/*
* 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 java.io.IOException;
/**
* Interface for files that can be stored in FileCache.
* Requirements:
* 1. hashCode() must return Object.hashCode()
* 2. close() must call cache.release(this) if cache is not null.
* 3. must be able to detect changes in underlying object, and indicate whether it has changed.
*
* @author caron
* @since Jun 2, 2008
*/
public interface FileCacheable {
/**
* The location of the FileCacheable. This must be sufficient for FileFactory.factory() to create the FileCacheable object
* @return location
*/
String getLocation();
/**
* Close the FileCacheable, release all resources.
* Must call cache.release(this) if cache is not null.
* @throws IOException on io error
*/
void close() throws IOException;
/**
* Returns the time that the underlying file(s) were last modified. If they've changed since they were stored in the
* cache, they will be closed and reopened with {@link ucar.nc2.util.cache.FileFactory}.
*
* @return a {@code long} value representing the time the file(s) were last modified or {@code 0L} if the
* last-modified time couldn't be determined for any reason.
*/
long getLastModified();
/**
* If the FileCache is not null, FileCacheable.close() must call FileCache.release()
<pre>
public synchronized void close() throws java.io.IOException {
if (cache != null) {
if (cache.release(this)) return;
}
reallyClose();
} </pre>
*
* @param fileCache must store this, use it on close as above.
*/
void setFileCache( FileCacheIF fileCache);
// release any resources like file handles
void release() throws IOException;
// reacquire any resources like file handles
void reacquire() throws IOException;
}