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 java.util.Objects.requireNonNull;
import static org.apache.jackrabbit.oak.segment.Segment.RECORD_ID_BYTES;
import java.io.UnsupportedEncodingException;
import java.util.Arrays;
import java.util.function.Supplier;
import org.apache.jackrabbit.oak.api.PropertyState;
import org.apache.jackrabbit.oak.api.Type;
import org.apache.jackrabbit.oak.cache.CacheStats;
import org.apache.jackrabbit.oak.plugins.memory.PropertyStates;
import org.apache.jackrabbit.oak.segment.util.SafeEncode;
import org.apache.jackrabbit.oak.spi.blob.BlobStore;
import org.apache.jackrabbit.oak.spi.state.NodeState;
import org.apache.jackrabbit.oak.stats.MeterStats;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* 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;
private static final Logger LOG = LoggerFactory.getLogger(LoggingHook.class.getName() + ".reader");
@NotNull
private final Supplier writer;
@Nullable
private final BlobStore blobStore;
/**
* Cache for string records
*/
@NotNull
private final StringCache stringCache;
/**
* Cache for template records
*/
@NotNull
private final TemplateCache templateCache;
private final MeterStats readStats;
/**
* 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(
@NotNull Supplier writer,
@Nullable BlobStore blobStore,
long stringCacheMB,
long templateCacheMB,
MeterStats readStats
) {
this.writer = requireNonNull(writer);
this.blobStore = blobStore;
stringCache = new StringCache(stringCacheMB * 1024 * 1024);
templateCache = new TemplateCache(templateCacheMB * 1024 * 1024);
this.readStats = readStats;
}
/**
* Cached reading of a string.
*/
@NotNull
@Override
public String readString(@NotNull RecordId id) {
final SegmentId segmentId = id.getSegmentId();
long msb = segmentId.getMostSignificantBits();
long lsb = segmentId.getLeastSignificantBits();
return stringCache.get(msb, lsb, id.getRecordNumber(),
offset -> segmentId.getSegment().readString(offset));
}
@NotNull
@Override
public MapRecord readMap(@NotNull RecordId id) {
return new MapRecord(this, id);
}
/**
* Cached reading of a template.
*/
@NotNull
@Override
public Template readTemplate(@NotNull RecordId id) {
final SegmentId segmentId = id.getSegmentId();
long msb = segmentId.getMostSignificantBits();
long lsb = segmentId.getLeastSignificantBits();
return templateCache.get(msb, lsb, id.getRecordNumber(),
offset -> readTemplate(segmentId.getSegment(), offset));
}
private Template readTemplate(Segment segment, int recordNumber) {
int head = segment.readInt(recordNumber);
boolean hasPrimaryType = (head & (1 << 31)) != 0;
boolean hasMixinTypes = (head & (1 << 30)) != 0;
boolean zeroChildNodes = (head & (1 << 29)) != 0;
boolean manyChildNodes = (head & (1 << 28)) != 0;
int mixinCount = (head >> 18) & ((1 << 10) - 1);
int propertyCount = head & ((1 << 18) - 1);
int offset = 4;
PropertyState primaryType = null;
if (hasPrimaryType) {
RecordId primaryId = segment.readRecordId(recordNumber, offset);
primaryType = PropertyStates.createProperty(
"jcr:primaryType", readString(primaryId), Type.NAME);
offset += RECORD_ID_BYTES;
}
PropertyState mixinTypes = null;
if (hasMixinTypes) {
String[] mixins = new String[mixinCount];
for (int i = 0; i < mixins.length; i++) {
RecordId mixinId = segment.readRecordId(recordNumber, offset);
mixins[i] = readString(mixinId);
offset += RECORD_ID_BYTES;
}
mixinTypes = PropertyStates.createProperty(
"jcr:mixinTypes", Arrays.asList(mixins), Type.NAMES);
}
String childName = Template.ZERO_CHILD_NODES;
if (manyChildNodes) {
childName = Template.MANY_CHILD_NODES;
} else if (!zeroChildNodes) {
RecordId childNameId = segment.readRecordId(recordNumber, offset);
childName = readString(childNameId);
offset += RECORD_ID_BYTES;
}
PropertyTemplate[] properties;
properties = readProps(segment, propertyCount, recordNumber, offset);
return new Template(this, primaryType, mixinTypes, properties, childName);
}
private PropertyTemplate[] readProps(Segment segment,
int propertyCount,
int recordNumber,
int offset) {
PropertyTemplate[] properties = new PropertyTemplate[propertyCount];
if (propertyCount > 0) {
RecordId id = segment.readRecordId(recordNumber, offset);
ListRecord propertyNames = new ListRecord(id, properties.length);
offset += RECORD_ID_BYTES;
for (int i = 0; i < propertyCount; i++) {
byte type = segment.readByte(recordNumber, offset++);
properties[i] = new PropertyTemplate(i,
readString(propertyNames.getEntry(i)), Type.fromTag(
Math.abs(type), type < 0));
}
}
return properties;
}
private static String safeEncode(String value) {
try {
return SafeEncode.safeEncode(value);
} catch (UnsupportedEncodingException e) {
return "ERROR: " + e;
}
}
@NotNull
@Override
public SegmentNodeState readNode(@NotNull RecordId id) {
if (LOG.isTraceEnabled()) {
LOG.trace("{} n? {}", Thread.currentThread().getId(), id);
}
return new SegmentNodeState(this, writer, blobStore, id, readStats);
}
@NotNull
@Override
public SegmentNodeState readHeadState(@NotNull Revisions revisions) {
return readNode(revisions.getHead());
}
@NotNull
@Override
public SegmentPropertyState readProperty(@NotNull RecordId id, @NotNull PropertyTemplate template) {
if (LOG.isTraceEnabled()) {
LOG.trace("{} p? {}", Thread.currentThread().getId(), id);
}
return new SegmentPropertyState(this, id, template);
}
@NotNull
@Override
public SegmentBlob readBlob(@NotNull RecordId id) {
return new SegmentBlob(blobStore, id);
}
@NotNull
public CacheStats getStringCacheStats() {
return stringCache.getStats();
}
@NotNull
public CacheStats getTemplateCacheStats() {
return templateCache.getStats();
}
}
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