org.apache.hadoop.hbase.procedure2

Class StateMachineProcedure<TEnvironment,TState>

java.lang.Object

org.apache.hadoop.hbase.procedure2.Procedure<TEnvironment>

org.apache.hadoop.hbase.procedure2.StateMachineProcedure<TEnvironment,TState>

All Implemented Interfaces:

Comparable<Procedure>

Direct Known Subclasses:

AddColumnFamilyProcedure, CreateTableProcedure, DeleteColumnFamilyProcedure, DeleteTableProcedure, DisableTableProcedure, EnableTableProcedure, ModifyColumnFamilyProcedure, ModifyTableProcedure, TestProcedureRecovery.TestStateMachineProcedure, TruncateTableProcedure

@InterfaceAudience.Private
 @InterfaceStability.Evolving
public abstract class StateMachineProcedure<TEnvironment,TState>
extends Procedure<TEnvironment>

Procedure described by a series of steps. The procedure implementor must have an enum of 'states', describing the various step of the procedure. Once the procedure is running, the procedure-framework will call executeFromState() using the 'state' provided by the user. The first call to executeFromState() will be performed with 'state = null'. The implementor can jump between states using setNextState(MyStateEnum.ordinal()). The rollback will call rollbackState() for each state that was executed, in reverse order.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	StateMachineProcedure.Flow

Constructor Summary

Constructors

Constructor and Description
StateMachineProcedure()

Method Summary

Modifier and Type	Method and Description
protected void	deserializeStateData(InputStream stream) Called on store load to allow the user to decode the previously serialized state.
protected Procedure[]	execute(TEnvironment env) The main code of the procedure.
protected abstract StateMachineProcedure.Flow	executeFromState(TEnvironment env, TState state) called to perform a single step of the specified 'state' of the procedure
protected abstract TState	getInitialState() Return the initial state object that will be used for the first call to executeFromState().
protected abstract TState	getState(int stateId) Convert an ordinal (or state id) to an Enum (or more descriptive) state object.
protected abstract int	getStateId(TState state) Convert the Enum (or more descriptive) state object to an ordinal (or state id).
protected void	rollback(TEnvironment env) The code to undo what done by the execute() code.
protected abstract void	rollbackState(TEnvironment env, TState state) called to perform the rollback of the specified state
protected void	serializeStateData(OutputStream stream) The user-level code of the procedure may have some state to persist (e.g.
protected void	setNextState(TState state) Set the next state for the procedure.

Methods inherited from class org.apache.hadoop.hbase.procedure2.Procedure

abort, acquireLock, addStackIndex, beforeReplay, childrenCountDown, compareTo, completionCleanup, convert, convert, createProcedureInfo, doExecute, doRollback, elapsedTime, getException, getLastUpdate, getOwner, getParentProcId, getProcId, getResult, getRootProcedureId, getStackIndexes, getStartTime, getState, getTimeout, getTimeRemaining, hasException, hasOwner, hasParent, hasTimeout, incChildrenLatch, isFailed, isFinished, isSuccess, isWaiting, newInstance, releaseLock, removeStackIndex, setAbortFailure, setChildrenLatch, setFailure, setFailure, setOwner, setParentProcId, setProcId, setResult, setStackIndexes, setStartTime, setState, setTimeout, setTimeoutFailure, toString, toStringClass, toStringClassDetails, updateTimestamp, validateClass, wasExecuted

Methods inherited from class java.lang.Object

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

Constructor Detail

StateMachineProcedure

public StateMachineProcedure()

Method Detail

executeFromState

protected abstract StateMachineProcedure.Flow executeFromState(TEnvironment env,
                                                               TState state)
                                                        throws ProcedureYieldException

called to perform a single step of the specified 'state' of the procedure

Parameters:

state - state to execute

Returns:

Flow.NO_MORE_STATE if the procedure is completed, Flow.HAS_MORE_STATE if there is another step.

Throws:

ProcedureYieldException

rollbackState

protected abstract void rollbackState(TEnvironment env,
                                      TState state)
                               throws IOException

called to perform the rollback of the specified state

Parameters:

state - state to rollback

Throws:

IOException - temporary failure, the rollback will retry later

getState

protected abstract TState getState(int stateId)

Convert an ordinal (or state id) to an Enum (or more descriptive) state object.

Parameters:

stateId - the ordinal() of the state enum (or state id)

Returns:

the state enum object

getStateId

protected abstract int getStateId(TState state)

Convert the Enum (or more descriptive) state object to an ordinal (or state id).

Parameters:

state - the state enum object

Returns:

stateId the ordinal() of the state enum (or state id)

getInitialState

protected abstract TState getInitialState()

Return the initial state object that will be used for the first call to executeFromState().

Returns:

the initial state enum object

setNextState

protected void setNextState(TState state)

Set the next state for the procedure.

Parameters:

state - the state enum object

execute

protected Procedure[] execute(TEnvironment env)
                       throws ProcedureYieldException

Description copied from class: Procedure

The main code of the procedure. It must be idempotent since execute() may be called multiple time in case of machine failure in the middle of the execution.

Specified by:

execute in class Procedure<TEnvironment>

Returns:

a set of sub-procedures or null if there is nothing else to execute.

Throws:

ProcedureYieldException

rollback

protected void rollback(TEnvironment env)
                 throws IOException

Description copied from class: Procedure

The code to undo what done by the execute() code. It is called when the procedure or one of the sub-procedure failed or an abort was requested. It should cleanup all the resources created by the execute() call. The implementation must be idempotent since rollback() may be called multiple time in case of machine failure in the middle of the execution.

Specified by:

rollback in class Procedure<TEnvironment>

Throws:

IOException - temporary failure, the rollback will retry later

serializeStateData

protected void serializeStateData(OutputStream stream)
                           throws IOException

Description copied from class: Procedure

The user-level code of the procedure may have some state to persist (e.g. input arguments) to be able to resume on failure.

Specified by:

serializeStateData in class Procedure<TEnvironment>

Parameters:

stream - the stream that will contain the user serialized data

Throws:

IOException

deserializeStateData

protected void deserializeStateData(InputStream stream)
                             throws IOException

Description copied from class: Procedure

Called on store load to allow the user to decode the previously serialized state.

Specified by:

deserializeStateData in class Procedure<TEnvironment>

Parameters:

stream - the stream that contains the user serialized data

Throws:

IOException