net.sf.fsp.fsplib

Class FSPsession

java.lang.Object

net.sf.fsp.fsplib.FSPsession

public class FSPsession
extends Object

This class represents one live FSP session.

FSPsession class takes care about FSP session management. It handles packet resends on timeouts and key management. It also handles locks for synchronizing multi session access to same FSP server.

Since:

1.0

Version:

1.0rc7

Author:

Radim Kolar

See Also:

FSPpacket

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_DELAY default resent delay (msec)
static int	DEFAULT_TIMEOUT default timeout (msec)
static int	MAX_DELAY maximum resent delay.
static int	MIN_DELAY minimum resent delay (msec)

Constructor Summary

Constructors

Constructor and Description
FSPsession(InetAddress host, int port) Creates a new FSP session
FSPsession(String host, int port) Creates a new FSP session

Method Summary

Modifier and Type	Method and Description
void	close() Close a session.
void	finalize() closes session before doing GC.
int	getDelay() Gets the delay time before we resent packet for first time.
InetAddress	getHost() Get FSP host.
int	getMaxDelay() Gets the maximum delay time between packet resents.
int	getPort() Get FSP port.
int	getTimeout() Get timeout value used by session.
FSPpacket	interact(byte cmd, long filepos, byte[] data1, int offset1, int length1, byte[] data2, int offset2, int length2) Sends FSP packet and waits for reply, packet is resent if lost.
void	lockWriter(Object lock, boolean wait) Set Writer lock.
void	setDelay(int delay) Sets the delay.
void	setMaxDelay(int delay) Sets the maximum delay time between resent packets.
void	setTimeout(int timeout) Set timeout value.
void	unlockWriter(Object lock) Release Writer lock.

Methods inherited from class java.lang.Object

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

Field Detail

MIN_DELAY

public static final int MIN_DELAY

minimum resent delay (msec)

See Also:

Constant Field Values

DEFAULT_DELAY

public static final int DEFAULT_DELAY

default resent delay (msec)

See Also:

Constant Field Values

MAX_DELAY

public static final int MAX_DELAY

maximum resent delay. FSP protocol has max delay 300s, but we are using 60s for faster recovery on common Internet/Wifi lines.

See Also:

Constant Field Values

DEFAULT_TIMEOUT

public static final int DEFAULT_TIMEOUT

default timeout (msec)

See Also:

Constant Field Values

Constructor Detail

FSPsession

public FSPsession(String host,
                  int port)
           throws SocketException,
                  UnknownHostException

Creates a new FSP session

Parameters:

host - hostname of fsp server

port - port number on fsp server

Throws:

SocketException - if socket can not be created

UnknownHostException - if hostname fails to resolve

Since:

1.0

FSPsession

public FSPsession(InetAddress host,
                  int port)
           throws SocketException

Creates a new FSP session

Parameters:

host - address of fsp server

port - port number on fsp server

Throws:

SocketException - if socket can not be created

Since:

1.0

Method Detail

interact

public FSPpacket interact(byte cmd,
                          long filepos,
                          byte[] data1,
                          int offset1,
                          int length1,
                          byte[] data2,
                          int offset2,
                          int length2)
                   throws SocketTimeoutException

Sends FSP packet and waits for reply, packet is resent if lost.

Parameters:

cmd - FSP command to be sent to server

filepos - position in file

data1 - array contains data for FSP packet

offset1 - starting offset of data in array

length1 - length of data

data2 - array with extra data

offset2 - starting offset of data in array

length2 - length of extra data

Returns:

Received valid packet

Throws:

SocketTimeoutException - if server can't be reached within timeout

Since:

1.0

close

public void close()

Close a session.

Session object can't be used after session is closed. This also sends CC_BYE command to server.

Since:

1.0

getDelay

public int getDelay()

Gets the delay time before we resent packet for first time.

Returns:

delay in milliseconds

Since:

1.0

setDelay

public void setDelay(int delay)

Sets the delay.

This functions sets delay parameter of FSP protocol stack. This is timeout value for first packet. If packet is lost delay is multiplied by 1.5. Delay is in milliseconds and must be between MIN_DELAY and MAX_DELAY

Parameters:

delay - new delay in milliseconds

Since:

1.0

getMaxDelay

public int getMaxDelay()

Gets the maximum delay time between packet resents.

Returns:

max delay in milliseconds

Since:

1.0

setMaxDelay

public void setMaxDelay(int delay)

Sets the maximum delay time between resent packets.

Parameters:

delay - new maximum delay time in milliseconds.

Since:

1.0

getTimeout

public int getTimeout()

Get timeout value used by session.

Returns:

timeout value in milliseconds. 0 means infinite timeout

Since:

1.0

setTimeout

public void setTimeout(int timeout)

Set timeout value.

If no packet from server is received in this time, session will time out.

Parameters:

timeout - timeout value in milliseconds. 0 means infinite timeout

Since:

1.0

getHost

public InetAddress getHost()

Get FSP host.

Get InetAddress of FSP server we are connected to.

Returns:

InetAddress of connected FSP server or null if session is closed.

Since:

1.0rc7

getPort

public int getPort()

Get FSP port.

Get port of connected FSP server.

Returns:

port of connected FSP Server or zero if session is closed

Since:

1.0rc7

finalize

public void finalize()

closes session before doing GC.

If session is not closed, close it before doing GC on this object. Timeout is set to 7 sec when doing it.

Overrides:

finalize in class Object

Since:

1.0

lockWriter

public void lockWriter(Object lock,
                       boolean wait)

Set Writer lock. FSP protocol supports only one writer per session. If you need more writers you need to open more sessions to target server. For synchronization purposes before starting write operation you have to call lockWriter.

Parameters:

lock - object writing to FSP session

wait - wait if we can't acquire lock now

Throws:

IllegalStateException - if session is already write locked and no wait was specified

Since:

1.0rc8

unlockWriter

public void unlockWriter(Object lock)

Release Writer lock. After you are done writing data to FSP server you have to call this function for writer lock release. Failure to call this function will leave other threads waiting.

Parameters:

lock - object writing to fsp session

Throws:

IllegalStateException - if lock is invalid

Since:

1.0rc8