com.opsbears.webcomponents.servicepool.StartupService Maven / Gradle / Ivy

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package com.opsbears.webcomponents.servicepool;

import javax.annotation.ParametersAreNonnullByDefault;
import java.util.Collection;
import java.util.Collections;
import java.util.concurrent.Future;

/**
 * The startup service launches a task at startup and returns the healthy status once the task is completed.
 */
@ParametersAreNonnullByDefault
public class StartupService extends AbstractService {
    public StartupService(
        String name,
        Runnable runnable,
        StatusChangeListener statusChangeListener
    ) {
        super(name, Collections.emptyList(), Collections.emptyList(), statusChangeListener, runnable);
    }

    public StartupService(
        String name,
        Runnable runnable,
        StatusChangeListener statusChangeListener,
        Collection needs,
        Collection provides
    ) {
        super(name, needs, provides, statusChangeListener, runnable);
    }

    @Override
    public Future start() throws ServiceAlreadyRunningException {
        synchronized (statusLock) {
            if (status == Status.STARTING || status == Status.HEALTHY || status == Status.UNHEALTHY || status == Status.STOPPING) {
                throw new ServiceAlreadyRunningException();
            }
            status = Status.STARTING;
            statusChangeListener.onStatusChange(this, status);
            Future future = executor.submit(new RunnableProxy());
            return new ProxyFuture(future, service, service::updateTerminatedStatus);
        }
    }

    private class RunnableProxy implements Runnable {
        @Override
        public void run() {
            try {
                runnable.run();
                synchronized (statusLock) {
                    if (status == Status.STARTING) {
                        status = Status.HEALTHY;
                        statusChangeListener.onStatusChange(service, status);
                    }
                }
            } catch (RuntimeException e) {
                synchronized (statusLock) {
                    if (status == Status.STARTING) {
                        status = Status.CRASHED;
                        crashException = e;
                        statusChangeListener.onStatusChange(service, status);
                    }
                }
            }
        }
    }
}