com.sun.jini.mercury

Class StreamPool

java.lang.Object

com.sun.jini.mercury.StreamPool

 class StreamPool
extends Object

This class provides a pool of LogStream objects. Each LogStream has an associated FileDescriptor, which is the system resource we are trying to manage. This pool limits the (user configurable) number of concurrent, open FileDescriptors.

Since:

1.1

Author:

Sun Microsystems, Inc.

Field Summary

Fields

Modifier and Type	Field and Description
private LinkedList	freeList Holds stream references in least recently used (released) order.
private int	maxPoolSize Maximum limit for the number of concurrent LogStreams in the stream pool.
private static Logger	persistenceLogger Logger for lease related messages
private HashMap	pool Holds stream references by associated key

Constructor Summary

Constructors

Constructor and Description
StreamPool(int size) Simple constructor that creates a pool of given size.

Method Summary

Methods

Modifier and Type	Method and Description
(package private) void	dump()
private void	ensurePoolSpace() Ensures that room is available in the pool.
(package private) ControlLog	getControlLog(File file) Returns a ControlLog object for the specified file from the pool if it already exists.
(package private) int	getFreeSize()
(package private) LogInputStream	getLogInputStream(File file, long offset) Returns a LogInputStream object from the pool if it already exists.
(package private) LogOutputStream	getLogOutputStream(File file, long offset) Returns a LogOutputStream object for the specified file from the pool if it already exists.
(package private) int	getPoolSize()
(package private) void	releaseLogStream(LogStream stream) Marks a stream as available for closing.
(package private) void	removeLogStream(LogStream stream) Removes the given LogStream from the pool and closes it, if possible.

Methods inherited from class java.lang.Object

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

Field Detail

persistenceLogger

private static final Logger persistenceLogger

Logger for lease related messages

maxPoolSize

private final int maxPoolSize

Maximum limit for the number of concurrent LogStreams in the stream pool.

pool

private final HashMap pool

Holds stream references by associated key

freeList

private final LinkedList freeList

Holds stream references in least recently used (released) order. It's used in order determine which stream to discard upon reaching the maximum pool limit.

Constructor Detail

StreamPool

StreamPool(int size)

Simple constructor that creates a pool of given size.

Throws:

IllegalArgumentException - Thrown if the value of maxPoolSize is less than 1.

Method Detail

getControlLog

ControlLog getControlLog(File file)
                   throws IOException

Returns a ControlLog object for the specified file from the pool if it already exists. Otherwise, it creates a new instance and adds it to the pool.

Throws:

IOException - if an I/O error occurs

getLogInputStream

LogInputStream getLogInputStream(File file,
                               long offset)
                           throws IOException

Returns a LogInputStream object from the pool if it already exists. Otherwise, it creates a new instance and adds it to the pool.

Throws:

IOException - if an I/O error occurs

getLogOutputStream

LogOutputStream getLogOutputStream(File file,
                                 long offset)
                             throws IOException

Returns a LogOutputStream object for the specified file from the pool if it already exists. Otherwise, it creates a new instance and adds it to the pool.

Throws:

IOException - if an I/O error occurs

ensurePoolSpace

private void ensurePoolSpace()
                      throws IOException

Ensures that room is available in the pool. If the pool is currently full, then the least recently used LogStream will be removed and closed to make room. This method will block if the pool is full and no LogStream objects can be closed.

Throws:

IOException - if an I/O error occurs

releaseLogStream

void releaseLogStream(LogStream stream)

Marks a stream as available for closing. A log will only be closed if a new log is requested and the pool has reached its maximum size.

removeLogStream

void removeLogStream(LogStream stream)

Removes the given LogStream from the pool and closes it, if possible. The intent is for this method to be called for unusable logs so that they will no longer be returned by a subsequent call to one of the "get" methods.

getPoolSize

int getPoolSize()

getFreeSize

int getFreeSize()

dump

void dump()