зеркало из https://github.com/github/ruby.git
Warn on a finalizer that captures the object to be finalized
Also improve specs and documentation for finalizers and more clearly recommend a safe code pattern to use them.
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64
gc.c
64
gc.c
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@ -3384,6 +3384,57 @@ should_be_finalizable(VALUE obj)
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* as an argument to <i>aProc</i>. If <i>aProc</i> is a lambda or
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* method, make sure it can be called with a single argument.
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*
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* The return value is an array <code>[0, aProc]</code>.
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*
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* The two recommended patterns are to either create the finaliser proc
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* in a non-instance method where it can safely capture the needed state,
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* or to use a custom callable object that stores the needed state
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* explicitly as instance variables.
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*
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* class Foo
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* def initialize(data_needed_for_finalization)
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* ObjectSpace.define_finalizer(self, self.class.create_finalizer(data_needed_for_finalization))
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* end
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*
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* def self.create_finalizer(data_needed_for_finalization)
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* proc {
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* puts "finalizing #{data_needed_for_finalization}"
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* }
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* end
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* end
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*
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* class Bar
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* class Remover
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* def initialize(data_needed_for_finalization)
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* @data_needed_for_finalization = data_needed_for_finalization
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* end
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*
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* def call(id)
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* puts "finalizing #{@data_needed_for_finalization}"
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* end
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* end
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*
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* def initialize(data_needed_for_finalization)
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* ObjectSpace.define_finalizer(self, Remover.new(data_needed_for_finalization))
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* end
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* end
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*
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* Note that if your finalizer references the object to be
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* finalized it will never be run on GC, although it will still be
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* run at exit. You will get a warning if you capture the object
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* to be finalized as the receiver of the finalizer.
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*
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* class CapturesSelf
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* def initialize(name)
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* ObjectSpace.define_finalizer(self, proc {
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* # this finalizer will only be run on exit
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* puts "finalizing #{name}"
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* })
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* end
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* end
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*
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* Also note that finalization can be unpredictable and is never guaranteed
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* to be run except on exit.
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*/
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static VALUE
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@ -3400,6 +3451,10 @@ define_final(int argc, VALUE *argv, VALUE os)
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should_be_callable(block);
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}
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if (rb_callable_receiver(block) == obj) {
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rb_warn("finalizer references object to be finalized");
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}
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return define_final0(obj, block);
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}
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@ -12101,9 +12156,9 @@ rb_gcdebug_remove_stress_to_class(int argc, VALUE *argv, VALUE self)
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*
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* ObjectSpace also provides support for object finalizers, procs that will be
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* called when a specific object is about to be destroyed by garbage
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* collection.
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*
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* require 'objspace'
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* collection. See the documentation for
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* <code>ObjectSpace.define_finalizer</code> for important information on
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* how to use this method correctly.
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*
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* a = "A"
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* b = "B"
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@ -12111,6 +12166,9 @@ rb_gcdebug_remove_stress_to_class(int argc, VALUE *argv, VALUE self)
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* ObjectSpace.define_finalizer(a, proc {|id| puts "Finalizer one on #{id}" })
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* ObjectSpace.define_finalizer(b, proc {|id| puts "Finalizer two on #{id}" })
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*
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* a = nil
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* b = nil
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*
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* _produces:_
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*
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* Finalizer two on 537763470
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@ -46,6 +46,7 @@ VALUE rb_method_call_with_block(int, const VALUE *, VALUE, VALUE);
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VALUE rb_method_call_with_block_kw(int, const VALUE *, VALUE, VALUE, int);
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int rb_mod_method_arity(VALUE, ID);
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int rb_obj_method_arity(VALUE, ID);
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VALUE rb_callable_receiver(VALUE);
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VALUE rb_protect(VALUE (*)(VALUE), VALUE, int*);
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RBIMPL_SYMBOL_EXPORT_END()
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12
proc.c
12
proc.c
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@ -2739,6 +2739,18 @@ rb_obj_method_arity(VALUE obj, ID id)
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return rb_mod_method_arity(CLASS_OF(obj), id);
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}
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VALUE
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rb_callable_receiver(VALUE callable) {
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if (rb_obj_is_proc(callable)) {
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VALUE binding = rb_funcall(callable, rb_intern("binding"), 0);
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return rb_funcall(binding, rb_intern("receiver"), 0);
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} else if (rb_obj_is_method(callable)) {
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return method_receiver(callable);
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} else {
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return Qundef;
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}
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}
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const rb_method_definition_t *
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rb_method_def(VALUE method)
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{
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@ -1,24 +1,42 @@
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require_relative '../../spec_helper'
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require_relative 'fixtures/classes'
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# NOTE: A call to define_finalizer does not guarantee that the
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# passed proc or callable will be called at any particular time.
