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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* 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
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*/
package org.apache.cassandra.db.partitions;
import java.io.IOException;
import org.apache.cassandra.db.*;
import org.apache.cassandra.db.filter.DataLimits;
import org.apache.cassandra.db.rows.*;
import org.apache.cassandra.io.ISerializer;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.net.MessagingService;
import org.apache.cassandra.schema.Schema;
import org.apache.cassandra.schema.TableId;
import org.apache.cassandra.schema.TableMetadata;
import org.apache.cassandra.utils.CassandraUInt;
import org.apache.cassandra.utils.btree.BTree;
public class CachedBTreePartition extends ImmutableBTreePartition implements CachedPartition
{
private final long createdAtInSec;
private final int cachedLiveRows;
private final int rowsWithNonExpiringCells;
private CachedBTreePartition(TableMetadata metadata,
DecoratedKey partitionKey,
BTreePartitionData holder,
long createdAtInSec,
int cachedLiveRows,
int rowsWithNonExpiringCells)
{
super(metadata, partitionKey, holder);
this.createdAtInSec = createdAtInSec;
this.cachedLiveRows = cachedLiveRows;
this.rowsWithNonExpiringCells = rowsWithNonExpiringCells;
}
/**
* Creates an {@code ArrayBackedCachedPartition} holding all the data of the provided iterator.
*
* Warning: Note that this method does not close the provided iterator and it is
* up to the caller to do so.
*
* @param iterator the iterator got gather in memory.
* @param nowInSec the time of the creation in seconds. This is the time at which {@link #cachedLiveRows} applies.
* @return the created partition.
*/
public static CachedBTreePartition create(UnfilteredRowIterator iterator, long nowInSec)
{
return create(iterator, 16, nowInSec);
}
/**
* Creates an {@code ArrayBackedCachedPartition} holding all the data of the provided iterator.
*
* Warning: Note that this method does not close the provided iterator and it is
* up to the caller to do so.
*
* @param iterator the iterator got gather in memory.
* @param initialRowCapacity sizing hint (in rows) to use for the created partition. It should ideally
* correspond or be a good estimation of the number or rows in {@code iterator}.
* @param nowInSec the time of the creation in seconds. This is the time at which {@link #cachedLiveRows} applies.
* @return the created partition.
*/
public static CachedBTreePartition create(UnfilteredRowIterator iterator, int initialRowCapacity, long nowInSec)
{
BTreePartitionData holder = ImmutableBTreePartition.build(iterator, initialRowCapacity);
int cachedLiveRows = 0;
int rowsWithNonExpiringCells = 0;
boolean enforceStrictLiveness = iterator.metadata().enforceStrictLiveness();
for (Row row : BTree.iterable(holder.tree))
{
if (row.hasLiveData(nowInSec, enforceStrictLiveness))
++cachedLiveRows;
boolean hasNonExpiringLiveCell = false;
for (Cell cell : row.cells())
{
if (!cell.isTombstone() && !cell.isExpiring())
{
hasNonExpiringLiveCell = true;
break;
}
}
if (hasNonExpiringLiveCell)
++rowsWithNonExpiringCells;
}
return new CachedBTreePartition(iterator.metadata(),
iterator.partitionKey(),
holder,
nowInSec,
cachedLiveRows,
rowsWithNonExpiringCells);
}
/**
* The number of rows that were live at the time the partition was cached.
*
* See {@link ColumnFamilyStore#isFilterFullyCoveredBy} to see why we need this.
*
* @return the number of rows in this partition that were live at the time the
* partition was cached (this can be different from the number of live rows now
* due to expiring cells).
*/
public int cachedLiveRows()
{
return cachedLiveRows;
}
/**
* The number of rows in this cached partition that have at least one non-expiring
* non-deleted cell.
*
* Note that this is generally not a very meaningful number, but this is used by
* {@link DataLimits#hasEnoughLiveData} as an optimization.
*
* @return the number of row that have at least one non-expiring non-deleted cell.
*/
public int rowsWithNonExpiringCells()
{
return rowsWithNonExpiringCells;
}
static class Serializer implements ISerializer
{
public void serialize(CachedPartition partition, DataOutputPlus out) throws IOException
{
int version = MessagingService.current_version;
assert partition instanceof CachedBTreePartition;
CachedBTreePartition p = (CachedBTreePartition)partition;
out.writeInt(CassandraUInt.fromLong(p.createdAtInSec));
out.writeInt(p.cachedLiveRows);
out.writeInt(p.rowsWithNonExpiringCells);
partition.metadata().id.serialize(out);
try (UnfilteredRowIterator iter = p.unfilteredIterator())
{
UnfilteredRowIteratorSerializer.serializer.serialize(iter, null, out, version, p.rowCount());
}
}
public CachedPartition deserialize(DataInputPlus in) throws IOException
{
int version = MessagingService.current_version;
// Note that it would be slightly simpler to just do
// ArrayBackedCachedPiartition.create(UnfilteredRowIteratorSerializer.serializer.deserialize(...));
// However deserializing the header separatly is not a lot harder and allows us to:
// 1) get the capacity of the partition so we can size it properly directly
// 2) saves the creation of a temporary iterator: rows are directly written to the partition, which
// is slightly faster.
long createdAtInSec = CassandraUInt.toLong(in.readInt());
int cachedLiveRows = in.readInt();
int rowsWithNonExpiringCells = in.readInt();
TableMetadata metadata = Schema.instance.getExistingTableMetadata(TableId.deserialize(in));
UnfilteredRowIteratorSerializer.Header header = UnfilteredRowIteratorSerializer.serializer.deserializeHeader(metadata, null, in, version, DeserializationHelper.Flag.LOCAL);
assert !header.isReversed && header.rowEstimate >= 0;
BTreePartitionData holder;
try (UnfilteredRowIterator partition = UnfilteredRowIteratorSerializer.serializer.deserialize(in, version, metadata, DeserializationHelper.Flag.LOCAL, header))
{
holder = ImmutableBTreePartition.build(partition, header.rowEstimate);
}
return new CachedBTreePartition(metadata,
header.key,
holder,
createdAtInSec,
cachedLiveRows,
rowsWithNonExpiringCells);
}
public long serializedSize(CachedPartition partition)
{
int version = MessagingService.current_version;
assert partition instanceof CachedBTreePartition;
CachedBTreePartition p = (CachedBTreePartition)partition;
try (UnfilteredRowIterator iter = p.unfilteredIterator())
{
return TypeSizes.INT_SIZE //createdAtInSec
+ TypeSizes.sizeof(p.cachedLiveRows)
+ TypeSizes.sizeof(p.rowsWithNonExpiringCells)
+ partition.metadata().id.serializedSize()
+ UnfilteredRowIteratorSerializer.serializer.serializedSize(iter, null, MessagingService.current_version, p.rowCount());
}
}
}
}