org.apache.hadoop.metrics2.lib.MethodMetric.java Source code

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Here is the source code for org.apache.hadoop.metrics2.lib.MethodMetric.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * 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
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.metrics2.lib;

import java.lang.reflect.Method;

import static com.google.common.base.Preconditions.*;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.apache.hadoop.metrics2.MetricsException;
import org.apache.hadoop.metrics2.MetricsRecordBuilder;
import org.apache.hadoop.metrics2.MetricsInfo;
import org.apache.hadoop.metrics2.annotation.Metric;
import static org.apache.hadoop.metrics2.util.Contracts.*;

/**
 * Metric generated from a method, mostly used by annotation
 */
class MethodMetric extends MutableMetric {
    private static final Log LOG = LogFactory.getLog(MethodMetric.class);

    private final Object obj;
    private final Method method;
    private final MetricsInfo info;
    private final MutableMetric impl;

    MethodMetric(Object obj, Method method, MetricsInfo info, Metric.Type type) {
        this.obj = checkNotNull(obj, "object");
        this.method = checkArg(method, method.getParameterTypes().length == 0,
                "Metric method should have no arguments");
        this.method.setAccessible(true);
        this.info = checkNotNull(info, "info");
        impl = newImpl(checkNotNull(type, "metric type"));
    }

    private MutableMetric newImpl(Metric.Type metricType) {
        Class<?> resType = method.getReturnType();
        switch (metricType) {
        case COUNTER:
            return newCounter(resType);
        case GAUGE:
            return newGauge(resType);
        case DEFAULT:
            return resType == String.class ? newTag(resType) : newGauge(resType);
        case TAG:
            return newTag(resType);
        default:
            checkArg(metricType, false, "unsupported metric type");
            return null;
        }
    }

    MutableMetric newCounter(final Class<?> type) {
        if (isInt(type) || isLong(type)) {
            return new MutableMetric() {
                @Override
                public void snapshot(MetricsRecordBuilder rb, boolean all) {
                    try {
                        Object ret = method.invoke(obj, (Object[]) null);
                        if (isInt(type))
                            rb.addCounter(info, ((Integer) ret).intValue());
                        else
                            rb.addCounter(info, ((Long) ret).longValue());
                    } catch (Exception ex) {
                        LOG.error("Error invoking method " + method.getName(), ex);
                    }
                }
            };
        }
        throw new MetricsException("Unsupported counter type: " + type.getName());
    }

    static boolean isInt(Class<?> type) {
        boolean ret = type == Integer.TYPE || type == Integer.class;
        return ret;
    }

    static boolean isLong(Class<?> type) {
        return type == Long.TYPE || type == Long.class;
    }

    static boolean isFloat(Class<?> type) {
        return type == Float.TYPE || type == Float.class;
    }

    static boolean isDouble(Class<?> type) {
        return type == Double.TYPE || type == Double.class;
    }

    MutableMetric newGauge(final Class<?> t) {
        if (isInt(t) || isLong(t) || isFloat(t) || isDouble(t)) {
            return new MutableMetric() {
                @Override
                public void snapshot(MetricsRecordBuilder rb, boolean all) {
                    try {
                        Object ret = method.invoke(obj, (Object[]) null);
                        if (isInt(t))
                            rb.addGauge(info, ((Integer) ret).intValue());
                        else if (isLong(t))
                            rb.addGauge(info, ((Long) ret).longValue());
                        else if (isFloat(t))
                            rb.addGauge(info, ((Float) ret).floatValue());
                        else
                            rb.addGauge(info, ((Double) ret).doubleValue());
                    } catch (Exception ex) {
                        LOG.error("Error invoking method " + method.getName(), ex);
                    }
                }
            };
        }
        throw new MetricsException("Unsupported gauge type: " + t.getName());
    }

    MutableMetric newTag(Class<?> resType) {
        if (resType == String.class) {
            return new MutableMetric() {
                @Override
                public void snapshot(MetricsRecordBuilder rb, boolean all) {
                    try {
                        Object ret = method.invoke(obj, (Object[]) null);
                        rb.tag(info, (String) ret);
                    } catch (Exception ex) {
                        LOG.error("Error invoking method " + method.getName(), ex);
                    }
                }
            };
        }
        throw new MetricsException("Unsupported tag type: " + resType.getName());
    }

    @Override
    public void snapshot(MetricsRecordBuilder builder, boolean all) {
        impl.snapshot(builder, all);
    }

    static MetricsInfo metricInfo(Method method) {
        return Interns.info(nameFrom(method), "Metric for " + method.getName());
    }

    static String nameFrom(Method method) {
        String methodName = method.getName();
        if (methodName.startsWith("get")) {
            return StringUtils.capitalize(methodName.substring(3));
        }
        return StringUtils.capitalize(methodName);
    }
}