io.atomix.copycat.server.storage.compaction.MajorCompactionManager Maven / Gradle / Ivy
/*
* Copyright 2015 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License
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package io.atomix.copycat.server.storage.compaction;
import io.atomix.copycat.server.storage.Segment;
import io.atomix.copycat.server.storage.SegmentManager;
import io.atomix.copycat.server.storage.Storage;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* Builds tasks for the {@link Compaction#MAJOR} compaction process.
*
* Major compaction works by iterating through all committed {@link Segment}s 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 {@link 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 {@link Storage#maxSegmentSize()}
* - The combined number of entries after compaction is less than the configured {@link Storage#maxEntriesPerSegment()}
*
*
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