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RotatingFileOutputStreamSupplier.java
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RotatingFileOutputStreamSupplier.java
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/*
* Copyright (c) 2002-2017 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.logging;
import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.util.concurrent.Executor;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.function.LongSupplier;
import java.util.function.Supplier;
import org.neo4j.io.NullOutputStream;
import org.neo4j.io.fs.FileSystemAbstraction;
import static org.neo4j.io.file.Files.createOrOpenAsOuputStream;
/**
* A {@link Supplier} of {@link OutputStream}s backed by on-disk files, which
* are rotated and archived when a specified size is reached. The {@link #get()} method
* will always return an OutputStream to the current output file without directly performing
* any IO or blocking, and, when necessary, will trigger rotation via the {@link Executor}
* supplied during construction.
*/
public class RotatingFileOutputStreamSupplier implements Supplier<OutputStream>, Closeable
{
/**
* A listener for the rotation process
*/
public static class RotationListener
{
public void outputFileCreated( OutputStream out )
{
}
public void rotationCompleted( OutputStream out )
{
}
public void rotationError( Exception e, OutputStream out )
{
}
}
private static final LongSupplier DEFAULT_CURRENT_TIME_SUPPLIER = System::currentTimeMillis;
// Used only in case no new output file can be created during rotation
private static final OutputStream nullStream = NullOutputStream.NULL_OUTPUT_STREAM;
private final LongSupplier currentTimeSupplier;
private final FileSystemAbstraction fileSystem;
private final File outputFile;
private final long rotationThresholdBytes;
private final long rotationDelay;
private final int maxArchives;
private final RotationListener rotationListener;
private final Executor rotationExecutor;
private final ReadWriteLock logFileLock = new ReentrantReadWriteLock( true );
private final OutputStream streamWrapper;
private final AtomicBoolean closed = new AtomicBoolean( false );
private final AtomicBoolean rotating = new AtomicBoolean( false );
private final AtomicLong earliestRotationTimeRef = new AtomicLong( 0 );
private OutputStream outRef = nullStream;
/**
* @param fileSystem The filesystem to use
* @param outputFile The file that the latest {@link OutputStream} should output to
* @param rotationThresholdBytes The size above which the file should be rotated
* @param rotationDelay The minimum time (ms) after last rotation before the file may be rotated again
* @param maxArchives The maximum number of archived output files to keep
* @param rotationExecutor An {@link Executor} for performing the rotation
* @throws IOException If the output file cannot be created
*/
public RotatingFileOutputStreamSupplier( FileSystemAbstraction fileSystem, File outputFile,
long rotationThresholdBytes, long rotationDelay, int maxArchives, Executor rotationExecutor )
throws IOException
{
this( fileSystem, outputFile, rotationThresholdBytes, rotationDelay, maxArchives, rotationExecutor,
new RotationListener() );
}
/**
* @param fileSystem The filesystem to use
* @param outputFile The file that the latest {@link OutputStream} should output to
* @param rotationThresholdBytes The size above which the file should be rotated
* @param rotationDelay The minimum time (ms) after last rotation before the file may be rotated again
* @param maxArchives The maximum number of archived output files to keep
* @param rotationExecutor An {@link Executor} for performing the rotation
* @param rotationListener A {@link org.neo4j.logging.RotatingFileOutputStreamSupplier.RotationListener} that can
* observe the rotation process and be notified of errors
* @throws IOException If the output file cannot be created
*/
public RotatingFileOutputStreamSupplier( FileSystemAbstraction fileSystem, File outputFile,
long rotationThresholdBytes, long rotationDelay, int maxArchives, Executor rotationExecutor,
RotationListener rotationListener ) throws IOException
{
this( DEFAULT_CURRENT_TIME_SUPPLIER, fileSystem, outputFile, rotationThresholdBytes, rotationDelay,
maxArchives, rotationExecutor, rotationListener );
}
RotatingFileOutputStreamSupplier( LongSupplier currentTimeSupplier, FileSystemAbstraction fileSystem,
File outputFile, long rotationThresholdBytes, long rotationDelay, int maxArchives,
