Class MemoryBasedStateMachine

Represents memory-based state machine with snapshotting support.

Inheritance

object

Disposable

PersistentState

MemoryBasedStateMachine

Implements

IDisposable

IPersistentState

IAuditTrail<IRaftLogEntry>

IAuditTrail

Inherited Members

PersistentState.CreateBackupAsync(Stream, CancellationToken)

PersistentState.RestoreFromBackupAsync(Stream, DirectoryInfo, CancellationToken)

PersistentState.Location

PersistentState.ReadAsync<TResult>(ILogEntryConsumer<IRaftLogEntry, TResult>, long, long, CancellationToken)

PersistentState.ReadAsync<TResult>(ILogEntryConsumer<IRaftLogEntry, TResult>, long, CancellationToken)

PersistentState.AppendAsync<TEntry>(TEntry, long, CancellationToken)

PersistentState.AppendAsync<TEntry>(TEntry, CancellationToken)

PersistentState.AppendAsync<TEntry>(TEntry, bool, CancellationToken)

PersistentState.AppendAsync<TEntry>(ILogEntryProducer<TEntry>, CancellationToken)

PersistentState.DropAsync(long, bool, CancellationToken)

PersistentState.WaitForApplyAsync(CancellationToken)

PersistentState.WaitForApplyAsync(long, CancellationToken)

PersistentState.CommitAsync(long, CancellationToken)

PersistentState.CommitAsync(CancellationToken)

PersistentState.Term

PersistentState.CreateJsonLogEntry<T>(T)

PersistentState.CreateBinaryLogEntry(ReadOnlyMemory<byte>)

PersistentState.CreateBinaryLogEntry<T>(T)

PersistentState.LastCommittedEntryIndex

PersistentState.LastEntryIndex

Disposable.IsDisposed

Disposable.IsDisposing

Disposable.IsDisposingOrDisposed

Disposable.CreateException()

Disposable.DisposedTask

Disposable.GetDisposedTask<T>()

Disposable.TrySetDisposedException<T>(TaskCompletionSource<T>)

Disposable.TrySetDisposedException(TaskCompletionSource)

Disposable.DisposeAsyncCore()

Disposable.DisposeAsync()

Disposable.TryBeginDispose()

Disposable.Dispose()

Disposable.Dispose(IEnumerable<IDisposable>)

Disposable.DisposeAsync(IEnumerable<IAsyncDisposable>)

Disposable.Dispose<T>(ReadOnlySpan<T>)

Disposable.DisposeAsync(params IAsyncDisposable[])

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: DotNext.Net.Cluster.Consensus.Raft

Assembly: DotNext.Net.Cluster.dll

Syntax

public abstract class MemoryBasedStateMachine : PersistentState, IDisposable, IPersistentState, IAuditTrail<IRaftLogEntry>, IAuditTrail

Remarks

The layout of the audit trail file system:

node.state	file containing internal state of Raft node
<partition>	file containing log partition with log records
snapshot	file containing snapshot

The audit trail supports log compaction. However, it doesn't know how to interpret and reduce log records during compaction. To do that, you can override CreateSnapshotBuilder(in SnapshotBuilderContext) method and implement state machine logic.

Constructors

MemoryBasedStateMachine(DirectoryInfo, int, Options?)

Initializes a new memory-based state machine.

Declaration

protected MemoryBasedStateMachine(DirectoryInfo path, int recordsPerPartition, MemoryBasedStateMachine.Options? configuration = null)

Parameters

Type	Name	Description
DirectoryInfo	path	The path to the folder to be used by audit trail.
int	recordsPerPartition	The maximum number of log entries that can be stored in the single file called partition.
MemoryBasedStateMachine.Options	configuration	The configuration of the persistent audit trail.

Exceptions

Type	Condition
ArgumentOutOfRangeException	recordsPerPartition is less than 2.

MemoryBasedStateMachine(string, int, Options?)

Initializes a new memory-based state machine.

Declaration

protected MemoryBasedStateMachine(string path, int recordsPerPartition, MemoryBasedStateMachine.Options? configuration = null)

Parameters

Type	Name	Description
string	path	The path to the folder to be used by audit trail.
int	recordsPerPartition	The maximum number of log entries that can be stored in the single file called partition.
MemoryBasedStateMachine.Options	configuration	The configuration of the persistent audit trail.

Exceptions

Type	Condition
ArgumentOutOfRangeException	recordsPerPartition is less than 2.

Properties

CompactionCount

Gets approximate number of partitions that can be compacted.

Declaration

public long CompactionCount { get; }

Property Value

Type	Description
long

IsBackgroundCompaction

Gets a value indicating that log compaction should be called manually using ForceCompactionAsync(long, CancellationToken) in the background.

