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author | Chris Seaton <chris.seaton@shopify.com> | 2020-09-16 19:59:36 +0100 |
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committer | Aaron Patterson <aaron.patterson@gmail.com> | 2020-09-16 13:52:24 -0700 |
commit | 8e173d8b2709f47cc0709f699640dafe850c9a8f (patch) | |
tree | 8c5421a14acb0bce87a723ae1b4a8959dc7f2326 /spec | |
parent | f75009c1222621836b2340bbb5f4d4274972ccb4 (diff) |
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.
Notes
Notes:
Merged: https://github.com/ruby/ruby/pull/3444
Diffstat (limited to 'spec')
-rw-r--r-- | spec/ruby/core/objectspace/define_finalizer_spec.rb | 128 |
1 files changed, 116 insertions, 12 deletions
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 |