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package com.sun.grizzly.connectioncache.spi.transport;

import java.io.Closeable;

/** A connection cache manages a group of connections which may be re-used
 * for sending and receiving messages.
 * @param C  a connection
 */
public interface ConnectionCache {
    /** User-provided indentifier for an instance of the 
     * {@link ConnectionCache}.
     * @return  a String identifying an instance of a {@link ConnectionCache}
     */
    String getCacheType() ;

    /** Total number of connections currently managed by the cache.
     * @return  number of connections currently managed by the cache
     */
    long numberOfConnections() ;

    /** Number of idle connections; that is, connections for which the number of
     * get/release or responseReceived/responseProcessed calls are equal.
     * @return  number of idle connections
     */
    long numberOfIdleConnections() ;

    /** Number of non-idle connections.  Normally, busy+idle==total, but this
     * may not be strictly true due to concurrent updates to the connection 
     * cache.
     * @return  number of busy connections
     */
    long numberOfBusyConnections() ;

    /** Number of idle connections that are reclaimable.  Such connections
     * are not in use, and are not waiting to handle any responses.
     * @return  number of idle connections that are reclaimable
     */
    long numberOfReclaimableConnections() ;

    /** Threshold at which connection reclamation begins.
     * @return  threshold at which connection reclamation begins.
     */
    int highWaterMark() ;

    /** Number of connections to reclaim each time reclamation starts.
     * @return  number of connections to reclaim
     */
    int numberToReclaim() ;
    
    /** Close a connection, regardless of its state.  This may cause requests
     * to fail to be sent, and responses to be lost.  Intended for 
     * handling serious errors, such as loss of framing on a TCP stream,
     * that require closing the connection.
     * @param conn  a connection
     */
    void close( final C conn ) ;
}