JournalStateMachine (Alluxio Parent 2.4.2-SNAPSHOT API)

java.lang.Object
- org.apache.ratis.statemachine.impl.BaseStateMachine
- - alluxio.master.journal.raft.JournalStateMachine

All Implemented Interfaces:

Closeable, AutoCloseable, org.apache.ratis.statemachine.StateMachine, org.apache.ratis.statemachine.StateMachine.DataApi
```
@ThreadSafe
public class JournalStateMachine
extends org.apache.ratis.statemachine.impl.BaseStateMachine
```
A state machine for managing all of Alluxio's journaled state. Entries applied to this state machine will be forwarded to the appropriate internal master. The state machine starts by resetting all state, then applying the entries offered by Ratis. When the master becomes primary, it should wait until the state machine is up to date and no other primary master is serving, then call upgrade(). Once the state machine is upgraded, it will ignore all entries appended by Ratis because those entries are applied to primary master state before being written to Rati.

Nested Class Summary
- Nested classes/interfaces inherited from class org.apache.ratis.statemachine.impl.BaseStateMachine
  org.apache.ratis.statemachine.impl.BaseStateMachine.Task
- Nested classes/interfaces inherited from interface org.apache.ratis.statemachine.StateMachine
  org.apache.ratis.statemachine.StateMachine.DataApi, org.apache.ratis.statemachine.StateMachine.DataStream, org.apache.ratis.statemachine.StateMachine.Registry

Field Summary
- Fields inherited from interface org.apache.ratis.statemachine.StateMachine.DataApi
  DEFAULT

Constructor Summary

Constructors
Constructor and Description

JournalStateMachine(Map<String,RaftJournal> journals, RaftJournalSystem journalSystem)

Constructors
Constructor and Description
`JournalStateMachine(Map<String,RaftJournal> journals, RaftJournalSystem journalSystem)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`applyJournalEntryCommand(org.apache.ratis.statemachine.TransactionContext commit)` Applies a journal entry commit to the state machine.
`CompletableFuture<org.apache.ratis.protocol.Message>`	`applyTransaction(org.apache.ratis.statemachine.TransactionContext trx)`
`CatchupFuture`	`catchup(long sequence)` Initiates catching up of masters to given sequence.
`void`	`close()`
`long`	`getLastAppliedSequenceNumber()`
`long`	`getLastPrimaryStartSequenceNumber()`
`org.apache.ratis.statemachine.SnapshotInfo`	`getLatestSnapshot()`
`SnapshotReplicationManager`	`getSnapshotReplicationManager()`
`org.apache.ratis.statemachine.StateMachineStorage`	`getStateMachineStorage()`
`void`	`initialize(org.apache.ratis.server.RaftServer server, org.apache.ratis.protocol.RaftGroupId groupId, org.apache.ratis.server.storage.RaftStorage raftStorage)`
`boolean`	`isSnapshotting()`
`boolean`	`isSuspended()`
`CompletableFuture<org.apache.ratis.server.protocol.TermIndex>`	`notifyInstallSnapshotFromLeader(org.apache.ratis.proto.RaftProtos.RoleInfoProto roleInfoProto, org.apache.ratis.server.protocol.TermIndex firstTermIndexInLog)`
`void`	`notifyLeaderChanged(org.apache.ratis.protocol.RaftGroupMemberId groupMemberId, org.apache.ratis.protocol.RaftPeerId raftPeerId)`
`void`	`notifyNotLeader(Collection<org.apache.ratis.statemachine.TransactionContext> pendingEntries)`
`void`	`pause()`
`CompletableFuture<org.apache.ratis.protocol.Message>`	`query(org.apache.ratis.protocol.Message request)`
`void`	`reinitialize()`
`void`	`resume()` Resumes applying to masters.
`void`	`suspend(Runnable interruptCallback)` Suspends applying to masters.
`long`	`takeLocalSnapshot()` Takes a snapshot of local state machine.
`long`	`takeSnapshot()`
`void`	`unpause()` Unpause the StateMachine.
`long`	`upgrade()` Upgrades the journal state machine to primary mode.

