diff options
| -rw-r--r-- | gc.c | 64 | ||||
| -rw-r--r-- | include/ruby/internal/intern/proc.h | 1 | ||||
| -rw-r--r-- | proc.c | 12 | ||||
| -rw-r--r-- | spec/ruby/core/objectspace/define_finalizer_spec.rb | 128 |
4 files changed, 190 insertions, 15 deletions
@@ -3384,6 +3384,57 @@ should_be_finalizable(VALUE obj) * as an argument to <i>aProc</i>. If <i>aProc</i> is a lambda or * method, make sure it can be called with a single argument. * + * The return value is an array <code>[0, aProc]</code>. + * + * The two recommended patterns are to either create the finaliser proc + * in a non-instance method where it can safely capture the needed state, + * or to use a custom callable object that stores the needed state + * explicitly as instance variables. + * + * class Foo + * def initialize(data_needed_for_finalization) + * ObjectSpace.define_finalizer(self, self.class.create_finalizer(data_needed_for_finalization)) + * end + * + * def self.create_finalizer(data_needed_for_finalization) + * proc { + * puts "finalizing #{data_needed_for_finalization}" + * } + * end + * end + * + * class Bar + * class Remover + * def initialize(data_needed_for_finalization) + * @data_needed_for_finalization = data_needed_for_finalization + * end + * + * def call(id) + * puts "finalizing #{@data_needed_for_finalization}" + * end + * end + * + * def initialize(data_needed_for_finalization) + * ObjectSpace.define_finalizer(self, Remover.new(data_needed_for_finalization)) + * end + * end + * + * Note that if your finalizer references the object to be + * finalized it will never be run on GC, although it will still be + * run at exit. You will get a warning if you capture the object + * to be finalized as the receiver of the finalizer. + * + * class CapturesSelf + * def initialize(name) + * ObjectSpace.define_finalizer(self, proc { + * # this finalizer will only be run on exit + * puts "finalizing #{name}" + * }) + * end + * end + * + * Also note that finalization can be unpredictable and is never guaranteed + * to be run except on exit. */ static VALUE @@ -3400,6 +3451,10 @@ define_final(int argc, VALUE *argv, VALUE os) should_be_callable(block); } + if (rb_callable_receiver(block) == obj) { + rb_warn("finalizer references object to be finalized"); + } + return define_final0(obj, block); } @@ -12101,9 +12156,9 @@ rb_gcdebug_remove_stress_to_class(int argc, VALUE *argv, VALUE self) * * ObjectSpace also provides support for object finalizers, procs that will be * called when a specific object is about to be destroyed by garbage - * collection. - * - * require 'objspace' + * collection. See the documentation for + * <code>ObjectSpace.define_finalizer</code> for important information on + * how to use this method correctly. * * a = "A" * b = "B" @@ -12111,6 +12166,9 @@ rb_gcdebug_remove_stress_to_class(int argc, VALUE *argv, VALUE self) * ObjectSpace.define_finalizer(a, proc {|id| puts "Finalizer one on #{id}" }) * ObjectSpace.define_finalizer(b, proc {|id| puts "Finalizer two on #{id}" }) * + * a = nil + * b = nil + * * _produces:_ * * Finalizer two on 537763470 diff --git a/include/ruby/internal/intern/proc.h b/include/ruby/internal/intern/proc.h index d6f77cbd4d..24336a6a66 100644 --- a/include/ruby/internal/intern/proc.h +++ b/include/ruby/internal/intern/proc.h @@ -46,6 +46,7 @@ VALUE rb_method_call_with_block(int, const VALUE *, VALUE, VALUE); VALUE rb_method_call_with_block_kw(int, const VALUE *, VALUE, VALUE, int); int rb_mod_method_arity(VALUE, ID); int rb_obj_method_arity(VALUE, ID); +VALUE rb_callable_receiver(VALUE); VALUE rb_protect(VALUE (*)(VALUE), VALUE, int*); RBIMPL_SYMBOL_EXPORT_END() @@ -2739,6 +2739,18 @@ rb_obj_method_arity(VALUE obj, ID id) return rb_mod_method_arity(CLASS_OF(obj), id); } +VALUE +rb_callable_receiver(VALUE callable) { + if (rb_obj_is_proc(callable)) { + VALUE binding = rb_funcall(callable, rb_intern("binding"), 0); + return rb_funcall(binding, rb_intern("receiver"), 0); + } else if (rb_obj_is_method(callable)) { + return method_receiver(callable); + } else { + return Qundef; + } +} + const rb_method_definition_t * rb_method_def(VALUE method) { diff --git a/spec/ruby/core/objectspace/define_finalizer_spec.rb b/spec/ruby/core/objectspace/define_finalizer_spec.rb index 3f7b1ae576..d25d2a923f 100644 --- a/spec/ruby/core/objectspace/define_finalizer_spec.rb +++ b/spec/ruby/core/objectspace/define_finalizer_spec.rb @@ -1,24 +1,42 @@ require_relative '../../spec_helper' require_relative 'fixtures/classes' -# NOTE: A call to define_finalizer does not guarantee that the -# passed proc or callable will be