/*
* Copyright 1998-2009 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
* and understandings on the user. The user is granted the right, without
* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
* supporting documentation. Further, UCAR requests that the user credit
* UCAR/Unidata in any publications that result from the use of this
* software or in any product that includes this software. The names UCAR
* and/or Unidata, however, may not be used in any advertising or publicity
* to endorse or promote any products or commercial entity unless specific
* written permission is obtained from UCAR/Unidata. The user also
* understands that UCAR/Unidata is not obligated to provide the user with
* any support, consulting, training or assistance of any kind with regard
* to the use, operation and performance of this software nor to provide
* the user with any updates, revisions, new versions or "bug fixes."
*
* THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package ucar.nc2.util.cache;
import ucar.unidata.io.RandomAccessFile;
import ucar.nc2.util.CancelTask;
import java.util.*;
import java.io.IOException;
/**
* Keep cache of open RandomAccessFile, for performance.
* Used by TDS to optimize serving netCDF files over HTTP.
* <p/>
* <pre>
* RandomAccessFile raf = null;
* try {
* RandomAccessFile raf = FileCache.acquire(location, cancelTask);
* ...
* } finally {
* FileCache.release( raf)
* }
* </pre>
* <p/>
* <p/>
* <p/>
* Library ships with cache disabled.
* If you want to use, call init() and make sure you call exit() when exiting program.
* All methods are thread safe.
* Cleanup is done automatically in a background thread, using LRU.
*
* @author jcaron
*/
public class FileCacheRaf {
private FileCache cache;
private FileFactory factory;
public FileCacheRaf(int minElementsInMemory, int maxElementsInMemory, int period) {
cache = new FileCache("FileCacheRaf", minElementsInMemory, maxElementsInMemory, -1, period);
factory = new RafFactory();
}
public void clearCache(boolean force) {
cache.clearCache(force);
}
public Collection getCache() {
return cache.getCache().values();
}
static public void shutdown() {
FileCache.shutdown();
}
public Raf acquire(String filename) throws IOException {
return (Raf) cache.acquire(factory, filename, null);
}
public void release(Raf craf) throws IOException {
cache.release(craf);
}
private class RafFactory implements FileFactory {
public FileCacheable open(String location, int buffer_size, CancelTask cancelTask, Object iospMessage) throws IOException {
return new Raf( location);
}
}
public class Raf implements FileCacheable {
private ucar.unidata.io.RandomAccessFile raf;
Raf(String location) throws IOException {
this.raf = new RandomAccessFile( location, "r");
}
public String getLocation() {
return raf.getLocation();
}
public ucar.unidata.io.RandomAccessFile getRaf() { return raf; }
public void close() throws IOException {
raf.close();
}
public boolean sync() throws IOException {
return false;
}
public void setFileCache(FileCache fileCache) {
}
}
}