Methods inherited from class org.apache.ratis.statemachine.impl.BaseStateMachine
applyTransactionSerial, cancelTransaction, getGroupId, getId, getLastAppliedTermIndex, getLifeCycle, getLifeCycleState, getServer, notifyIndexUpdate, preAppendTransaction, queryStale, recordTime, setLastAppliedTermIndex, startTransaction, toString, updateLastAppliedTermIndex

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.ratis.statemachine.StateMachine
data, notifyExtendedNoLeader, notifyGroupRemove, notifyLogFailed, notifySlowness, toStateMachineLogEntryString

Methods inherited from interface org.apache.ratis.statemachine.StateMachine.DataApi
flush, link, read, stream, truncate, write

- Constructor Detail
  - JournalStateMachine
```
public JournalStateMachine(Map<String,RaftJournal> journals,
                           RaftJournalSystem journalSystem)
```
    Parameters:
    
    journals - master journals; these journals are still owned by the caller, not by the journal state machine
    
    journalSystem - the raft journal system
- Method Detail
  - initialize
```
public void initialize(org.apache.ratis.server.RaftServer server,
                       org.apache.ratis.protocol.RaftGroupId groupId,
                       org.apache.ratis.server.storage.RaftStorage raftStorage)
                throws IOException
```
    Specified by:
    
    initialize in interface org.apache.ratis.statemachine.StateMachine
    
    Overrides:
    
    initialize in class org.apache.ratis.statemachine.impl.BaseStateMachine
    
    Throws:
    
    IOException
  - reinitialize
```
public void reinitialize()
                  throws IOException
```
    Specified by:
    
    reinitialize in interface org.apache.ratis.statemachine.StateMachine
    
    Overrides:
    
    reinitialize in class org.apache.ratis.statemachine.impl.BaseStateMachine
    
    Throws:
    
    IOException
  - takeSnapshot
```
public long takeSnapshot()
```
    Specified by:
    
    takeSnapshot in interface org.apache.ratis.statemachine.StateMachine
    
    Overrides:
    
    takeSnapshot in class org.apache.ratis.statemachine.impl.BaseStateMachine
  - getLatestSnapshot
```
public org.apache.ratis.statemachine.SnapshotInfo getLatestSnapshot()
```
    Specified by:
    
    getLatestSnapshot in interface org.apache.ratis.statemachine.StateMachine
    
    Overrides:
    
    getLatestSnapshot in class org.apache.ratis.statemachine.impl.BaseStateMachine
  - getStateMachineStorage
```
public org.apache.ratis.statemachine.StateMachineStorage getStateMachineStorage()
```
    Specified by:
    
    getStateMachineStorage in interface org.apache.ratis.statemachine.StateMachine
    
    Overrides:
    
    getStateMachineStorage in class org.apache.ratis.statemachine.impl.BaseStateMachine
  - query
```
public CompletableFuture<org.apache.ratis.protocol.Message> query(org.apache.ratis.protocol.Message request)
```
    Specified by:
    
    query in interface org.apache.ratis.statemachine.StateMachine
    
    Overrides:
    
    query in class org.apache.ratis.statemachine.impl.BaseStateMachine
  - close
```
public void close()
```
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable
    
    Overrides:
    
    close in class org.apache.ratis.statemachine.impl.BaseStateMachine
  - applyTransaction
```
public CompletableFuture<org.apache.ratis.protocol.Message> applyTransaction(org.apache.ratis.statemachine.TransactionContext trx)
```
    Specified by:
    
    applyTransaction in interface org.apache.ratis.statemachine.StateMachine
    
    Overrides:
    
    applyTransaction in class org.apache.ratis.statemachine.impl.BaseStateMachine
  - notifyNotLeader
```
public void notifyNotLeader(Collection<org.apache.ratis.statemachine.TransactionContext> pendingEntries)
```
    Specified by:
    
    notifyNotLeader in interface org.apache.ratis.statemachine.StateMachine
    
    Overrides:
    
