lib/src/support/bus/queue/QueueFactory.ts

import {
    AbstractFactory,
    Container,
    DependencyRequirement,
    PropertyDependency,
    isInstantiable,
    DEPENDENCY_KEYS_METADATA_KEY,
    DEPENDENCY_KEYS_PROPERTY_METADATA_KEY,
    StaticInstantiable,
    FactoryProducer,
} from '../../../di'
import {Collection, ErrorWithContext} from '../../../util'
import {Logging} from '../../../service/Logging'
import {Config} from '../../../service/Config'
import {Queue} from './Queue'
import {SyncQueue} from './SyncQueue'

/**
 * Dependency container factory that matches the abstract Queue token, but
 * produces an instance of whatever Queue driver is configured in the `server.queue.driver` config.
 */
@FactoryProducer()
export class QueueFactory extends AbstractFactory<Queue> {
    /** true if we have printed the synchronous queue driver warning once. */
    private static loggedSyncQueueWarningOnce = false

    private di(): [Logging, Config] {
        return [
            Container.getContainer().make(Logging),
            Container.getContainer().make(Config),
        ]
    }

    produce(): Queue {
        return new (this.getQueueClass())()
    }

    match(something: unknown): boolean {
        return something === Queue
    }

    getDependencyKeys(): Collection<DependencyRequirement> {
        const meta = Reflect.getMetadata(DEPENDENCY_KEYS_METADATA_KEY, this.getQueueClass())
        if ( meta ) {
            return meta
        }
        return new Collection<DependencyRequirement>()
    }

    getInjectedProperties(): Collection<PropertyDependency> {
        const meta = new Collection<PropertyDependency>()
        let currentToken = this.getQueueClass()

        do {
            const loadedMeta = Reflect.getMetadata(DEPENDENCY_KEYS_PROPERTY_METADATA_KEY, currentToken)
            if ( loadedMeta ) {
                meta.concat(loadedMeta)
            }
            currentToken = Object.getPrototypeOf(currentToken)
        } while (Object.getPrototypeOf(currentToken) !== Function.prototype && Object.getPrototypeOf(currentToken) !== Object.prototype)

        return meta
    }

    /**
     * Get the configured queue driver and return some Instantiable<Queue>.
     * @protected
     */
    protected getQueueClass(): StaticInstantiable<Queue> {
        const [logging, config] = this.di()
        const QueueClass = config.get('server.queue.driver', SyncQueue)
        if ( QueueClass === SyncQueue && !QueueFactory.loggedSyncQueueWarningOnce ) {
            logging.warn(`You are using the default synchronous queue driver. It is recommended you configure a background queue driver instead.`)
            QueueFactory.loggedSyncQueueWarningOnce = true
        }

        if ( !isInstantiable(QueueClass) || !(QueueClass.prototype instanceof Queue) ) {
            const e = new ErrorWithContext('Provided queue class does not extend from @extollo/lib.Queue')
            e.context = {
                configKey: 'server.queue.driver',
                class: QueueClass.toString(),
            }
        }

        return QueueClass
    }
}