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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.sling.distribution.queue;
import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;
import aQute.bnd.annotation.ProviderType;
import org.apache.sling.distribution.serialization.DistributionPackage;
/**
* A queue is responsible for collecting the {@link DistributionPackage}s
* exported by a {@link org.apache.sling.distribution.agent.DistributionAgent} in
* order to be able to process them also when there are multiple (concurrent)
* {@link org.apache.sling.distribution.DistributionRequest}s executed
* on that same agent.
* <p/>
* The items (packages) in the queue can then get processed according to a FIFO
* strategy or in parallel, or some other way, via {@link org.apache.sling.distribution.queue.DistributionQueueProcessor}s.
*/
@ProviderType
public interface DistributionQueue {
/**
* get this queue name
*
* @return the queue name
*/
@Nonnull
String getName();
/**
* add a distribution item to this queue
*
* @param item a distribution item, typically representing a {@link DistributionPackage}
* to distribute
* @return the queue entry created for this item or {@code noll} if none is created
*/
DistributionQueueEntry add(@Nonnull DistributionQueueItem item);
/**
* get the first item (in a FIFO strategy, the next to be processed) from the queue
*
* @return the first item into the queue or {@code null} if the queue is empty
*/
@CheckForNull
DistributionQueueEntry getHead();
/**
* get all the items in the queue
*
* @param skip the number of items to skip
* @param limit the maximum number of items to return. use -1 to return all items.
* @return a {@link java.lang.Iterable} of {@link DistributionQueueItem}s
*/
@Nonnull
Iterable<DistributionQueueEntry> getItems(int skip, int limit);
/**
* gets an item from the queue by specifying its id
*
* @param itemId the id of the item
* @return the item, or {@code null} if the item with the given id
* doesn't exist
*/
@CheckForNull
DistributionQueueEntry getItem(@Nonnull String itemId);
/**
* remove an item from the queue by specifying its id
*
* @param itemId the id the item
* @return the removed item, or {@code null} if the item with the given id
* doesn't exist
*/
@CheckForNull
DistributionQueueEntry remove(@Nonnull String itemId);
/**
* returns the status of the queue
* @return the queue status
*/
@Nonnull
DistributionQueueStatus getStatus();
}