api/src/main/java/org/apache/edgent/window/Partition.java

/*
Licensed to the Apache Software Foundation (ASF) under one
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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

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specific language governing permissions and limitations
under the License.
*/
package org.apache.edgent.window;

import java.io.Serializable;
import java.util.List;

/**
 * A partition within a {@code Window}. The contents of the list
 * returned by {@code getContents} is stable when synchronizing 
 * on the partition object. For example:
 * 
 * <pre>{@code
 * Partition<Integer, Integer, ArrayList<Integer>> part = ...;
 * synchronized(part){
 *  List<Integer> = part.getContents();
 *  // stable operation on contents of partition
 * }
 * }</pre>
 *
 * @param <T> Type of tuples in the partition.
 * @param <K> Type of the partition's key.
 * @param <L> Type of the list holding the partition's tuples.
 * 
 * @see Window
 */
public interface Partition<T, K, L extends List<T>> extends Serializable{    
    /**
     * Offers a tuple to be inserted into the partition.
     * @param tuple Tuple to be offered.
     * @return True if the tuple was inserted into this partition, false if it was rejected.
     */
    boolean insert(T tuple);
        
    /**
     * Invoke the WindowProcessor's processWindow method. A partition processor
     * must be registered prior to invoking process().
     */
    void process();
    
    /** 
     * Calls the partition's evictDeterminer.
     */
    void evict();
    
    /**
     * Retrieves the window contents.
     * @return list of partition contents
     */
    L getContents();
    
    /**
     * Return the window in which this partition is contained.
     * @return the partition's window
     */
    Window<T, K, L> getWindow();
    
    /**
     * Returns the key associated with this partition
     * @return The key of the partition.
     */
    K getKey();
}