io.aeron.cluster

Class NodeStateFile

java.lang.Object

io.aeron.cluster.NodeStateFile

All Implemented Interfaces:

AutoCloseable

public class NodeStateFile
extends Object
implements AutoCloseable

An extensible list of information relating to a specific cluster node. Used to track persistent state that is node specific and shouldn't be present in the snapshot. E.g. candidateTermId.

The structure consists of a node header at the beginning of the file followed by n entries that use the standard open framing header, followed by the message header, and finally the body.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                     Node State Header                         |
  +---------------------------------------------------------------+
  

Entry. All records must be laid out so that the body has an 8-byte alignment. Fields that require volatile accesses must be aligned to an 8-byte boundary. The message header is 8-bytes long to aid with this. Records are padded to a 8-byte boundary before the next record.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +---------------------------------------------------------------+
  |                       Message Header                          |
  |                                                               |
  +---------------------------------------------------------------+
  |                       Message Body (Variable)               ...
  ...                                                             |
  +---------------------------------------------------------------+
 

The current structure contains:

     <Node State Header>
     <Candidate Term>
     <Cluster Members>
     <Node State Footer>
 

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	NodeStateFile.CandidateTerm Wrapper class for the candidate term.

Field Summary

Fields

Modifier and Type	Field and Description
static String	FILENAME

Constructor Summary

Constructors

Constructor and Description
NodeStateFile(File clusterDir, boolean createNew, int fileSyncLevel) Construct the NodeStateFile.

Method Summary

Modifier and Type	Method and Description
NodeStateFile.CandidateTerm	candidateTerm() Get the reference to CandidateTerm wrapper that can be used to fetch the values associated with the current candidate term.
void	close()
long	proposeMaxCandidateTermId(long candidateTermId, long logPosition, long timestampMs) Set the current candidate term id with associated information.
void	updateCandidateTermId(long candidateTermId, long logPosition, long timestampMs) Set the current candidate term id with associated information.

Methods inherited from class java.lang.Object

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

Field Detail

FILENAME

public static final String FILENAME

See Also:

Constant Field Values

Constructor Detail

NodeStateFile

public NodeStateFile(File clusterDir,
                     boolean createNew,
                     int fileSyncLevel)
              throws IOException

Construct the NodeStateFile.

Parameters:

clusterDir - directory containing the NodeStateFile.

createNew - whether a new file should be created if one does not already exist.

fileSyncLevel - whether the mapped byte buffer should be synchronised with the underlying filesystem on change.

Throws:

IOException - if there is an error creating the file or createNew == false and the file does not already exist.

Method Detail

close

public void close()

Specified by:

close in interface AutoCloseable

updateCandidateTermId

public void updateCandidateTermId(long candidateTermId,
                                  long logPosition,
                                  long timestampMs)

Set the current candidate term id with associated information.

Parameters:

candidateTermId - current candidate term id.

logPosition - log position where the term id change occurred.

timestampMs - timestamp of the candidate term id change.

proposeMaxCandidateTermId

public long proposeMaxCandidateTermId(long candidateTermId,
                                      long logPosition,
                                      long timestampMs)

Set the current candidate term id with associated information.

Parameters:

candidateTermId - current candidate term id.

logPosition - log position where the term id change occurred.

timestampMs - timestamp of the candidate term id change.

Returns:

the new candidate term id.

candidateTerm

public NodeStateFile.CandidateTerm candidateTerm()

Get the reference to CandidateTerm wrapper that can be used to fetch the values associated with the current candidate term.

Returns:

the CandidateTerm wrapper.