package net.openhft.chronicle.hash;

import net.openhft.chronicle.hash.locks.InterProcessReadWriteUpdateLock;

/**
 * Context of {@link ChronicleHash} operations with <i>individual keys</i>.
 *  
 * @param <K> the hash key type
 * @see ChronicleHash#queryContext(Object)     
 */
public interface HashQueryContext<K> extends HashContext<K>, InterProcessReadWriteUpdateLock {

    /**
     * Returns the queried key as a {@code Value}.
     */
    Value<K, ?> queriedKey();

    /**
     * Returns the entry context, if the entry with the queried key is <i>present</i>
     * in the {@code ChronicleHash}, returns {@code null} is the entry is <i>absent</i>.
     *  
     * @implNote Might acquire {@link #readLock} before searching for the key, if the context
     * is not locked yet.
     */
    HashEntry<K> entry();

    /**
     * Returns the special <i>absent entry</i> object, if the entry with the queried key
     * is <i>absent</i> in the hash, returns {@code null}, if the entry is <i>present</i>.
     * 
     * @implNote Might acquire {@link #readLock} before searching for the key, if the context
     * is not locked yet.
     */
    HashAbsentEntry<K> absentEntry();
}