/*
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* The contents of this file are subject to the terms of the Common Development and
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* Distribution License (the License). You may not use this file except in compliance with the
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* License.
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*
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* You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
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* specific language governing permission and limitations under the License.
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*
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* When distributing Covered Software, include this CDDL Header Notice in each file and include
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* the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
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* Header, with the fields enclosed by brackets [] replaced by your own identifying
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* information: "Portions Copyright [year] [name of copyright owner]".
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*
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* Copyright 2015 ForgeRock AS.
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*/
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package org.opends.server.backends.pluggable;
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import static org.opends.server.backends.pluggable.CursorTransformer.*;
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import org.forgerock.opendj.ldap.ByteSequence;
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import org.forgerock.opendj.ldap.ByteSequenceReader;
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import org.forgerock.opendj.ldap.ByteString;
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import org.forgerock.opendj.ldap.ByteStringBuilder;
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import org.forgerock.util.Function;
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import org.forgerock.util.Reject;
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import org.forgerock.util.promise.NeverThrowsException;
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import org.opends.server.backends.pluggable.OnDiskMergeImporter.Collector;
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import org.opends.server.backends.pluggable.spi.Importer;
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import org.opends.server.backends.pluggable.spi.ReadableTransaction;
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import org.opends.server.backends.pluggable.spi.SequentialCursor;
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import org.opends.server.backends.pluggable.spi.TreeName;
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import org.opends.server.backends.pluggable.spi.WriteableTransaction;
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import com.forgerock.opendj.util.PackedLong;
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/** Maintain counters reflecting the total number of entries and the number of immediate children for each entry. */
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final class ID2ChildrenCount extends AbstractTree
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{
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private static final EntryID TOTAL_COUNT_ENTRY_ID = new EntryID(PackedLong.COMPACTED_MAX_VALUE);
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private static final Function<ByteString, EntryID, NeverThrowsException> TO_ENTRY_ID =
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new Function<ByteString, EntryID, NeverThrowsException>()
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{
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@Override
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public EntryID apply(ByteString value) throws NeverThrowsException
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{
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return new EntryID(value.asReader().readCompactUnsignedLong());
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}
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};
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private final ShardedCounter counter;
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ID2ChildrenCount(TreeName name)
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{
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super(name);
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this.counter = new ShardedCounter(name);
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}
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SequentialCursor<EntryID, Void> openCursor(ReadableTransaction txn)
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{
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return transformKeysAndValues(counter.openCursor(txn),
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TO_ENTRY_ID, CursorTransformer.<ByteString, Void> keepValuesUnchanged());
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}
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/**
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* Updates the number of children for a given entry without updating the total number of entries.
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* <p>
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* Implementation note: this method accepts a {@code null} entryID in order to eliminate null checks in client code.
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* In particular, client code has to deal with the special case where a target entry does not have a parent because
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* the target entry is a base entry within the backend.
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*
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* @param txn storage transaction
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* @param entryID The entryID identifying to the counter, which may be
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* {@code null} in which case calling this method has no effect.
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* @param delta The value to add. Can be negative to decrease counter value.
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*/
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void updateCount(final WriteableTransaction txn, final EntryID entryID, final long delta) {
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if (entryID != null)
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{
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addToCounter(txn, entryID, delta);
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}
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}
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/**
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* Updates the total number of entries which should be the sum of all counters.
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* @param txn storage transaction
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* @param delta The value to add. Can be negative to decrease counter value.
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*/
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void updateTotalCount(final WriteableTransaction txn, final long delta) {
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addToCounter(txn, TOTAL_COUNT_ENTRY_ID, delta);
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}
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private void addToCounter(WriteableTransaction txn, EntryID entryID, final long delta)
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{
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counter.addCount(txn, toKey(entryID), delta);
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}
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void importPut(Importer importer, EntryID entryID, long total)
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{
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Reject.ifTrue(entryID.longValue() >= TOTAL_COUNT_ENTRY_ID.longValue(), "EntryID overflow.");
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importPut0(importer, entryID, total);
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}
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void importPutTotalCount(Importer importer, long total)
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{
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importPut0(importer, TOTAL_COUNT_ENTRY_ID, total);
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}
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private void importPut0(Importer importer, EntryID entryID, final long delta)
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{
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counter.importPut(importer, toKey(entryID), delta);
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}
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@Override
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public String keyToString(ByteString key)
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{
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ByteSequenceReader keyReader = key.asReader();
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long keyID = keyReader.readCompactUnsignedLong();
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long shardBucket = keyReader.readByte();
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return (keyID == TOTAL_COUNT_ENTRY_ID.longValue() ? "Total Children Count" : keyID) + "#" + shardBucket;
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}
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@Override
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public String valueToString(ByteString value)
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{
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return counter.valueToString(value);
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}
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@Override
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public ByteString generateKey(String data)
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{
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return new EntryID(Long.parseLong(data)).toByteString();
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}
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/**
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* Get the number of children for the given entry.
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* @param txn storage transaction
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* @param entryID The entryID identifying to the counter
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* @return Value of the counter. 0 if no counter is associated yet.
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*/
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long getCount(ReadableTransaction txn, EntryID entryID)
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{
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return counter.getCount(txn, toKey(entryID));
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}
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/**
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* Get the total number of entries.
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* @param txn storage transaction
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* @return Sum of all the counter contained in this tree
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*/
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long getTotalCount(ReadableTransaction txn)
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{
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return getCount(txn, TOTAL_COUNT_ENTRY_ID);
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}
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/**
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* Removes the counter associated to the given entry, but does not update the total count.
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* @param txn storage transaction
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* @param entryID The entryID identifying the counter
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* @return Value of the counter before it's deletion.
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*/
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long removeCount(final WriteableTransaction txn, final EntryID entryID) {
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return counter.removeCount(txn, toKey(entryID));
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}
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private static ByteSequence toKey(EntryID entryID)
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{
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return new ByteStringBuilder(ByteStringBuilder.MAX_COMPACT_SIZE).appendCompactUnsigned(entryID.longValue());
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}
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static Collector<Long, ByteString> getSumLongCollectorInstance()
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{
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return ShardedCounterCollector.INSTANCE;
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}
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/**
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* {@link Collector} that accepts sharded-counter values encoded into {@link ByteString} objects and produces a
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* {@link ByteString} representing the sum of the sharded-counter values.
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*/
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private static final class ShardedCounterCollector implements Collector<Long, ByteString>
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{
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private static final Collector<Long, ByteString> INSTANCE = new ShardedCounterCollector();
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@Override
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public Long get()
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{
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return 0L;
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}
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@Override
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public Long accept(Long resultContainer, ByteString value)
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{
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return resultContainer + ShardedCounter.decodeValue(value);
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}
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@Override
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public ByteString merge(Long resultContainer)
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{
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return ShardedCounter.encodeValue(resultContainer);
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}
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}
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}
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