RaftStorage (Atomix API Reference (2.0.4))

java.lang.Object
- io.atomix.protocols.raft.storage.RaftStorage

```
public class RaftStorage
extends Object
```
Immutable log configuration and RaftLog factory.
This class provides a factory for RaftLog objects. Storage objects are immutable and can be created only via the RaftStorage.Builder. To create a new Storage.Builder, use the static newBuilder() factory method:
```
   
     Storage storage = Storage.builder()
       .withDirectory(new File("logs"))
       .withStorageLevel(StorageLevel.DISK)
       .build();
   
 
```
See Also:

RaftLog

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class RaftStorage.Builder
Builds a RaftStorage configuration.

Nested Classes
Modifier and Type	Class and Description
`static class`	`RaftStorage.Builder` Builds a `RaftStorage` configuration.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`deleteLog()` Deletes a `RaftLog` from disk.
`void`	`deleteMetaStore()` Deletes a `MetaStore` from disk.
`void`	`deleteSnapshotStore()` Deletes a `SnapshotStore` from disk.
`File`	`directory()` Returns the storage directory.
`boolean`	`dynamicCompaction()` Returns whether dynamic log compaction is enabled.
`double`	`freeDiskBuffer()` Returns the percentage of disk space that must be available before log compaction is forced.
`boolean`	`isFlushOnCommit()` Returns whether to flush buffers to disk when entries are committed.
`boolean`	`isRetainStaleSnapshots()` Returns a boolean value indicating whether to retain stale snapshots on disk.
`int`	`maxLogEntriesPerSegment()` Returns the maximum number of entries per segment.
`int`	`maxLogSegmentSize()` Returns the maximum log segment size.
`static RaftStorage.Builder`	`newBuilder()` Returns a new storage builder.
`RaftLog`	`openLog()` Opens a new `RaftLog`, recovering the log from disk if it exists.
`MetaStore`	`openMetaStore()` Opens a new `MetaStore`, recovering metadata from disk if it exists.
`SnapshotStore`	`openSnapshotStore()` Opens a new `SnapshotStore`, recovering snapshots from disk if they exist.
`String`	`prefix()` Returns the storage filename prefix.
`io.atomix.serializer.Serializer`	`serializer()` Returns the storage serializer.
`io.atomix.storage.statistics.StorageStatistics`	`statistics()` Returns the Raft storage statistics.
`io.atomix.storage.StorageLevel`	`storageLevel()` Returns the storage level.
`String`	`toString()`

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

- Method Detail
  - newBuilder
```
public static RaftStorage.Builder newBuilder()
```
    Returns a new storage builder.
    
    Returns:
    
    A new storage builder.
  - prefix
```
public String prefix()
```
    Returns the storage filename prefix.
    
    Returns:
    
    The storage filename prefix.
  - serializer
```
public io.atomix.serializer.Serializer serializer()
```
    Returns the storage serializer.
    
    Returns:
    
    The storage serializer.
  - directory
```
public File directory()
```
    Returns the storage directory.
    The storage directory is the directory to which all RaftLogs write files. Segment files for multiple logs may be stored in the storage directory, and files for each log instance will be identified by the name provided when the log is opened.
    
    Returns:
    
    The storage directory.
  - storageLevel
```
public io.atomix.storage.StorageLevel storageLevel()
```
    Returns the storage level.
    The storage level dictates how entries within individual log RaftLogs should be stored.
    
    Returns:
    
    The storage level.
  - maxLogSegmentSize
```
public int maxLogSegmentSize()
```
    Returns the maximum log segment size.
    The maximum segment size dictates the maximum size any segment in a RaftLog may consume in bytes.
    
    Returns:
    
    The maximum segment size in bytes.
  - maxLogEntriesPerSegment
```
public int maxLogEntriesPerSegment()
```
    Returns the maximum number of entries per segment.
    The maximum entries per segment dictates the maximum number of entries that are allowed to be stored in any segment in a RaftLog.
    
    Returns:
    
    The maximum number of entries per segment.
  - dynamicCompaction
```
public boolean dynamicCompaction()
```
    Returns whether dynamic log compaction is enabled.
    
    Returns:
    
    whether dynamic log compaction is enabled
  - freeDiskBuffer
```
public double freeDiskBuffer()
```
    Returns the percentage of disk space that must be available before log compaction is forced.
    
    Returns:
    
    the percentage of disk space that must be available before log compaction is forced
  - isFlushOnCommit
```
public boolean isFlushOnCommit()
```
    Returns whether to flush buffers to disk when entries are committed.
    
    Returns:
    
    Whether to flush buffers to disk when entries are committed.
  - isRetainStaleSnapshots
```
public boolean isRetainStaleSnapshots()
```
    Returns a boolean value indicating whether to retain stale snapshots on disk.
    If this option is enabled, snapshots will be retained on disk even after they no longer contribute to the state of the system (there's a more recent snapshot). Users may want to disable this option for backup purposes.
    
    Returns:
    
    Indicates whether to retain stale snapshots on disk.
  - statistics
```
public io.atomix.storage.statistics.StorageStatistics statistics()
```
    Returns the Raft storage statistics.
    
    Returns:
    
    the Raft storage statistics
  - openMetaStore
```
public MetaStore openMetaStore()
```
    Opens a new MetaStore, recovering metadata from disk if it exists.
    The meta store will be loaded using based on the configured StorageLevel. If the storage level is persistent then the meta store will be loaded from disk, otherwise a new meta store will be created.
    
    Returns:
    
    The metastore.
  - deleteMetaStore
```
public void deleteMetaStore()
```
    Deletes a MetaStore from disk.
    The meta store will be deleted by simply reading meta file names from disk and deleting metadata files directly. Deleting the meta store does not involve reading any metadata files into memory.
  - openSnapshotStore
```
public SnapshotStore openSnapshotStore()
```
    Opens a new SnapshotStore, recovering snapshots from disk if they exist.
    The snapshot store will be loaded using based on the configured StorageLevel. If the storage level is persistent then the snapshot store will be loaded from disk, otherwise a new snapshot store will be created.
    
    Returns:
    
    The snapshot store.
  - deleteSnapshotStore
```
public void deleteSnapshotStore()
```
    Deletes a SnapshotStore from disk.
    The snapshot store will be deleted by simply reading snapshot file names from disk and deleting snapshot files directly. Deleting the snapshot store does not involve reading any snapshot files into memory.
  - openLog
```
public RaftLog openLog()
```
    Opens a new RaftLog, recovering the log from disk if it exists.
    When a log is opened, the log will attempt to load segments from the storage directory() according to the provided log name. If segments for the given log name are present on disk, segments will be loaded and indexes will be rebuilt from disk. If no segments are found, an empty log will be created.
    When log files are loaded from disk, the file names are expected to be based on the provided log name.
    
    Returns:
    
    The opened log.
  - deleteLog
```
public void deleteLog()
```
    Deletes a RaftLog from disk.
    The log will be deleted by simply reading log file names from disk and deleting log files directly. Deleting log files does not involve rebuilding indexes or reading any logs into memory.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class RaftStorage

Nested Class Summary

Method Summary

Methods inherited from class java.lang.Object

Method Detail

newBuilder

prefix

serializer

directory

storageLevel

maxLogSegmentSize

maxLogEntriesPerSegment

dynamicCompaction

freeDiskBuffer

isFlushOnCommit

isRetainStaleSnapshots

statistics

openMetaStore

deleteMetaStore

openSnapshotStore

deleteSnapshotStore

openLog

deleteLog

toString