com.sun.corba.ee.impl.transport.connection

Class InboundConnectionCacheImpl<C extends Connection>

java.lang.Object

com.sun.corba.ee.impl.transport.connection.ConnectionCacheBase<C>

com.sun.corba.ee.impl.transport.connection.InboundConnectionCacheImpl<C>

All Implemented Interfaces:

ConnectionCache<C>, InboundConnectionCache<C>

public final class InboundConnectionCacheImpl<C extends Connection>
extends ConnectionCacheBase<C>
implements InboundConnectionCache<C>

Manage connections that are initiated from another VM. Connections are reclaimed when they are no longer in use and there are too many connections open.

A connection basically represents some sort of communication channel, but few requirements are placed on the connection. Basically the ability to close a connection is required in order for reclamation to work.

Author:

Ken Cavanaugh

Field Summary

Fields

Modifier and Type	Field and Description
protected AtomicInteger	totalBusy
protected AtomicInteger	totalIdle

Fields inherited from class com.sun.corba.ee.impl.transport.connection.ConnectionCacheBase

reclaimableConnections

Constructor Summary

Constructors

Constructor and Description
InboundConnectionCacheImpl(String cacheType, int highWaterMark, int numberToReclaim, long ttl)

Method Summary

Modifier and Type	Method and Description
void	close(C conn) Close a connection, regardless of whether the connection is busy or not.
long	numberOfBusyConnections() Number of non-idle connections.
long	numberOfConnections() Total number of connections currently managed by the cache.
long	numberOfIdleConnections() Number of idle connections; that is, connections for which the number of get/release or responseReceived/responseProcessed calls are equal.
long	numberOfReclaimableConnections() Number of idle connections that are reclaimable.
void	requestProcessed(C conn, int numResponsesExpected) Indicate that request processing has been completed for a request received on conn.
void	requestReceived(C conn) Mark a connection as busy because a request is being processed on the connection.
void	responseSent(C conn) Decrement the number of expected responses.
protected String	thisClassName()

Methods inherited from class com.sun.corba.ee.impl.transport.connection.ConnectionCacheBase

getCacheType, highWaterMark, numberToReclaim, reclaim, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.sun.corba.ee.spi.transport.connection.ConnectionCache

getCacheType, highWaterMark, numberOfBusyConnections, numberOfConnections, numberOfIdleConnections, numberOfReclaimableConnections, numberToReclaim

Field Detail

totalBusy

protected final AtomicInteger totalBusy

totalIdle

protected final AtomicInteger totalIdle

Constructor Detail

InboundConnectionCacheImpl

public InboundConnectionCacheImpl(String cacheType,
                                  int highWaterMark,
                                  int numberToReclaim,
                                  long ttl)

Method Detail

thisClassName

protected String thisClassName()

Specified by:

thisClassName in class ConnectionCacheBase<C extends Connection>

requestReceived

public void requestReceived(C conn)

Description copied from interface: InboundConnectionCache

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.

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.

Specified by:

requestReceived in interface InboundConnectionCache<C extends Connection>

requestProcessed

public void requestProcessed(C conn,
                             int numResponsesExpected)

Description copied from interface: InboundConnectionCache

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.

Specified by:

requestProcessed in interface InboundConnectionCache<C extends Connection>

responseSent

public void responseSent(C conn)

Decrement the number of expected responses. When a connection is idle and has no expected responses, it can be reclaimed.

Specified by:

responseSent in interface InboundConnectionCache<C extends Connection>

close

public void close(C conn)

Close a connection, regardless of whether the connection is busy or not.

Specified by:

close in interface ConnectionCache<C extends Connection>

numberOfConnections

public long numberOfConnections()

Description copied from interface: ConnectionCache

Total number of connections currently managed by the cache.

numberOfIdleConnections

public long numberOfIdleConnections()

Description copied from interface: ConnectionCache

Number of idle connections; that is, connections for which the number of get/release or responseReceived/responseProcessed calls are equal.

numberOfBusyConnections

public long numberOfBusyConnections()

Description copied from interface: ConnectionCache

Number of non-idle connections. Normally, busy+idle==total, but this may not be strictly true due to concurrent updates to the connection cache.

numberOfReclaimableConnections

public long numberOfReclaimableConnections()

Description copied from interface: ConnectionCache

Number of idle connections that are reclaimable. Such connections are not in use, and are not waiting to handle any responses.