New finalizer specs

Author: chrisseaton

spec/tags/truffle/objspace/define_finalizer_tags.txt

@@ -0,0 +1 @@
+slow:ObjectSpace.define_finalizer will call the finalizer

spec/tags/truffle/objspace/undefine_finalizer_tags.txt

@@ -1 +1,2 @@
 fails:ObjectSpace.undefine_finalizer if not used leaves the finalizer in place
+slow:ObjectSpace.undefine_finalizer successfully unregisters a finalizer

spec/truffle/objspace/define_finalizer_spec.rb

@@ -1,24 +1,38 @@
-# Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved. This
+# Copyright (c) 2017, 2019 Oracle and/or its affiliates. All rights reserved. This
 # code is released under a tri EPL/GPL/LGPL license. You can use it,
 # redistribute it and/or modify it under the terms of the:
 #
 # Eclipse Public License version 1.0, or
 # GNU General Public License version 2, or
 # GNU Lesser General Public License version 2.1.
 
+require 'objspace'
+
 require_relative '../../ruby/spec_helper'
 
 describe "ObjectSpace.define_finalizer" do
 
-  it "will eventually call the finalizer with enough GC activity" do
-    do_break = false
-    until do_break
-      expected_id = nil
-      ObjectSpace.define_finalizer Object.new.tap { |object| expected_id = object.object_id }, proc { |finalized_id|
-        finalized_id.should == expected_id
-        do_break = true
-      }
+  # These specs require that the GC runs a full stop-the-world collection that
+  # will push references on Runtime#gc(). All GCs on HotSpot and the SVM do
+  # this, apart from the Epsilon collector on HotSpot. The remaining issue is
+  # that the references are popped asynchronously at the JVM level, and then
+  # from there popped again asynchronously in TruffleRuby, so we do still need
+  # to wait with a timeout in order to assert that it has been done.
+  # Truffle::Debug.drain_finalization_queue, which drains the queue in
+  # TruffleRuby in the foreground, does seem to help increase test throughput.
+
+  it "will call the finalizer" do
+    channel = Truffle::Channel.new
+    finalizer = proc {
+      channel.send :finalized
+    }
+    Object.new.tap do |object|
+      ObjectSpace.define_finalizer object, finalizer
+      ObjectSpace.reachable_objects_from(object).should include(finalizer)
     end
+    GC.start
+    Truffle::Debug.drain_finalization_queue   # Not needed for correctness
+    channel.receive_timeout(3).should == :finalized
   end
 
 end

spec/truffle/objspace/reachable_objects_from_spec.rb

@@ -1,16 +1,19 @@
-# Copyright (c) 2015, 2017 Oracle and/or its affiliates. All rights reserved. This
+# Copyright (c) 2015, 2019 Oracle and/or its affiliates. All rights reserved. This
 # code is released under a tri EPL/GPL/LGPL license. You can use it,
 # redistribute it and/or modify it under the terms of the:
 #
 # Eclipse Public License version 1.0, or
 # GNU General Public License version 2, or
 # GNU Lesser General Public License version 2.1.
 
-require_relative '../../ruby/spec_helper'
 require 'objspace'
 
-# Truffle-specific behavior
+require_relative '../../ruby/spec_helper'
+
 describe "ObjectSpace.reachable_objects_from" do
+
+  # This is a standard method, but our implementation returns more objects so we keep this spec here
+
   it "enumerates objects directly reachable from a given object" do
     ObjectSpace.reachable_objects_from(nil).should == [NilClass]
     ObjectSpace.reachable_objects_from(['a', 'b', 'c']).should include(Array, 'a', 'b', 'c')
@@ -62,4 +65,13 @@
     reachable = ObjectSpace.reachable_objects_from(q)
     reachable.should include(o)
   end
+
+  it "finds finalizers" do
+    object = Object.new
+    finalizer = proc { }
+    ObjectSpace.define_finalizer object, finalizer
+    reachable = ObjectSpace.reachable_objects_from(object)
+    reachable.should include(finalizer)
+  end
+  
 end

spec/truffle/objspace/undefine_finalizer_spec.rb

@@ -1,40 +1,33 @@
-# Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved. This
+# Copyright (c) 2017, 2019 Oracle and/or its affiliates. All rights reserved. This
 # code is released under a tri EPL/GPL/LGPL license. You can use it,
 # redistribute it and/or modify it under the terms of the:
 #
 # Eclipse Public License version 1.0, or
 # GNU General Public License version 2, or
 # GNU Lesser General Public License version 2.1.
 
