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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
* 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
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package org.apache.cassandra.db.memtable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.Callable;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.db.ColumnFamilyStore;
import org.apache.cassandra.db.Directories;
import org.apache.cassandra.db.DiskBoundaries;
import org.apache.cassandra.db.PartitionPosition;
import org.apache.cassandra.db.SerializationHeader;
import org.apache.cassandra.db.SystemKeyspace;
import org.apache.cassandra.db.commitlog.IntervalSet;
import org.apache.cassandra.db.lifecycle.LifecycleTransaction;
import org.apache.cassandra.db.partitions.Partition;
import org.apache.cassandra.db.rows.UnfilteredRowIterator;
import org.apache.cassandra.io.sstable.Descriptor;
import org.apache.cassandra.io.sstable.SSTableMultiWriter;
import org.apache.cassandra.io.sstable.format.SSTableFormat;
import org.apache.cassandra.metrics.TableMetrics;
import org.apache.cassandra.service.ActiveRepairService;
import org.apache.cassandra.utils.FBUtilities;
public class Flushing
{
private static final Logger logger = LoggerFactory.getLogger(Flushing.class);
private Flushing() // prevent instantiation
{
}
public static List flushRunnables(ColumnFamilyStore cfs,
Memtable memtable,
LifecycleTransaction txn)
{
LifecycleTransaction ongoingFlushTransaction = memtable.setFlushTransaction(txn);
Preconditions.checkState(ongoingFlushTransaction == null,
"Attempted to flush Memtable more than once on %s.%s",
cfs.keyspace.getName(),
cfs.name);
DiskBoundaries diskBoundaries = cfs.getDiskBoundaries();
List boundaries = diskBoundaries.positions;
List locations = diskBoundaries.directories;
if (boundaries == null)
{
FlushRunnable runnable = flushRunnable(cfs, memtable, null, null, txn, null);
return Collections.singletonList(runnable);
}
List runnables = new ArrayList<>(boundaries.size());
PartitionPosition rangeStart = boundaries.get(0).getPartitioner().getMinimumToken().minKeyBound();
try
{
for (int i = 0; i < boundaries.size(); i++)
{
PartitionPosition t = boundaries.get(i);
FlushRunnable runnable = flushRunnable(cfs, memtable, rangeStart, t, txn, locations.get(i));
runnables.add(runnable);
rangeStart = t;
}
return runnables;
}
catch (Throwable e)
{
Throwable t = abortRunnables(runnables, e);
Throwables.throwIfUnchecked(t);
throw new RuntimeException(t);
}
}
static FlushRunnable flushRunnable(ColumnFamilyStore cfs,
Memtable memtable,
PartitionPosition from,
PartitionPosition to,
LifecycleTransaction txn,
Directories.DataDirectory flushLocation)
{
Memtable.FlushablePartitionSet flushSet = memtable.getFlushSet(from, to);
SSTableFormat format = DatabaseDescriptor.getSelectedSSTableFormat();
long estimatedSize = format.getWriterFactory().estimateSize(flushSet);
Descriptor descriptor = flushLocation == null
? cfs.newSSTableDescriptor(cfs.getDirectories().getWriteableLocationAsFile(estimatedSize), format)
: cfs.newSSTableDescriptor(cfs.getDirectories().getLocationForDisk(flushLocation), format);
SSTableMultiWriter writer = createFlushWriter(cfs,
flushSet,
txn,
descriptor,
flushSet.partitionCount());
return new FlushRunnable(flushSet, writer, cfs.metric, true);
}
public static Throwable abortRunnables(List runnables, Throwable t)
{
if (runnables != null)
for (FlushRunnable runnable : runnables)
t = runnable.writer.abort(t);
return t;
}
public static class FlushRunnable implements Callable
{
private final Memtable.FlushablePartitionSet toFlush;
private final SSTableMultiWriter writer;
private final TableMetrics metrics;
private final boolean isBatchLogTable;
private final boolean logCompletion;
public FlushRunnable(Memtable.FlushablePartitionSet flushSet,
SSTableMultiWriter writer,
TableMetrics metrics,
boolean logCompletion)
{
this.toFlush = flushSet;
this.writer = writer;
this.metrics = metrics;
this.isBatchLogTable = toFlush.metadata() == SystemKeyspace.Batches;
this.logCompletion = logCompletion;
}
private void writeSortedContents()
{
logger.info("Writing {}, flushed range = [{}, {})", toFlush.memtable(), toFlush.from(), toFlush.to());
// (we can't clear out the map as-we-go to free up memory,
// since the memtable is being used for queries in the "pending flush" category)
for (Partition partition : toFlush)
{
// Each batchlog partition is a separate entry in the log. And for an entry, we only do 2
// operations: 1) we insert the entry and 2) we delete it. Further, BL data is strictly local,
// we don't need to preserve tombstones for repair. So if both operation are in this
// memtable (which will almost always be the case if there is no ongoing failure), we can
// just skip the entry (CASSANDRA-4667).
if (isBatchLogTable && !partition.partitionLevelDeletion().isLive() && partition.hasRows())
continue;
if (!partition.isEmpty())
{
try (UnfilteredRowIterator iter = partition.unfilteredIterator())
{
writer.append(iter);
}
}
}
if (logCompletion)
{
long bytesFlushed = writer.getBytesWritten();
logger.info("Completed flushing {} ({}) for commitlog position {}",
writer.getFilename(),
FBUtilities.prettyPrintMemory(bytesFlushed),
toFlush.memtable().getFinalCommitLogUpperBound());
// Update the metrics
metrics.bytesFlushed.inc(bytesFlushed);
}
}
@Override
public SSTableMultiWriter call()
{
writeSortedContents();
return writer;
// We don't close the writer on error as the caller aborts all runnables if one happens.
}
@Override
public String toString()
{
return "Flush " + toFlush.metadata().keyspace + '.' + toFlush.metadata().name;
}
}
public static SSTableMultiWriter createFlushWriter(ColumnFamilyStore cfs,
Memtable.FlushablePartitionSet flushSet,
LifecycleTransaction txn,
Descriptor descriptor,
long partitionCount)
{
return cfs.createSSTableMultiWriter(descriptor,
partitionCount,
ActiveRepairService.UNREPAIRED_SSTABLE,
ActiveRepairService.NO_PENDING_REPAIR,
false,
new IntervalSet<>(flushSet.commitLogLowerBound(),
flushSet.commitLogUpperBound()),
new SerializationHeader(true,
flushSet.metadata(),
flushSet.columns(),
flushSet.encodingStats()),
txn);
}
}