org.apache.storm.spout

Class CheckPointState

java.lang.Object

org.apache.storm.spout.CheckPointState

public class CheckPointState
extends Object

Captures the current state of the transaction in CheckpointSpout. The state transitions are as follows.

                  ROLLBACK(tx2)
               <-------------                  PREPARE(tx2)                     COMMIT(tx2)
 COMMITTED(tx1)-------------> PREPARING(tx2) --------------> COMMITTING(tx2) -----------------> COMMITTED (tx2)

 

During recovery, if a previous transaction is in PREPARING state, it is rolled back since all bolts in the topology might not have prepared (saved) the data for commit. If the previous transaction is in COMMITTING state, it is rolled forward (committed) since some bolts might have already committed the data.

During normal flow, the state transitions from PREPARING to COMMITTING to COMMITTED. In case of failures the prepare/commit operation is retried.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CheckPointState.Action
static class	CheckPointState.State

Constructor Summary

Constructors

Constructor and Description
CheckPointState()
CheckPointState(long txid, CheckPointState.State state)

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object o)
CheckPointState.State	getState()
long	getTxid()
int	hashCode()
CheckPointState.Action	nextAction(boolean recovering) Get the next action to perform based on this checkpoint state.
CheckPointState	nextState(boolean recovering) Get the next state based on this checkpoint state.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

CheckPointState

public CheckPointState(long txid,
                       CheckPointState.State state)

CheckPointState

public CheckPointState()

Method Detail

getTxid

public long getTxid()

getState

public CheckPointState.State getState()

nextState

public CheckPointState nextState(boolean recovering)

Get the next state based on this checkpoint state.

Parameters:

recovering - if in recovering phase

Returns:

the next checkpoint state based on this state.

nextAction

public CheckPointState.Action nextAction(boolean recovering)

Get the next action to perform based on this checkpoint state.

Parameters:

recovering - if in recovering phase

Returns:

the next action to perform based on this state

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object