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package jdk.internal.perf;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.LongBuffer;
import java.security.AccessController;

Performance counter support for internal JRE classes. This class defines a fixed list of counters for the platform to use as an interim solution until RFE# 6209222 is implemented. The perf counters will be created in the jvmstat perf buffer that the HotSpot VM creates. The default size is 32K and thus the number of counters is bounded. You can alter the size with -XX:PerfDataMemorySize=<bytes> option. If there is insufficient memory in the jvmstat perf buffer, the C heap memory will be used and thus the application will continue to run if the counters added exceeds the buffer size but the counters will be missing. See HotSpot jvmstat implementation for certain circumstances that the jvmstat perf buffer is not supported. /**
 * Performance counter support for internal JRE classes.
 * This class defines a fixed list of counters for the platform
 * to use as an interim solution until RFE# 6209222 is implemented.
 * The perf counters will be created in the jvmstat perf buffer
 * that the HotSpot VM creates. The default size is 32K and thus
 * the number of counters is bounded.  You can alter the size
 * with {@code -XX:PerfDataMemorySize=<bytes>} option. If there is
 * insufficient memory in the jvmstat perf buffer, the C heap memory
 * will be used and thus the application will continue to run if
 * the counters added exceeds the buffer size but the counters
 * will be missing.
 *
 * See HotSpot jvmstat implementation for certain circumstances
 * that the jvmstat perf buffer is not supported.
 *
 */
public class PerfCounter {
    private static final Perf perf =
        AccessController.doPrivileged(new Perf.GetPerfAction());

    // Must match values defined in hotspot/src/share/vm/runtime/perfdata.hpp
    private static final int V_Constant  = 1;
    private static final int V_Monotonic = 2;
    private static final int V_Variable  = 3;
    private static final int U_None      = 1;

    private final String name;
    private final LongBuffer lb;

    private PerfCounter(String name, int type) {
        this.name = name;
        ByteBuffer bb = perf.createLong(name, type, U_None, 0L);
        bb.order(ByteOrder.nativeOrder());
        this.lb = bb.asLongBuffer();
    }

    public static PerfCounter newPerfCounter(String name) {
        return new PerfCounter(name, V_Variable);
    }

    public static PerfCounter newConstantPerfCounter(String name) {
        PerfCounter c = new PerfCounter(name, V_Constant);
        return c;
    }

    
Returns the current value of the perf counter.
/**
     * Returns the current value of the perf counter.
     */
    public synchronized long get() {
        return lb.get(0);
    }

    
Sets the value of the perf counter to the given newValue.
/**
     * Sets the value of the perf counter to the given newValue.
     */
    public synchronized void set(long newValue) {
        lb.put(0, newValue);
    }

    
Adds the given value to the perf counter.
/**
     * Adds the given value to the perf counter.
     */
    public synchronized void add(long value) {
        long res = get() + value;
        lb.put(0, res);
    }

    
Increments the perf counter with 1.
/**
     * Increments the perf counter with 1.
     */
    public void increment() {
        add(1);
    }

    
Adds the given interval to the perf counter.
/**
     * Adds the given interval to the perf counter.
     */
    public void addTime(long interval) {
        add(interval);
    }

    
Adds the elapsed time from the given start time (ns) to the perf counter.
/**
     * Adds the elapsed time from the given start time (ns) to the perf counter.
     */
    public void addElapsedTimeFrom(long startTime) {
        add(System.nanoTime() - startTime);
    }

    @Override
    public String toString() {
        return name + " = " + get();
    }

    static class CoreCounters {
        static final PerfCounter pdt   = newPerfCounter("sun.classloader.parentDelegationTime");
        static final PerfCounter lc    = newPerfCounter("sun.classloader.findClasses");
        static final PerfCounter lct   = newPerfCounter("sun.classloader.findClassTime");
        static final PerfCounter rcbt  = newPerfCounter("sun.urlClassLoader.readClassBytesTime");
        static final PerfCounter zfc   = newPerfCounter("sun.zip.zipFiles");
        static final PerfCounter zfot  = newPerfCounter("sun.zip.zipFile.openTime");
    }

    
Number of findClass calls
/**
     * Number of findClass calls
     */
    public static PerfCounter getFindClasses() {
        return CoreCounters.lc;
    }

    
Time (ns) spent in finding classes that includes
lookup and read class bytes and defineClass
/**
     * Time (ns) spent in finding classes that includes
     * lookup and read class bytes and defineClass
     */
    public static PerfCounter getFindClassTime() {
        return CoreCounters.lct;
    }

    
Time (ns) spent in finding classes
/**
     * Time (ns) spent in finding classes
     */
    public static PerfCounter getReadClassBytesTime() {
        return CoreCounters.rcbt;
    }

    
Time (ns) spent in the parent delegation to
the parent of the defining class loader
/**
     * Time (ns) spent in the parent delegation to
     * the parent of the defining class loader
     */
    public static PerfCounter getParentDelegationTime() {
        return CoreCounters.pdt;
    }

    
Number of zip files opened.
/**
     * Number of zip files opened.
     */
    public static PerfCounter getZipFileCount() {
        return CoreCounters.zfc;
    }

    
Time (ns) spent in opening the zip files that
includes building the entries hash table
/**
     * Time (ns) spent in opening the zip files that
     * includes building the entries hash table
     */
    public static PerfCounter getZipFileOpenTime() {
        return CoreCounters.zfot;
    }

}