io.atomix.copycat.server.storage

Class Storage.Builder

java.lang.Object

io.atomix.copycat.server.storage.Storage.Builder

All Implemented Interfaces:

Builder<Storage>

Enclosing class:

Storage

public static class Storage.Builder
extends Object
implements Builder<Storage>

Builds a Storage configuration.

The storage builder provides simplifies building more complex Storage configurations. To create a storage builder, use the Storage.builder() factory method. Set properties of the configured Storage object with the various with* methods. Once the storage has been configured, call build() to build the object.

   
   Storage storage = Storage.builder()
     .withDirectory(new File("logs"))
     .withPersistenceLevel(PersistenceLevel.DISK)
     .build();
   
 

Method Summary

Modifier and Type	Method and Description
Storage	build() Builds the Storage object.
Storage.Builder	withCompactionThreads(int compactionThreads) Sets the number of log compaction threads, returning the builder for method chaining.
Storage.Builder	withCompactionThreshold(double threshold) Sets the percentage of entries in the segment that must be released before a segment can be compacted, returning the builder for method chaining.
Storage.Builder	withDirectory(File directory) Sets the log directory, returning the builder for method chaining.
Storage.Builder	withDirectory(String directory) Sets the log directory, returning the builder for method chaining.
Storage.Builder	withEntryBufferSize(int entryBufferSize) Sets the entry buffer size.
Storage.Builder	withFlushOnCommit() Enables flushing buffers to disk when entries are committed to a segment, returning the builder for method chaining.
Storage.Builder	withFlushOnCommit(boolean flushOnCommit) Sets whether to flush buffers to disk when entries are committed to a segment, returning the builder for method chaining.
Storage.Builder	withMajorCompactionInterval(Duration interval) Sets the major compaction interval, returning the builder for method chaining.
Storage.Builder	withMaxEntriesPerSegment(int maxEntriesPerSegment) Sets the maximum number of allows entries per segment, returning the builder for method chaining.
Storage.Builder	withMaxSegmentSize(int maxSegmentSize) Sets the maximum segment size in bytes, returning the builder for method chaining.
Storage.Builder	withMinorCompactionInterval(Duration interval) Sets the minor compaction interval, returning the builder for method chaining.
Storage.Builder	withRetainStaleSnapshots() Enables retaining stale snapshots on disk, returning the builder for method chaining.
Storage.Builder	withRetainStaleSnapshots(boolean retainStaleSnapshots) Sets whether to retain stale snapshots on disk, returning the builder for method chaining.
Storage.Builder	withStorageLevel(StorageLevel storageLevel) Sets the log storage level, returning the builder for method chaining.

Methods inherited from class java.lang.Object

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

Method Detail

withStorageLevel

public Storage.Builder withStorageLevel(StorageLevel storageLevel)

Sets the log storage level, returning the builder for method chaining.

The storage level indicates how individual entries should be persisted in the log.

Parameters:

storageLevel - The log storage level.

Returns:

The storage builder.

withDirectory

public Storage.Builder withDirectory(String directory)

Sets the log directory, returning the builder for method chaining.

The log will write segment files into the provided directory. If multiple Storage objects are located on the same machine, they write logs to different directories.

Parameters:

directory - The log directory.

Returns:

The storage builder.

Throws:

NullPointerException - If the directory is null

withDirectory

public Storage.Builder withDirectory(File directory)

Sets the log directory, returning the builder for method chaining.

The log will write segment files into the provided directory. If multiple Storage objects are located on the same machine, they write logs to different directories.

Parameters:

directory - The log directory.

Returns:

The storage builder.

Throws:

NullPointerException - If the directory is null

withMaxSegmentSize

public Storage.Builder withMaxSegmentSize(int maxSegmentSize)

Sets the maximum segment size in bytes, returning the builder for method chaining.

The maximum segment size dictates when logs should roll over to new segments. As entries are written to a segment of the log, once the size of the segment surpasses the configured maximum segment size, the log will create a new segment and append new entries to that segment.

By default, the maximum segment size is 1024 * 1024 * 32.

Parameters:

maxSegmentSize - The maximum segment size in bytes.

Returns:

The storage builder.

Throws:

IllegalArgumentException - If the maxSegmentSize is not positive

withMaxEntriesPerSegment

public Storage.Builder withMaxEntriesPerSegment(int maxEntriesPerSegment)

Sets the maximum number of allows entries per segment, returning the builder for method chaining.

The maximum entry count dictates when logs should roll over to new segments. As entries are written to a segment of the log, if the entry count in that segment meets the configured maximum entry count, the log will create a new segment and append new entries to that segment.

By default, the maximum entries per segment is 1024 * 1024.

Parameters:

maxEntriesPerSegment - The maximum number of entries allowed per segment.

Returns:

The storage builder.

