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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.cache;
import java.io.*;
import java.util.*;
import java.util.concurrent.Callable;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import org.cliffc.high_scale_lib.NonBlockingHashSet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.common.util.concurrent.MoreExecutors;
import org.apache.cassandra.concurrent.ScheduledExecutors;
import org.apache.cassandra.schema.TableId;
import org.apache.cassandra.schema.TableMetadata;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.schema.Schema;
import org.apache.cassandra.schema.SchemaConstants;
import org.apache.cassandra.db.ColumnFamilyStore;
import org.apache.cassandra.db.compaction.CompactionInfo;
import org.apache.cassandra.db.compaction.CompactionManager;
import org.apache.cassandra.db.compaction.OperationType;
import org.apache.cassandra.db.compaction.CompactionInfo.Unit;
import org.apache.cassandra.io.FSWriteError;
import org.apache.cassandra.io.util.*;
import org.apache.cassandra.io.util.CorruptFileException;
import org.apache.cassandra.io.util.DataInputPlus.DataInputStreamPlus;
import org.apache.cassandra.service.CacheService;
import org.apache.cassandra.utils.JVMStabilityInspector;
import org.apache.cassandra.utils.Pair;
import org.apache.cassandra.utils.UUIDGen;
public class AutoSavingCache extends InstrumentingCache
{
public interface IStreamFactory
{
InputStream getInputStream(File dataPath, File crcPath) throws IOException;
OutputStream getOutputStream(File dataPath, File crcPath) throws FileNotFoundException;
}
private static final Logger logger = LoggerFactory.getLogger(AutoSavingCache.class);
/** True if a cache flush is currently executing: only one may execute at a time. */
public static final Set flushInProgress = new NonBlockingHashSet();
protected volatile ScheduledFuture saveTask;
protected final CacheService.CacheType cacheType;
private final CacheSerializer cacheLoader;
/*
* CASSANDRA-10155 required a format change to fix 2i indexes and caching.
* 2.2 is already at version "c" and 3.0 is at "d".
*
* Since cache versions match exactly and there is no partial fallback just add
* a minor version letter.
*
* Sticking with "d" is fine for 3.0 since it has never been released or used by another version
*
* "e" introduced with CASSANDRA-11206, omits IndexInfo from key-cache, stores offset into index-file
*
* "f" introduced with CASSANDRA-9425, changes "keyspace.table.index" in cache keys to TableMetadata.id+TableMetadata.indexName
*/
private static final String CURRENT_VERSION = "f";
private static volatile IStreamFactory streamFactory = new IStreamFactory()
{
private final SequentialWriterOption writerOption = SequentialWriterOption.newBuilder()
.trickleFsync(DatabaseDescriptor.getTrickleFsync())
.trickleFsyncByteInterval(DatabaseDescriptor.getTrickleFsyncIntervalInKb() * 1024)
.finishOnClose(true).build();
public InputStream getInputStream(File dataPath, File crcPath) throws IOException
{
return ChecksummedRandomAccessReader.open(dataPath, crcPath);
}
public OutputStream getOutputStream(File dataPath, File crcPath)
{
return new ChecksummedSequentialWriter(dataPath, crcPath, null, writerOption);
}
};
// Unused, but exposed for a reason. See CASSANDRA-8096.
