[GR-15739] Add the necessary write barriers for Array and Hash.

PullRequest: truffleruby/865

Author: eregon

CHANGELOG.md

@@ -14,6 +14,7 @@ Bug fixes:
 * Implemented `FFI::Pointer#clear` (#1687).
 * Procs will now yield to the block in their declaration context even when called with a block argument (#1657).
 * Fixed problems with calling POSIX methods if `Symbol#[]` is redefined (#1665).
+* Fixed sharing of `Array` and `Hash` elements for thread-safety of objects (#1601).
 
 Compatibility
 

lib/truffle/objspace.rb

@@ -154,7 +154,12 @@ def dump_all(output: :file)
   def memsize_of(object)
     size = Truffle::ObjSpace.memsize_of(object)
 
-    size + Truffle::ObjSpace.sizer(object).call unless Truffle::ObjSpace.sizer(object).nil?
+    memsizer = Truffle::CExt.hidden_variable_get object, :data_memsizer
+    if memsizer
+      size + memsizer.call
+    else
+      size
+    end
   end
   module_function :memsize_of
 

lib/truffle/truffle/cext.rb

@@ -1449,8 +1449,10 @@ def rb_data_typed_object_wrap(ruby_class, data, data_type, mark, free, size)
     data_holder = DataHolder.new(data)
     hidden_variable_set object, :data_type, data_type
     hidden_variable_set object, :data_holder, data_holder
+    hidden_variable_set object, :data_memsizer, data_sizer(size, data_holder) unless size.nil?
+
     ObjectSpace.define_finalizer object, data_finalizer(free, data_holder) unless free.nil?
-    Truffle::ObjSpace.define_sizer object, data_sizer(size, data_holder) unless size.nil?
+
     define_marker object, data_marker(mark, data_holder) unless mark.nil?
     object
   end

spec/ruby/library/objectspace/memsize_of_spec.rb

@@ -0,0 +1,30 @@
+require_relative '../../spec_helper'
+require 'objspace'
+
+describe "ObjectSpace.memsize_of" do
+  it "returns 0 for true, false and nil" do
+    ObjectSpace.memsize_of(true).should == 0
+    ObjectSpace.memsize_of(false).should == 0
+    ObjectSpace.memsize_of(nil).should == 0
+  end
+
+  it "returns 0 for small Integers" do
+    ObjectSpace.memsize_of(42).should == 0
+  end
+
+  it "returns an Integer for an Object" do
+    obj = Object.new
+    ObjectSpace.memsize_of(obj).should be_kind_of(Integer)
+    ObjectSpace.memsize_of(obj).should > 0
+  end
+
+  it "is larger if the Object has more instance variables" do
+    obj = Object.new
+    before = ObjectSpace.memsize_of(obj)
+    100.times do |i|
+      obj.instance_variable_set(:"@foo#{i}", nil)
+    end
+    after = ObjectSpace.memsize_of(obj)
+    after.should > before
+  end
+end

spec/ruby/library/objectspace/reachable_objects_from_spec.rb

@@ -0,0 +1,61 @@
+require_relative '../../spec_helper'
+require 'objspace'
+
+describe "ObjectSpace.reachable_objects_from" do
+  it "returns nil for true and false" do
+    ObjectSpace.reachable_objects_from(true).should == nil
+    ObjectSpace.reachable_objects_from(false).should == nil
+  end
+
+  it "returns nil for nil" do
+    ObjectSpace.reachable_objects_from(nil).should == nil
+  end
+
+  it "returns nil for small Integers" do
+    ObjectSpace.reachable_objects_from(42).should == nil
+  end
+
+  it "enumerates objects directly reachable from a given object" do
+    ObjectSpace.reachable_objects_from(['a', 'b', 'c']).should include(Array, 'a', 'b', 'c')
+    ObjectSpace.reachable_objects_from(Object.new).should == [Object]
+  end
+
+  it "finds an object stored in an Array" do
+    obj = Object.new
+    ary = [obj]
+    reachable = ObjectSpace.reachable_objects_from(ary)
+    reachable.should include(obj)
+  end
+
+  it "finds an object stored in a copy-on-write Array" do
+    removed = Object.new
+    obj = Object.new
+    ary = [removed, obj]
+    ary.shift
+    reachable = ObjectSpace.reachable_objects_from(ary)
+    reachable.should include(obj)
+    reachable.should_not include(removed)
+  end
+
+  it "finds an object stored in a Queue" do
+    require 'thread'
+    o = Object.new
+    q = Queue.new
+    q << o
+
+    reachable = ObjectSpace.reachable_objects_from(q)
+    reachable = reachable + reachable.flat_map { |r| ObjectSpace.reachable_objects_from(r) }
+    reachable.should include(o)
+  end
+
+  it "finds an object stored in a SizedQueue" do
+    require 'thread'
+    o = Object.new
+    q = SizedQueue.new(3)
+    q << o
+
+    reachable = ObjectSpace.reachable_objects_from(q)
+    reachable = reachable + reachable.flat_map { |r| ObjectSpace.reachable_objects_from(r) }
+    reachable.should include(o)
+  end
+end

spec/tags/library/objectspace/reachable_objects_from_tags.txt

@@ -0,0 +1 @@
+fails:ObjectSpace.reachable_objects_from returns nil for nil

spec/truffle/objspace/reachable_objects_from_spec.rb

@@ -12,12 +12,10 @@
 
 describe "ObjectSpace.reachable_objects_from" do
 
-  # This is a standard method, but our implementation returns more objects so we keep this spec here
+  # This is a standard method, but our implementation returns more objects so we add extra specs here
 
-  it "enumerates objects directly reachable from a given object" do
+  it "returns [NilClass] for nil" do
     ObjectSpace.reachable_objects_from(nil).should == [NilClass]
-    ObjectSpace.reachable_objects_from(['a', 'b', 'c']).should include(Array, 'a', 'b', 'c')
-    ObjectSpace.reachable_objects_from(Object.new).should == [Object]
   end
 
   it "finds the superclass and included/prepended modules of a class" do
@@ -46,26 +44,6 @@
     reachable.should include(captured)
   end
 
-  it "finds an object stored in a Queue" do
-    require 'thread'
-    o = Object.new
-    q = Queue.new
-    q << o
-
-    reachable = ObjectSpace.reachable_objects_from(q)
-    reachable.should include(o)
-  end
-
-  it "finds an object stored in a SizedQueue" do
-    require 'thread'
-    o = Object.new
-    q = SizedQueue.new(3)
-    q << o
-
-    reachable = ObjectSpace.reachable_objects_from(q)
-    reachable.should include(o)
-  end
-
   it "finds finalizers" do
     object = Object.new
     finalizer = proc { }