gw.fs.physical.FuzzyTimestampCachingPhysicalFileSystem Maven / Gradle / Ivy
/*
* Copyright 2014 Guidewire Software, Inc.
*/
package gw.fs.physical;
import gw.fs.ResourcePath;
import gw.lang.UnstableAPI;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
@UnstableAPI
public class FuzzyTimestampCachingPhysicalFileSystem extends AbstractCachingPhysicalFileSystem {
private Map _dirCache = new HashMap();
private Lock _lock = new ReentrantLock();
public FuzzyTimestampCachingPhysicalFileSystem(IPhysicalFileSystem delegate) {
super(delegate);
}
@Override
public List listFiles(ResourcePath directoryPath) {
_lock.lock();
try {
String pathString = directoryPath.getPathString();
DirCacheInfo cacheInfo = _dirCache.get(pathString);
if (cacheInfo == null) {
cacheInfo = new DirCacheInfo(directoryPath);
_dirCache.put(pathString, cacheInfo);
}
return cacheInfo.listFiles();
} finally {
_lock.unlock();
}
}
@Override
public IFileMetadata getFileMetadata(ResourcePath filePath) {
return _delegate.getFileMetadata(filePath);
}
@Override
public void clearDirectoryCaches(ResourcePath dirPath) {
_lock.lock();
try {
_dirCache.remove(dirPath.getPathString());
} finally {
_lock.unlock();
}
_delegate.clearDirectoryCaches(dirPath);
}
public void clearAllCaches() {
_lock.lock();
try {
_dirCache.clear();
} finally {
_lock.unlock();
}
_delegate.clearAllCaches();
}
// TODO - Timestamping?
private class DirCacheInfo {
private List _files;
private ResourcePath _absolutePath;
private long _lastFileTimestamp;
private long _lastRefreshTimestamp;
private DirCacheInfo(ResourcePath absolutePath) {
_absolutePath = absolutePath;
_lastFileTimestamp = -1;
}
public List listFiles() {
maybeRefreshList();
return _files;
}
private void maybeRefreshList() {
if (_lastFileTimestamp == -1) {
doRefreshImpl();
} else {
long currentTimestamp = _delegate.getFileMetadata(_absolutePath).lastModifiedTime();
if (currentTimestamp == 0) {
// If the timestamp is 0, assume it's been deleted
_files = Collections.emptyList();
} else if (_lastFileTimestamp != currentTimestamp) {
doRefreshImpl();
} else {
long refreshDelta = _lastRefreshTimestamp - currentTimestamp;
if(refreshDelta > -16 && refreshDelta < 16) {
doRefreshImpl();
}
}
}
}
private void doRefreshImpl() {
_lastRefreshTimestamp = System.currentTimeMillis();
_files = _delegate.listFiles(_absolutePath);
}
}
}