vulcain-corejs/dist/commands/command/circuitBreaker.js

Vulcain micro-service framework

"use strict";
const actualTime_1 = require("../../utils/actualTime");
const commandMetricsFactory_1 = require("../metrics/commandMetricsFactory");
class NoOpCircuitBreaker {
    constructor(commandKey, properties) {
        this.commandKey = commandKey;
        this.properties = properties;
    }
    allowRequest() { return true; }
    markSuccess() { }
    isOpen() { return false; }
}
class DefaultCircuitBreaker {
    constructor(commandKey, properties) {
        this.commandKey = commandKey;
        this.properties = properties;
        this.circuitOpen = false;
        this.circuitOpenedOrLastTestedTime = actualTime_1.default.getCurrentTime();
    }
    allowRequest() {
        if (this.properties.circuitBreakerForceOpen.value) {
            return false;
        }
        if (this.properties.circuitBreakerForceClosed.value) {
            this.isOpen();
            return true;
        }
        return !this.isOpen() || this.allowSingleTest();
    }
    get metrics() {
        return commandMetricsFactory_1.CommandMetricsFactory.getOrCreate(this.properties);
    }
    allowSingleTest() {
        if (this.circuitOpen && actualTime_1.default.getCurrentTime() > this.circuitOpenedOrLastTestedTime + this.properties.circuitBreakerSleepWindowInMilliseconds.value) {
            this.circuitOpenedOrLastTestedTime = actualTime_1.default.getCurrentTime();
            return true;
        }
        else {
            return false;
        }
    }
    isOpen() {
        if (this.circuitOpen) {
            return true;
        }
        let { totalCount = 0, errorCount, errorPercentage } = this.metrics.getHealthCounts();
        if (totalCount < this.properties.circuitBreakerRequestVolumeThreshold.value) {
            return false;
        }
        if (errorPercentage > this.properties.circuitBreakerErrorThresholdPercentage.value) {
            this.circuitOpen = true;
            this.circuitOpenedOrLastTestedTime = actualTime_1.default.getCurrentTime();
            return true;
        }
        else {
            return false;
        }
    }
    markSuccess() {
        if (this.circuitOpen) {
            this.circuitOpen = false;
            this.metrics.reset();
        }
    }
}
const circuitBreakersByCommand = new Map();
class CircuitBreakerFactory {
    static getOrCreate(properties) {
        let previouslyCached = circuitBreakersByCommand.get(properties.commandName);
        if (previouslyCached) {
            return previouslyCached;
        }
        let circuitBreaker = properties.circuitBreakerEnabled ?
            new DefaultCircuitBreaker(properties.commandName, properties) :
            new NoOpCircuitBreaker(properties.commandName, properties);
        circuitBreakersByCommand.set(properties.commandName, circuitBreaker);
        return circuitBreakersByCommand.get(properties.commandName);
    }
    static get(commandName) {
        return circuitBreakersByCommand.get(commandName);
    }
    static getCache() {
        return circuitBreakersByCommand;
    }
    static resetCache() {
        circuitBreakersByCommand.clear();
    }
}
exports.CircuitBreakerFactory = CircuitBreakerFactory;

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