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# Why do we not test that finalizers are run by the GC? The documentation
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# says that finalizers are never guaranteed to be run, so we can't
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# spec that they are. On some implementations of Ruby the finalizers may
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# run asyncronously, meaning that we can't predict when they'll run,
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# even if they were guaranteed to do so. Even on MRI finalizers can be
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# very unpredictable, due to conservative stack scanning and references
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# left in unused memory.
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describe "ObjectSpace.define_finalizer" do
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it "raises an ArgumentError if the action does not respond to call" do
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-> {
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ObjectSpace.define_finalizer("", mock("ObjectSpace.define_finalizer no #call"))
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ObjectSpace.define_finalizer(Object.new, mock("ObjectSpace.define_finalizer no #call"))
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}.should raise_error(ArgumentError)
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end
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it "accepts an object and a proc" do
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handler = -> obj { obj }
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ObjectSpace.define_finalizer("garbage", handler).should == [0, handler]
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handler = -> id { id }
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ObjectSpace.define_finalizer(Object.new, handler).should == [0, handler]
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end
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it "accepts an object and a bound method" do
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handler = mock("callable")
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def handler.finalize(id) end
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finalize = handler.method(:finalize)
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ObjectSpace.define_finalizer(Object.new, finalize).should == [0, finalize]
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end
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it "accepts an object and a callable" do
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handler = mock("callable")
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def handler.call(obj) end
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ObjectSpace.define_finalizer("garbage", handler).should == [0, handler]
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def handler.call(id) end
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ObjectSpace.define_finalizer(Object.new, handler).should == [0, handler]
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end
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it "accepts an object and a block" do
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handler = -> id { id }
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ObjectSpace.define_finalizer(Object.new, &handler).should == [0, handler]
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end
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it "raises ArgumentError trying to define a finalizer on a non-reference" do
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@ -31,7 +49,7 @@ describe "ObjectSpace.define_finalizer" do
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it "calls finalizer on process termination" do
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code = <<-RUBY
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def scoped
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Proc.new { puts "finalized" }
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Proc.new { puts "finalizer run" }
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end
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handler = scoped
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obj = "Test"
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@ -39,18 +57,104 @@ describe "ObjectSpace.define_finalizer" do
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exit 0
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RUBY
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ruby_exe(code).should == "finalized\n"
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ruby_exe(code, :args => "2>&1").should include("finalizer run\n")
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end
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it "calls finalizer at exit even if it is self-referencing" do
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ruby_version_is "2.8" do
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it "warns if the finalizer has the object as the receiver" do
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code = <<-RUBY
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class CapturesSelf
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def initialize
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ObjectSpace.define_finalizer(self, proc {
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puts "finalizer run"
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})
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end
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end
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CapturesSelf.new
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exit 0
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RUBY
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ruby_exe(code, :args => "2>&1").should include("warning: finalizer references object to be finalized\n")
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end
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it "warns if the finalizer is a method bound to the receiver" do
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code = <<-RUBY
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class CapturesSelf
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def initialize
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ObjectSpace.define_finalizer(self, method(:finalize))
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end
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def finalize(id)
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puts "finalizer run"
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end
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end
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CapturesSelf.new
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exit 0
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RUBY
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ruby_exe(code, :args => "2>&1").should include("warning: finalizer references object to be finalized\n")
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end
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it "warns if the finalizer was a block in the reciever" do
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code = <<-RUBY
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class CapturesSelf
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def initialize
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ObjectSpace.define_finalizer(self) do
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puts "finalizer run"
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end
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end
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end
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CapturesSelf.new
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exit 0
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RUBY
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ruby_exe(code, :args => "2>&1").should include("warning: finalizer references object to be finalized\n")
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end
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end
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it "calls a finalizer at exit even if it is self-referencing" do
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code = <<-RUBY
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obj = "Test"
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handler = Proc.new { puts "finalized" }
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handler = Proc.new { puts "finalizer run" }
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ObjectSpace.define_finalizer(obj, handler)
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exit 0
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RUBY
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ruby_exe(code).should == "finalized\n"
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ruby_exe(code).should include("finalizer run\n")
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end
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it "calls a finalizer at exit even if it is indirectly self-referencing" do
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code = <<-RUBY
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class CapturesSelf
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def initialize
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ObjectSpace.define_finalizer(self, finalizer(self))
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end
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def finalizer(zelf)
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proc do
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puts "finalizer run"
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end
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end
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end
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CapturesSelf.new
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exit 0
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RUBY
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ruby_exe(code, :args => "2>&1").should include("finalizer run\n")
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end
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it "calls a finalizer defined in a finalizer running at exit" do
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code = <<-RUBY
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obj = "Test"
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handler = Proc.new do
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obj2 = "Test"
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handler2 = Proc.new { puts "finalizer 2 run" }
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ObjectSpace.define_finalizer(obj2, handler2)
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exit 0
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end
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ObjectSpace.define_finalizer(obj, handler)
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exit 0
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RUBY
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ruby_exe(code, :args => "2>&1").should include("finalizer 2 run\n")
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end
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it "allows multiple finalizers with different 'callables' to be defined" do
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