public static void setStreamFactory(IStreamFactory streamFactory)
{
AutoSavingCache.streamFactory = streamFactory;
}
public AutoSavingCache(ICache cache, CacheService.CacheType cacheType, CacheSerializer cacheloader)
{
super(cacheType.toString(), cache);
this.cacheType = cacheType;
this.cacheLoader = cacheloader;
}
public File getCacheDataPath(String version)
{
return DatabaseDescriptor.getSerializedCachePath( cacheType, version, "db");
}
public File getCacheCrcPath(String version)
{
return DatabaseDescriptor.getSerializedCachePath( cacheType, version, "crc");
}
public Writer getWriter(int keysToSave)
{
return new Writer(keysToSave);
}
public void scheduleSaving(int savePeriodInSeconds, final int keysToSave)
{
if (saveTask != null)
{
saveTask.cancel(false); // Do not interrupt an in-progress save
saveTask = null;
}
if (savePeriodInSeconds > 0)
{
Runnable runnable = new Runnable()
{
public void run()
{
submitWrite(keysToSave);
}
};
saveTask = ScheduledExecutors.optionalTasks.scheduleWithFixedDelay(runnable,
savePeriodInSeconds,
savePeriodInSeconds,
TimeUnit.SECONDS);
}
}
public ListenableFuture loadSavedAsync()
{
final ListeningExecutorService es = MoreExecutors.listeningDecorator(Executors.newSingleThreadExecutor());
final long start = System.nanoTime();
ListenableFuture cacheLoad = es.submit(new Callable()
{
@Override
public Integer call()
{
return loadSaved();
}
});
cacheLoad.addListener(new Runnable()
{
@Override
public void run()
{
if (size() > 0)
logger.info("Completed loading ({} ms; {} keys) {} cache",
TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start),
CacheService.instance.keyCache.size(),
cacheType);
es.shutdown();
}
}, MoreExecutors.directExecutor());
return cacheLoad;
}
public int loadSaved()
{
int count = 0;
long start = System.nanoTime();
// modern format, allows both key and value (so key cache load can be purely sequential)
File dataPath = getCacheDataPath(CURRENT_VERSION);
File crcPath = getCacheCrcPath(CURRENT_VERSION);
if (dataPath.exists() && crcPath.exists())
{
DataInputStreamPlus in = null;
try
{
logger.info("reading saved cache {}", dataPath);
in = new DataInputStreamPlus(new LengthAvailableInputStream(new BufferedInputStream(streamFactory.getInputStream(dataPath, crcPath)), dataPath.length()));
//Check the schema has not changed since CFs are looked up by name which is ambiguous
UUID schemaVersion = new UUID(in.readLong(), in.readLong());
if (!schemaVersion.equals(Schema.instance.getVersion()))
throw new RuntimeException("Cache schema version "
+ schemaVersion
+ " does not match current schema version "
+ Schema.instance.getVersion());
ArrayDeque>> futures = new ArrayDeque>>();
while (in.available() > 0)
{
//tableId and indexName are serialized by the serializers in CacheService
//That is delegated there because there are serializer specific conditions
//where a cache key is skipped and not written
TableId tableId = TableId.deserialize(in);
String indexName = in.readUTF();
if (indexName.isEmpty())
indexName = null;
ColumnFamilyStore cfs = Schema.instance.getColumnFamilyStoreInstance(tableId);
if (indexName != null && cfs != null)
cfs = cfs.indexManager.getIndexByName(indexName).getBackingTable().orElse(null);
Future> entryFuture = cacheLoader.deserialize(in, cfs);
// Key cache entry can return null, if the SSTable doesn't exist.
if (entryFuture == null)
continue;
futures.offer(entryFuture);
count++;
/*
* Kind of unwise to accrue an unbounded number of pending futures
* So now there is this loop to keep a bounded number pending.
*/
do
{
while (futures.peek() != null && futures.peek().isDone())
{
Future> future = futures.poll();
Pair entry = future.get();
if (entry != null && entry.right != null)
put(entry.left, entry.right);
}
if (futures.size() > 1000)
Thread.yield();
} while(futures.size() > 1000);
}
Future> future = null;
while ((future = futures.poll()) != null)
{
Pair entry = future.get();
if (entry != null && entry.right != null)
put(entry.left, entry.right);
}
}
catch (CorruptFileException e)
{
JVMStabilityInspector.inspectThrowable(e);
logger.warn(String.format("Non-fatal checksum error reading saved cache %s", dataPath.getAbsolutePath()), e);
}
catch (Throwable t)
{
JVMStabilityInspector.inspectThrowable(t);
logger.info(String.format("Harmless error reading saved cache %s", dataPath.getAbsolutePath()), t);
}
finally
{
FileUtils.closeQuietly(in);
}
}
if (logger.isTraceEnabled())
logger.trace("completed reading ({} ms; {} keys) saved cache {}",
TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start), count, dataPath);
