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 *    and Distribution License("CDDL") (collectively, the "License").  You
 *    may not use this file except in compliance with the License.  You can
 *    obtain a copy of the License at
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package fish.payara.nucleus.microprofile.config.spi;

import org.eclipse.microprofile.config.Config;
import org.eclipse.microprofile.config.spi.ConfigBuilder;
import org.eclipse.microprofile.config.spi.ConfigProviderResolver;

import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * This class was created to resolve race condition, caused by independent parallel initialization
 * of the server components, where some may init undesired automatical service lookup.
 * That lookup should lead to this class, which will block all requests until
 * this global resolver instance provided by the {@link ConfigProviderResolver#instance()} would
 * be replaced by the HK2 service.
 * 
 * The problem cannot be resolved by any other way, because Microprofile components use the global
 * service mechanism, which is not capable to inject HK2 dependencies.
 *
 * @author Patrik Dudits
 * @author David Matejcek
 */
public class ConfigProviderResolverSync extends ConfigProviderResolver {

    private static final Logger LOG = Logger.getLogger(ConfigProviderResolverSync.class.getName());

    /**
     * Logs the creation of this class on finest level.
     */
    public ConfigProviderResolverSync() {
        LOG.finest("ConfigProviderResolverSync()");
    }

    @Override
    public Config getConfig() {
        return await().getConfig();
    }

    @Override
    public Config getConfig(ClassLoader loader) {
        return await().getConfig(loader);
    }

    @Override
    public ConfigBuilder getBuilder() {
        return await().getBuilder();
    }

    @Override
    public void registerConfig(Config config, ClassLoader classLoader) {
        await().registerConfig(config, classLoader);
    }

    @Override
    public void releaseConfig(Config config) {
        await().releaseConfig(config);
    }


    private ConfigProviderResolver await() {
        LOG.log(Level.WARNING, "Payara Microprofile Config requested too early, the HK2 service is not initialized yet."
            + " Waiting until it will be active.");
        while (true) {
            final ConfigProviderResolver resolver = instance();
            if (resolver != null && resolver != this) {
                return resolver;
            }
            Thread.yield();
        }
    }
}