--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/instrument/ProbeNode.java	Sun Nov 23 16:07:23 2014 -0800
@@ -0,0 +1,362 @@
+/*
+ * Copyright (c) 2013, 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.truffle.api.instrument;
+
+import com.oracle.truffle.api.*;
+import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
+import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
+import com.oracle.truffle.api.frame.*;
+import com.oracle.truffle.api.instrument.Instrument.InstrumentNode;
+import com.oracle.truffle.api.nodes.*;
+import com.oracle.truffle.api.source.*;
+
+/**
+ * Implementation interfaces and classes for attaching {@link Probe}s to {@link WrapperNode}s.
+ */
+public abstract class ProbeNode extends Node implements TruffleEventReceiver, InstrumentationNode {
+
+    /**
+     * Any Truffle node implementing this interface can be "instrumented" by installing a
+     * {@link Probe} that intercepts execution events at the node and routes them to any
+     * {@link Instrument}s that have been attached to the {@link Probe}. Only one {@link Probe} may
+     * be installed at each node; subsequent calls return the one already installed.
+     *
+     * @see Instrument
+     */
+    public interface Instrumentable {
+
+        /**
+         * Enables "instrumentation" of a Guest Language Truffle node, where the node is presumed to
+         * be part of a well-formed Truffle AST that is not being executed. The AST may be modified
+         * as a side effect.
+         * <p>
+         * This interface is not intended to be visible as part of the API for tools
+         * (instrumentation clients).
+         *
+         * @return a (possibly newly created) {@link Probe} associated with this node.
+         */
+        Probe probe();
+
+        /**
+         * Enables a one-time, unchangeable "instrumentation" of a Guest Language Truffle node,
+         * where the node is presumed to be part of a well-formed Truffle AST that is not being
+         * executed. The AST may be modified as a side-effect. Unlike {@link #probe()}, once
+         * {@link #probeLite(TruffleEventReceiver)} is called at a node, no additional probing can
+         * be added and no additional instrumentation can be attached.
+         * <p>
+         * This interface is not intended to be visible as part of the API for tools
+         * (instrumentation clients).
+         *
+         * @param eventReceiver The {@link TruffleEventReceiver} for the single "instrument" being
+         *            attached to this node.
+         */
+        void probeLite(TruffleEventReceiver eventReceiver);
+    }
+
+    /**
+     * A node that can be inserted into a Truffle AST, and which enables <em>instrumentation</em> at
+     * a particular Guest Language (GL) node.
+     * <p>
+     * The implementation must be GL-specific. A wrapper <em>decorates</em> a GL AST node (the
+     * wrapper's <em>child</em>) by acting as a transparent <em>proxy</em> with respect to the GL's
+     * execution semantics.
+     * <p>
+     * Instrumentation at the wrapped node is implemented by an instance of {@link ProbeNode}
+     * attached as a second child of the {@link WrapperNode}.
+     * <p>
+     * A wrapper is obliged to notify its attached {@link ProbeNode} when execution events occur at
+     * the wrapped AST node during program execution.
+     * <p>
+     * When a GL AST is cloned, the {@link WrapperNode}, its {@link ProbeNode} and any
+     * {@linkplain Instrument instrumentation} are also cloned; they are in effect part of the GL
+     * AST. An instance of {@link Probe} represents abstractly the instrumentation at a particular
+     * location in a GL AST; it tracks all the copies of the Wrapper and attached instrumentation,
+     * and acts as a single point of access for tools.
+     * <p>
+     * This interface is not intended to be visible as part of the API for tools (instrumentation
+     * clients).
+     * <p>
+     * Implementation guidelines:
+     * <ol>
+     * <li>Each GL implementation should include a WrapperNode implementation; usually only one is
+     * needed.</li>
+     * <li>The wrapper type should descend from the <em>GL-specific node class</em>.</li>
+     * <li>Must have a field: {@code @Child private <GL>Node child;}</li>
+     * <li>Must have a field: {@code @Child private ProbeNode probeNode;}</li>
+     * <li>The wrapper must act as a <em>proxy</em> for its child, which means implementing every
+     * possible <em>execute-</em> method that gets called on guest language AST node types by their
+     * parents, and passing along each call to its child.</li>
+     * <li>Method {@code Probe getProbe()} should be implemented as {@code probeNode.getProbe();}
+     * <li>Method {@code insertProbe(ProbeNode)} should be implemented as
+     * {@code this.probeNode=insert(newProbeNode);}</li>
+     * <li>Most importantly, Wrappers must be implemented so that Truffle optimization will reduce
+     * their runtime overhead to zero when there are no attached {@link Instrument}s.</li>
+     * </ol>
+     * <p>
+     * <strong>Disclaimer:</strong> experimental interface under development.
