001: /*
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003: *
004: * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
005: *
006: * The contents of this file are subject to the terms of either the GNU
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008: * and Distribution License("CDDL") (collectively, the "License"). You
009: * may not use this file except in compliance with the License. You can obtain
010: * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
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018: * accompanied this code. If applicable, add the following below the License
019: * Header, with the fields enclosed by brackets [] replaced by your own
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035: */
036:
037: package com.sun.xml.ws.transport.tcp.connectioncache.spi.transport;
038:
039: /** A concurrent connection cache for passively created connections (e.g.
040: * from an acceptor). Here a Connection is an
041: * abstraction of a Socket or SocketChannel: basically some sort of resource
042: * that is expensive to acquire, and can be re-used freely.
043: * The cache maintains a loose
044: * upper bound on the number of cached connections, and reclaims connections as
045: * needed.
046: * <P>
047: * This cache places minimal requirements on the Connections that it contains:
048: * <ol>
049: * <li>A Connection must implement a close() method. This is called when idle
050: * connections are reclaimed.
051: * <li>A Connection must be usable as a HashMap key.
052: * </ol>
053: * <P>
054: * Some simple methods are provided for monitoring the state of the cache:
055: * numbers of busy and idle connections, and the total number of
056: * connections in the cache.
057: * <P>
058: * Access is also provided to the cache configuration: maxParallelConnections,
059: * highWaterMark, and numberToReclaim. Currently these can only be set when
060: * the cache is created.
061: *
062: * XXX We may wish to make the cache configuration dynamically configurable.
063: */
064: public interface InboundConnectionCache<C extends Connection> extends
065: ConnectionCache<C> {
066: /** Mark a connection as busy because a request is being processed
067: * on the connection. The connection may or may not be previously
068: * known to the cache when this method is called.
069: * Busy connections cannot be reclaimed.
070: * This provides an early indication that a Connection is in use,
071: * before we know how many responses still need to be sent on
072: * the Connection for this request. This reduces the likelyhood
073: * of reclaiming a connection on which we are processing a request.
074: * <P>
075: * Note that this problem is inherent in a distributed system.
076: * We could in any case reclaim a connection AFTER a client
077: * has sent a request but BEFORE the request is received.
078: * Note that AFTER and BEFORE refer to global time which does
079: * not really exist in a distributed system (or at least we
080: * want to pretend it is not available).
081: *
082: * XXX Should we age out connections?
083: * This would require actual time stamps, rather than just an LRU queue.
084: */
085: void requestReceived(C conn);
086:
087: /** Indicate that request processing has been completed for a request
088: * received on conn. This indicates that a Connection that received
089: * a request as indicated in a previous call to requestReceived has
090: * completed request processing for that request. Responses may still
091: * need to be sent. Some number of
092: * responses (usually 0 or 1) may be expected ON THE SAME CONNECTION
093: * even for an idle connection. We maintain a count of the number of
094: * outstanding responses we expect for protocols that return the response
095: * on the same connection on which the request was received. This is
096: * necessary to prevent reclamation of a Connection that is idle, but
097: * still needed to send responses to old requests.
098: */
099: void requestProcessed(C conn, int numResponseExpected);
100:
101: /** Inform the cache that a response has been sent on a particular
102: * connection.
103: * <P>
104: * When a Connection is idle, and has no pending responses, it is
105: * eligible for reclamation.
106: */
107: void responseSent(C conn);
108: }
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