plugins/network-elements/juniper-contrail/src/net/juniper/contrail/model/ModelObject.java

package net.juniper.contrail.model;

import java.io.IOException;
import java.lang.ref.WeakReference;
import java.util.TreeSet;

import com.cloud.exception.InternalErrorException;

/**
 * ModelObject
 * 
 * A model object represents the desired state of the system.
 * 
 * The object constructor should set the uuid and the internal id of the cloudstack objects.
 * 
 * The build method reads the master database (typically cloudstack mysql) and derives the state that
 * we wish to reflect in the contrail API. This method should not modify the Contrail API state.
 * 
 * The verify method reads the API server state and compares with cached properties.
 * 
 * The update method pushes updates to the contrail API server.
 */
public interface ModelObject {
    public static class ModelReference implements Comparable<ModelReference> {
        WeakReference<ModelObject> reference;
        ModelReference(ModelObject obj) {
            reference = new WeakReference<ModelObject>(obj);
        }

        @Override
        public int compareTo(ModelReference other) {
            ModelObject lhs = reference.get();
            ModelObject rhs = other.reference.get();
            if (lhs == null) {
                if (rhs == null) {
                    return 0;
                }
                return -1;
            }
            
            return lhs.compareTo(rhs);
        }
        @Override
        public boolean equals(Object other) {
            try {
                ModelReference rhs = (ModelReference) other;
                return compareTo(rhs) == 0;
            } catch (ClassCastException ex) {
            }
            return false;
        }
        public ModelObject get() {
            return reference.get();
        }
    };
    
    public void addSuccessor(ModelObject child);
    
    public TreeSet<ModelReference> ancestors();
    public void clearSuccessors();
    public int compareTo(ModelObject o);

    /**
     * Delete the object from the API server.
     * @param controller
     * @throws IOException
     */
    public void delete(ModelController controller) throws IOException;

    /**
     * Deletes the object from the data model graph.
     * 
     * @param controller
     * @throws IOException
     */
    public void destroy(ModelController controller) throws IOException;
    
    public void removeSuccessor(ModelObject child);
    
    public TreeSet<ModelObject> successors();
    
    /**
     * Push updates to Contrail API server. This API is only valid for objects in the database.
     * @param controller
     * @throws IOException 
     * @throws InternalErrorException 
     */
    public void update(ModelController controller) throws InternalErrorException, IOException;
    
    /**
     * Check that the state of the current object matches the state of the API server.
     * @param controller
     * @return
     */
    public boolean verify(ModelController controller);
    
    /*
     * Compare the state of existing model object with latest model object
     */
    public boolean compare(ModelController controller, ModelObject current);
}