org.deephacks.tools4j.config.Index Maven / Gradle / Ivy
package org.deephacks.tools4j.config;
import org.deephacks.tools4j.config.query.ConfigQuery;
import org.deephacks.tools4j.config.query.ConfigQueryBuilder;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* This annotation is used to mark fields as indexed which is requirement when using
* {@link ConfigQuery} in order to compose queries.
*
* Every indexed field of bean instances are kept on-heap and enable queries with
* ultra-low latency over many instances.
*
* Instances themselves are generally not kept on-heap in order to lower the pressure
* on garbage collection. Usually instances are cached in direct memory off-heap,
* as directed by the cache manager. Indexes and caches are automatically kept in sync
* with bean manager storage as instances are administrated (created, updated, deleted).
*
* Note that a CacheManager MUST be available in order to perform queries. It is the
* CacheManager that store and fetch particular instances from query result sets.
*
* @see {@link ConfigQueryBuilder}
*/
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.TYPE, ElementType.FIELD })
@Inherited
public @interface Index {
}