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* 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.nio.ByteBuffer;
import java.util.*;
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 org.apache.cassandra.config.CFMetaData;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.db.ColumnFamilyType;
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.marshal.BytesType;
import org.apache.cassandra.db.ColumnFamilyStore;
import org.apache.cassandra.db.Keyspace;
import org.apache.cassandra.io.FSWriteError;
import org.apache.cassandra.io.util.FileUtils;
import org.apache.cassandra.io.util.LengthAvailableInputStream;
import org.apache.cassandra.io.util.SequentialWriter;
import org.apache.cassandra.service.CacheService;
import org.apache.cassandra.service.StorageService;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.Pair;
public class AutoSavingCache<K extends CacheKey, V> extends InstrumentingCache<K, V>
{
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<CacheService.CacheType> flushInProgress = new NonBlockingHashSet<CacheService.CacheType>();
protected volatile ScheduledFuture<?> saveTask;
protected final CacheService.CacheType cacheType;
private CacheSerializer<K, V> cacheLoader;
private static final String CURRENT_VERSION = "b";
public AutoSavingCache(ICache<K, V> cache, CacheService.CacheType cacheType, CacheSerializer<K, V> cacheloader)
{
super(cacheType.toString(), cache);
this.cacheType = cacheType;
this.cacheLoader = cacheloader;
}
public File getCachePath(String ksName, String cfName, String version)
{
return DatabaseDescriptor.getSerializedCachePath(ksName, cfName, cacheType, version);
}
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 = StorageService.optionalTasks.scheduleWithFixedDelay(runnable,
savePeriodInSeconds,
savePeriodInSeconds,
TimeUnit.SECONDS);
}
}
public int loadSaved(ColumnFamilyStore cfs)
{
int count = 0;
long start = System.nanoTime();
// modern format, allows both key and value (so key cache load can be purely sequential)
File path = getCachePath(cfs.keyspace.getName(), cfs.name, CURRENT_VERSION);
if (path.exists())
{
DataInputStream in = null;
try
{
logger.info(String.format("reading saved cache %s", path));
in = new DataInputStream(new LengthAvailableInputStream(new BufferedInputStream(new FileInputStream(path)), path.length()));
List<Future<Pair<K, V>>> futures = new ArrayList<Future<Pair<K, V>>>();
while (in.available() > 0)
{
Future<Pair<K, V>> entry = cacheLoader.deserialize(in, cfs);
// Key cache entry can return null, if the SSTable doesn't exist.
if (entry == null)
continue;
futures.add(entry);
count++;
}
for (Future<Pair<K, V>> future : futures)
{
Pair<K, V> entry = future.get();
if (entry != null && entry.right != null)
put(entry.left, entry.right);
}
}
catch (Exception e)
{
logger.debug(String.format("harmless error reading saved cache %s", path.getAbsolutePath()), e);
}
finally
{
FileUtils.closeQuietly(in);
}
}
if (logger.isDebugEnabled())
logger.debug("completed reading ({} ms; {} keys) saved cache {}",
TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start), count, path);
return count;
}
public Future<?> submitWrite(int keysToSave)
{
return CompactionManager.instance.submitCacheWrite(getWriter(keysToSave));
}
public class Writer extends CompactionInfo.Holder
{
private final Set<K> keys;
private final CompactionInfo info;
private long keysWritten;
protected Writer(int keysToSave)
{
if (keysToSave >= getKeySet().size())
keys = getKeySet();
else
keys = hotKeySet(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
type = OperationType.UNKNOWN;
info = new CompactionInfo(new CFMetaData(Keyspace.SYSTEM_KS, cacheType.toString(), ColumnFamilyType.Standard, BytesType.instance, null),
type,
0,
keys.size(),
"keys");
}
public CacheService.CacheType cacheType()
{
return cacheType;
}
public CompactionInfo getCompactionInfo()
{
// keyset can change in size, thus total can too
return info.forProgress(keysWritten, Math.max(keysWritten, keys.size()));
}
public void saveCache()
{
logger.debug("Deleting old {} files.", cacheType);
deleteOldCacheFiles();
if (keys.isEmpty())
{
logger.debug("Skipping {} save, cache is empty.", cacheType);
return;
}
long start = System.nanoTime();
HashMap<Pair<String, String>, SequentialWriter> writers = new HashMap<Pair<String, String>, SequentialWriter>();
try
{
for (K key : keys)
{
Pair<String, String> path = key.getPathInfo();
SequentialWriter writer = writers.get(path);
if (writer == null)
{
writer = tempCacheFile(path);
writers.put(path, writer);
}
try
{
cacheLoader.serialize(key, writer.stream);
}
catch (IOException e)
{
throw new FSWriteError(e, writer.getPath());
}
keysWritten++;
}
}
finally
{
for (SequentialWriter writer : writers.values())
FileUtils.closeQuietly(writer);
}
for (Map.Entry<Pair<String, String>, SequentialWriter> info : writers.entrySet())
{
Pair<String, String> path = info.getKey();
SequentialWriter writer = info.getValue();
File tmpFile = new File(writer.getPath());
File cacheFile = getCachePath(path.left, path.right, CURRENT_VERSION);
cacheFile.delete(); // ignore error if it didn't exist
if (!tmpFile.renameTo(cacheFile))
logger.error("Unable to rename {} to {}", tmpFile, cacheFile);
}
logger.info("Saved {} ({} items) in {} ms", cacheType, keys.size(), TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start));
}
private SequentialWriter tempCacheFile(Pair<String, String> pathInfo)
{
File path = getCachePath(pathInfo.left, pathInfo.right, CURRENT_VERSION);
File tmpFile = FileUtils.createTempFile(path.getName(), null, path.getParentFile());
return SequentialWriter.open(tmpFile, true);
}
private void deleteOldCacheFiles()
{
File savedCachesDir = new File(DatabaseDescriptor.getSavedCachesLocation());
assert savedCachesDir.exists() && savedCachesDir.isDirectory();
File[] files = savedCachesDir.listFiles();
if (files != null)
{
for (File file : files)
{
if (!file.isFile())
continue; // someone's been messing with our directory. naughty!
if (file.getName().endsWith(cacheType.toString())
|| file.getName().endsWith(String.format("%s-%s.db", cacheType.toString(), CURRENT_VERSION)))
{
if (!file.delete())
logger.warn("Failed to delete {}", file.getAbsolutePath());
}
}
}
else
logger.warn("Could not list files in {}", savedCachesDir);
}
}
public interface CacheSerializer<K extends CacheKey, V>
{
void serialize(K key, DataOutput out) throws IOException;
Future<Pair<K, V>> deserialize(DataInputStream in, ColumnFamilyStore cfs) throws IOException;
}
}