com.github.rahulsom.grooves.grails.BlockingSnapshotSource Maven / Gradle / Ivy

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Integration with Grails' GORM API
There is a newer version: 0.6.1
package com.github.rahulsom.grooves.grails;

import com.github.rahulsom.grooves.api.AggregateType;
import com.github.rahulsom.grooves.api.events.BaseEvent;
import com.github.rahulsom.grooves.api.snapshots.Snapshot;
import com.github.rahulsom.grooves.queries.QuerySupport;
import com.github.rahulsom.grooves.queries.internal.BaseQuery;
import org.codehaus.groovy.runtime.DefaultGroovyMethods;
import org.grails.datastore.gorm.GormEntity;
import rx.Observable;

import java.util.Date;
import java.util.List;

import static com.github.rahulsom.grooves.grails.QueryUtil.LATEST_BY_POSITION;
import static com.github.rahulsom.grooves.grails.QueryUtil.LATEST_BY_TIMESTAMP;
import static com.github.rahulsom.grooves.grails.QueryUtil.SNAPSHOTS_BY_AGGREGATE;
import static org.codehaus.groovy.runtime.InvokerHelper.invokeStaticMethod;
import static rx.Observable.defer;
import static rx.Observable.empty;
import static rx.Observable.just;

/**
 * Supplies Snapshots from a Blocking Gorm Source.
 *
 * @param   The aggregate over which the query executes
 * @param     The type of the Event's id field
 * @param       The type of the Event
 * @param  The type of the Snapshot's id field
 * @param    The type of the Snapshot
 *
 * @author Rahul Somasunderam
 */
public interface BlockingSnapshotSource<
        AggregateIdT,
        AggregateT extends AggregateType,
        EventIdT,
        EventT extends BaseEvent,
        SnapshotIdT,
        SnapshotT extends Snapshot &
                GormEntity,
        QueryT extends BaseQuery
        > extends QuerySupport {

    SnapshotT detachSnapshot(SnapshotT snapshot);

    @Override
    default Observable getSnapshot(long maxPosition, AggregateT aggregate) {
        return defer(() -> {
            //noinspection unchecked
            List snapshots = (List) (maxPosition == Long.MAX_VALUE ?
                    invokeStaticMethod(
                            getSnapshotClass(),
                            SNAPSHOTS_BY_AGGREGATE,
                            new Object[]{aggregate.getId(), LATEST_BY_POSITION}) :
                    invokeStaticMethod(
                            getSnapshotClass(),
                            QueryUtil.SNAPSHOTS_BY_POSITION,
                            new Object[]{aggregate.getId(), maxPosition, LATEST_BY_POSITION}));

            return DefaultGroovyMethods.asBoolean(snapshots) ?
                    just(detachSnapshot(snapshots.get(0))) :
                    empty();
        });
    }

    @Override
    default Observable getSnapshot(Date maxTimestamp, AggregateT aggregate) {
        return defer(() -> {
            //noinspection unchecked
            List snapshots = (List) (maxTimestamp == null ?
                    invokeStaticMethod(
                            getSnapshotClass(),
                            SNAPSHOTS_BY_AGGREGATE,
                            new Object[]{aggregate.getId(), LATEST_BY_TIMESTAMP}) :
                    invokeStaticMethod(
                            getSnapshotClass(),
                            QueryUtil.SNAPSHOTS_BY_TIMETTAMP,
                            new Object[]{aggregate.getId(), maxTimestamp, LATEST_BY_TIMESTAMP}));
            return DefaultGroovyMethods.asBoolean(snapshots) ?
                    just(detachSnapshot(snapshots.get(0))) :
                    empty();
        });
    }

    Class getSnapshotClass();

}