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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
* limitations under the License.
*/
package org.apache.cassandra.db.commitlog;
import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.UUID;
import java.util.function.Function;
import java.util.zip.CRC32;
import com.google.common.annotations.VisibleForTesting;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.config.ParameterizedClass;
import org.apache.cassandra.db.Mutation;
import org.apache.cassandra.exceptions.CDCWriteException;
import org.apache.cassandra.io.FSWriteError;
import org.apache.cassandra.io.compress.ICompressor;
import org.apache.cassandra.io.util.BufferedDataOutputStreamPlus;
import org.apache.cassandra.io.util.DataOutputBuffer;
import org.apache.cassandra.io.util.DataOutputBufferFixed;
import org.apache.cassandra.io.util.FileUtils;
import org.apache.cassandra.metrics.CommitLogMetrics;
import org.apache.cassandra.net.MessagingService;
import org.apache.cassandra.schema.CompressionParams;
import org.apache.cassandra.schema.TableId;
import org.apache.cassandra.security.EncryptionContext;
import org.apache.cassandra.service.StorageService;
import org.apache.cassandra.utils.JVMStabilityInspector;
import org.apache.cassandra.utils.MBeanWrapper;
import static org.apache.cassandra.db.commitlog.CommitLogSegment.Allocation;
import static org.apache.cassandra.db.commitlog.CommitLogSegment.CommitLogSegmentFileComparator;
import static org.apache.cassandra.db.commitlog.CommitLogSegment.ENTRY_OVERHEAD_SIZE;
import static org.apache.cassandra.utils.FBUtilities.updateChecksum;
import static org.apache.cassandra.utils.FBUtilities.updateChecksumInt;
/*
* Commit Log tracks every write operation into the system. The aim of the commit log is to be able to
* successfully recover data that was not stored to disk via the Memtable.
*/
public class CommitLog implements CommitLogMBean
{
private static final Logger logger = LoggerFactory.getLogger(CommitLog.class);
public static final CommitLog instance = CommitLog.construct();
private static final FilenameFilter unmanagedFilesFilter = (dir, name) -> CommitLogDescriptor.isValid(name) && CommitLogSegment.shouldReplay(name);
final public AbstractCommitLogSegmentManager segmentManager;
public CommitLogArchiver archiver;
public final CommitLogMetrics metrics;
final AbstractCommitLogService executor;
volatile Configuration configuration;
private boolean started = false;
private static CommitLog construct()
{
CommitLog log = new CommitLog(CommitLogArchiver.construct(), DatabaseDescriptor.getCommitLogSegmentMgrProvider());
MBeanWrapper.instance.registerMBean(log, "org.apache.cassandra.db:type=Commitlog");
return log;
}
@VisibleForTesting
CommitLog(CommitLogArchiver archiver)
{
this(archiver, DatabaseDescriptor.getCommitLogSegmentMgrProvider());
}
@VisibleForTesting
CommitLog(CommitLogArchiver archiver, Function segmentManagerProvider)
{
this.configuration = new Configuration(DatabaseDescriptor.getCommitLogCompression(),
DatabaseDescriptor.getEncryptionContext());
DatabaseDescriptor.createAllDirectories();
this.archiver = archiver;
metrics = new CommitLogMetrics();
switch (DatabaseDescriptor.getCommitLogSync())
{
case periodic:
executor = new PeriodicCommitLogService(this);
break;
case batch:
executor = new BatchCommitLogService(this);
break;
case group:
executor = new GroupCommitLogService(this);
break;
default:
throw new IllegalArgumentException("Unknown commitlog service type: " + DatabaseDescriptor.getCommitLogSync());
}
segmentManager = segmentManagerProvider.apply(this);
// register metrics
metrics.attach(executor, segmentManager);
}
/**
* Tries to start the CommitLog if not already started.
*/
synchronized public CommitLog start()
{
if (started)
return this;
try
{
segmentManager.start();
executor.start();
started = true;
} catch (Throwable t)
{
started = false;
throw t;
}
return this;
}
public boolean isStarted()
{
return started;
}
public boolean hasFilesToReplay()
{
return getUnmanagedFiles().length > 0;
}
public File[] getUnmanagedFiles()
{
File[] files = new File(segmentManager.storageDirectory).listFiles(unmanagedFilesFilter);
if (files == null)
return new File[0];
return files;
}
/**
* Perform recovery on commit logs located in the directory specified by the config file.
