/**
 *    Copyright (C) 2020-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the Server Side Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#pragma once

#include <map>
#include <string>

#include "mongo/db/operation_context.h"
#include "mongo/platform/mutex.h"

namespace mongo {

/**
 * ResourceConsumption maintains thread-safe access into a map of resource consumption Metrics.
 */
class ResourceConsumption {
public:
    static ResourceConsumption& get(OperationContext* opCtx);
    static ResourceConsumption& get(ServiceContext* svcCtx);

    /**
     * Metrics maintains non-thread-safe, per-operation resource consumption metrics for a specific
     * database.
     */
    class Metrics {
    public:
        static Metrics& get(OperationContext* opCtx);

        /**
         * Adds other Metrics to this one.
         */
        void add(const Metrics& other){};
        Metrics& operator+=(const Metrics& other) {
            add(other);
            return *this;
        }

        /**
         * Set the database name associated with these metrics.
         */
        void setDbName(const std::string& dbName) {
            _dbName = dbName;
        }

        const std::string& getDbName() const {
            return _dbName;
        }

    private:
        std::string _dbName;
    };

    /**
     * Adds a Metrics object to an existing Metrics object in the map, keyed by database name. If no
     * Metrics exist for the database, the value is initialized with the provided Metrics.
     *
     * The Metrics database name must not be an empty string.
     */
    void add(const Metrics& metrics);

    /**
     * Returns a copy of the Metrics map.
     */
    using MetricsMap = std::map<std::string, Metrics>;
    MetricsMap getMetrics() const;

private:
    // Protects _metrics
    mutable Mutex _mutex = MONGO_MAKE_LATCH("ResourceConsumption::_mutex");
    MetricsMap _metrics;
};

}  // namespace mongo