vrack-db/src/MetricWrite.ts

This is an In Memory database designed for storing time series (graphs).

/*
 * Copyright © 2023 Boris Bobylev. All rights reserved.
 * Licensed under the Apache License, Version 2.0
*/

import ErrorManager from "./Errors/ErrorManager";

ErrorManager.register('f0aInXAQsqNs', 'VDB_METRIC_MODIFY_TYPE', 'Unknown modify type')
/**
 * Helper for writing data to the database
*/
export default class MetricWrite {

    /**
     * Modifies the data before writing it to the database
     * 
     * By default, the `last' function is used in the database *
     * 
     * List of all modifiers:
     * - **last** - Permanently overwrites the metric index value
     * - **first** - Leaves the first metric value to be overwritten
     * - **max** - Overwrites the value if the new value is greater than the old one.
     * - **min** - Overwrites the value if the new value is less than the old value
     * - **avg** - Calculates the average value between the current value and the previous value.
     * - **sum** - Adds the current value to the past value
     * 
     * @param {number} a Current index value
     * @param {number} b New index value
     * @param {string} func Modification function
     * @return {number} New index value
    */
    static modify(a: number, b: number, func: string) {
        switch (func) {
            case 'last':
                return b
            case 'first':
                return a
            case 'max':
                if (b > a) return b; else return a
            case 'min':
                if (b < a) return b; else return a
            case 'avg':
                return a + b / 2
            case 'sum':
                return a + b
            default:
                throw ErrorManager.make(new Error, 'VDB_METRIC_MODIFY_TYPE', { func })
        }
    }
}