+     *
+     * @see Instrument
+     */
+    public interface WrapperNode extends InstrumentationNode {
+
+        /**
+         * Gets the node being "wrapped", i.e. the AST node for which
+         * {@linkplain TruffleEventReceiver execution events} will be reported through the
+         * Instrumentation Framework.
+         */
+        Node getChild();
+
+        /**
+         * Gets the {@link Probe} responsible for installing this wrapper; none if the wrapper
+         * installed via {@linkplain Instrumentable#probeLite(TruffleEventReceiver) "lite-Probing"}.
+         */
+        Probe getProbe();
+
+        /**
+         * Implementation support for completing a newly created wrapper node.
+         */
+        void insertProbe(ProbeNode probeNode);
+
+    }
+
+    /**
+     * Create a new {@link Probe} associated with, and attached to, a Guest Language specific
+     * instance of {@link WrapperNode}.
+     */
+    public static Probe insertProbe(WrapperNode wrapper) {
+        final SourceSection sourceSection = wrapper.getChild().getSourceSection();
+        final ProbeFullNode probeFullNode = new ProbeFullNode(); // private constructor
+        final Probe probe = new Probe(probeFullNode, sourceSection);  // package private access
+        probeFullNode.setProbe(probe);
+        wrapper.insertProbe(probeFullNode);
+        return probe;
+    }
+
+    /**
+     * Creates a new {@link ProbeLiteNode} associated with, and attached to, a Guest Language
+     * specific instance of {@link WrapperNode}.
+     */
+    public static void insertProbeLite(WrapperNode wrapper, TruffleEventReceiver eventReceiver) {
+        final ProbeLiteNode probeLiteNode = new ProbeLiteNode(eventReceiver);
+        wrapper.insertProbe(probeLiteNode);
+    }
+
+    /**
+     * @return the {@link Probe} permanently associated with this {@link ProbeNode}.
+     *
+     * @throws IllegalStateException if this location was "lite-Probed"
+     */
+    public abstract Probe getProbe() throws IllegalStateException;
+
+    /**
+     * Adds an {@link InstrumentNode} to this chain.
+     *
+     * @throws IllegalStateException if at a "lite-Probed" location.
+     */
+    abstract void addInstrument(Instrument instrument);
+
+    /**
+     * Removes an instrument from this chain of instruments.
+     *
+     * @throws IllegalStateException if at a "lite-Probed" location.
+     * @throws RuntimeException if no matching instrument is found,
+     */
+    abstract void removeInstrument(Instrument instrument);
+
+    /**
+     * Implementation class & interfaces for enabling the attachment of {@linkplain Probe Probes} to
+     * Truffle ASTs.
+     * <p>
+     * Head of a chain of nodes acting on behalf of {@linkplain Instrument instruments}, attached to
+     * a Guest Language (GL) AST as a child of a GL-specific {@link WrapperNode} node.
+     * <p>
+     * When Truffle clones an AST, the chain, including all attached {@linkplain Instrument
+     * instruments} will be cloned along with the {@link WrapperNode} to which it is attached. An
+     * instance of {@link Probe} represents abstractly the instrumentation at a particular location
+     * in a GL AST, tracks the clones of the chain, and keeps the instrumentation attached to the
+     * clones consistent.
+     */
+    @NodeInfo(cost = NodeCost.NONE)
+    private static final class ProbeFullNode extends ProbeNode {
+
+        /**
+         * First {@link InstrumentNode} node in chain; {@code null} of no instruments in chain.
+         */
+        @Child protected InstrumentNode firstInstrument;
+
+        // Never changed once set.
+        @CompilationFinal private Probe probe = null;
+
+        /**
+         * An assumption that the state of the {@link Probe} with which this chain is associated has
+         * not changed since the last time checking such an assumption failed and a reference to a
+         * new assumption (associated with a new state of the {@link Probe} was retrieved.
