Package org.apache.mina.filter.executor

Class WriteRequestFilter

java.lang.Object

org.apache.mina.core.filterchain.IoFilterAdapter

org.apache.mina.filter.executor.WriteRequestFilter

All Implemented Interfaces:

IoFilter

public class WriteRequestFilter
extends IoFilterAdapter

Attaches an IoEventQueueHandler to an IoSession's WriteRequest queue to provide accurate write queue status tracking.

The biggest difference from OrderedThreadPoolExecutor and UnorderedThreadPoolExecutor is that IoEventQueueHandler.polled(Object, IoEvent) is invoked when the write operation is completed by an IoProcessor, consequently providing the accurate tracking of the write request queue status to the IoEventQueueHandler.

Most common usage of this filter could be detecting an IoSession which writes too fast which will cause OutOfMemoryError soon:

     session.getFilterChain().addLast(
             "writeThrottle",
             new WriteRequestFilter(new IoEventQueueThrottle()));
 

Known issues

You can run into a dead lock if you run this filter with the blocking IoEventQueueHandler implementation such as IoEventQueueThrottle in the IoProcessor thread. It's because an IoProcessor thread is what processes the WriteRequests and notifies related WriteFutures; the IoEventQueueHandler implementation that waits for the size of the write request queue to decrease will never wake up. To use such an handler, you have to insert an ExecutorFilter before this filter or call IoSession.write(Object) method always from a different thread.

Author:

Apache MINA Project

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.mina.core.filterchain.IoFilter

IoFilter.NextFilter

Constructor Summary

Constructors

Constructor	Description
WriteRequestFilter()	Creates a new instance with a new default IoEventQueueThrottle.
WriteRequestFilter(IoEventQueueHandler queueHandler)	Creates a new instance with the specified IoEventQueueHandler.

Method Summary

Modifier and Type	Method	Description
void	filterWrite(IoFilter.NextFilter nextFilter, IoSession session, WriteRequest writeRequest)	Filters IoSession.write(Object) method invocation.
IoEventQueueHandler	getQueueHandler()

Methods inherited from class org.apache.mina.core.filterchain.IoFilterAdapter

destroy, event, exceptionCaught, filterClose, init, inputClosed, messageReceived, messageSent, onPostAdd, onPostRemove, onPreAdd, onPreRemove, sessionClosed, sessionCreated, sessionIdle, sessionOpened, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

WriteRequestFilter

public WriteRequestFilter()

Creates a new instance with a new default IoEventQueueThrottle.

WriteRequestFilter

public WriteRequestFilter(IoEventQueueHandler queueHandler)

Creates a new instance with the specified IoEventQueueHandler.

Parameters:

queueHandler - The IoEventQueueHandler instance to use

Method Detail

getQueueHandler

public IoEventQueueHandler getQueueHandler()

Returns:

the IoEventQueueHandler which is attached to this filter.

filterWrite

public void filterWrite(IoFilter.NextFilter nextFilter,
                        IoSession session,
                        WriteRequest writeRequest)
                 throws Exception

Filters IoSession.write(Object) method invocation.

Specified by:

filterWrite in interface IoFilter

Overrides:

filterWrite in class IoFilterAdapter

Parameters:

nextFilter - the IoFilter.NextFilter for this filter. You can reuse this object until this filter is removed from the chain.

session - The IoSession which has to process this invocation

writeRequest - The WriteRequest to process

Throws:

Exception - If an error occurred while processing the event