/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
* or http://forgerock.org/license/CDDLv1.0.html.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at legal-notices/CDDLv1_0.txt.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information:
* Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*
* Copyright 2015 ForgeRock AS
*/
package org.opends.server.backends.pluggable;
import static org.opends.server.backends.pluggable.CursorTransformer.*;
import org.forgerock.opendj.ldap.ByteSequence;
import org.forgerock.opendj.ldap.ByteSequenceReader;
import org.forgerock.opendj.ldap.ByteString;
import org.forgerock.opendj.ldap.ByteStringBuilder;
import org.forgerock.util.Function;
import org.forgerock.util.Reject;
import org.forgerock.util.promise.NeverThrowsException;
import org.opends.server.backends.pluggable.OnDiskMergeImporter.Collector;
import org.opends.server.backends.pluggable.spi.Importer;
import org.opends.server.backends.pluggable.spi.ReadableTransaction;
import org.opends.server.backends.pluggable.spi.SequentialCursor;
import org.opends.server.backends.pluggable.spi.TreeName;
import org.opends.server.backends.pluggable.spi.WriteableTransaction;
import com.forgerock.opendj.util.PackedLong;
/** Maintain counters reflecting the total number of entries and the number of immediate children for each entry. */
final class ID2ChildrenCount extends AbstractTree
{
private static final EntryID TOTAL_COUNT_ENTRY_ID = new EntryID(PackedLong.COMPACTED_MAX_VALUE);
private static final Function<ByteString, EntryID, NeverThrowsException> TO_ENTRY_ID =
new Function<ByteString, EntryID, NeverThrowsException>()
{
@Override
public EntryID apply(ByteString value) throws NeverThrowsException
{
return new EntryID(value.asReader().readCompactUnsignedLong());
}
};
private final ShardedCounter counter;
ID2ChildrenCount(TreeName name)
{
super(name);
this.counter = new ShardedCounter(name);
}
SequentialCursor<EntryID, Void> openCursor(ReadableTransaction txn)
{
return transformKeysAndValues(counter.openCursor(txn),
TO_ENTRY_ID, CursorTransformer.<ByteString, Void> keepValuesUnchanged());
}
/**
* Updates the number of children for a given entry without updating the total number of entries.
* <p>
* Implementation note: this method accepts a {@code null} entryID in order to eliminate null checks in client code.
* In particular, client code has to deal with the special case where a target entry does not have a parent because
* the target entry is a base entry within the backend.
*
* @param txn storage transaction
* @param entryID The entryID identifying to the counter, which may be
* {@code null} in which case calling this method has no effect.
* @param delta The value to add. Can be negative to decrease counter value.
*/
void updateCount(final WriteableTransaction txn, final EntryID entryID, final long delta) {
if (entryID != null)
{
addToCounter(txn, entryID, delta);
}
}
/**
* Updates the total number of entries which should be the sum of all counters.
* @param txn storage transaction
* @param delta The value to add. Can be negative to decrease counter value.
*/
void updateTotalCount(final WriteableTransaction txn, final long delta) {
addToCounter(txn, TOTAL_COUNT_ENTRY_ID, delta);
}
private void addToCounter(WriteableTransaction txn, EntryID entryID, final long delta)
{
counter.addCount(txn, toKey(entryID), delta);
}
void importPut(Importer importer, EntryID entryID, long total)
{
Reject.ifTrue(entryID.longValue() >= TOTAL_COUNT_ENTRY_ID.longValue(), "EntryID overflow.");
importPut0(importer, entryID, total);
}
void importPutTotalCount(Importer importer, long total)
{
importPut0(importer, TOTAL_COUNT_ENTRY_ID, total);
}
private void importPut0(Importer importer, EntryID entryID, final long delta)
{
counter.importPut(importer, toKey(entryID), delta);
}
@Override
public String keyToString(ByteString key)
{
ByteSequenceReader keyReader = key.asReader();
long keyID = keyReader.readCompactUnsignedLong();
long shardBucket = keyReader.readByte();
return (keyID == TOTAL_COUNT_ENTRY_ID.longValue() ? "Total Children Count" : keyID) + "#" + shardBucket;
}
@Override
public String valueToString(ByteString value)
{
return counter.valueToString(value);
}
@Override
public ByteString generateKey(String data)
{
return new EntryID(Long.parseLong(data)).toByteString();
}
/**
* Get the number of children for the given entry.
* @param txn storage transaction
* @param entryID The entryID identifying to the counter
* @return Value of the counter. 0 if no counter is associated yet.
*/
long getCount(ReadableTransaction txn, EntryID entryID)
{
return counter.getCount(txn, toKey(entryID));
}
/**
* Get the total number of entries.
* @param txn storage transaction
* @return Sum of all the counter contained in this tree
*/
long getTotalCount(ReadableTransaction txn)
{
return getCount(txn, TOTAL_COUNT_ENTRY_ID);
}
/**
* Removes the counter associated to the given entry, but does not update the total count.
* @param txn storage transaction
* @param entryID The entryID identifying the counter
* @return Value of the counter before it's deletion.
*/
long removeCount(final WriteableTransaction txn, final EntryID entryID) {
return counter.removeCount(txn, toKey(entryID));
}
private static ByteSequence toKey(EntryID entryID)
{
return new ByteStringBuilder(ByteStringBuilder.MAX_COMPACT_SIZE).appendCompactUnsigned(entryID.longValue());
}
static Collector<Long, ByteString> getSumLongCollectorInstance()
{
return ShardedCounterCollector.INSTANCE;
}
/**
* {@link Collector} that accepts sharded-counter values encoded into {@link ByteString} objects and produces a
* {@link ByteString} representing the sum of the sharded-counter values.
*/
private static final class ShardedCounterCollector implements Collector<Long, ByteString>
{
private static final Collector<Long, ByteString> INSTANCE = new ShardedCounterCollector();
@Override
public Long get()
{
return 0L;
}
@Override
public Long accept(Long resultContainer, ByteString value)
{
return resultContainer + ShardedCounter.decodeValue(value);
}
@Override
public ByteString merge(Long resultContainer)
{
return ShardedCounter.encodeValue(resultContainer);
}
}
}