*
* @return the number of mutations replayed
* @throws IOException
*/
public int recoverSegmentsOnDisk() throws IOException
{
// submit all files for this segment manager for archiving prior to recovery - CASSANDRA-6904
// The files may have already been archived by normal CommitLog operation. This may cause errors in this
// archiving pass, which we should not treat as serious.
for (File file : getUnmanagedFiles())
{
archiver.maybeArchive(file.getPath(), file.getName());
archiver.maybeWaitForArchiving(file.getName());
}
assert archiver.archivePending.isEmpty() : "Not all commit log archive tasks were completed before restore";
archiver.maybeRestoreArchive();
// List the files again as archiver may have added segments.
File[] files = getUnmanagedFiles();
int replayed = 0;
if (files.length == 0)
{
logger.info("No commitlog files found; skipping replay");
}
else
{
Arrays.sort(files, new CommitLogSegmentFileComparator());
logger.info("Replaying {}", StringUtils.join(files, ", "));
replayed = recoverFiles(files);
logger.info("Log replay complete, {} replayed mutations", replayed);
for (File f : files)
segmentManager.handleReplayedSegment(f);
}
return replayed;
}
/**
* Perform recovery on a list of commit log files.
*
* @param clogs the list of commit log files to replay
* @return the number of mutations replayed
*/
public int recoverFiles(File... clogs) throws IOException
{
CommitLogReplayer replayer = CommitLogReplayer.construct(this, getLocalHostId());
replayer.replayFiles(clogs);
return replayer.blockForWrites();
}
public void recoverPath(String path) throws IOException
{
CommitLogReplayer replayer = CommitLogReplayer.construct(this, getLocalHostId());
replayer.replayPath(new File(path), false);
replayer.blockForWrites();
}
private static UUID getLocalHostId()
{
return StorageService.instance.getLocalHostUUID();
}
/**
* Perform recovery on a single commit log. Kept w/sub-optimal name due to coupling w/MBean / JMX
*/
public void recover(String path) throws IOException
{
recoverPath(path);
}
/**
* @return a CommitLogPosition which, if {@code >= one} returned from add(), implies add() was started
* (but not necessarily finished) prior to this call
*/
public CommitLogPosition getCurrentPosition()
{
return segmentManager.getCurrentPosition();
}
/**
* Flushes all dirty CFs, waiting for them to free and recycle any segments they were retaining
*/
public void forceRecycleAllSegments(Iterable droppedTables)
{
segmentManager.forceRecycleAll(droppedTables);
}
/**
* Flushes all dirty CFs, waiting for them to free and recycle any segments they were retaining
*/
public void forceRecycleAllSegments()
{
segmentManager.forceRecycleAll(Collections.emptyList());
}
/**
* Forces a disk flush on the commit log files that need it. Blocking.
*/
public void sync(boolean flush) throws IOException
{
segmentManager.sync(flush);
}
/**
* Preempts the CLExecutor, telling to to sync immediately
*/
public void requestExtraSync()
{
executor.requestExtraSync();
}
/**
* Add a Mutation to the commit log. If CDC is enabled, this can fail.
*
* @param mutation the Mutation to add to the log
* @throws CDCWriteException
*/
public CommitLogPosition add(Mutation mutation) throws CDCWriteException
{
assert mutation != null;
mutation.validateSize(MessagingService.current_version, ENTRY_OVERHEAD_SIZE);
try (DataOutputBuffer dob = DataOutputBuffer.scratchBuffer.get())
{
Mutation.serializer.serialize(mutation, dob, MessagingService.current_version);
int size = dob.getLength();
int totalSize = size + ENTRY_OVERHEAD_SIZE;
Allocation alloc = segmentManager.allocate(mutation, totalSize);
CRC32 checksum = new CRC32();
final ByteBuffer buffer = alloc.getBuffer();
try (BufferedDataOutputStreamPlus dos = new DataOutputBufferFixed(buffer))
{
// checksummed length
dos.writeInt(size);
updateChecksumInt(checksum, size);
buffer.putInt((int) checksum.getValue());
// checksummed mutation
dos.write(dob.getData(), 0, size);
updateChecksum(checksum, buffer, buffer.position() - size, size);
buffer.putInt((int) checksum.getValue());
}
catch (IOException e)
{
throw new FSWriteError(e, alloc.getSegment().getPath());
}
finally
{
alloc.markWritten();
}
executor.finishWriteFor(alloc);
return alloc.getCommitLogPosition();
}
catch (IOException e)
{
throw new FSWriteError(e, segmentManager.allocatingFrom().getPath());
}
}
/**
* Modifies the per-CF dirty cursors of any commit log segments for the column family according to the position
* given. Discards any commit log segments that are no longer used.
