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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
* 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
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package org.apache.cassandra.db.compaction;
import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.UUID;
import java.util.concurrent.TimeUnit;
import com.google.common.base.Predicate;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Sets;
import org.apache.commons.lang3.StringUtils;
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.RowIndexEntry;
import org.apache.cassandra.db.SystemKeyspace;
import org.apache.cassandra.db.compaction.CompactionManager.CompactionExecutorStatsCollector;
import org.apache.cassandra.io.sstable.SSTableReader;
import org.apache.cassandra.io.sstable.SSTableRewriter;
import org.apache.cassandra.io.sstable.SSTableWriter;
import org.apache.cassandra.io.sstable.metadata.MetadataCollector;
import org.apache.cassandra.service.ActiveRepairService;
import org.apache.cassandra.utils.CloseableIterator;
public class CompactionTask extends AbstractCompactionTask
{
protected static final Logger logger = LoggerFactory.getLogger(CompactionTask.class);
protected final int gcBefore;
private final boolean offline;
protected static long totalBytesCompacted = 0;
private CompactionExecutorStatsCollector collector;
public CompactionTask(ColumnFamilyStore cfs, Iterable sstables, int gcBefore, boolean offline)
{
super(cfs, Sets.newHashSet(sstables));
this.gcBefore = gcBefore;
this.offline = offline;
}
public static synchronized long addToTotalBytesCompacted(long bytesCompacted)
{
return totalBytesCompacted += bytesCompacted;
}
protected int executeInternal(CompactionExecutorStatsCollector collector)
{
this.collector = collector;
run();
return sstables.size();
}
public long getExpectedWriteSize()
{
return cfs.getExpectedCompactedFileSize(sstables, compactionType);
}
public boolean reduceScopeForLimitedSpace()
{
if (partialCompactionsAcceptable() && sstables.size() > 1)
{
// Try again w/o the largest one.
logger.warn("insufficient space to compact all requested files {}", StringUtils.join(sstables, ", "));
// Note that we have removed files that are still marked as compacting.
// This suboptimal but ok since the caller will unmark all the sstables at the end.
SSTableReader removedSSTable = cfs.getMaxSizeFile(sstables);
if (sstables.remove(removedSSTable))
{
cfs.getDataTracker().unmarkCompacting(Arrays.asList(removedSSTable));
return true;
}
}
return false;
}
/**
* For internal use and testing only. The rest of the system should go through the submit* methods,
* which are properly serialized.
* Caller is in charge of marking/unmarking the sstables as compacting.
*/
protected void runMayThrow() throws Exception
{
// The collection of sstables passed may be empty (but not null); even if
// it is not empty, it may compact down to nothing if all rows are deleted.
assert sstables != null;
if (sstables.size() == 0)
return;
// Note that the current compaction strategy, is not necessarily the one this task was created under.
// This should be harmless; see comments to CFS.maybeReloadCompactionStrategy.
