io.pravega.client.stream

Interface Transaction<Type>

Type Parameters:

Type - The type of events in the associated stream.

public interface Transaction<Type>

Provides a mechanism for writing many events atomically. A Transaction is unbounded in size but is bounded in time. If it has not been committed within a time window specified at the time of its creation it will be automatically aborted. All methods on this class may block.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	Transaction.Status

Method Summary

Modifier and Type	Method and Description
void	abort() Drops the transaction, causing all events written to it to be deleted.
Transaction.Status	checkStatus() Gets the status of the transaction.
void	commit() Causes all messages previously written to the transaction to go into the stream contiguously.
void	flush() Blocks until all events passed to writeEvent(String, Object) make it to durable storage.
java.util.UUID	getTxnId() Returns a unique ID that can be used to identify this transaction.
void	writeEvent(java.lang.String routingKey, Type event) Sends an event to the stream just like EventStreamWriter.writeEvent(Type) but with the caveat that the message will not be visible to anyone until commit() is called.
void	writeEvent(Type event) Sends an event to the stream just like EventStreamWriter.writeEvent(Type) but with the caveat that the message will not be visible to anyone until commit() is called.

Method Detail

getTxnId

java.util.UUID getTxnId()

Returns a unique ID that can be used to identify this transaction.

Returns:

Unique identifier of the transaction

writeEvent

void writeEvent(Type event)
         throws TxnFailedException

Sends an event to the stream just like EventStreamWriter.writeEvent(Type) but with the caveat that the message will not be visible to anyone until commit() is called. A routing key will automatically be inferred from the transactionID. So all events written this way will be fully ordered and contiguous when read.

Parameters:

event - The Event to write. (Null is disallowed)

Throws:

TxnFailedException - The Transaction is no longer in state Transaction.Status.OPEN

writeEvent

void writeEvent(java.lang.String routingKey,
                Type event)
         throws TxnFailedException

Sends an event to the stream just like EventStreamWriter.writeEvent(Type) but with the caveat that the message will not be visible to anyone until commit() is called.

Parameters:

routingKey - The Routing Key to use for writing.

event - The Event to write. (Null is disallowed)

Throws:

TxnFailedException - The Transaction is no longer in state Transaction.Status.OPEN

flush

void flush()
    throws TxnFailedException

Blocks until all events passed to writeEvent(String, Object) make it to durable storage. This is only needed if the transaction is going to be serialized.

Throws:

TxnFailedException - The Transaction is no longer in state Transaction.Status.OPEN

commit

void commit()
     throws TxnFailedException

Causes all messages previously written to the transaction to go into the stream contiguously. This operation will either fully succeed making all events consumable or fully fail such that none of them are. There may be some time delay before readers see the events after this call has returned.

Throws:

TxnFailedException - The Transaction is no longer in state Transaction.Status.OPEN

abort

void abort()

Drops the transaction, causing all events written to it to be deleted.

checkStatus

Transaction.Status checkStatus()

Gets the status of the transaction.

Returns:

Current status of the transaction