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Event capture and querying framework for Java
There is a newer version: 0.4.6
/**
 * Copyright (c) 2016, All Contributors (see CONTRIBUTORS file)
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
package com.eventsourcing;

import com.eventsourcing.hlc.HybridTimestamp;
import com.google.common.util.concurrent.Service;
import com.googlecode.cqengine.index.support.CloseableIterator;
import lombok.SneakyThrows;

import java.util.Optional;
import java.util.Set;
import java.util.UUID;
import java.util.function.Consumer;
import java.util.stream.Stream;

/**
 * Journal is the storage of all events and commands registered
 * through Eventsourcing.
 */
public interface Journal extends Service {

    Listener DEFAULT_LISTENER = new Listener() {};

    default void onCommandsAdded(Set> commands) {}

    default void onEventsAdded(Set> events) {}

    /**
     * Set repository. Should be done before invoking {@link #startAsync()}
     *
     * @param repository
     */
    void setRepository(Repository repository);

    /**
     * Get repository
     * @return
     */
    Repository getRepository();

    /**
     * Retrieves a command or event by UUID
     *
     * @param uuid
     * @param 
     * @return Empty {@link Optional} if neither a command nor an event are found by uuid
     */
     Optional get(UUID uuid);

    /**
     * Iterate over commands of a specific type (through {@code EntityHandler})
     *
     * @param klass
     * @param 
     * @return iterator
     */
    > CloseableIterator> commandIterator(Class klass);

    /**
     * Iterate over events of a specific type (through {@code EntityHandler})
     *
     * @param klass
     * @param 
     * @return iterator
     */
     CloseableIterator> eventIterator(Class klass);

    /**
     * Removes everything from the journal.
     * 
     * Use with caution: the data will be lost irrevocably
     */
    void clear();

    /**
     * Returns the count of entities of specified type
     *
     * @param klass
     * @param 
     * @return
     */
     long size(Class klass);

    /**
     * Returns true if there are no entities of specified type stored
     *
     * @param klass
     * @param 
     * @return
     */
     boolean isEmpty(Class klass);

    /**
     * Record command within a transaction
     * @param tx
     * @param command
     * @param 
     * @param 
     * @return
     */
     Command journal(Transaction tx, Command command);

    /**
     * Record event within a transaction
     * @param tx
     * @param event
     * @return
     */
    Event journal(Transaction tx, Event event);

    /**
     * Starts a transaction
     * @return
     */
    Transaction beginTransaction();

    /**
     * An interface abstracting journal's transaction
     */
    interface Transaction {
        void commit();
        void rollback();
    }

}