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SEWOL provides support for the handling of workflow traces. Specifically it allows to specify the shape and content of process traces in terms of entries representing the execution of a specific workflow activity. SEWOL also allows to write these traces on disk as a log file with the help of a special file writer for process logs. Currently it supports plain text, Petrify, MXML and XES log file types. In order to specify security-related context information, SEWOL provides access control models such as access control lists (ACL) and role-based access control models (RBAC). All types of models can be conveniently edited with the help of appropriate dialogs.
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/*
* OpenXES
*
* The reference implementation of the XES meta-model for event
* log data management.
*
* Copyright (c) 2008 Christian W. Guenther ([email protected])
*
*
* LICENSE:
*
* This code is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
*
* EXEMPTION:
*
* The use of this software can also be conditionally licensed for
* other programs, which do not satisfy the specified conditions. This
* requires an exemption from the general license, which may be
* granted on a per-case basis.
*
* If you want to license the use of this software with a program
* incompatible with the LGPL, please contact the author for an
* exemption at the following email address:
* [email protected]
*
*/
package org.deckfour.xes.nikefs2;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.deckfour.xes.logging.XLogging;
import org.deckfour.xes.logging.XLogging.Importance;
/**
* Virtual file system authority, managing swap files and virtual file
* abstractions. Implements the storage provider interface for use by file
* abstractions, and performs cleanup after a shutdown of the host application.
*
* This class must be used as a singleton. There is no need for multiple virtual
* file systems per application. A single VFS instance operates with maximum
* efficiency, and guarantees that no data corruption or swap loss will occur.
*
* @author Christian W. Guenther ([email protected])
*
*/
public class NikeFS2VirtualFileSystem implements NikeFS2StorageProvider {
/**
* The singleton VFS instance.
*/
protected static NikeFS2VirtualFileSystem instance = null;
/**
* Singleton access method.
*
* @return The singleton instance.
*/
public synchronized static NikeFS2VirtualFileSystem instance() {
if (instance == null) {
instance = new NikeFS2VirtualFileSystem();
}
return instance;
}
/**
* Block size, in bytes, of virtual storage blocks. Default value is 2048,
* i.e. 2kB.
*/
protected int blockSize = 2048;
/**
* Size of swap files which are used to provide blocks. Default is 67108864,
* i.e. 64 MB.
*/
protected int swapFileSize = 67108864;
/**
* Flag determining whether to use soft copies for virtual file duplication.
* This greatly enhances performance with negligible memory penalties, thus
* the default value is true.
*/
protected boolean useLazyCopies = true;
/**
* List of block providers, i.e. currently used swap files that serve for
* providing storage blocks to virtual file abstractions.
*/
protected List blockProviders;
/**
* Creates a new virtual file system instance. (Hidden private constructor,
* use singleton accessor method!)
*/
private NikeFS2VirtualFileSystem() {
blockProviders = new ArrayList();
}
/**
* Sets this VFS's property of whether to use soft copies for virtual file
* duplication. This will only affect newly created virtual files.
*
* @param useLazyCopies
* Whether to use soft copies for virtual file duplication.
*/
public synchronized void setUseLazyCopies(boolean useLazyCopies) {
this.useLazyCopies = useLazyCopies;
}
/**
* Sets the swap file size of the virtual file system. (used henceforth
* until successive change).
*
* @param bytes
* Size of swap files, in bytes.
*/
public synchronized void setSwapFileSize(int bytes) {
this.swapFileSize = bytes;
}
/**
* Sets the block size of the virtual file system. (used henceforth until
* successive change).
*
* @param bytes
* Size of blocks, in bytes.
*/
public synchronized void setBlockSize(int bytes) {
this.blockSize = bytes;
}
/*
* (non-Javadoc)
*
* @see
* org.processmining.framework.log.rfb.io.StorageProvider#createStorage()
*/
public NikeFS2RandomAccessStorage createStorage() throws IOException {
if (useLazyCopies == true) {
return new NikeFS2LazyRandomAccessStorageImpl(this);
} else {
return new NikeFS2RandomAccessStorageImpl(this);
}
}
/**
* Returns the block size of this VFS.
*
* @return The size of virtual storage blocks served by this VFS, in bytes.
*/
public int blockSize() {
return blockSize;
}
/**
* Allocates a new virtual storage block from this virtual file system
* instance. If no currently allocated swap file can provide any more
* storage blocks, a new swap file will be allocated.
*
* @return An empty storage block abstraction.
*/
public NikeFS2Block allocateBlock() throws IOException {
// synchronized (this) {
// // try to allocate from already created providers first
// for (NikeFS2BlockProvider provider : blockProviders) {
// if (provider.numberOfFreeBlocks() > 0) {
// NikeFS2Block block = provider.allocateBlock();
// if (block != null) {
// return block;
// }
// }
// }
// }
// // force garbage collection and try again (stale files still around?)
// // Running the finalization might cause the Finalizer thread to call the allocateBlock method again,
// // hence the lock on "this" should be removed before calling System.runFinalization
// System.gc();
// System.runFinalization();
// Thread.yield();
synchronized (this) {
for (NikeFS2BlockProvider provider : blockProviders) {
if (provider.numberOfFreeBlocks() > 0) {
NikeFS2Block block = provider.allocateBlock();
if (block != null) {
return block;
}
}
}
// ok, we give up:
// create new swap file and provider, and allocate from there
XLogging.log("NikeFS2: Allocating new swap file. (#"
+ (blockProviders.size() + 1) + ": " + swapFileSize
+ " bytes)", Importance.DEBUG);
File swapFile = NikeFS2SwapFileManager.createSwapFile();
NikeFS2BlockProvider addedProvider = new NikeFS2BlockProvider(
swapFile, swapFileSize, blockSize, true);
blockProviders.add(addedProvider);
return addedProvider.allocateBlock();
}
}
}