary) < ARY_DEFAULT_SIZE) {
+	    RARRAY_PTR_USE(ary, ptr, {
+		MEMMOVE(ptr, ptr+n, VALUE, RARRAY_LEN(ary)-n);
+	    }); /* WB: no new reference */
+	}
+	else {
+	    ary_make_shared(ary);
+	    goto setup_occupied_shared;
+	}
     }
     ARY_INCREASE_LEN(ary, -n);
 
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 49113)
+++ ChangeLog	(revision 49114)
@@ -1,3 +1,10 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1
+Sat Jan  3 11:27:46 2015  SHIBATA Hiroshi  <shibata.hiroshi@g...>
+
+	* array.c: Improve performance of Array#shift. use shared instead of
+	  MEMMOVE if with arguments. Patch by @ksss [fix GH-537]
+	* test/ruby/test_array.rb: ditto.
+	* benchmark/bm_array_shift.rb: Added benchmark of GH-537 issue.
+
 Sat Jan  3 10:38:52 2015  SHIBATA Hiroshi  <shibata.hiroshi@g...>
 
 	* lib/net/http.rb: More descriptive error message when net/http fails
Index: benchmark/bm_array_shift.rb
===================================================================
--- benchmark/bm_array_shift.rb	(revision 0)
+++ benchmark/bm_array_shift.rb	(revision 49114)
@@ -0,0 +1,14 @@ https://github.com/ruby/ruby/blob/trunk/benchmark/bm_array_shift.rb#L1
+require 'benchmark'
+
+Benchmark.bm do |x|
+  [10_000,1_000_000,100_000_000].each do |n|
+    ary = Array.new(n,0)
+    GC.start
+    x.report("#{n}:shift"){ ary.shift }
+    (0..4).each do |i|
+      ary = Array.new(n,0)
+      GC.start
+      x.report("#{n}:shift(#{i})"){ ary.shift(i) }
+    end
+  end
+end
Index: test/ruby/test_array.rb
===================================================================
--- test/ruby/test_array.rb	(revision 49113)
+++ test/ruby/test_array.rb	(revision 49114)
@@ -1904,6 +1904,8 @@ class TestArray < Test::Unit::TestCase https://github.com/ruby/ruby/blob/trunk/test/ruby/test_array.rb#L1904
     a[3] = 3
     a.shift(2)
     assert_equal([2, 3], a)
+
+    assert_equal([1,1,1], ([1] * 100).shift(3))
   end
 
   def test_unshift_error
@@ -2356,6 +2358,11 @@ class TestArray < Test::Unit::TestCase https://github.com/ruby/ruby/blob/trunk/test/ruby/test_array.rb#L2358
     b.replace(a)
     assert_equal((1..10).to_a, a.shift(10))
     assert_equal((11..100).to_a, a)
+
+    a = (1..30).to_a
+    assert_equal((1..3).to_a, a.shift(3))
+    # occupied
+    assert_equal((4..6).to_a, a.shift(3))
   end
 
   def test_replace_shared_ary

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