/**
* 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.Set;
import java.util.TreeSet;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
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.ColumnFamilyStore;
import org.apache.cassandra.db.CompactionManager;
import org.apache.cassandra.db.DecoratedKey;
import org.apache.cassandra.io.CompactionInfo;
import org.apache.cassandra.io.CompactionType;
import org.apache.cassandra.io.util.BufferedRandomAccessFile;
import org.apache.cassandra.io.util.FileUtils;
import org.apache.cassandra.service.StorageService;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.WrappedRunnable;
public abstract class AutoSavingCache<K, 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 AtomicBoolean flushInProgress = new AtomicBoolean(false);
protected final String cfName;
protected final String tableName;
protected volatile ScheduledFuture<?> saveTask;
protected final ColumnFamilyStore.CacheType cacheType;
public AutoSavingCache(ICache<K, V> cache, String tableName, String cfName, ColumnFamilyStore.CacheType cacheType)
{
super(cache, tableName, cfName + cacheType);
this.tableName = tableName;
this.cfName = cfName;
this.cacheType = cacheType;
}
public abstract ByteBuffer translateKey(K key);
public abstract double getConfiguredCacheSize(CFMetaData cfm);
public int getAdjustedCacheSize(long expectedKeys)
{
CFMetaData cfm = DatabaseDescriptor.getCFMetaData(tableName, cfName);
return (int)Math.min(FBUtilities.absoluteFromFraction(getConfiguredCacheSize(cfm), expectedKeys), Integer.MAX_VALUE);
}
public File getCachePath()
{
return DatabaseDescriptor.getSerializedCachePath(tableName, cfName, cacheType);
}
public Writer getWriter()
{
return new Writer(tableName, cfName);
}
public void scheduleSaving(int savePeriodInSeconds)
{
if (saveTask != null)
{
saveTask.cancel(false); // Do not interrupt an in-progress save
saveTask = null;
}
if (savePeriodInSeconds > 0)
{
Runnable runnable = new WrappedRunnable()
{
public void runMayThrow()
{
submitWrite();
}
};
saveTask = StorageService.tasks.scheduleWithFixedDelay(runnable,
savePeriodInSeconds,
savePeriodInSeconds,
TimeUnit.SECONDS);
}
}
public Future<?> submitWrite()
{
return CompactionManager.instance.submitCacheWrite(getWriter());
}
public Set<DecoratedKey> readSaved()
{
File path = getCachePath();
Set<DecoratedKey> keys = new TreeSet<DecoratedKey>();
if (path.exists())
{
DataInputStream in = null;
try
{
long start = System.currentTimeMillis();
logger.info(String.format("reading saved cache %s", path));
in = new DataInputStream(new BufferedInputStream(new FileInputStream(path)));
while (in.available() > 0)
{
int size = in.readInt();
byte[] bytes = new byte[size];
in.readFully(bytes);
ByteBuffer buffer = ByteBuffer.wrap(bytes);
DecoratedKey key;
try
{
key = StorageService.getPartitioner().decorateKey(buffer);
}
catch (Exception e)
{
logger.info(String.format("unable to read entry #%s from saved cache %s; skipping remaining entries",
keys.size(), path.getAbsolutePath()), e);
break;
}
keys.add(key);
}
if (logger.isDebugEnabled())
logger.debug(String.format("completed reading (%d ms; %d keys) saved cache %s",
System.currentTimeMillis() - start, keys.size(), path));
}
catch (IOException ioe)
{
logger.warn(String.format("error reading saved cache %s", path.getAbsolutePath()), ioe);
}
finally
{
FileUtils.closeQuietly(in);
}
}
return keys;
}
/**
* Resizes the cache based on a key estimate.
* Caller is in charge of synchronizing this correctly if needed
*/
public void updateCacheSize(long keys)
{
if (!isCapacitySetManually())
{
int cacheSize = getAdjustedCacheSize(keys);
if (cacheSize != getCapacity())
{
// update cache size for the new volume
if (logger.isDebugEnabled())
logger.debug(cacheType + " capacity for " + cfName + " is " + cacheSize);
updateCapacity(cacheSize);
}
}
}
public void reduceCacheSize()
{
if (getCapacity() > 0)
{
int newCapacity = (int) (DatabaseDescriptor.getReduceCacheCapacityTo() * size());
logger.warn(String.format("Reducing %s %s capacity from %d to %s to reduce memory pressure",
cfName, cacheType, getCapacity(), newCapacity));
setCapacity(newCapacity);
}
}
public class Writer implements CompactionInfo.Holder
{
private final Set<K> keys;
private final CompactionInfo info;
private final long estimatedTotalBytes;
private long bytesWritten;
private Writer(String ksname, String cfname)
{
keys = getKeySet();
long bytes = 0;
for (K key : keys)
bytes += translateKey(key).remaining();
// an approximation -- the keyset can change while saving
estimatedTotalBytes = bytes;
CompactionType type;
if (cacheType.equals(ColumnFamilyStore.CacheType.KEY_CACHE_TYPE))
type = CompactionType.KEY_CACHE_SAVE;
else if (cacheType.equals(ColumnFamilyStore.CacheType.ROW_CACHE_TYPE))
type = CompactionType.ROW_CACHE_SAVE;
else
type = CompactionType.UNKNOWN;
info = new CompactionInfo(ksname,
cfname,
type,
0,
estimatedTotalBytes);
}
public CompactionInfo getCompactionInfo()
{
long bytesWritten = this.bytesWritten;
// keyset can change in size, thus totalBytes can too
return info.forProgress(bytesWritten,
Math.max(bytesWritten, estimatedTotalBytes));
}
public void saveCache() throws IOException
{
long start = System.currentTimeMillis();
File path = getCachePath();
if (keys.size() == 0 || estimatedTotalBytes == 0)
{
logger.debug("Deleting {} (cache is empty)");
path.delete();
return;
}
logger.debug("Saving {}", path);
File tmpFile = File.createTempFile(path.getName(), null, path.getParentFile());
BufferedRandomAccessFile out = new BufferedRandomAccessFile(tmpFile, "rw", BufferedRandomAccessFile.DEFAULT_BUFFER_SIZE, true);
try
{
for (K key : keys)
{
ByteBuffer bytes = translateKey(key);
ByteBufferUtil.writeWithLength(bytes, out);
bytesWritten += bytes.remaining();
}
}
finally
{
out.close();
}
path.delete(); // ignore error if it didn't exist
if (!tmpFile.renameTo(path))
throw new IOException("Unable to rename " + tmpFile + " to " + path);
logger.info(String.format("Saved %s (%d items) in %d ms",
path.getName(), keys.size(), (System.currentTimeMillis() - start)));
}
}
}