001/*
002 * Copyright (c) 2012, 2014, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package jdk.internal.jvmci.meta;
024
025import java.util.*;
026import java.util.concurrent.*;
027
028/**
029 * Manages a list of unique deoptimization reasons.
030 *
031 */
032public abstract class SpeculationLog {
033    private volatile Object lastFailed;
034    private volatile Collection<Object> speculations;
035    private Set<Object> failedSpeculations;
036
037    public synchronized void collectFailedSpeculations() {
038        if (lastFailed != null) {
039            if (failedSpeculations == null) {
040                failedSpeculations = new HashSet<>(2);
041            }
042            failedSpeculations.add(lastFailed);
043            lastFailed = null;
044            speculations = null;
045        }
046    }
047
048    public boolean maySpeculate(Object reason) {
049        if (failedSpeculations != null && failedSpeculations.contains(reason)) {
050            return false;
051        }
052        return true;
053    }
054
055    protected void addSpeculation(Object reason) {
056        assert maySpeculate(reason);
057        if (speculations == null) {
058            synchronized (this) {
059                if (speculations == null) {
060                    speculations = new ConcurrentLinkedQueue<>();
061                }
062            }
063        }
064        speculations.add(reason);
065    }
066
067    public abstract JavaConstant speculate(Object reason);
068}