io.atomix.copycat.server.storage.compaction

Class MajorCompactionManager

java.lang.Object

io.atomix.copycat.server.storage.compaction.MajorCompactionManager

All Implemented Interfaces:

CompactionManager

public final class MajorCompactionManager
extends Object
implements CompactionManager

Builds tasks for the Compaction.MAJOR compaction process.

Major compaction works by iterating through all committed Segments in the log and rewriting and combining segments to compact them together. Because of the sequential nature of major compaction, the major compaction manager builds only a single MajorCompactionTask which will rewrite the log sequentially. Segments are provided to the major compaction task in groups that indicate which segments to combine. A set of segments can be combined if they meet the following criteria:

• The entries in the set of segments are sequential; there are no missing segments in the set such that combining the segments would result in a segment with missing entries
• The combined size of all segments in the set is less than the configured Storage.maxSegmentSize()
• The combined number of entries after compaction is less than the configured Storage.maxEntriesPerSegment()

Author:

Method Summary

Modifier and Type	Method and Description
List<CompactionTask>	buildTasks(Storage storage, SegmentManager segments) Builds compaction tasks for the given segments.
List<List<Segment>>	getCompactableGroups(Storage storage, SegmentManager manager) Returns a list of segments lists to compact, where segments are grouped according to how they will be merged during compaction.

Methods inherited from class java.lang.Object

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

Method Detail

buildTasks

public List<CompactionTask> buildTasks(Storage storage,
                                       SegmentManager segments)

Description copied from interface: CompactionManager

Builds compaction tasks for the given segments.

The collection of compaction tasks will be run in parallel in a pool of Storage.compactionThreads() background threads. Implementations should ensure that individual tasks can be run in parallel by operating on different segments in the log.

Specified by:

buildTasks in interface CompactionManager

Parameters:

storage - The storage configuration.

segments - The segments for which to build compaction tasks.

Returns:

An iterable of compaction tasks.

getCompactableGroups

public List<List<Segment>> getCompactableGroups(Storage storage,
                                                SegmentManager manager)

Returns a list of segments lists to compact, where segments are grouped according to how they will be merged during compaction.