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package com.sun.xml.ws.transport.tcp.connectioncache.spi.transport;
/** A concurrent connection cache for passively created connections (e.g.
* from an acceptor). Here a Connection is an
* abstraction of a Socket or SocketChannel: basically some sort of resource
* that is expensive to acquire, and can be re-used freely.
* The cache maintains a loose
* upper bound on the number of cached connections, and reclaims connections as
* needed.
* <P>
* This cache places minimal requirements on the Connections that it contains:
* <ol>
* <li>A Connection must implement a close() method. This is called when idle
* connections are reclaimed.
* <li>A Connection must be usable as a HashMap key.
* </ol>
* <P>
* Some simple methods are provided for monitoring the state of the cache:
* numbers of busy and idle connections, and the total number of
* connections in the cache.
* <P>
* Access is also provided to the cache configuration: maxParallelConnections,
* highWaterMark, and numberToReclaim. Currently these can only be set when
* the cache is created.
*
* XXX We may wish to make the cache configuration dynamically configurable.
*/
public interface InboundConnectionCache<C extends Connection> extends ConnectionCache<C> {
/** Mark a connection as busy because a request is being processed
* on the connection. The connection may or may not be previously
* known to the cache when this method is called.
* Busy connections cannot be reclaimed.
* This provides an early indication that a Connection is in use,
* before we know how many responses still need to be sent on
* the Connection for this request. This reduces the likelyhood
* of reclaiming a connection on which we are processing a request.
* <P>
* Note that this problem is inherent in a distributed system.
* We could in any case reclaim a connection AFTER a client
* has sent a request but BEFORE the request is received.
* Note that AFTER and BEFORE refer to global time which does
* not really exist in a distributed system (or at least we
* want to pretend it is not available).
*
* XXX Should we age out connections?
* This would require actual time stamps, rather than just an LRU queue.
*/
void requestReceived( C conn ) ;
/** Indicate that request processing has been completed for a request
* received on conn. This indicates that a Connection that received
* a request as indicated in a previous call to requestReceived has
* completed request processing for that request. Responses may still
* need to be sent. Some number of
* responses (usually 0 or 1) may be expected ON THE SAME CONNECTION
* even for an idle connection. We maintain a count of the number of
* outstanding responses we expect for protocols that return the response
* on the same connection on which the request was received. This is
* necessary to prevent reclamation of a Connection that is idle, but
* still needed to send responses to old requests.
*/
void requestProcessed( C conn, int numResponseExpected ) ;
/** Inform the cache that a response has been sent on a particular
* connection.
* <P>
* When a Connection is idle, and has no pending responses, it is
* eligible for reclamation.
*/
void responseSent( C conn ) ;
}
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