/*******************************************************************************
* Copyright (c) 2014, 2014 Bruno Medeiros and other Contributors.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Bruno Medeiros - initial API and implementation
*******************************************************************************/
package dtool.engine.util;
import static melnorme.utilbox.core.Assert.AssertNamespace.assertNotNull;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.attribute.FileTime;
/**
* An entry caching some value, derived from a file as input.
* Keeps tracks of file and value timestamps, to see if current value is stale or not with regards to the file input.
*/
public class FileCachingEntry<VALUE> {
protected final Path filePath;
protected volatile VALUE value;
protected volatile FileTime valueTimeStamp;
public FileCachingEntry(Path path) {
this.filePath = path;
}
public VALUE getValue() {
return value;
}
public FileTime getValueTimeStamp() {
return valueTimeStamp;
}
public void markStale() {
valueTimeStamp = null;
}
public synchronized boolean isStale() {
FileTime lastModifiedTime;
try {
lastModifiedTime = Files.getLastModifiedTime(filePath);
} catch (IOException e) {
return true;
}
if(valueTimeStamp == null || valueTimeStamp.toMillis() < lastModifiedTime.toMillis()) {
return true;
}
return false;
}
public void updateValue(VALUE value) {
updateValue(value, null);
}
public void updateValue(VALUE value, FileTime newTimeStampMaximum) {
assertNotNull(newTimeStampMaximum);
FileTime newValueTimeStamp;
try {
newValueTimeStamp = Files.getLastModifiedTime(filePath);
} catch (IOException e) {
newValueTimeStamp = FileTime.fromMillis(0);
}
if(newTimeStampMaximum != null && newTimeStampMaximum.compareTo(newValueTimeStamp) < 0) {
newValueTimeStamp = newTimeStampMaximum;
}
internalSetValue(value, newValueTimeStamp);
}
protected synchronized void internalSetValue(VALUE value, FileTime newTimeStamp) {
this.value = value;
this.valueTimeStamp = newTimeStamp;
}
}