AbstractCompactionStrategy strategy = cfs.getCompactionStrategy();
if (DatabaseDescriptor.isSnapshotBeforeCompaction())
cfs.snapshotWithoutFlush(System.currentTimeMillis() + "-compact-" + cfs.name);
// note that we need to do a rough estimate early if we can fit the compaction on disk - this is pessimistic, but
// since we might remove sstables from the compaction in checkAvailableDiskSpace it needs to be done here
long earlySSTableEstimate = Math.max(1, cfs.getExpectedCompactedFileSize(sstables, compactionType) / strategy.getMaxSSTableBytes());
checkAvailableDiskSpace(earlySSTableEstimate);
// sanity check: all sstables must belong to the same cfs
assert !Iterables.any(sstables, new Predicate()
{
@Override
public boolean apply(SSTableReader sstable)
{
return !sstable.descriptor.cfname.equals(cfs.name);
}
});
UUID taskId = SystemKeyspace.startCompaction(cfs, sstables);
// new sstables from flush can be added during a compaction, but only the compaction can remove them,
// so in our single-threaded compaction world this is a valid way of determining if we're compacting
// all the sstables (that existed when we started)
logger.info("Compacting {}", sstables);
long start = System.nanoTime();
long totalKeysWritten = 0;
try (CompactionController controller = getCompactionController(sstables);)
{
Set actuallyCompact = Sets.difference(sstables, controller.getFullyExpiredSSTables());
long estimatedTotalKeys = Math.max(cfs.metadata.getMinIndexInterval(), SSTableReader.getApproximateKeyCount(actuallyCompact));
long estimatedSSTables = Math.max(1, cfs.getExpectedCompactedFileSize(actuallyCompact, compactionType) / strategy.getMaxSSTableBytes());
long keysPerSSTable = (long) Math.ceil((double) estimatedTotalKeys / estimatedSSTables);
long expectedSSTableSize = Math.min(getExpectedWriteSize(), strategy.getMaxSSTableBytes());
logger.debug("Expected bloom filter size : {}", keysPerSSTable);
List newSStables;
AbstractCompactionIterable ci;
// SSTableScanners need to be closed before markCompactedSSTablesReplaced call as scanners contain references
// to both ifile and dfile and SSTR will throw deletion errors on Windows if it tries to delete before scanner is closed.
// See CASSANDRA-8019 and CASSANDRA-8399
try (AbstractCompactionStrategy.ScannerList scanners = strategy.getScanners(actuallyCompact))
{
ci = new CompactionIterable(compactionType, scanners.scanners, controller);
Iterator iter = ci.iterator();
// we can't preheat until the tracker has been set. This doesn't happen until we tell the cfs to
// replace the old entries. Track entries to preheat here until then.
long minRepairedAt = getMinRepairedAt(actuallyCompact);
// we only need the age of the data that we're actually retaining
long maxAge = getMaxDataAge(actuallyCompact);
if (collector != null)
collector.beginCompaction(ci);
long lastCheckObsoletion = start;
SSTableRewriter writer = new SSTableRewriter(cfs, sstables, maxAge, offline);
try
{
if (!iter.hasNext())
{
// don't mark compacted in the finally block, since if there _is_ nondeleted data,
// we need to sync it (via closeAndOpen) first, so there is no period during which
// a crash could cause data loss.
cfs.markObsolete(sstables, compactionType);
return;
}
writer.switchWriter(createCompactionWriter(cfs.directories.getLocationForDisk(getWriteDirectory(expectedSSTableSize)), keysPerSSTable, minRepairedAt));
while (iter.hasNext())
{
if (ci.isStopRequested())
throw new CompactionInterruptedException(ci.getCompactionInfo());
AbstractCompactedRow row = iter.next();
if (writer.append(row) != null)
{
totalKeysWritten++;
if (newSSTableSegmentThresholdReached(writer.currentWriter()))
{
writer.switchWriter(createCompactionWriter(cfs.directories.getLocationForDisk(getWriteDirectory(expectedSSTableSize)), keysPerSSTable, minRepairedAt));
}
}
if (System.nanoTime() - lastCheckObsoletion > TimeUnit.MINUTES.toNanos(1L))
{
controller.maybeRefreshOverlaps();
lastCheckObsoletion = System.nanoTime();
}
}
// don't replace old sstables yet, as we need to mark the compaction finished in the system table
