genetic-search/es/scheduler.js

Multiprocessing genetic algorithm implementation library

import { ArrayManager } from "./utils";
/**
 * A scheduler for a genetic search algorithm.
 *
 * The scheduler is responsible for executing scheduled tasks or operations
 * in the genetic search algorithm.
 *
 * @template TGenome The type of genome objects in the population.
 * @template TConfig The type of configuration object of macro parameters,
 * which the scheduler will be able to manipulate.
 *
 * @category Scheduler
 */
export class Scheduler {
    /**
     * Constructor of the Scheduler class.
     *
     * @param params - The parameters to initialize the scheduler.
     */
    constructor(params) {
        /**
         * An array of log messages generated by the scheduler.
         */
        this.logs = [];
        /**
         * The history of population summaries.
         */
        this.history = [];
        this.runner = params.runner;
        this.config = params.config;
        this.actions = params.actions;
        this.maxHistoryLength = params.maxHistoryLength;
        this.logger = (message) => {
            this.logs.push(message);
        };
    }
    /**
     * Executes a single step or iteration in the scheduler.
     */
    step(evaluatedPopulation) {
        this.clearLogs();
        this.handleHistory();
        for (const rule of this.actions) {
            try {
                rule(this.getRuleInput(evaluatedPopulation));
            }
            catch (e) {
                if (e.name === 'SchedulerConditionException') {
                    continue;
                }
                throw e;
            }
        }
    }
    /**
     * Handles the history of population summaries.
     *
     * Adds the current population summary to the history. If the history
     * exceeds the maximum allowed length, it trims the oldest entries.
     */
    handleHistory() {
        this.history.push(this.runner.getPopulationSummary());
        if (this.history.length >= this.maxHistoryLength) {
            this.history = this.history.slice(this.history.length - this.maxHistoryLength);
        }
    }
    /**
     * Constructs the input data for a scheduler rule.
     *
     * This input is used by both the `condition` and `action` functions
     * of a scheduler rule.
     *
     * @returns An object containing the runner, history, config, and logger.
     */
    getRuleInput(evaluatedPopulation) {
        const evaluatedPopulationManager = new ArrayManager(evaluatedPopulation);
        return {
            runner: this.runner,
            evaluatedPopulation,
            evaluatedPopulationManager,
            history: this.history,
            config: this.config,
            logger: this.logger,
        };
    }
    /**
     * Clears all the logs stored in the scheduler.
     */
    clearLogs() {
        this.logs.length = 0;
    }
}
/**
 * An exception thrown when a scheduler condition is not satisfied.
 *
 * This exception is thrown when a scheduler rule's condition function
 * returns false.
 *
 * @category Exceptions
 * @category Scheduler
 */
export class SchedulerConditionException extends Error {
    constructor() {
        super();
        this.name = 'SchedulerConditionException';
    }
}
/**
 * Checks if a scheduler condition is satisfied.
 *
 * If the condition is not satisfied, this function throws a {@link SchedulerConditionException}`.
 *
 * @see SchedulerConditionException
 *
 * @param condition - The result of the scheduler condition check.
 *
 * @category Scheduler
 */
export function checkSchedulerCondition(condition) {
    if (!condition) {
        throw new SchedulerConditionException();
    }
}
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