    notifyNotLeader in class org.apache.ratis.statemachine.impl.BaseStateMachine
  - notifyInstallSnapshotFromLeader
```
public CompletableFuture<org.apache.ratis.server.protocol.TermIndex> notifyInstallSnapshotFromLeader(org.apache.ratis.proto.RaftProtos.RoleInfoProto roleInfoProto,
                                                                                                     org.apache.ratis.server.protocol.TermIndex firstTermIndexInLog)
```
  - pause
```
public void pause()
```
    Specified by:
    
    pause in interface org.apache.ratis.statemachine.StateMachine
    
    Overrides:
    
    pause in class org.apache.ratis.statemachine.impl.BaseStateMachine
  - unpause
```
public void unpause()
```
    Unpause the StateMachine. This should be done after uploading new state to the StateMachine.
  - applyJournalEntryCommand
```
public void applyJournalEntryCommand(org.apache.ratis.statemachine.TransactionContext commit)
```
    Applies a journal entry commit to the state machine.
    
    Parameters:
    
    commit - the commit
  - takeLocalSnapshot
```
public long takeLocalSnapshot()
```
    Takes a snapshot of local state machine.
    
    Returns:
    
    the index of last included entry, or RaftLog.INVALID_LOG_INDEX if it fails
  - suspend
```
public void suspend(Runnable interruptCallback)
             throws IOException
```
    Suspends applying to masters. When using suspend, the caller needs to provide a callback method as parameter. This callback is invoked when the journal needs to reload and thus cannot suspend the state changes any more. The callback should cancel any tasks that access the master states. After the callback returns, the journal assumes that the states is no longer being accessed and will reload immediately.
    
    Parameters:
    
    interruptCallback - a callback function to be called when the suspend is interrupted
    
    Throws:
    
    IOException
  - resume
```
public void resume()
            throws IOException
```
    Resumes applying to masters.
    
    Throws:
    
    IOException
  - catchup
```
public CatchupFuture catchup(long sequence)
```
    Initiates catching up of masters to given sequence.
    
    Parameters:
    
    sequence - the target sequence
    
    Returns:
    
    the future to track when catching up is done
  - upgrade
```
public long upgrade()
```
    Upgrades the journal state machine to primary mode.
    
    Returns:
    
    the last sequence number read while in secondary mode
  - getLastAppliedSequenceNumber
```
public long getLastAppliedSequenceNumber()
```
    Returns:
    
    the sequence number of the last entry applied to the state machine
  - getLastPrimaryStartSequenceNumber
```
public long getLastPrimaryStartSequenceNumber()
```
    Returns:
    
    the last primary term start sequence number applied to this state machine
  - isSnapshotting
```
public boolean isSnapshotting()
```
    Returns:
    
    whether the state machine is in the process of taking a snapshot
  - notifyLeaderChanged
```
public void notifyLeaderChanged(org.apache.ratis.protocol.RaftGroupMemberId groupMemberId,
                                org.apache.ratis.protocol.RaftPeerId raftPeerId)
```
  - getSnapshotReplicationManager
```
public SnapshotReplicationManager getSnapshotReplicationManager()
```
    Returns:
    
    the snapshot replication manager
  - isSuspended
```
public boolean isSuspended()
```
    Returns:
    
    whether the journal is suspended

Class JournalStateMachine

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.ratis.statemachine.impl.BaseStateMachine

Nested classes/interfaces inherited from interface org.apache.ratis.statemachine.StateMachine

Field Summary

Fields inherited from interface org.apache.ratis.statemachine.StateMachine.DataApi

Constructor Summary

Method Summary

Methods inherited from class org.apache.ratis.statemachine.impl.BaseStateMachine

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.ratis.statemachine.StateMachine

Methods inherited from interface org.apache.ratis.statemachine.StateMachine.DataApi

Constructor Detail

JournalStateMachine

Method Detail

initialize

reinitialize

takeSnapshot

getLatestSnapshot

getStateMachineStorage

query

close

applyTransaction

notifyNotLeader

notifyInstallSnapshotFromLeader

pause

unpause

applyJournalEntryCommand

takeLocalSnapshot

suspend

resume

catchup

upgrade

getLastAppliedSequenceNumber

getLastPrimaryStartSequenceNumber

isSnapshotting

notifyLeaderChanged

getSnapshotReplicationManager

isSuspended