org.apache.jackrabbit.oak.segment.CachingSegmentReader Maven / Gradle / Ivy
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* 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.jackrabbit.oak.segment;
import static com.google.common.base.Preconditions.checkNotNull;
import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import com.google.common.base.Function;
import com.google.common.base.Supplier;
import org.apache.jackrabbit.oak.cache.CacheStats;
import org.apache.jackrabbit.oak.spi.blob.BlobStore;
import org.apache.jackrabbit.oak.spi.state.NodeState;
/**
* This {@code SegmentReader} implementation implements caching for
* strings and templates. It can also optionally rely on a {@link BlobStore} for resolving blobs.
*/
public class CachingSegmentReader implements SegmentReader {
public static final int DEFAULT_STRING_CACHE_MB = 256;
public static final int DEFAULT_TEMPLATE_CACHE_MB = 64;
@Nonnull
private final Supplier writer;
@CheckForNull
private final BlobStore blobStore;
/**
* Cache for string records
*/
@Nonnull
private final StringCache stringCache;
/**
* Cache for template records
*/
@Nonnull
private final TemplateCache templateCache;
/**
* Create a new instance based on the supplied arguments.
* @param writer A {@code Supplier} for a the {@code SegmentWriter} used by the segment
* builders returned from {@link NodeState#builder()} to write ahead changes.
* {@code writer.get()} must not return {@code null}.
* @param blobStore {@code BlobStore} instance of the underlying {@link SegmentStore}, or
* {@code null} if none.
* @param stringCacheMB the size of the string cache in MBs or {@code 0} for no cache.
* @param templateCacheMB the size of the template cache in MBs or {@code 0} for no cache.
*/
public CachingSegmentReader(
@Nonnull Supplier writer,
@Nullable BlobStore blobStore,
long stringCacheMB,
long templateCacheMB) {
this.writer = checkNotNull(writer);
this.blobStore = blobStore;
stringCache = new StringCache(stringCacheMB * 1024 * 1024);
templateCache = new TemplateCache(templateCacheMB * 1024 * 1024);
}
/**
* Cached reading of a string.
*/
@Nonnull
@Override
public String readString(@Nonnull RecordId id) {
final SegmentId segmentId = id.getSegmentId();
long msb = segmentId.getMostSignificantBits();
long lsb = segmentId.getLeastSignificantBits();
return stringCache.get(msb, lsb, id.getRecordNumber(), new Function() {
@Nonnull
@Override
public String apply(Integer offset) {
return segmentId.getSegment().readString(offset);
}
});
}
@Nonnull
@Override
public MapRecord readMap(@Nonnull RecordId id) {
return new MapRecord(this, id);
}
/**
* Cached reading of a template.
*/
@Nonnull
@Override
public Template readTemplate(@Nonnull RecordId id) {
final SegmentId segmentId = id.getSegmentId();
long msb = segmentId.getMostSignificantBits();
long lsb = segmentId.getLeastSignificantBits();
return templateCache.get(msb, lsb, id.getRecordNumber(), new Function() {
@Nonnull
@Override
public Template apply(Integer offset) {
return segmentId.getSegment().readTemplate(offset);
}
});
}
@Nonnull
@Override
public SegmentNodeState readNode(@Nonnull RecordId id) {
return new SegmentNodeState(this, writer, blobStore, id);
}
@Nonnull
@Override
public SegmentNodeState readHeadState(@Nonnull Revisions revisions) {
return readNode(revisions.getHead());
}
@Nonnull
@Override
public SegmentPropertyState readProperty(
@Nonnull RecordId id, @Nonnull PropertyTemplate template) {
return new SegmentPropertyState(this, id, template);
}
@Nonnull
@Override
public SegmentBlob readBlob(@Nonnull RecordId id) {
return new SegmentBlob(blobStore, id);
}
@Nonnull
public CacheStats getStringCacheStats() {
return stringCache.getStats();
}
@Nonnull
public CacheStats getTemplateCacheStats() {
return templateCache.getStats();
}
}
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