io.openmessaging.storage.dledger.statemachine

Interface StateMachine

public interface StateMachine

Finite state machine, which should be implemented by user.

Method Summary

Modifier and Type	Method and Description
default String	generateDLedgerId(String dLedgerGroupId, String dLedgerSelfId) User must create DLedgerId by this method, it will generate the DLedgerId with format like that: 'dLedgerGroupId#dLedgerSelfId'
String	getBindDLedgerId() User should return the DLedgerId which can be created by the method 'StateMachine#generateDLedgerId'
void	onApply(CommittedEntryIterator iter) Update the user statemachine with a batch a tasks that can be accessed through |iterator|.
void	onShutdown() Invoked once when the raft node was shut down.
boolean	onSnapshotLoad(SnapshotReader reader) User defined snapshot load function.
void	onSnapshotSave(SnapshotWriter writer, CompletableFuture<Boolean> done) User defined snapshot generate function, this method will block StateMachine#onApply(Iterator).

Method Detail

onApply

void onApply(CommittedEntryIterator iter)

Update the user statemachine with a batch a tasks that can be accessed through |iterator|.

Parameters:

iter - iterator of committed entry

onSnapshotSave

void onSnapshotSave(SnapshotWriter writer,
                    CompletableFuture<Boolean> done)

User defined snapshot generate function, this method will block StateMachine#onApply(Iterator). Call done.run(status) when snapshot finished.

Parameters:

writer - snapshot writer

done - callback

onSnapshotLoad

boolean onSnapshotLoad(SnapshotReader reader)

User defined snapshot load function.

Parameters:

reader - snapshot reader

Returns:

true on success

onShutdown

void onShutdown()

Invoked once when the raft node was shut down. Default do nothing

generateDLedgerId

default String generateDLedgerId(String dLedgerGroupId,
                                 String dLedgerSelfId)

User must create DLedgerId by this method, it will generate the DLedgerId with format like that: 'dLedgerGroupId#dLedgerSelfId'

Parameters:

dLedgerGroupId - the group id of the DLedgerServer

dLedgerSelfId - the self id of the DLedgerServer

Returns:

generated unique DLedgerId

getBindDLedgerId

String getBindDLedgerId()

User should return the DLedgerId which can be created by the method 'StateMachine#generateDLedgerId'

Returns:

DLedgerId