Throws:

IllegalArgumentException - If the maxEntriesPerSegment not greater than the default max entries per segment

withEntryBufferSize

public Storage.Builder withEntryBufferSize(int entryBufferSize)

Sets the entry buffer size.

The entry buffer size dictates the number of entries to hold in memory at the tail of the log. Increasing the buffer size increases the number of entries that will be held in memory and thus implies greater memory consumption, but server performance may be improved due to reduced disk access.

Parameters:

entryBufferSize - The entry buffer size.

Returns:

The storage builder.

Throws:

IllegalArgumentException - if the buffer size is not positive

withFlushOnCommit

public Storage.Builder withFlushOnCommit()

Enables flushing buffers to disk when entries are committed to a segment, returning the builder for method chaining.

When flush-on-commit is enabled, log entry buffers will be automatically flushed to disk each time an entry is committed in a given segment.

Returns:

The storage builder.

withFlushOnCommit

public Storage.Builder withFlushOnCommit(boolean flushOnCommit)

Sets whether to flush buffers to disk when entries are committed to a segment, returning the builder for method chaining.

When flush-on-commit is enabled, log entry buffers will be automatically flushed to disk each time an entry is committed in a given segment.

Parameters:

flushOnCommit - Whether to flush buffers to disk when entries are committed to a segment.

Returns:

The storage builder.

withRetainStaleSnapshots

public Storage.Builder withRetainStaleSnapshots()

Enables retaining stale snapshots on disk, returning the builder for method chaining.

As the system state progresses, periodic snapshots of the state machine's state are taken. Once a new snapshot of the state machine is taken, all preceding snapshots no longer contribute to the state of the system and can therefore be removed from disk. By default, snapshots will not be retained once a new snapshot is stored on disk. Enabling snapshot retention will ensure that all snapshots will be saved, e.g. for backup purposes.

Returns:

The storage builder.

withRetainStaleSnapshots

public Storage.Builder withRetainStaleSnapshots(boolean retainStaleSnapshots)

Sets whether to retain stale snapshots on disk, returning the builder for method chaining.

As the system state progresses, periodic snapshots of the state machine's state are taken. Once a new snapshot of the state machine is taken, all preceding snapshots no longer contribute to the state of the system and can therefore be removed from disk. By default, snapshots will not be retained once a new snapshot is stored on disk. Enabling snapshot retention will ensure that all snapshots will be saved, e.g. for backup purposes.

Parameters:

retainStaleSnapshots - Whether to retain stale snapshots on disk.

Returns:

The storage builder.

withCompactionThreads

public Storage.Builder withCompactionThreads(int compactionThreads)

Sets the number of log compaction threads, returning the builder for method chaining.

The compaction thread count dictates the parallelism with which the log Compactor can rewrite segments of the log. By default, the log uses Runtime.getRuntime().availableProcessors() / 2 compaction threads.

Parameters:

compactionThreads - The number of log compaction threads.

Returns:

The storage builder.

Throws:

IllegalArgumentException - if compactionThreads is not positive

withMinorCompactionInterval

public Storage.Builder withMinorCompactionInterval(Duration interval)

Sets the minor compaction interval, returning the builder for method chaining.

The minor compaction interval dictates the interval at which the MinorCompactionManager should evaluate Segments in the log for minor compaction. It is recommended that the minor compaction interval be at least an order of magnitude smaller than the major compaction interval.

Parameters:

interval - The minor compaction interval.

Returns:

The storage builder.

Throws:

NullPointerException - if the interval is null

See Also:

MinorCompactionManager, MinorCompactionTask

withMajorCompactionInterval

public Storage.Builder withMajorCompactionInterval(Duration interval)

Sets the major compaction interval, returning the builder for method chaining.

The major compaction interval dictates the interval at which the MajorCompactionManager should evaluate Segments in the log for major compaction. Because of the performance costs of major compaction, it is recommended that the major compaction interval be at least an order of magnitude greater than the minor compaction interval.

Parameters:

interval - The major compaction interval.

Returns:

The storage builder.

Throws:

NullPointerException - if the interval is null

See Also:

MajorCompactionManager, MajorCompactionTask

withCompactionThreshold

public Storage.Builder withCompactionThreshold(double threshold)

Sets the percentage of entries in the segment that must be released before a segment can be compacted, returning the builder for method chaining.

The compaction threshold is used during minor compaction to determine the set of segments to compact. By default, the compaction threshold is 0.5. Increasing the compaction threshold will increase the number of entries that must be released from the segment before compaction and thus decrease the likelihood that a segment will be compacted. Conversely, decreasing the compaction threshold will increase the frequency of compaction at the cost of unnecessary I/O.

Parameters:

threshold - The segment compact threshold.

Returns:

The storage builder.

Throws:

IllegalArgumentException - if the threashold is not positive

See Also:

MinorCompactionManager

build

public Storage build()

Builds the Storage object.

Specified by:

build in interface Builder<Storage>

Returns:

The built storage configuration.