+         */
+        private Assumption probeUnchangedAssumption;
+
+        private ProbeFullNode() {
+            this.firstInstrument = null;
+        }
+
+        @Override
+        public Probe getProbe() throws IllegalStateException {
+            return probe;
+        }
+
+        @Override
+        public Node copy() {
+            Node node = super.copy();
+            probe.registerProbeNodeClone((ProbeNode) node);
+            return node;
+        }
+
+        private void setProbe(Probe probe) {
+            this.probe = probe;
+            this.probeUnchangedAssumption = probe.getUnchangedAssumption();
+        }
+
+        private void checkProbeUnchangedAssumption() {
+            try {
+                probeUnchangedAssumption.check();
+            } catch (InvalidAssumptionException ex) {
+                // Failure creates an implicit deoptimization
+                // Get the assumption associated with the new probe state
+                this.probeUnchangedAssumption = probe.getUnchangedAssumption();
+            }
+        }
+
+        @Override
+        @TruffleBoundary
+        void addInstrument(Instrument instrument) {
+            assert instrument.getProbe() == probe;
+            // The existing chain of nodes may be empty
+            // Attach the modified chain.
+            firstInstrument = insert(instrument.addToChain(firstInstrument));
+        }
+
+        @Override
+        @TruffleBoundary
+        void removeInstrument(Instrument instrument) {
+            assert instrument.getProbe() == probe;
+            final InstrumentNode modifiedChain = instrument.removeFromChain(firstInstrument);
+            if (modifiedChain == null) {
+                firstInstrument = null;
+            } else {
+                firstInstrument = insert(modifiedChain);
+            }
+        }
+
+        public void enter(Node node, VirtualFrame frame) {
+            final SyntaxTagTrap trap = probe.getTrap();
+            if (trap != null) {
+                checkProbeUnchangedAssumption();
+                trap.tagTrappedAt(((WrapperNode) this.getParent()).getChild(), frame.materialize());
+            }
+            if (firstInstrument != null) {
+                checkProbeUnchangedAssumption();
+                firstInstrument.enter(node, frame);
+            }
+        }
+
+        public void returnVoid(Node node, VirtualFrame frame) {
+            if (firstInstrument != null) {
+                checkProbeUnchangedAssumption();
+                firstInstrument.returnVoid(node, frame);
+            }
+        }
+
+        public void returnValue(Node node, VirtualFrame frame, Object result) {
+            if (firstInstrument != null) {
+                checkProbeUnchangedAssumption();
+                firstInstrument.returnValue(node, frame, result);
+            }
+        }
+
+        public void returnExceptional(Node node, VirtualFrame frame, Exception exception) {
+            if (firstInstrument != null) {
+                checkProbeUnchangedAssumption();
+                firstInstrument.returnExceptional(node, frame, exception);
+            }
+        }
+
+        public String instrumentationInfo() {
+            return "Standard probe";
+        }
+
+    }
+
+    /**
+     * Implementation of a probe that only ever has a single "instrument" associated with it. No
+     * {@link Instrument} is ever created; instead this method simply delegates the various enter
+     * and return events to a {@link TruffleEventReceiver} passed in during construction.
+     */
+    @NodeInfo(cost = NodeCost.NONE)
+    private static final class ProbeLiteNode extends ProbeNode {
+
+        private final TruffleEventReceiver eventReceiver;
+
+        private ProbeLiteNode(TruffleEventReceiver eventReceiver) {
+            this.eventReceiver = eventReceiver;
+        }
+
+        @Override
+        public Probe getProbe() throws IllegalStateException {
+            throw new IllegalStateException("\"lite-Probed\" nodes have no explicit Probe");
+        }
+
+        @Override
+        @TruffleBoundary
+        void addInstrument(Instrument instrument) {
+            throw new IllegalStateException("Instruments may not be added at a \"lite-probed\" location");
+        }
+
+        @Override
+        @TruffleBoundary
+        void removeInstrument(Instrument instrument) {
+            throw new IllegalStateException("Instruments may not be removed at a \"lite-probed\" location");
+        }
+
+        public void enter(Node node, VirtualFrame frame) {
+            eventReceiver.enter(node, frame);
+        }
+
+        public void returnVoid(Node node, VirtualFrame frame) {
+            eventReceiver.returnVoid(node, frame);
+        }
+
+        public void returnValue(Node node, VirtualFrame frame, Object result) {
+            eventReceiver.returnValue(node, frame, result);
+        }
+
+        public void returnExceptional(Node node, VirtualFrame frame, Exception exception) {
+            eventReceiver.returnExceptional(node, frame, exception);
+        }
+
+        public String instrumentationInfo() {
+            return "\"Lite\" probe";
+        }
+
+    }
+}