/*
 * FindBugs - Find Bugs in Java programs
 * Copyright (C) 2006, University of Maryland
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston MA 02111-1307, USA
 */

package edu.umd.cs.findbugs;

import java.lang.management.GarbageCollectorMXBean;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryPoolMXBean;
import java.util.List;

/**
 * Class to maintain a snapshot of a processes's time and memory usage.
 * 
 * This uses some JDK 1.5 APIs so must be careful that it doesn't cause any harm
 * when run from 1.4.
 * 
 * @see FindBugs
 * @author Brian Cole
 */
public class Footprint {

    /**
     *
     */
    private static final int NOCLASSDEF_ERROR = -9;

    private static final int CLASSCAST_ERROR = -8;

    private static final int ERROR_ERROR = -7;

    private static final int RUNTIME_EXCEPTION = -6;

    private long cpuTime = -1; // in nanoseconds

    private long clockTime = -1; // in milliseconds

    private long peakMem = -1; // in bytes

    private long collectionTime = -1; // in milliseconds

    public Footprint() {
        pullData();
    }

    /** uses deltas from base for cpuTime and clockTime (but not peakMemory) */
    public Footprint(Footprint base) {
        pullData();
        if (cpuTime >= 0) {
            cpuTime = (base.cpuTime >= 0) ? cpuTime - base.cpuTime : base.cpuTime;
        }
        if (clockTime >= 0) {
            clockTime = (base.clockTime >= 0) ? clockTime - base.clockTime : base.clockTime;
        }
        // leave peakMem alone
        if (collectionTime >= 0) {
            collectionTime = (base.collectionTime >= 0) ? collectionTime - base.collectionTime : base.collectionTime;
        }
    }

    private void pullData() {

        try {
            cpuTime = new OperatingSystemBeanWrapper().getProcessCpuTime();
        } catch (NoClassDefFoundError ncdfe) {
            cpuTime = NOCLASSDEF_ERROR;
        } catch (ClassCastException cce) {
            cpuTime = CLASSCAST_ERROR;
        } catch (Error error) {
            cpuTime = ERROR_ERROR;
        } // catch possible Error thrown when complied by the Eclipse compiler
        catch (RuntimeException error) {
            cpuTime = RUNTIME_EXCEPTION;
        } // catch possible Error thrown when complied by the Eclipse compiler

        clockTime = System.currentTimeMillis(); // or new
                                                // java.util.Date().getTime() ;

        try {
            peakMem = new MemoryBeanWrapper().getPeakUsage();
        } catch (NoClassDefFoundError ncdfe) {
            peakMem = NOCLASSDEF_ERROR;
        } catch (Error ncdfe) {
            peakMem = CLASSCAST_ERROR;
        } catch (RuntimeException ncdfe) {
            peakMem = RUNTIME_EXCEPTION;
        }

        try {
            collectionTime = new CollectionBeanWrapper().getCollectionTime();
        } catch (NoClassDefFoundError ncdfe) {
            collectionTime = NOCLASSDEF_ERROR;
        } catch (Error ncdfe) {
            peakMem = ERROR_ERROR;
        } catch (RuntimeException ncdfe) {
            collectionTime = RUNTIME_EXCEPTION;
        }
    }

    public long getCpuTime() {
        return cpuTime;
    }

    public long getClockTime() {
        return clockTime;
    }

    public long getPeakMemory() {
        return peakMem;
    }

    public long getCollectionTime() {
        return collectionTime;
    }

    @Override
    public String toString() {
        return "cpuTime=" + cpuTime + ", clockTime=" + clockTime + ", peakMemory=" + peakMem;
    }

    public static void main(String[] argv) {
        System.out.println(new Footprint());
    }

    // -------- begin static inner classes --------

    /**
     * Wrapper so that possible NoClassDefFoundError can be caught.
     * Instantiating this class will throw a NoClassDefFoundError on JDK 1.4 and
     * earlier.
     */
    public static class MemoryBeanWrapper {
        List<MemoryPoolMXBean> mlist = ManagementFactory.getMemoryPoolMXBeans();

        // java.lang.management.MemoryMXBean memBean =
        // ManagementFactory.getMemoryMXBean();
        // java.lang.management.MemoryUsage memUsage =
        // memBean.getHeapMemoryUsage();

        public long getPeakUsage() {
            long sum = 0;
            // problem: sum of the peaks is not necessarily the peak of the sum.
            // For example, objects migrate from the 'eden' to the 'survivor'
            // area.
            for (MemoryPoolMXBean mpBean : mlist) {
                try {
                    java.lang.management.MemoryUsage memUsage = mpBean.getPeakUsage();
                    if (memUsage != null)
                        sum += memUsage.getUsed(); // or getCommitted()
                    // System.out.println(mpBean.getType()+", "+mpBean.getName()+", "+memUsage.getUsed());
                    // System.out.println("Memory type="+mpBean.getType()+", Pool name="+mpBean.getName()+", Memory usage="+mpBean.getPeakUsage());
                } catch (RuntimeException e) {
                    assert true;
                    // AnalysisContext.logError("Error getting peak usage", e);
                }
            }
            // System.out.println();
            return sum;
        }
    }

    /**
     * Wrapper so that possbile NoClassDefFoundError can be caught.
     * Instantiating this class will throw a NoClassDefFoundError on JDK 1.4 and
     * earlier, or will throw a ClassCastException on a 1.5-compliant non-sun
     * JRE where the osBean is not a sunBean. (If compiled by Eclipse,
     * instantiating it will throw an unsubclassed java.lang.Error.)
     */
    public static class OperatingSystemBeanWrapper {
        java.lang.management.OperatingSystemMXBean osBean = ManagementFactory.getOperatingSystemMXBean();

        // next line compiles fine with sun JDK 1.5 but the eclipse compiler may
        // complain "The type
        // OperatingSystemMXBean is not accessible due to restriction on
        // required library classes.jar"
        // depending on the contents of the .classpath file.
        com.sun.management.OperatingSystemMXBean sunBean = (com.sun.management.OperatingSystemMXBean) osBean;

        public long getProcessCpuTime() {
            return sunBean.getProcessCpuTime();
        }
    }

    /**
     * Wrapper so that possible NoClassDefFoundError can be caught.
     * Instantiating this class will throw a NoClassDefFoundError on JDK 1.4 and
     * earlier.
     */
    public static class CollectionBeanWrapper {
        List<GarbageCollectorMXBean> clist = ManagementFactory.getGarbageCollectorMXBeans();

        public long getCollectionTime() {
            long sum = 0;
            for (GarbageCollectorMXBean gcBean : clist) {
                sum += gcBean.getCollectionTime();
            }
            return sum;
        }
    }

}
