org.apache.flume.channel
Class MemoryChannel

java.lang.Object
  org.apache.flume.channel.MemoryChannel

All Implemented Interfaces:

Channel, Configurable

public class MemoryChannel
extends Object
implements Channel, Configurable

Memory channel that with full transaction support Uses transaction object for each thread (source and sink) attached to channel. The events are stored in the thread safe Dequeue. * The put and take are directly executed in the common queue. Channel has a marker for the last committed event in order to avoid sink reading uncommitted data. The transactions keep track of the actions to perform undo when rolled back.

Nested Class Summary

class

MemoryChannel.MemTransaction

Constructor Summary

MemoryChannel()
Channel constructor

Method Summary

void	configure(Context context) set the event queue capacity
protected MemoryChannel.MemTransaction	findTransaction()
protected void	forgetTransaction(MemoryChannel.MemTransaction myTxn) Remove the given transaction from the list of open transactions
String	getName()
Transaction	getTransaction()
void	put(Event event) Puts the given event in the channel.
void	shutdown() Instructs the channel to release any resources held in preparation of shutting down.
Event	take() Returns the next event from the channel if available.
protected void	undoPut(MemoryChannel.MemTransaction myTxn) undo of put for all the events in the undoPut queue, remove those from the event queue
protected void	undoTake(MemoryChannel.MemTransaction myTxn) undo of take operation for each event in the undoTake list, add it back to the event queue

Methods inherited from class java.lang.Object

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

Constructor Detail

MemoryChannel

public MemoryChannel()

Channel constructor

Method Detail

configure

public void configure(Context context)

set the event queue capacity

Specified by:

configure in interface Configurable

put

public void put(Event event)

Description copied from interface: Channel

Puts the given event in the channel.

Note: This method must be invoked within an active Transaction boundary. Failure to do so can lead to unpredictable results.

Specified by:

put in interface Channel

Parameters:

event - the event to transport.

See Also:

Transaction.begin()

undoPut

protected void undoPut(MemoryChannel.MemTransaction myTxn)

undo of put for all the events in the undoPut queue, remove those from the event queue

Parameters:

myTxn -

take

public Event take()

Description copied from interface: Channel

Returns the next event from the channel if available. If the channel does not have any events available, this method would return null.

Note: This method must be invoked within an active Transaction boundary. Failure to do so can lead to unpredictable results.

Specified by:

take in interface Channel

Returns:

the next available event or null if no events are available.

See Also:

Transaction.begin()

undoTake

protected void undoTake(MemoryChannel.MemTransaction myTxn)

undo of take operation for each event in the undoTake list, add it back to the event queue

Parameters:

myTxn -

getTransaction

public Transaction getTransaction()

Specified by:

getTransaction in interface Channel

Returns:

the transaction instance associated with this channel.

forgetTransaction

protected void forgetTransaction(MemoryChannel.MemTransaction myTxn)

Remove the given transaction from the list of open transactions

Parameters:

myTxn -

findTransaction

protected MemoryChannel.MemTransaction findTransaction()

shutdown

public void shutdown()

Description copied from interface: Channel

Instructs the channel to release any resources held in preparation of shutting down.

Specified by:

shutdown in interface Channel

getName

public String getName()

Specified by:

getName in interface Channel

Returns:

the channel name.