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Java 1.8+ Library with tons of utility classes required in all projects
/*
* Copyright (C) 2014-2024 Philip Helger (www.helger.com)
* philip[at]helger[dot]com
*
* Licensed 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 com.helger.commons.id.factory;
import java.io.File;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.ThreadSafe;
import com.helger.commons.ValueEnforcer;
import com.helger.commons.annotation.ELockType;
import com.helger.commons.annotation.MustBeLocked;
import com.helger.commons.hashcode.HashCodeGenerator;
import com.helger.commons.io.file.EFileIOErrorCode;
import com.helger.commons.io.file.EFileIOOperation;
import com.helger.commons.io.file.FileHelper;
import com.helger.commons.io.file.FileIOError;
import com.helger.commons.io.file.FileOperationManager;
import com.helger.commons.io.file.SimpleFileIO;
import com.helger.commons.string.StringParser;
import com.helger.commons.string.ToStringGenerator;
/**
* {@link File} based persisting {@link IIntIDFactory} implementation.
*
* @author Philip Helger
*/
@ThreadSafe
public class FileIntIDFactory extends AbstractPersistingIntIDFactory
{
/** The charset to use for writing the file */
public static final Charset CHARSET_TO_USE = StandardCharsets.ISO_8859_1;
/** The default number of values to reserve with a single IO action */
public static final int DEFAULT_RESERVE_COUNT = 20;
private final File m_aFile;
private final File m_aPrevFile;
private final File m_aNewFile;
public FileIntIDFactory (@Nonnull final File aFile)
{
this (aFile, DEFAULT_RESERVE_COUNT);
}
public FileIntIDFactory (@Nonnull final File aFile, @Nonnegative final int nReserveCount)
{
super (nReserveCount);
ValueEnforcer.notNull (aFile, "File");
m_aFile = aFile;
m_aPrevFile = new File (aFile.getParentFile (), aFile.getName () + ".prev");
m_aNewFile = new File (aFile.getParentFile (), aFile.getName () + ".new");
if (!FileHelper.canReadAndWriteFile (m_aFile))
throw new IllegalArgumentException ("Cannot read and/or write the file " + m_aFile + "!");
if (!FileHelper.canReadAndWriteFile (m_aPrevFile))
throw new IllegalArgumentException ("Cannot read and/or write the file " + m_aPrevFile + "!");
if (!FileHelper.canReadAndWriteFile (m_aNewFile))
throw new IllegalArgumentException ("Cannot read and/or write the file " + m_aNewFile + "!");
if (m_aNewFile.exists ())
throw new IllegalStateException ("The temporary ID file '" +
m_aNewFile.getAbsolutePath () +
"' already exists! Please use the file with the highest number. Please resolve this conflict manually.");
if (m_aPrevFile.exists ())
throw new IllegalStateException ("The temporary ID file '" +
m_aPrevFile.getAbsolutePath () +
"' already exists! If the ID file '" +
m_aFile.getAbsolutePath () +
"' exists and contains a higher number, you may consider deleting this file. Please resolve this conflict manually.");
}
/**
* @return The {@link File} to write to, as provided in the constructor. Never
* null.
*/
@Nonnull
public final File getFile ()
{
return m_aFile;
}
/*
* Note: this method must only be called from within a locked section!
*/
@Override
@MustBeLocked (ELockType.WRITE)
protected final int readAndUpdateIDCounter (@Nonnegative final int nReserveCount)
{
// Read the old content
final String sContent = SimpleFileIO.getFileAsString (m_aFile, CHARSET_TO_USE);
final int nRead = sContent != null ? StringParser.parseInt (sContent.trim (), 0) : 0;
// Write the new content to the new file
// This will fail, if the disk is full
SimpleFileIO.writeFile (m_aNewFile, Integer.toString (nRead + nReserveCount), CHARSET_TO_USE);
FileIOError aIOError;
boolean bRenamedToPrev = false;
if (m_aFile.exists ())
{
// Rename the existing file to the prev file
aIOError = FileOperationManager.INSTANCE.renameFile (m_aFile, m_aPrevFile);
bRenamedToPrev = true;
}
else
aIOError = new FileIOError (EFileIOOperation.RENAME_FILE, EFileIOErrorCode.NO_ERROR);
if (aIOError.isSuccess ())
{
// Rename the new file to the destination file
aIOError = FileOperationManager.INSTANCE.renameFile (m_aNewFile, m_aFile);
if (aIOError.isSuccess ())
{
// Finally delete the prev file (may not be existing for fresh
// instances)
aIOError = FileOperationManager.INSTANCE.deleteFileIfExisting (m_aPrevFile);
}
else
{
// 2nd rename failed
// -> Revert original rename to stay as consistent as possible
if (bRenamedToPrev)
FileOperationManager.INSTANCE.renameFile (m_aPrevFile, m_aFile);
}
}
if (aIOError.isFailure ())
throw new IllegalStateException ("Error on rename(existing-old)/rename(new-existing)/delete(old): " + aIOError);
return nRead;
}
@Override
public boolean equals (final Object o)
{
if (o == this)
return true;
if (!super.equals (o))
return false;
final FileIntIDFactory rhs = (FileIntIDFactory) o;
return m_aFile.equals (rhs.m_aFile);
}
@Override
public int hashCode ()
{
return HashCodeGenerator.getDerived (super.hashCode ()).append (m_aFile).getHashCode ();
}
@Override
public String toString ()
{
return ToStringGenerator.getDerived (super.toString ()).append ("file", m_aFile).getToString ();
}
}