com.ibm.di.queue
Class MemBufferQ

java.lang.Object
  com.ibm.di.queue.MemBufferQ

public class MemBufferQ
extends Object

A FIFO queue

Constructor Summary

MemBufferQ(int nEntries)
Deprecated.

MemBufferQ(int nEntries, int pagesize)
Constructor Initializes the memory buffer pipe when paging is enabled.

MemBufferQ(int nEntries, int pagesize, boolean doNotInitialiseDB)
Constructor Initializes the memory buffer pipe when paging is enabled.Initialization of the DB properties is done only when the queue is being created from the UserFunctions.

Method Summary

void	acquireLock()
void	blockAdd(boolean enable) Enable disable blocking add this is used only when paging support is disabled.
void	enablePersistence(boolean enable) enablePersistence : enable/disable paging support using system store
DBHandler	getDbHandler()
int	getPercentMemoryUse()
void	initDB(String sDBName, String jdbcLogin, String jdbcPassword, String sTblName) Initializes the system store paramemters.
boolean	isEmpty()
boolean	isMemoryAvailable() Checks if there is enough memory available as specified by the user
boolean	isPurging()
Object	peek() Same as read but does not remove data from the memq
void	purgeQueue() Purges the queue.
Object	read() synchronized method: The first item inserted in the queue and not yet removed.
Object	read(int timeout) synchronized method: The first item inserted in the queue and not yet removed.
void	releaseLock()
void	setDbHandler(DBHandler dbHandler)
void	setPercentMemoryUse(int percentMemoryUse)
int	size()
void	terminate(boolean dropSystemStore) terminates the system store threads and drops table if dropSystemStore set to true
void	write(Object x) write : add an object to the end of memq

Methods inherited from class java.lang.Object

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

Constructor Detail

MemBufferQ

public MemBufferQ(int nEntries,
                  int pagesize)
           throws Exception

Constructor Initializes the memory buffer pipe when paging is enabled.

Throws:

Exception

MemBufferQ

public MemBufferQ(int nEntries,
                  int pagesize,
                  boolean doNotInitialiseDB)
           throws Exception

Constructor Initializes the memory buffer pipe when paging is enabled.Initialization of the DB properties is done only when the queue is being created from the UserFunctions. For queues being created from the MemQueue Connector or FC , the DB table name is required to be specified by the user.

Throws:

Exception

MemBufferQ

@Deprecated
public MemBufferQ(int nEntries)

Deprecated.

Constructor Initializes the memory buffer pipe when paging is disabled

Method Detail

initDB

public void initDB(String sDBName,
                   String jdbcLogin,
                   String jdbcPassword,
                   String sTblName)
            throws Exception

Initializes the system store paramemters.

Parameters:

sDBName - system store database name

jdbcLogin - username to connect to the db

jdbcPassword - password to connect to the db

sTblName - table name

Throws:

Exception - if system store is not initialized properly

isEmpty

public boolean isEmpty()

Returns:

True if memQ is empty

size

public int size()

Returns:

Number of items in the memq.

read

public Object read()
            throws Exception

synchronized method: The first item inserted in the queue and not yet removed. Requires !isEmpty (). Reading removes the item from the queue. read with no timeout.

Throws:

Exception

read

public Object read(int timeout)
            throws Exception

synchronized method: The first item inserted in the queue and not yet removed. Requires !isEmpty (). Reading removes the item from the queue. Waits for timeout

Throws:

Exception

acquireLock

public void acquireLock()
                 throws InterruptedException

Throws:

InterruptedException

releaseLock

public void releaseLock()

write

public void write(Object x)
           throws Exception

write : add an object to the end of memq

Parameters:

x - object to be added

Throws:

Exception - if add fails

peek

public Object peek()

Same as read but does not remove data from the memq

Returns:

object read

enablePersistence

public void enablePersistence(boolean enable)

enablePersistence : enable/disable paging support using system store

Parameters:

enable - paging support enabled if true and disabled if false

isPurging

public boolean isPurging()

Returns:

isBeingPurged Returns if purging is enabled/disabled.

blockAdd

public void blockAdd(boolean enable)

Enable disable blocking add this is used only when paging support is disabled.

Parameters:

enable - if true, add to memq blocks infinitely until there is space for an object to be added to memq if false, add throws an exception if memq is full

terminate

public void terminate(boolean dropSystemStore)

terminates the system store threads and drops table if dropSystemStore set to true

Parameters:

dropSystemStore -

purgeQueue

public void purgeQueue()
                throws Exception

Purges the queue. The isBeingPurged Flag is set which blocks all reader or writer threads until the purge operation is not completed. Deletes all data from the associated table in System Store if this queue has paging enabled.

Throws:

Exception

getPercentMemoryUse

public int getPercentMemoryUse()

setPercentMemoryUse

public void setPercentMemoryUse(int percentMemoryUse)

isMemoryAvailable

public boolean isMemoryAvailable()

Checks if there is enough memory available as specified by the user

getDbHandler

public DBHandler getDbHandler()

setDbHandler

public void setDbHandler(DBHandler dbHandler)