org.apache.ratis.statemachine

Interface TransactionContext

All Known Implementing Classes:

TransactionContextImpl

public interface TransactionContext

Context for a transaction. The transaction might have originated from a client request, or it maybe coming from another replica of the state machine through the RAFT log. TransactionContext can be created from either the StateMachine or the state machine updater. In the first case, the StateMachine is a leader. When it receives a StateMachine.startTransaction(RaftClientRequest) request, it returns a TransactionContext with the changes from the StateMachine. The same context will be passed back to the StateMachine via the StateMachine.applyTransaction(TransactionContext) call or the StateMachine.notifyNotLeader(java.util.Collection) call. In the second case, the StateMachine is a follower. The TransactionContext will be a committed entry coming from the RAFT log from the leader.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	TransactionContext.Builder

Method Summary

Modifier and Type	Method and Description
TransactionContext	cancelTransaction() Called to notify the state machine that the Transaction passed cannot be appended (or synced).
RaftClientRequest	getClientRequest() Returns the original request from the RaftClientRequest
Exception	getException() Returns the exception from the StateMachine or the log
org.apache.ratis.proto.RaftProtos.LogEntryProto	getLogEntry() Returns the committed log entry
org.apache.ratis.proto.RaftProtos.RaftPeerRole	getServerRole()
Object	getStateMachineContext() Returns the StateMachine the current TransactionContext specific to
org.apache.ratis.proto.RaftProtos.StateMachineLogEntryProto	getStateMachineLogEntry() Returns the data from the StateMachine
org.apache.ratis.proto.RaftProtos.LogEntryProto	initLogEntry(long term, long index) Initialize RaftProtos.LogEntryProto using the internal RaftProtos.StateMachineLogEntryProto.
static TransactionContext.Builder	newBuilder()
TransactionContext	preAppendTransaction() This is called before the transaction passed from the StateMachine is appended to the raft log.
TransactionContext	setException(Exception exception) Set exception in case of failure.
TransactionContext	setShouldCommit(boolean shouldCommit) Sets whether to commit the transaction to the RAFT log or not
TransactionContext	setStateMachineContext(Object stateMachineContext) Sets the StateMachine the TransactionContext is specific to, the method would not create a new transaction context, it updates the StateMachine it associates with
TransactionContext	setStateMachineLogEntryProto(org.apache.ratis.proto.RaftProtos.StateMachineLogEntryProto smLogEntryProto) Sets the data from the StateMachine
boolean	shouldCommit() It indicates if the transaction should be committed to the RAFT log

Method Detail

getServerRole

org.apache.ratis.proto.RaftProtos.RaftPeerRole getServerRole()

Returns:

the role of the server when this context is created.

getClientRequest

RaftClientRequest getClientRequest()

Returns the original request from the RaftClientRequest

Returns:

the original request from the RaftClientRequest

getStateMachineLogEntry

org.apache.ratis.proto.RaftProtos.StateMachineLogEntryProto getStateMachineLogEntry()

Returns the data from the StateMachine

Returns:

the data from the StateMachine

setException

TransactionContext setException(Exception exception)

Set exception in case of failure.

getException

Exception getException()

Returns the exception from the StateMachine or the log

Returns:

the exception from the StateMachine or the log

setStateMachineContext

TransactionContext setStateMachineContext(Object stateMachineContext)

Sets the StateMachine the TransactionContext is specific to, the method would not create a new transaction context, it updates the StateMachine it associates with

Parameters:

stateMachineContext - state machine context

Returns:

transaction context specific to the given StateMachine

getStateMachineContext

Object getStateMachineContext()

Returns the StateMachine the current TransactionContext specific to

Returns:

the StateMachine the current TransactionContext specific to

initLogEntry

org.apache.ratis.proto.RaftProtos.LogEntryProto initLogEntry(long term,
                                                             long index)

Initialize RaftProtos.LogEntryProto using the internal RaftProtos.StateMachineLogEntryProto.

Parameters:

term - The current term.

index - The index of the log entry.

Returns:

the result RaftProtos.LogEntryProto

setStateMachineLogEntryProto

TransactionContext setStateMachineLogEntryProto(org.apache.ratis.proto.RaftProtos.StateMachineLogEntryProto smLogEntryProto)

Sets the data from the StateMachine

Parameters:

smLogEntryProto - data from StateMachine

Returns:

the current TransactionContext itself

getLogEntry

org.apache.ratis.proto.RaftProtos.LogEntryProto getLogEntry()

Returns the committed log entry

Returns:

the committed log entry

setShouldCommit

TransactionContext setShouldCommit(boolean shouldCommit)

Sets whether to commit the transaction to the RAFT log or not

Parameters:

shouldCommit - true if the transaction is supposed to be committed to the RAFT log

Returns:

the current TransactionContext itself

shouldCommit

boolean shouldCommit()

It indicates if the transaction should be committed to the RAFT log

Returns:

true if it commits the transaction to the RAFT log, otherwise, false

preAppendTransaction

TransactionContext preAppendTransaction()
                                 throws IOException

This is called before the transaction passed from the StateMachine is appended to the raft log. This method will be called from log append and having the same strict serial order that the Transactions will have in the RAFT log. Since this is called serially in the critical path of log append, it is important to do only required operations here.

Returns:

The Transaction context.

Throws:

IOException

cancelTransaction

TransactionContext cancelTransaction()
                              throws IOException

Called to notify the state machine that the Transaction passed cannot be appended (or synced). The exception field will indicate whether there was an exception or not.

Returns:

cancelled transaction

Throws:

IOException

newBuilder

static TransactionContext.Builder newBuilder()