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comparison truffle/com.oracle.truffle.api/src/com/oracle/truffle/api/utilities/CyclicAssumption.java @ 22342:a1b3b7894611

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CyclicAssumption: use AtomicReferenceFieldUpdater for the assumption field
author Andreas Woess <andreas.woess@oracle.com>
date Wed, 04 Nov 2015 11:03:08 +0100
parents dc83cc1f94f2
children
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22341:4df3d8fd6cfd 22342:a1b3b7894611
22 * or visit www.oracle.com if you need additional information or have any 22 * or visit www.oracle.com if you need additional information or have any
23 * questions. 23 * questions.
24 */ 24 */
25 package com.oracle.truffle.api.utilities; 25 package com.oracle.truffle.api.utilities;
26 26
27 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
28
27 import com.oracle.truffle.api.Assumption; 29 import com.oracle.truffle.api.Assumption;
28 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary; 30 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
29 import com.oracle.truffle.api.Truffle; 31 import com.oracle.truffle.api.Truffle;
30 import java.util.concurrent.atomic.AtomicReference;
31 32
32 /** 33 /**
33 * Holds an {@link Assumption}, and knows how to recreate it with the same properties on 34 * Holds an {@link Assumption}, and knows how to recreate it with the same properties on
34 * invalidation. Used so that mutability is isolated in this class, and all other classes that need 35 * invalidation. Used so that mutability is isolated in this class, and all other classes that need
35 * an assumption that may be recreated can have a final reference to an object of this class. Note 36 * an assumption that may be recreated can have a final reference to an object of this class. Note
37 * same way that you would with any other assumption. 38 * same way that you would with any other assumption.
38 */ 39 */
39 public class CyclicAssumption { 40 public class CyclicAssumption {
40 41
41 private final String name; 42 private final String name;
42 private final AtomicReference<Assumption> assumption; 43 private volatile Assumption assumption;
44
45 private static final AtomicReferenceFieldUpdater<CyclicAssumption, Assumption> ASSUMPTION_UPDATER = AtomicReferenceFieldUpdater.newUpdater(CyclicAssumption.class, Assumption.class, "assumption");
43 46
44 public CyclicAssumption(String name) { 47 public CyclicAssumption(String name) {
45 this.name = name; 48 this.name = name;
46 this.assumption = new AtomicReference<>(Truffle.getRuntime().createAssumption(name)); 49 this.assumption = Truffle.getRuntime().createAssumption(name);
47 } 50 }
48 51
49 @TruffleBoundary 52 @TruffleBoundary
50 public void invalidate() { 53 public void invalidate() {
51 Assumption newAssumption = Truffle.getRuntime().createAssumption(name); 54 Assumption newAssumption = Truffle.getRuntime().createAssumption(name);
52 Assumption oldAssumption = assumption.getAndSet(newAssumption); 55 Assumption oldAssumption = ASSUMPTION_UPDATER.getAndSet(this, newAssumption);
53 oldAssumption.invalidate(); 56 oldAssumption.invalidate();
54 } 57 }
55 58
56 public Assumption getAssumption() { 59 public Assumption getAssumption() {
57 return assumption.get(); 60 return assumption;
58 } 61 }
59 62
60 } 63 }