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BTrace: A safe, dynamic tracing tool for the Java platform
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * accompanied this code).
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import org.openjdk.btrace.core.annotations.BTrace;
import org.openjdk.btrace.core.annotations.OnMethod;
import org.openjdk.btrace.core.annotations.OnTimer;
import org.openjdk.btrace.core.annotations.Property;
import org.openjdk.btrace.core.annotations.Self;

import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;

import static org.openjdk.btrace.core.BTraceUtils.*;

/**
 * This sample collects histogram of javax.swing.JComponets
 * created by traced app. The histogram is printed once
 * every 4 seconds. Also, this example exposes the trace class
 * as a JMX bean. After connecting BTrace to the target
 * application, connect VisualVM or jconsole or any other
 * JMX client to the same application.
 */
@BTrace
public class HistogramBean {
    // @Property exposes this field as MBean attribute
    @Property
    private static Map histo = newHashMap();

    @OnMethod(
            clazz = "javax.swing.JComponent",
            method = ""
    )
    public static void onnewObject(@Self Object obj) {
        String cn = name(classOf(obj));
        AtomicInteger ai = get(histo, cn);
        if (ai == null) {
            ai = newAtomicInteger(1);
            put(histo, cn, ai);
        } else {
            incrementAndGet(ai);
        }
    }

    @OnTimer(4000)
    public static void print() {
        if (size(histo) != 0) {
            printNumberMap("Component Histogram", histo);
        }
    }
}