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BTrace: A safe, dynamic tracing tool for the Java platform

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/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * version 2 for more details (a copy is included in the LICENSE file that
 * 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 static org.openjdk.btrace.core.BTraceUtils.println;

/**
 * This sample demonstrates that you can expose a BTrace
 * class as a JMX MBean. After connecting BTrace to the
 * target application, connect VisualVM or jconsole or
 * any other JMX client to the same application.
 */
@BTrace
public class ThreadCounterBean {

    // @Property makes the count field to be exposed
    // as an attribute of this MBean.
    @Property
    private static long count;

    @OnMethod(
            clazz = "java.lang.Thread",
            method = "start"
    )
    public static void onnewThread(@Self Thread t) {
        count++;
    }

    @OnTimer(2000)
    public static void ontimer() {
        println(count);
    }
}