Package io.camunda.zeebe.logstreams.storage

Interface LogStorage

public interface LogStorage

Storage abstraction for the log stream API. The storage is expected to store the given blocks of data atomically (i.e. a block is fully written or not at all), in the order in which they were appended.

The main access pattern is via the LogStorageReader, and is expected to be sequential. The reader should support seek as efficiently as possible, but random access is not the common case.

The lifecycle of the storage is expected to be independent of the log stream, and the storage is simply passed along to the stream.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	LogStorage.AppendListener	An append listener can be added to an append call to be notified of different events that can occur during the append operation.
static interface	LogStorage.CommitListener	Consumers of LogStorage can use this listener to get notified when new records are committed.

Method Summary

Modifier and Type	Method	Description
void	addCommitListener(LogStorage.CommitListener listener)	Register a commit listener
void	append(long lowestPosition, long highestPosition, BufferWriter bufferWriter, LogStorage.AppendListener listener)	Writes a block containing one or multiple log entries in the storage and returns the address at which the block has been written.
default void	append(long lowestPosition, long highestPosition, ByteBuffer blockBuffer, LogStorage.AppendListener listener)	Writes a block containing one or multiple log entries in the storage and returns the address at which the block has been written.
LogStorageReader	newReader()	Creates a new reader initialized at the given address.
void	removeCommitListener(LogStorage.CommitListener listener)	Remove a commit listener

Method Details

newReader

LogStorageReader newReader()

Creates a new reader initialized at the given address.

Returns:

a new stateful storage reader

append

void append(long lowestPosition,
 long highestPosition,
 BufferWriter bufferWriter,
 LogStorage.AppendListener listener)

Writes a block containing one or multiple log entries in the storage and returns the address at which the block has been written.

Storage implementations must guarantee eventually atomicity. When this method completes, either all the bytes must be written or none at all.

The caller of this method must guarantee that the provided block contains unfragmented log entries.

Parameters:

lowestPosition - the lowest record position of all records in the block buffer

highestPosition - the highest record position of all records in the block buffer

bufferWriter - the buffer containing a block of log entries to be written into storage

append

default void append(long lowestPosition,
 long highestPosition,
 ByteBuffer blockBuffer,
 LogStorage.AppendListener listener)

Writes a block containing one or multiple log entries in the storage and returns the address at which the block has been written.

Storage implementations must guarantee eventually atomicity. When this method completes, either all the bytes must be written or none at all.

The caller of this method must guarantee that the provided block contains unfragmented log entries.

Parameters:

lowestPosition - the lowest record position of all records in the block buffer

highestPosition - the highest record position of all records in the block buffer

blockBuffer - the buffer containing a block of log entries to be written into storage

addCommitListener

void addCommitListener(LogStorage.CommitListener listener)

Register a commit listener

Parameters:

listener - the listener which will be notified when a new record is committed.

removeCommitListener

void removeCommitListener(LogStorage.CommitListener listener)

Remove a commit listener

Parameters:

listener - the listener to remove