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A fork of the Apache Cassandra Project ready to embed Elasticsearch.
/*
* 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.lifecycle;
import java.io.File;
import org.apache.cassandra.io.util.FileUtils;
import org.apache.cassandra.utils.CLibrary;
/**
* Because a column family may have sstables on different disks and disks can
* be removed, we duplicate log files into many replicas so as to have a file
* in each folder where sstables exist.
*
* Each replica contains the exact same content but we do allow for final
* partial records in case we crashed after writing to one replica but
* before compliting the write to another replica.
*
* @see LogFile
*/
final class LogReplica implements AutoCloseable
{
private final File file;
private int folderDescriptor;
static LogReplica create(File folder, String fileName)
{
return new LogReplica(new File(fileName), CLibrary.tryOpenDirectory(folder.getPath()));
}
static LogReplica open(File file)
{
return new LogReplica(file, CLibrary.tryOpenDirectory(file.getParentFile().getPath()));
}
LogReplica(File file, int folderDescriptor)
{
this.file = file;
this.folderDescriptor = folderDescriptor;
}
File file()
{
return file;
}
void append(LogRecord record)
{
boolean existed = exists();
FileUtils.appendAndSync(file, record.toString());
// If the file did not exist before appending the first
// line, then sync the folder as well since now it must exist
if (!existed)
syncFolder();
}
void syncFolder()
{
if (folderDescriptor >= 0)
CLibrary.trySync(folderDescriptor);
}
void delete()
{
LogTransaction.delete(file);
syncFolder();
}
boolean exists()
{
return file.exists();
}
public void close()
{
if (folderDescriptor >= 0)
{
CLibrary.tryCloseFD(folderDescriptor);
folderDescriptor = -1;
}
}
@Override
public String toString()
{
return String.format("[%s] ", file);
}
}