/*
 * Copyright 2016 Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.keycloak.cluster;


import org.keycloak.provider.Provider;

import java.util.concurrent.Callable;

/**
 * Various utils related to clustering and concurrent tasks on cluster nodes
 *
 * @author <a href="mailto:mposolda@redhat.com">Marek Posolda</a>
 */
public interface ClusterProvider extends Provider {

    /**
     * Same value for all cluster nodes. It will use startup time of this server in non-cluster environment.
     */
    int getClusterStartupTime();


    /**
     * Execute given task just if it's not already in progress (either on this or any other cluster node).
     *
     * @param taskKey
     * @param taskTimeoutInSeconds timeout for given task. If there is existing task in progress for longer time, it's considered outdated so we will start our task.
     * @param task
     * @param <T>
     * @return result with "executed" flag specifying if execution was executed or ignored.
     */
    <T> ExecutionResult<T> executeIfNotExecuted(String taskKey, int taskTimeoutInSeconds, Callable<T> task);


    /**
     * Register task (listener) under given key. When this key will be put to the cache on any cluster node, the task will be executed.
     * When using {@link #ALL} as the taskKey, then listener will be always triggered for any value put into the cache.
     *
     * @param taskKey
     * @param task
     */
    void registerListener(String taskKey, ClusterListener task);


    /**
     * Notify registered listeners on all cluster nodes. It will notify listeners registered under given taskKey AND also listeners registered with {@link #ALL} key (those are always executed)
     *
     * @param taskKey
     * @param event
     * @param ignoreSender if true, then sender node itself won't receive the notification
     */
    void notify(String taskKey, ClusterEvent event, boolean ignoreSender);


    /**
     * Special value to be used with {@link #registerListener}  to specify that particular listener will be always triggered for all notifications
     * with any key.
     */
    String ALL = "ALL";
}