org.apache.metron.common.message.metadata.MetadataUtil.java Source code

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Here is the source code for org.apache.metron.common.message.metadata.MetadataUtil.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.metron.common.message.metadata;

import org.apache.commons.lang3.StringUtils;
import org.apache.metron.common.utils.JSONUtils;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Tuple;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.lang.invoke.MethodHandles;
import java.util.HashMap;
import java.util.Map;

/**
 * Captures some common utility methods around metadata manipulation.
 */
public enum MetadataUtil {
    INSTANCE;
    private static final Logger LOG = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
    /**
     * The default metadata prefix.
     */
    public static final String METADATA_PREFIX = "metron.metadata";
    /**
     * The config key for defining the prefix.
     */
    public static final String METADATA_PREFIX_CONFIG = "metadataPrefix";
    static final int KEY_INDEX = 1;

    /**
     * Return the prefix that we want to use for metadata keys.  This comes from the config and is defaulted to
     * 'metron.metadata'.
     *
     * @param config The rawMessageStrategyConfig
     * @return
     */
    public String getMetadataPrefix(Map<String, Object> config) {
        String prefix = (String) config.getOrDefault(METADATA_PREFIX_CONFIG, METADATA_PREFIX);
        if (StringUtils.isEmpty(prefix)) {
            return null;
        }
        return prefix;
    }

    /**
     * Take a field and prefix it with the metadata key.
     *
     * @param prefix The metadata prefix to use (e.g. 'foo')
     * @param key The key name (e.g. my_field)
     * @return The prefixed key separated by a . (e.g. foo.my_field)
     */
    public String prefixKey(String prefix, String key) {
        if (StringUtils.isEmpty(prefix)) {
            return key;
        } else {
            return prefix + "." + key;
        }
    }

    /**
     * Default extraction of metadata.  This handles looking in the normal places for metadata
     * <ul>
     *   <li>The kafka key</li>
     *   <li>The tuple fields outside of the value (e.g. the topic)</li>
     * </ul>
     * In addition to extracting the metadata into a map, it applies the appropriate prefix (as configured in the rawMessageStrategyConfig).
     * @param prefix
     * @param t
     * @return
     */
    public Map<String, Object> extractMetadata(String prefix, Tuple t) {
        Map<String, Object> metadata = new HashMap<>();
        if (t == null) {
            return metadata;
        }
        Fields tupleFields = t.getFields();
        if (tupleFields == null) {
            return metadata;
        }
        for (int i = 2; i < tupleFields.size(); ++i) {
            String envMetadataFieldName = tupleFields.get(i);
            Object envMetadataFieldValue = t.getValue(i);
            if (!StringUtils.isEmpty(envMetadataFieldName) && envMetadataFieldValue != null) {
                metadata.put(prefixKey(prefix, envMetadataFieldName), envMetadataFieldValue);
            }
        }
        byte[] keyObj = t.getBinary(KEY_INDEX);
        String keyStr = null;
        try {
            keyStr = keyObj == null ? null : new String(keyObj);
            if (!StringUtils.isEmpty(keyStr)) {
                Map<String, Object> rawMetadata = JSONUtils.INSTANCE.load(keyStr, JSONUtils.MAP_SUPPLIER);
                for (Map.Entry<String, Object> kv : rawMetadata.entrySet()) {
                    metadata.put(prefixKey(prefix, kv.getKey()), kv.getValue());
                }

            }
        } catch (IOException e) {
            String reason = "Unable to parse metadata; expected JSON Map: "
                    + (keyStr == null ? "NON-STRING!" : keyStr);
            LOG.error(reason, e);
            throw new IllegalStateException(reason, e);
        }
        return metadata;
    }
}