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Entity implementation classes, events, and other core elements

There is a newer version: 0.7.0-M1

package brooklyn.entity.basic;

import java.util.Collection;

import brooklyn.entity.Entity;
import brooklyn.entity.Group;
import brooklyn.entity.trait.Changeable;

import com.google.common.base.Predicate;


/**
 * Represents a group of entities - sub-classes can support dynamically changing membership, 
 * ad hoc groupings, etc.
 *  
 * Synchronization model. When changing and reading the group membership, this class uses internal 
 * synchronization to ensure atomic operations and the "happens-before" relationship for reads/updates
 * from different threads. Sub-classes should not use this same synchronization mutex when doing 
 * expensive operations - e.g. if resizing a cluster, don't block everyone else from asking for the
 * current number of members.
 */
public interface AbstractGroup extends Entity, Group, Changeable {

    public void setMembers(Collection m);
    
    /**
     * Removes any existing members that do not match the given filter, and adds those entities in
     * the given collection that match the predicate.
     * 
     * @param mm     Entities to test against the filter, and to add 
     * @param filter Filter for entities that are to be members (or null for "all")
     */
    // FIXME Do we really want this method? "setMembers" is a misleading name
    public void setMembers(Collection mm, Predicate filter);
}