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A module that is everything required to understands Druid Segments
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
package org.apache.druid.segment.writeout;
import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.google.common.collect.ImmutableSet;
import java.io.File;
import java.io.IOException;
import java.util.Set;
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type", defaultImpl = TmpFileSegmentWriteOutMediumFactory.class)
@JsonSubTypes(value = {
@JsonSubTypes.Type(name = "tmpFile", value = TmpFileSegmentWriteOutMediumFactory.class),
@JsonSubTypes.Type(name = "offHeapMemory", value = OffHeapMemorySegmentWriteOutMediumFactory.class),
@JsonSubTypes.Type(name = "onHeapMemory", value = OnHeapMemorySegmentWriteOutMediumFactory.class),
})
public interface SegmentWriteOutMediumFactory
{
static Set builtInFactories()
{
return ImmutableSet.of(
TmpFileSegmentWriteOutMediumFactory.instance(),
OffHeapMemorySegmentWriteOutMediumFactory.instance(),
OnHeapMemorySegmentWriteOutMediumFactory.instance()
);
}
/**
* Creates a new SegmentWriteOutMedium. If this type of SegmentWriteOutMedium needs to create some temprorary files,
* it creates a *subdirectory* in the given outDir, stores the files there, and removes the files and the subdirectory
* when closed.
*/
SegmentWriteOutMedium makeSegmentWriteOutMedium(File outDir) throws IOException;
}