+require 'objspace'
+
 require_relative '../../ruby/spec_helper'
 
 describe "ObjectSpace.undefine_finalizer" do
 
-  it "if not used leaves the finalizer in place" do
-    finalized = 0
-    finalizer = proc {
-     finalized += 1
-    }
-    started = Time.now
-    until Time.now > started + 3
-      object = Object.new
-      ObjectSpace.define_finalizer object, finalizer
-    end
-    finalized.should > 0
-  end
+  # See comment in define_finalizer_spec.rb
 
   it "successfully unregisters a finalizer" do
-    finalized = 0
-    finalizer = proc {
-     finalized += 1
-    }
-    started = Time.now
-    until Time.now > started + 3
-      object = Object.new
+    channel = Truffle::Channel.new
+    Object.new.tap do |object|
+      finalizer = proc {
+        channel.send :finalized
+      }
       ObjectSpace.define_finalizer object, finalizer
+      ObjectSpace.reachable_objects_from(object).should include(finalizer)
       ObjectSpace.undefine_finalizer object
+      ObjectSpace.reachable_objects_from(object).should_not include(finalizer)
     end
-    finalized.should == 0
+    GC.start
+    Truffle::Debug.drain_finalization_queue               # Not needed for correctness
+    channel.try_receive.should be_nil
   end
 
 end

src/main/java/org/truffleruby/core/FinalizationService.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2018 Oracle and/or its affiliates. All rights reserved. This
+ * Copyright (c) 2013, 2019 Oracle and/or its affiliates. All rights reserved. This
  * code is released under a tri EPL/GPL/LGPL license. You can use it,
  * redistribute it and/or modify it under the terms of the:
  *
@@ -14,10 +14,12 @@
 import java.util.Collection;
 import java.util.Deque;
 import java.util.LinkedList;
+import java.util.Set;
 
 import org.truffleruby.RubyContext;
 
 import com.oracle.truffle.api.object.DynamicObject;
+import org.truffleruby.language.objects.ObjectGraphNode;
 
 /**
  * Finalizers are implemented with phantom references and reference queues, and are run in a
@@ -50,7 +52,7 @@ public DynamicObject getRoot() {
         }
     }
 
-    public static class FinalizerReference extends PhantomReference<Object> implements ReferenceProcessingService.ProcessingReference<FinalizerReference> {
+    public static class FinalizerReference extends PhantomReference<Object> implements ReferenceProcessingService.ProcessingReference<FinalizerReference>, ObjectGraphNode {
 
         /**
          * All accesses to this Deque must be synchronized by taking the
@@ -115,6 +117,11 @@ private void collectRoots(Collection<DynamicObject> roots) {
         public ReferenceProcessingService<FinalizerReference> service() {
             return service;
         }
+
+        @Override
+        public void getAdjacentObjects(Set<DynamicObject> reachable) {
+            collectRoots(reachable);
+        }
     }
 
     /** The finalizer Ruby thread, spawned lazily. */
@@ -135,6 +142,10 @@ public synchronized FinalizerReference addFinalizer(Object object, FinalizerRefe
         return finalizerReference;
     }
 
+    public final void drainFinalizationQueue() {
+        referenceProcessor.drainReferenceQueue();
+    }
+
     @Override
     protected void processReference(ProcessingReference<?> finalizerReference) {
         super.processReference(finalizerReference);

src/main/java/org/truffleruby/debug/TruffleDebugNodes.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2018 Oracle and/or its affiliates. All rights reserved. This
+ * Copyright (c) 2013, 2019 Oracle and/or its affiliates. All rights reserved. This
  * code is released under a tri EPL/GPL/LGPL license. You can use it,
  * redistribute it and/or modify it under the terms of the:
  *
@@ -962,4 +962,16 @@ protected ReadObjectFieldNode createReadAssociatedNode() {
 
     }
 
+    @CoreMethod(names = "drain_finalization_queue", onSingleton = true)
+    public abstract static class DrainFinalizationQueueNode extends CoreMethodArrayArgumentsNode {
+
+        @TruffleBoundary
+        @Specialization
+        public DynamicObject drainFinalizationQueue() {
+            getContext().getFinalizationService().drainFinalizationQueue();
+            return nil();
+        }
+
+    }
+
 }