AllocationContextKey.java

package com.bigdata.bop.fed;

import java.nio.ByteBuffer;

import com.bigdata.bop.BOp;
import com.bigdata.io.DirectBufferPoolAllocator.IAllocationContext;

/**
 * The allocation context key groups together allocations onto the same
 * direct {@link ByteBuffer}s. There are different implementations depending
 * on how it makes sense to group data data for a given query.
 * 
 * @see IAllocationContext
 */
public abstract class AllocationContextKey {

    /**
     * Must be overridden. The queryId must be a part of each hashCode() in
     * order to ensure that the hash codes are well distributed across
     * different queries on the same node.
     */
    @Override
    abstract public int hashCode();

    /**
     * Must be overridden.
     */
    @Override
    abstract public boolean equals(Object o);

    /**
     * Return <code>true</code> if the allocation context is scoped to the
     * specified operator.
     * 
     * @param bopId
     *            The {@link BOp} identifier.
     */
    abstract public boolean hasOperatorScope(int bopId);
    
}