CacheManager.java

package org.drip.service.env;

/*
 * -*- mode: java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 */

/*!
 * Copyright (C) 2020 Lakshmi Krishnamurthy
 * Copyright (C) 2019 Lakshmi Krishnamurthy
 * Copyright (C) 2018 Lakshmi Krishnamurthy
 * Copyright (C) 2017 Lakshmi Krishnamurthy
 * Copyright (C) 2016 Lakshmi Krishnamurthy
 * Copyright (C) 2015 Lakshmi Krishnamurthy
 * 
 *  This file is part of DROP, an open-source library targeting analytics/risk, transaction cost analytics,
 *      asset liability management analytics, capital, exposure, and margin analytics, valuation adjustment
 *      analytics, and portfolio construction analytics within and across fixed income, credit, commodity,
 *      equity, FX, and structured products. It also includes auxiliary libraries for algorithm support,
 *      numerical analysis, numerical optimization, spline builder, model validation, statistical learning,
 *      and computational support.
 *  
 *      https://lakshmidrip.github.io/DROP/
 *  
 *  DROP is composed of three modules:
 *  
 *  - DROP Product Core - https://lakshmidrip.github.io/DROP-Product-Core/
 *  - DROP Portfolio Core - https://lakshmidrip.github.io/DROP-Portfolio-Core/
 *  - DROP Computational Core - https://lakshmidrip.github.io/DROP-Computational-Core/
 * 
 *  DROP Product Core implements libraries for the following:
 *  - Fixed Income Analytics
 *  - Loan Analytics
 *  - Transaction Cost Analytics
 * 
 *  DROP Portfolio Core implements libraries for the following:
 *  - Asset Allocation Analytics
 *  - Asset Liability Management Analytics
 *  - Capital Estimation Analytics
 *  - Exposure Analytics
 *  - Margin Analytics
 *  - XVA Analytics
 * 
 *  DROP Computational Core implements libraries for the following:
 *  - Algorithm Support
 *  - Computation Support
 *  - Function Analysis
 *  - Model Validation
 *  - Numerical Analysis
 *  - Numerical Optimizer
 *  - Spline Builder
 *  - Statistical Learning
 * 
 *  Documentation for DROP is Spread Over:
 * 
 *  - Main                     => https://lakshmidrip.github.io/DROP/
 *  - Wiki                     => https://github.com/lakshmiDRIP/DROP/wiki
 *  - GitHub                   => https://github.com/lakshmiDRIP/DROP
 *  - Repo Layout Taxonomy     => https://github.com/lakshmiDRIP/DROP/blob/master/Taxonomy.md
 *  - Javadoc                  => https://lakshmidrip.github.io/DROP/Javadoc/index.html
 *  - Technical Specifications => https://github.com/lakshmiDRIP/DROP/tree/master/Docs/Internal
 *  - Release Versions         => https://lakshmidrip.github.io/DROP/version.html
 *  - Community Credits        => https://lakshmidrip.github.io/DROP/credits.html
 *  - Issues Catalog           => https://github.com/lakshmiDRIP/DROP/issues
 *  - JUnit                    => https://lakshmidrip.github.io/DROP/junit/index.html
 *  - Jacoco                   => https://lakshmidrip.github.io/DROP/jacoco/index.html
 * 
 *  Licensed 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.
 */

/**
 * <i>CacheManager</i> implements the DRIP Cache Management Functionality, and contains the Functions to Add,
 * Delete, Retrieve, and Time out a Key-Value Pair along the lines of memcached.
 * 
 * <br><br>
 *  <ul>
 *      <li><b>Module </b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/ComputationalCore.md">Computational Core Module</a></li>
 *      <li><b>Library</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/ComputationSupportLibrary.md">Computation Support</a></li>
 *      <li><b>Project</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/src/main/java/org/drip/service/README.md">Environment, Product/Definition Containers, and Scenario/State Manipulation APIs</a></li>
 *      <li><b>Package</b> = <a href = "https://github.com/lakshmiDRIP/DROP/tree/master/src/main/java/org/drip/service/env/README.md">Library Module Loader Environment Manager</a></li>
 *  </ul>
 * <br><br>
 *
 * @author Lakshmi Krishnamurthy
 */

public class CacheManager {
    private static final boolean s_bLog = true;
    private static java.util.concurrent.ConcurrentHashMap<java.lang.String, java.lang.String> s_mapCache =
        null;

    private static final java.util.concurrent.ScheduledExecutorService _ses =
        java.util.concurrent.Executors.newScheduledThreadPool (1);

    /**
     * Initialize the Cache Manager
     * 
     * @return TRUE - The Cache Manager successfully initialized
     */

    public static final boolean Init()
    {
        if (null != s_mapCache) return true;

        s_mapCache = new java.util.concurrent.ConcurrentHashMap<java.lang.String, java.lang.String>();

        return true;
    }

    /**
     * The Put Method adds a Key/Value Pair to the In-Memory KV Store
     * 
     * @param strKey The Key
     * @param strValue The Value
     * @param lSecondsToExpiry The Time to Expiry of the Key/Value Pair
     * 
     * @return Return Value from the Underlying HashMap.put
     */

    public static final java.lang.String Put (
        final java.lang.String strKey,
        final java.lang.String strValue,
        final long lSecondsToExpiry)
    {
        if (null == strKey || strKey.isEmpty() || null == strValue || strValue.isEmpty()) return null;

        if (0 < lSecondsToExpiry) {
            java.lang.Runnable timedTask = new java.lang.Runnable() {
                @Override public void run() {
                    if (s_bLog)
                        System.out.println ("\t\t[" + new java.util.Date() + "] Removing " + strKey +
                            " from Thread " + java.lang.Thread.currentThread());

                    if (s_mapCache.contains (strKey)) s_mapCache.remove (strKey);
                }
            };

            _ses.schedule (timedTask, lSecondsToExpiry, java.util.concurrent.TimeUnit.SECONDS);
        }

        return s_mapCache.put (strKey, strValue);
    }

    /**
     * The Contains Method checks the Presence of the specified Key
     * 
     * @param strKey The Key
     * 
     * @return Return Value from the Underlying HashMap.contains
     */

    public static final boolean Contains (
        final java.lang.String strKey)
    {
        if (null == strKey || strKey.isEmpty()) return false;

        return s_mapCache.contains (strKey);
    }

    /**
     * The Get Method retrieves the Value given the Key
     * 
     * @param strKey The Key
     * 
     * @return Return Value from the Underlying HashMap.get
     */

    public static final java.lang.String Get (
        final java.lang.String strKey)
    {
        if (null == strKey || strKey.isEmpty()) return null;

        return s_mapCache.get (strKey);
    }
}