ReflectionUtils.java

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// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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// software distributed under the License is distributed on an
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// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
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package org.apache.doris.common.util;

import com.google.common.collect.ImmutableMap;
import org.apache.logging.log4j.Logger;

import java.io.ByteArrayOutputStream;
import java.io.PrintWriter;
import java.lang.management.ManagementFactory;
import java.lang.management.ThreadInfo;
import java.lang.management.ThreadMXBean;
import java.lang.reflect.Constructor;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;

public class ReflectionUtils {
    private static final Class[] emptyArray = new Class[]{};
    private static final Map<Class, Class> boxToPrimitiveTypes = ImmutableMap.<Class, Class>builder()
            .put(Boolean.class, boolean.class)
            .put(Character.class, char.class)
            .put(Byte.class, byte.class)
            .put(Short.class, short.class)
            .put(Integer.class, int.class)
            .put(Long.class, long.class)
            .put(Float.class, float.class)
            .put(Double.class, double.class)
            .build();

    /**
     * Cache of constructors for each class. Pins the classes so they
     * can't be garbage collected until ReflectionUtils can be collected.
     */
    private static final Map<Class<?>, Constructor<?>> CONSTRUCTOR_CACHE =
            new ConcurrentHashMap<Class<?>, Constructor<?>>();

    /** Create an object for the given class and initialize it from conf
     * @param theClass class of which an object is created
     * @return a new object
     */
    public static <T> T newInstance(Class<T> theClass) {
        T result;
        try {
            Constructor<T> meth = (Constructor<T>) CONSTRUCTOR_CACHE.get(theClass);
            if (meth == null) {
                meth = theClass.getDeclaredConstructor(emptyArray);
                meth.setAccessible(true);
                CONSTRUCTOR_CACHE.put(theClass, meth);
            }
            result = meth.newInstance();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        return result;
    }

    private static ThreadMXBean threadBean =
            ManagementFactory.getThreadMXBean();

    public static void setContentionTracing(boolean val) {
        threadBean.setThreadContentionMonitoringEnabled(val);
    }

    private static String getTaskName(long id, String name) {
        if (name == null) {
            return Long.toString(id);
        }
        return id + " (" + name + ")";
    }

    /**
     * Print all of the thread's information and stack traces.
     *
     * @param stream the stream to
     * @param title a string title for the stack trace
     */
    public static void printThreadInfo(PrintWriter stream, String title) {
        final int stackDepth = 20;
        boolean contention = threadBean.isThreadContentionMonitoringEnabled();
        long[] threadIds = threadBean.getAllThreadIds();
        stream.println("Process Thread Dump: " + title);
        stream.println(threadIds.length + " active threads");

        for (long tid : threadIds) {
            ThreadInfo info = threadBean.getThreadInfo(tid, stackDepth);
            if (info == null) {
                stream.println("  Inactive");
                continue;
            }
            stream.println("Thread "
                    + getTaskName(info.getThreadId(), info.getThreadName()) + ":");
            Thread.State state = info.getThreadState();
            stream.println("  State: " + state);
            stream.println("  Blocked count: " + info.getBlockedCount());
            stream.println("  Waited count: " + info.getWaitedCount());
            if (contention) {
                stream.println("  Blocked time: " + info.getBlockedTime());
                stream.println("  Waited time: " + info.getWaitedTime());
            }
            if (state == Thread.State.WAITING) {
                stream.println("  Waiting on " + info.getLockName());
            } else  if (state == Thread.State.BLOCKED) {
                stream.println("  Blocked on " + info.getLockName());
                stream.println("  Blocked by "
                        + getTaskName(info.getLockOwnerId(), info.getLockOwnerName()));
            }
            stream.println("  Stack:");
            for (StackTraceElement frame : info.getStackTrace()) {
                stream.println("    " + frame.toString());
            }
        }

        stream.flush();
    }

    private static long previousLogTime = 0;

    /**
     * Log the current thread stacks at INFO level.
     * @param log the logger that logs the stack trace
     * @param title a descriptive title for the call stacks
     * @param minInterval the minimum time from the last
     */
    public static void logThreadInfo(Logger log, String title, long minInterval) {
        boolean dumpStack = false;
        if (log.isInfoEnabled()) {
            synchronized (ReflectionUtils.class) {
                long now = System.currentTimeMillis();
                if (now - previousLogTime >= minInterval * 1000) {
                    previousLogTime = now;
                    dumpStack = true;
                }
            }

            if (dumpStack) {
                ByteArrayOutputStream buffer = new ByteArrayOutputStream();
                printThreadInfo(new PrintWriter(buffer), title);
                log.info(buffer.toString());
            }
        }
    }

    /**
     * Return the correctly-typed {@link Class} of the given object.
     *
     * @param o object whose correctly-typed <code>Class</code> is to be obtained
     * @return the correctly typed <code>Class</code> of the given object.
     */
    public static <T> Class<T> getClass(T o) {
        return (Class<T>) o.getClass();
    }

    // methods to support testing
    static void clearCache() {
        CONSTRUCTOR_CACHE.clear();
    }

    static int getCacheSize() {
        return CONSTRUCTOR_CACHE.size();
    }

    public static Optional<Class> getPrimitiveType(Class<?> targetClass) {
        if (targetClass.isPrimitive()) {
            return Optional.of(targetClass);
        }
        return Optional.ofNullable(boxToPrimitiveTypes.get(targetClass));
    }
}