*
* @param id the table that was flushed
* @param lowerBound the lowest covered replay position of the flush
* @param lowerBound the highest covered replay position of the flush
*/
public void discardCompletedSegments(final TableId id, final CommitLogPosition lowerBound, final CommitLogPosition upperBound)
{
logger.trace("discard completed log segments for {}-{}, table {}", lowerBound, upperBound, id);
// Go thru the active segment files, which are ordered oldest to newest, marking the
// flushed CF as clean, until we reach the segment file containing the CommitLogPosition passed
// in the arguments. Any segments that become unused after they are marked clean will be
// recycled or discarded.
for (Iterator iter = segmentManager.getActiveSegments().iterator(); iter.hasNext();)
{
CommitLogSegment segment = iter.next();
segment.markClean(id, lowerBound, upperBound);
if (segment.isUnused())
{
logger.debug("Commit log segment {} is unused", segment);
segmentManager.archiveAndDiscard(segment);
}
else
{
if (logger.isTraceEnabled())
logger.trace("Not safe to delete{} commit log segment {}; dirty is {}",
(iter.hasNext() ? "" : " active"), segment, segment.dirtyString());
}
// Don't mark or try to delete any newer segments once we've reached the one containing the
// position of the flush.
if (segment.contains(upperBound))
break;
}
}
@Override
public String getArchiveCommand()
{
return archiver.archiveCommand;
}
@Override
public String getRestoreCommand()
{
return archiver.restoreCommand;
}
@Override
public String getRestoreDirectories()
{
return archiver.restoreDirectories;
}
@Override
public long getRestorePointInTime()
{
return archiver.restorePointInTimeInMicroseconds;
}
@Override
public String getRestorePrecision()
{
return archiver.precision.toString();
}
@VisibleForTesting
public void setCommitlogArchiver(CommitLogArchiver archiver)
{
this.archiver = archiver;
}
public List getActiveSegmentNames()
{
Collection segments = segmentManager.getActiveSegments();
List segmentNames = new ArrayList<>(segments.size());
for (CommitLogSegment seg : segments)
segmentNames.add(seg.getName());
return segmentNames;
}
public List getArchivingSegmentNames()
{
return new ArrayList<>(archiver.archivePending.keySet());
}
@Override
public long getActiveContentSize()
{
long size = 0;
for (CommitLogSegment seg : segmentManager.getActiveSegments())
size += seg.contentSize();
return size;
}
@Override
public long getActiveOnDiskSize()
{
return segmentManager.onDiskSize();
}
@Override
public Map getActiveSegmentCompressionRatios()
{
Map segmentRatios = new TreeMap<>();
for (CommitLogSegment seg : segmentManager.getActiveSegments())
segmentRatios.put(seg.getName(), 1.0 * seg.onDiskSize() / seg.contentSize());
return segmentRatios;
}
/**
* Shuts down the threads used by the commit log, blocking until completion.
* TODO this should accept a timeout, and throw TimeoutException
*/
synchronized public void shutdownBlocking() throws InterruptedException
{
if (!started)
return;
started = false;
executor.shutdown();
executor.awaitTermination();
segmentManager.shutdown();
segmentManager.awaitTermination();
}
/**
* FOR TESTING PURPOSES
* @return the number of files recovered
*/
@VisibleForTesting
synchronized public int resetUnsafe(boolean deleteSegments) throws IOException
{
stopUnsafe(deleteSegments);
resetConfiguration();
return restartUnsafe();
}
/**
* FOR TESTING PURPOSES.
