org.apache.flume.channel
Class BasicChannelSemantics

java.lang.Object
  org.apache.flume.channel.AbstractChannel
      org.apache.flume.channel.BasicChannelSemantics

All Implemented Interfaces:

Channel, Configurable, LifecycleAware, NamedComponent

Direct Known Subclasses:

FileChannel, KafkaChannel, MemoryChannel

@InterfaceAudience.Public
@InterfaceStability.Stable
public abstract class BasicChannelSemantics
extends AbstractChannel

An implementation of basic Channel semantics, including the implied thread-local semantics of the Transaction class, which is required to extend BasicTransactionSemantics.

Constructor Summary

BasicChannelSemantics()

Method Summary

protected abstract BasicTransactionSemantics	createTransaction() Called to create new Transaction objects, which must extend BasicTransactionSemantics.
Transaction	getTransaction() Initializes the channel if it is not already, then checks to see if there is an open transaction for this thread, creating a new one via createTransaction if not.
protected void	initialize() Called upon first getTransaction() request, while synchronized on this Channel instance.
void	put(Event event) Ensures that a transaction exists for this thread and then delegates the put to the thread's BasicTransactionSemantics instance.
Event	take() Ensures that a transaction exists for this thread and then delegates the take to the thread's BasicTransactionSemantics instance.

Methods inherited from class org.apache.flume.channel.AbstractChannel

configure, getLifecycleState, getName, setName, start, stop, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

BasicChannelSemantics

public BasicChannelSemantics()

Method Detail

initialize

protected void initialize()

Called upon first getTransaction() request, while synchronized on this Channel instance. Use this method to delay the initializization resources until just before the first transaction begins.

createTransaction

protected abstract BasicTransactionSemantics createTransaction()

Called to create new Transaction objects, which must extend BasicTransactionSemantics. Each object is used for only one transaction, but is stored in a thread-local and retrieved by getTransaction for the duration of that transaction.

put

public void put(Event event)
         throws ChannelException

Ensures that a transaction exists for this thread and then delegates the put to the thread's BasicTransactionSemantics instance.

Parameters:

event - the event to transport.

Throws:

ChannelException - in case this operation fails.

See Also:

Transaction.begin()

take

public Event take()
           throws ChannelException

Ensures that a transaction exists for this thread and then delegates the take to the thread's BasicTransactionSemantics instance.

Returns:

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

Throws:

ChannelException - in case this operation fails.

See Also:

Transaction.begin()

getTransaction

public Transaction getTransaction()

Initializes the channel if it is not already, then checks to see if there is an open transaction for this thread, creating a new one via createTransaction if not.

Returns:

the current Transaction object for the calling thread