Declaration

public bool IsBackgroundCompaction { get; }

Property Value

Type	Description
bool

Methods

ApplyAsync(LogEntry)

Applies the command represented by the log entry to the underlying database engine.

Declaration

protected abstract ValueTask ApplyAsync(PersistentState.LogEntry entry)

Parameters

Type	Name	Description
PersistentState.LogEntry	entry	The entry to be applied to the state machine.

Returns

Type	Description
ValueTask	The task representing asynchronous execution of this method.

Remarks

Context can be used to pass custom data through WAL processing pipeline. The value of this property is not persistent. The data can be passed as a part of log entry which is used as the argument of AppendAsync<TEntry>(TEntry, CancellationToken) method. The passed log entry type must implement IInputLogEntry interface.

See Also

CommandInterpreter

ClearAsync(CancellationToken)

Removes all log entries from the log.

Declaration

protected override sealed Task ClearAsync(CancellationToken token = default)

Parameters

Type	Name	Description
CancellationToken	token	The token that can be used to cancel the operation.

Returns

Type	Description
Task	The task representing asynchronous result of the method.

Overrides

PersistentState.ClearAsync(CancellationToken)

Exceptions

Type	Condition
OperationCanceledException	The operation has been cancelled.

CreateSnapshotBuilder(in SnapshotBuilderContext)

Creates a new snapshot builder.

Declaration

protected abstract MemoryBasedStateMachine.SnapshotBuilder CreateSnapshotBuilder(in MemoryBasedStateMachine.SnapshotBuilderContext context)

Parameters

Type	Name	Description
MemoryBasedStateMachine.SnapshotBuilderContext	context	The context of the snapshot builder.

Returns

Type	Description
MemoryBasedStateMachine.SnapshotBuilder	The snapshot builder.

Dispose(bool)

Releases all resources associated with this audit trail.

Declaration

protected override void Dispose(bool disposing)

Parameters

Type	Name	Description
bool	disposing	true if called from Dispose(); false if called from finalizer.

Overrides

PersistentState.Dispose(bool)

ForceCompactionAsync(long, CancellationToken)

Forces log compaction.

Declaration

public ValueTask ForceCompactionAsync(long count, CancellationToken token = default)

Parameters

Type	Name	Description
long	count	The number of partitions to be compacted.
CancellationToken	token	The token that can be used to cancel the operation.

Returns

Type	Description
ValueTask	The task representing asynchronous execution of this operation.

Remarks

Full compaction may be time-expensive operation. In this case, all readers will be blocked until the end of the compaction. Therefore, count can be used to reduce lock contention between compaction and readers. If it is 1 then compaction range is limited to the log entries contained in the single partition. This may be helpful if manual compaction is triggered by the background job. The job can wait for the commit using WaitForCommitAsync(CancellationToken) and then call this method with appropriate number of partitions to be collected according to CompactionCount property.

Exceptions

Type	Condition
ObjectDisposedException	This log is disposed.
OperationCanceledException	The operation has been canceled.

InitializeAsync(CancellationToken)

Initializes this state asynchronously.

Declaration

public override Task InitializeAsync(CancellationToken token = default)

Parameters

Type	Name	Description
CancellationToken	token	The token that can be used to cancel the operation.

Returns

Type	Description
Task	The task representing asynchronous result of the method.

Overrides

PersistentState.InitializeAsync(CancellationToken)

Exceptions

Type	Condition
OperationCanceledException	The operation has been cancelled.

ReplayAsync(CancellationToken)

Reconstructs dataset by calling ApplyAsync(LogEntry) for each committed entry.

Declaration

public Task ReplayAsync(CancellationToken token = default)

Parameters

Type	Name	Description
CancellationToken	token	The token that can be used to cancel the operation.

Returns

Type	Description
Task	The task representing asynchronous state of the method.

Implements

IDisposable

IPersistentState

IAuditTrail<TEntry>

IAuditTrail

Extension Methods

Command.AppendAsync<TCommand>(IPersistentState, TCommand, object?, CancellationToken)

PersistentStateExtensions.AppendAsync(IPersistentState, ReadOnlyMemory<byte>, object?, CancellationToken)

PersistentStateExtensions.AppendAsync<T>(IPersistentState, T, object?, CancellationToken)

PersistentStateExtensions.AppendJsonAsync<T>(IPersistentState, T, object?, CancellationToken)

BasicExtensions.As<T>(T)

BasicExtensions.GetUserData<T>(T)

BasicExtensions.IsBetween<T, TLowerBound, TUpperBound>(T, TLowerBound, TUpperBound)

BasicExtensions.IsOneOf<T>(T, ReadOnlySpan<T>)

ExpressionBuilder.Const<T>(T)