*/
@VisibleForTesting
synchronized public void resetConfiguration()
{
configuration = new Configuration(DatabaseDescriptor.getCommitLogCompression(),
DatabaseDescriptor.getEncryptionContext());
}
/**
* FOR TESTING PURPOSES
*/
@VisibleForTesting
synchronized public void stopUnsafe(boolean deleteSegments)
{
if (!started)
return;
started = false;
executor.shutdown();
try
{
executor.awaitTermination();
}
catch (InterruptedException e)
{
throw new RuntimeException(e);
}
segmentManager.stopUnsafe(deleteSegments);
CommitLogSegment.resetReplayLimit();
if (DatabaseDescriptor.isCDCEnabled() && deleteSegments)
for (File f : new File(DatabaseDescriptor.getCDCLogLocation()).listFiles())
FileUtils.deleteWithConfirm(f);
}
/**
* FOR TESTING PURPOSES
*/
@VisibleForTesting
synchronized public int restartUnsafe() throws IOException
{
started = false;
return start().recoverSegmentsOnDisk();
}
public static long freeDiskSpace()
{
return FileUtils.getFreeSpace(new File(DatabaseDescriptor.getCommitLogLocation()));
}
@VisibleForTesting
public static boolean handleCommitError(String message, Throwable t)
{
JVMStabilityInspector.inspectCommitLogThrowable(t);
switch (DatabaseDescriptor.getCommitFailurePolicy())
{
// Needed here for unit tests to not fail on default assertion
case die:
case stop:
StorageService.instance.stopTransports();
//$FALL-THROUGH$
case stop_commit:
String errorMsg = String.format("%s. Commit disk failure policy is %s; terminating thread.", message, DatabaseDescriptor.getCommitFailurePolicy());
logger.error(addAdditionalInformationIfPossible(errorMsg), t);
return false;
case ignore:
logger.error(addAdditionalInformationIfPossible(message), t);
return true;
default:
throw new AssertionError(DatabaseDescriptor.getCommitFailurePolicy());
}
}
/**
* Add additional information to the error message if the commit directory does not have enough free space.
*
* @param msg the original error message
* @return the message with additional information if possible
*/
private static String addAdditionalInformationIfPossible(String msg)
{
long unallocatedSpace = freeDiskSpace();
int segmentSize = DatabaseDescriptor.getCommitLogSegmentSize();
if (unallocatedSpace < segmentSize)
{
return String.format("%s. %d bytes required for next commitlog segment but only %d bytes available. Check %s to see if not enough free space is the reason for this error.",
msg, segmentSize, unallocatedSpace, DatabaseDescriptor.getCommitLogLocation());
}
return msg;
}
public static final class Configuration
{
/**
* The compressor class.
*/
private final ParameterizedClass compressorClass;
/**
* The compressor used to compress the segments.
*/
private final ICompressor compressor;
/**
* The encryption context used to encrypt the segments.
*/
private EncryptionContext encryptionContext;
public Configuration(ParameterizedClass compressorClass, EncryptionContext encryptionContext)
{
this.compressorClass = compressorClass;
this.compressor = compressorClass != null ? CompressionParams.createCompressor(compressorClass) : null;
this.encryptionContext = encryptionContext;
}
/**
* Checks if the segments must be compressed.
* @return true if the segments must be compressed, false otherwise.
*/
public boolean useCompression()
{
return compressor != null;
}
/**
* Checks if the segments must be encrypted.
* @return true if the segments must be encrypted, false otherwise.
*/
public boolean useEncryption()
{
return encryptionContext.isEnabled();
}
/**
* Returns the compressor used to compress the segments.
* @return the compressor used to compress the segments
*/
public ICompressor getCompressor()
{
return compressor;
}
/**
* Returns the compressor class.
* @return the compressor class
*/
public ParameterizedClass getCompressorClass()
{
return compressorClass;
}
/**
* Returns the compressor name.
* @return the compressor name.
*/
public String getCompressorName()
{
return useCompression() ? compressor.getClass().getSimpleName() : "none";
}
/**
* Returns the encryption context used to encrypt the segments.
* @return the encryption context used to encrypt the segments
*/
public EncryptionContext getEncryptionContext()
{
return encryptionContext;
}
}
}
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