return count;
}
public Future submitWrite(int keysToSave)
{
return CompactionManager.instance.submitCacheWrite(getWriter(keysToSave));
}
public class Writer extends CompactionInfo.Holder
{
private final Iterator keyIterator;
private final CompactionInfo info;
private long keysWritten;
private final long keysEstimate;
protected Writer(int keysToSave)
{
int size = size();
if (keysToSave >= size || keysToSave == 0)
{
keyIterator = keyIterator();
keysEstimate = size;
}
else
{
keyIterator = hotKeyIterator(keysToSave);
keysEstimate = keysToSave;
}
OperationType type;
if (cacheType == CacheService.CacheType.KEY_CACHE)
type = OperationType.KEY_CACHE_SAVE;
else if (cacheType == CacheService.CacheType.ROW_CACHE)
type = OperationType.ROW_CACHE_SAVE;
else if (cacheType == CacheService.CacheType.COUNTER_CACHE)
type = OperationType.COUNTER_CACHE_SAVE;
else
type = OperationType.UNKNOWN;
info = CompactionInfo.withoutSSTables(TableMetadata.minimal(SchemaConstants.SYSTEM_KEYSPACE_NAME, cacheType.toString()),
type,
0,
keysEstimate,
Unit.KEYS,
UUIDGen.getTimeUUID());
}
public CacheService.CacheType cacheType()
{
return cacheType;
}
public CompactionInfo getCompactionInfo()
{
// keyset can change in size, thus total can too
// TODO need to check for this one... was: info.forProgress(keysWritten, Math.max(keysWritten, keys.size()));
return info.forProgress(keysWritten, Math.max(keysWritten, keysEstimate));
}
public void saveCache()
{
logger.trace("Deleting old {} files.", cacheType);
deleteOldCacheFiles();
if (!keyIterator.hasNext())
{
logger.trace("Skipping {} save, cache is empty.", cacheType);
return;
}
long start = System.nanoTime();
Pair cacheFilePaths = tempCacheFiles();
try (WrappedDataOutputStreamPlus writer = new WrappedDataOutputStreamPlus(streamFactory.getOutputStream(cacheFilePaths.left, cacheFilePaths.right)))
{
//Need to be able to check schema version because CF names are ambiguous
UUID schemaVersion = Schema.instance.getVersion();
if (schemaVersion == null)
{
Schema.instance.updateVersion();
schemaVersion = Schema.instance.getVersion();
}
writer.writeLong(schemaVersion.getMostSignificantBits());
writer.writeLong(schemaVersion.getLeastSignificantBits());
while (keyIterator.hasNext())
{
K key = keyIterator.next();
ColumnFamilyStore cfs = Schema.instance.getColumnFamilyStoreInstance(key.tableId);
if (cfs == null)
continue; // the table or 2i has been dropped.
if (key.indexName != null)
cfs = cfs.indexManager.getIndexByName(key.indexName).getBackingTable().orElse(null);
cacheLoader.serialize(key, writer, cfs);
keysWritten++;
if (keysWritten >= keysEstimate)
break;
}
}
catch (FileNotFoundException e)
{
throw new RuntimeException(e);
}
catch (IOException e)
{
throw new FSWriteError(e, cacheFilePaths.left);
}
File cacheFile = getCacheDataPath(CURRENT_VERSION);
File crcFile = getCacheCrcPath(CURRENT_VERSION);
cacheFile.delete(); // ignore error if it didn't exist
crcFile.delete();
if (!cacheFilePaths.left.renameTo(cacheFile))
logger.error("Unable to rename {} to {}", cacheFilePaths.left, cacheFile);
if (!cacheFilePaths.right.renameTo(crcFile))
logger.error("Unable to rename {} to {}", cacheFilePaths.right, crcFile);
logger.info("Saved {} ({} items) in {} ms", cacheType, keysWritten, TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start));
}
private Pair tempCacheFiles()
{
File dataPath = getCacheDataPath(CURRENT_VERSION);
File crcPath = getCacheCrcPath(CURRENT_VERSION);
return Pair.create(FileUtils.createTempFile(dataPath.getName(), null, dataPath.getParentFile()),
FileUtils.createTempFile(crcPath.getName(), null, crcPath.getParentFile()));
}
private void deleteOldCacheFiles()
{
File savedCachesDir = new File(DatabaseDescriptor.getSavedCachesLocation());
assert savedCachesDir.exists() && savedCachesDir.isDirectory();
File[] files = savedCachesDir.listFiles();
if (files != null)
{
String cacheNameFormat = String.format("%s-%s.db", cacheType.toString(), CURRENT_VERSION);
for (File file : files)
{
if (!file.isFile())
continue; // someone's been messing with our directory. naughty!
if (file.getName().endsWith(cacheNameFormat)
|| file.getName().endsWith(cacheType.toString()))
{
if (!file.delete())
logger.warn("Failed to delete {}", file.getAbsolutePath());
}
}
}
else
{
logger.warn("Could not list files in {}", savedCachesDir);
}
}
public boolean isGlobal()
{
return false;
}
}
public interface CacheSerializer
{
void serialize(K key, DataOutputPlus out, ColumnFamilyStore cfs) throws IOException;
Future> deserialize(DataInputPlus in, ColumnFamilyStore cfs) throws IOException;
}
}