newSStables = writer.finish();
}
catch (Throwable t)
{
try
{
writer.abort();
}
catch (Throwable t2)
{
t.addSuppressed(t2);
}
throw t;
}
finally
{
// point of no return -- the new sstables are live on disk; next we'll start deleting the old ones
// (in replaceCompactedSSTables)
if (taskId != null)
SystemKeyspace.finishCompaction(taskId);
if (collector != null)
collector.finishCompaction(ci);
}
}
Collection oldSStables = this.sstables;
if (!offline)
cfs.getDataTracker().markCompactedSSTablesReplaced(oldSStables, newSStables, compactionType);
// log a bunch of statistics about the result and save to system table compaction_history
long dTime = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start);
long startsize = SSTableReader.getTotalBytes(oldSStables);
long endsize = SSTableReader.getTotalBytes(newSStables);
double ratio = (double) endsize / (double) startsize;
StringBuilder newSSTableNames = new StringBuilder();
for (SSTableReader reader : newSStables)
newSSTableNames.append(reader.descriptor.baseFilename()).append(",");
double mbps = dTime > 0 ? (double) endsize / (1024 * 1024) / ((double) dTime / 1000) : 0;
long totalSourceRows = 0;
long[] counts = ci.getMergedRowCounts();
StringBuilder mergeSummary = new StringBuilder(counts.length * 10);
Map mergedRows = new HashMap<>();
for (int i = 0; i < counts.length; i++)
{
long count = counts[i];
if (count == 0)
continue;
int rows = i + 1;
totalSourceRows += rows * count;
mergeSummary.append(String.format("%d:%d, ", rows, count));
mergedRows.put(rows, count);
}
SystemKeyspace.updateCompactionHistory(cfs.keyspace.getName(), cfs.name, System.currentTimeMillis(), startsize, endsize, mergedRows);
logger.info(String.format("Compacted %d sstables to [%s]. %,d bytes to %,d (~%d%% of original) in %,dms = %fMB/s. %,d total partitions merged to %,d. Partition merge counts were {%s}",
oldSStables.size(), newSSTableNames.toString(), startsize, endsize, (int) (ratio * 100), dTime, mbps, totalSourceRows, totalKeysWritten, mergeSummary.toString()));
logger.debug(String.format("CF Total Bytes Compacted: %,d", CompactionTask.addToTotalBytesCompacted(endsize)));
logger.debug("Actual #keys: {}, Estimated #keys:{}, Err%: {}", totalKeysWritten, estimatedTotalKeys, ((double)(totalKeysWritten - estimatedTotalKeys)/totalKeysWritten));
}
}
private long getMinRepairedAt(Set actuallyCompact)
{
long minRepairedAt= Long.MAX_VALUE;
for (SSTableReader sstable : actuallyCompact)
minRepairedAt = Math.min(minRepairedAt, sstable.getSSTableMetadata().repairedAt);
if (minRepairedAt == Long.MAX_VALUE)
return ActiveRepairService.UNREPAIRED_SSTABLE;
return minRepairedAt;
}
protected void checkAvailableDiskSpace(long estimatedSSTables)
{
while (!getDirectories().hasAvailableDiskSpace(estimatedSSTables, getExpectedWriteSize()))
{
if (!reduceScopeForLimitedSpace())
throw new RuntimeException(String.format("Not enough space for compaction, estimated sstables = %d, expected write size = %d", estimatedSSTables, getExpectedWriteSize()));
}
}
private SSTableWriter createCompactionWriter(File sstableDirectory, long keysPerSSTable, long repairedAt)
{
assert sstableDirectory != null;
return new SSTableWriter(cfs.getTempSSTablePath(sstableDirectory),
keysPerSSTable,
repairedAt,
cfs.metadata,
cfs.partitioner,
new MetadataCollector(sstables, cfs.metadata.comparator, getLevel()));
}
protected int getLevel()
{
return 0;
}
protected CompactionController getCompactionController(Set toCompact)
{
return new CompactionController(cfs, toCompact, gcBefore);
}
protected boolean partialCompactionsAcceptable()
{
return !isUserDefined;
}
// extensibility point for other strategies that may want to limit the upper bounds of the sstable segment size
protected boolean newSSTableSegmentThresholdReached(SSTableWriter writer)
{
return false;
}
public static long getMaxDataAge(Collection sstables)
{
long max = 0;
for (SSTableReader sstable : sstables)
{
if (sstable.maxDataAge > max)
max = sstable.maxDataAge;
}
return max;
}
}
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