Executor rotationExecutor, RotationListener rotationListener ) throws IOException
{
this.currentTimeSupplier = currentTimeSupplier;
this.fileSystem = fileSystem;
this.outputFile = outputFile;
this.rotationThresholdBytes = rotationThresholdBytes;
this.rotationDelay = rotationDelay;
this.maxArchives = maxArchives;
this.rotationListener = rotationListener;
this.rotationExecutor = rotationExecutor;
this.outRef = openOutputFile();
// Wrap the actual reference to prevent race conditions during log rotation
this.streamWrapper = new OutputStream()
{
@Override
public void write( int i ) throws IOException
{
logFileLock.readLock().lock();
try
{
outRef.write( i );
}
finally
{
logFileLock.readLock().unlock();
}
}
@Override
public void write( byte[] bytes ) throws IOException
{
logFileLock.readLock().lock();
try
{
outRef.write( bytes );
}
finally
{
logFileLock.readLock().unlock();
}
}
@Override
public void write( byte[] bytes, int off, int len ) throws IOException
{
logFileLock.readLock().lock();
try
{
outRef.write( bytes, off, len );
}
finally
{
logFileLock.readLock().unlock();
}
}
@Override
public void flush() throws IOException
{
logFileLock.readLock().lock();
try
{
outRef.flush();
}
finally
{
logFileLock.readLock().unlock();
}
}
};
}
/**
* @return A stream outputting to the latest output file
*/
@Override
public OutputStream get()
{
if ( !closed.get() && !rotating.get() )
{
// In case output file doesn't exist, call rotate so that it gets created
if ( rotationDelayExceeded() && rotationThresholdExceeded() ||
!fileSystem.fileExists( outputFile ) )
{
rotate();
}
}
return this.streamWrapper;
}
@Override
public void close() throws IOException
{
logFileLock.writeLock().lock();
try
{
closed.set( true );
outRef.close();
}
finally
{
outRef = nullStream;
logFileLock.writeLock().unlock();
}
}
private boolean rotationThresholdExceeded()
{
return fileSystem.fileExists( outputFile ) && rotationThresholdBytes > 0 &&
fileSystem.getFileSize( outputFile ) >= rotationThresholdBytes;
}
private boolean rotationDelayExceeded()
{
return earliestRotationTimeRef.get() <= currentTimeSupplier.getAsLong();
}
void rotate()
{
if ( rotating.getAndSet( true ) )
{
// Already rotating
return;
}
ByteArrayOutputStream bufferingOutputStream = new ByteArrayOutputStream();
Runnable runnable = () ->
{
logFileLock.writeLock().lock();
try
{
try
{
// Must close file prior to doing any operations on it or else it won't work on Windows
try
{
outRef.flush();
outRef.close();
outRef = nullStream;
}
catch ( Exception e )
{
rotationListener.rotationError( e, bufferingOutputStream );
return;
}
try
{
if ( fileSystem.fileExists( outputFile ) )
{
shiftArchivedOutputFiles();
fileSystem.renameFile( outputFile, archivedOutputFile( 1 ) );
}
}
catch ( Exception e )
{
rotationListener.rotationError( e, bufferingOutputStream );
return;
}
}
finally
{
try
{
if ( !closed.get() && outRef.equals( nullStream ) )
{
outRef = openOutputFile();
rotationListener.outputFileCreated( bufferingOutputStream );
}
}
catch ( IOException e )
{
System.err.println( "Failed to open log file after log rotation: " + e.getMessage() );
rotationListener.rotationError( e, bufferingOutputStream );
}
}
if ( rotationDelay > 0 )
{
earliestRotationTimeRef.set( currentTimeSupplier.getAsLong() + rotationDelay );
}
rotationListener.rotationCompleted( bufferingOutputStream );
}
finally
{
rotating.set( false );
try
{
bufferingOutputStream.writeTo( streamWrapper );
}
catch ( IOException e )
{
rotationListener.rotationError( e, streamWrapper );
}
logFileLock.writeLock().unlock();
}
};
try
{
rotationExecutor.execute( runnable );
}
catch ( Exception e )
{
rotationListener.rotationError( e, streamWrapper );
rotating.set( false );
}
}
private OutputStream openOutputFile() throws IOException
{
return createOrOpenAsOuputStream( fileSystem, outputFile, true );
}
private void shiftArchivedOutputFiles() throws IOException
{
for ( int i = lastArchivedOutputFileNumber(); i > 0; --i )
{
File archive = archivedOutputFile( i );
if ( i >= maxArchives )
{
fileSystem.deleteFile( archive );
}
else
{
fileSystem.renameFile( archive, archivedOutputFile( i + 1 ) );
}
}
}
private int lastArchivedOutputFileNumber()
{
int i = 1;
while ( fileSystem.fileExists( archivedOutputFile( i ) ) )
{
i++;
}
return i - 1;
}
private File archivedOutputFile( int archiveNumber )
{
return new File( String.format( "%s.%d", outputFile.getPath(), archiveNumber ) );
}
}