called at any particular time. +# Why do we not test that finalizers are run by the GC? The documentation +# says that finalizers are never guaranteed to be run, so we can't +# spec that they are. On some implementations of Ruby the finalizers may +# run asyncronously, meaning that we can't predict when they'll run, +# even if they were guaranteed to do so. Even on MRI finalizers can be +# very unpredictable, due to conservative stack scanning and references +# left in unused memory. + describe "ObjectSpace.define_finalizer" do it "raises an ArgumentError if the action does not respond to call" do -> { - ObjectSpace.define_finalizer("", mock("ObjectSpace.define_finalizer no #call")) + ObjectSpace.define_finalizer(Object.new, mock("ObjectSpace.define_finalizer no #call")) }.should raise_error(ArgumentError) end it "accepts an object and a proc" do - handler = -> obj { obj } - ObjectSpace.define_finalizer("garbage", handler).should == [0, handler] + handler = -> id { id } + ObjectSpace.define_finalizer(Object.new, handler).should == [0, handler] + end + + it "accepts an object and a bound method" do + handler = mock("callable") + def handler.finalize(id) end + finalize = handler.method(:finalize) + ObjectSpace.define_finalizer(Object.new, finalize).should == [0, finalize] end it "accepts an object and a callable" do handler = mock("callable") - def handler.call(obj) end - ObjectSpace.define_finalizer("garbage", handler).should == [0, handler] + def handler.call(id) end + ObjectSpace.define_finalizer(Object.new, handler).should == [0, handler] + end + + it "accepts an object and a block" do + handler = -> id { id } + ObjectSpace.define_finalizer(Object.new, &handler).should == [0, handler] end it "raises ArgumentError trying to define a finalizer on a non-reference" do @@ -31,7 +49,7 @@ describe "ObjectSpace.define_finalizer" do it "calls finalizer on process termination" do code = <<-RUBY def scoped - Proc.new { puts "finalized" } + Proc.new { puts "finalizer run" } end handler = scoped obj = "Test" @@ -39,18 +57,104 @@ describe "ObjectSpace.define_finalizer" do exit 0 RUBY - ruby_exe(code).should == "finalized\n" + ruby_exe(code, :args => "2>&1").should include("finalizer run\n") end - it "calls finalizer at exit even if it is self-referencing" do + ruby_version_is "2.8" do + it "warns if the finalizer has the object as the receiver" do + code = <<-RUBY + class CapturesSelf + def initialize + ObjectSpace.define_finalizer(self, proc { + puts "finalizer run" + }) + end + end + CapturesSelf.new + exit 0 + RUBY + + ruby_exe(code, :args => "2>&1").should include("warning: finalizer references object to be finalized\n") + end + + it "warns if the finalizer is a method bound to the receiver" do + code = <<-RUBY + class CapturesSelf + def initialize + ObjectSpace.define_finalizer(self, method(:finalize)) + end + def finalize(id) + puts "finalizer run" + end + end + CapturesSelf.new + exit 0 + RUBY + + ruby_exe(code, :args => "2>&1").should include("warning: finalizer references object to be finalized\n") + end + + it "warns if the finalizer was a block in the reciever" do + code = <<-RUBY + class CapturesSelf + def initialize + ObjectSpace.define_finalizer(self) do + puts "finalizer run" + end + end + end + CapturesSelf.new + exit 0 + RUBY + + ruby_exe(code, :args => "2>&1").should include("warning: finalizer references object to be finalized\n") + end + end + + it "calls a finalizer at exit even if it is self-referencing" do code = <<-RUBY obj = "Test" - handler = Proc.new { puts "finalized" } + handler = Proc.new { puts "finalizer run" } + ObjectSpace.define_finalizer(obj, handler) + exit 0 + RUBY + + ruby_exe(code).should include("finalizer run\n") + end + + it "calls a finalizer at exit even if it is indirectly self-referencing" do + code = <<-RUBY + class CapturesSelf + def initialize + ObjectSpace.define_finalizer(self, finalizer(self)) + end + def finalizer(zelf) + proc do + puts "finalizer run" + end + end + end + CapturesSelf.new + exit 0 + RUBY + + ruby_exe(code, :args => "2>&1").should include("finalizer run\n") + end + + it "calls a finalizer defined in a finalizer running at exit" do + code = <<-RUBY + obj = "Test" + handler = Proc.new do + obj2 = "Test" + handler2 = Proc.new { puts "finalizer 2 run" } + ObjectSpace.define_finalizer(obj2, handler2) + exit 0 + end ObjectSpace.define_finalizer(obj, handler) exit 0 RUBY - ruby_exe(code).should == "finalized\n" + ruby_exe(code, :args => "2>&1").should include("finalizer 2 run\n") end it "allows multiple finalizers with different 'callables' to be defined" do |