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/*
 * Licensed to Crate under one or more contributor license agreements.
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.  Crate 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.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial
 * agreement.
 */

package io.crate.jmx;

import javax.management.ObjectName;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * This object stores a mapping of mBean objectNames to mBean key property lists. The main purpose of it is to reduce
 * the frequency with which we invoke PROPERTY_PATTERN when discovering mBeans.
 *
 * Implementation derived from
 * https://github.com/prometheus/jmx_exporter/blob/master/collector/src/main/java/io/prometheus/jmx/JmxMBeanPropertyCache.java
 */
class MBeanPropertyCache {

    private static final Pattern PROPERTY_PATTERN = Pattern.compile(
            "([^,=:\\*\\?]+)" + // Name - non-empty, anything but comma, equals, colon, star, or question mark
                    "=" +  // Equals
                    "(" + // Either
                    "\"" + // Quoted
                    "(?:" + // A possibly empty sequence of
                    "[^\\\\\"]" + // Anything but backslash or quote
                    "|\\\\\\\\" + // or an escaped backslash
                    "|\\\\n" + // or an escaped newline
                    "|\\\\\"" + // or an escaped quote
                    "|\\\\\\?" + // or an escaped question mark
                    "|\\\\\\*" + // or an escaped star
                    ")*" +
                    "\"" +
                    "|" + // Or
                    "[^,=:\"]*" + // Unquoted - can be empty, anything but comma, equals, colon, or quote
                    ")");

    // Implement a version of ObjectName.getKeyPropertyList that returns the
    // properties in the order they were added.
    private final Map> keyPropertiesPerBean;

    MBeanPropertyCache() {
        this.keyPropertiesPerBean = new ConcurrentHashMap<>();
    }

    public LinkedHashMap getKeyPropertyList(ObjectName mbeanName) {
        LinkedHashMap keyProperties = keyPropertiesPerBean.get(mbeanName);
        if (keyProperties == null) {
            keyProperties = new LinkedHashMap<>();
            String properties = mbeanName.getKeyPropertyListString();
            Matcher match = PROPERTY_PATTERN.matcher(properties);
            while (match.lookingAt()) {
                keyProperties.put(match.group(1), match.group(2));
                properties = properties.substring(match.end());
                if (properties.startsWith(",")) {
                    properties = properties.substring(1);
                }
                match.reset(properties);
            }
            keyPropertiesPerBean.put(mbeanName, keyProperties);
        }
        return keyProperties;
    }
}