Copyright (c) 2000, 2009 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2009 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.team.internal.core;

import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Date;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.jobs.ILock;
import org.eclipse.osgi.util.NLS;
import org.eclipse.team.core.TeamException;
import org.eclipse.team.core.variants.CachedResourceVariant;

This class provides the implementation for the ICacheEntry
/**
 * This class provides the implementation for the ICacheEntry
 */
public class ResourceVariantCacheEntry {

	public static final int UNINITIALIZED = 0;
	public static final int READY = 1;
	public static final int DISPOSED = 2;

	private String id;
	private String filePath;
	private ResourceVariantCache cache;
	private int state = UNINITIALIZED;
	private long lastAccess;
	private CachedResourceVariant resourceVariant;
	private ILock lock;

	public ResourceVariantCacheEntry(ResourceVariantCache cache, ILock lock, String id, String filePath) {
		this.lock = lock;
		state = UNINITIALIZED;
		this.cache = cache;
		this.id = id;
		this.filePath = filePath;
		registerHit();
	}

	public InputStream getContents() throws TeamException {
		if (state != READY) return null;
		registerHit();
		File ioFile = getFile();
		try {
			try {
				if (ioFile.exists()) {
					return new FileInputStream(ioFile);
				}
			} catch (IOException e) {
				// Try to purge the cache and continue
				cache.purgeFromCache(this);
				throw e;
			}
		} catch (IOException e) {
			// We will end up here if we couldn't read or delete the cache file
			throw new TeamException(NLS.bind(Messages.RemoteContentsCache_fileError, new String[] { ioFile.getAbsolutePath() }), e);
		}
		// This can occur when there is no remote contents
		return new ByteArrayInputStream(new byte[0]);
	}

	protected File getFile() {
		return new File(cache.getCachePath().toFile(), filePath);
	}

	
Set the contents of for this cache entry. This method supports concurrency by only allowing
one cache entry to be written at a time. In the case of two concurrent writes to the same cache entry,
the contents from the first write is used and the content from subsequent writes is ignored.
Params:
stream – an InputStream that provides the contents to be cached
monitor – a progress monitor
Throws:
TeamException – if the entry is DISPOSED or an I/O error occurred/**
	 * Set the contents of for this cache entry. This method supports concurrency by only allowing
	 * one cache entry to be written at a time. In the case of two concurrent writes to the same cache entry,
	 * the contents from the first write is used and the content from subsequent writes is ignored.
	 * @param stream an InputStream that provides the contents to be cached
	 * @param monitor a progress monitor
	 * @throws TeamException if the entry is DISPOSED or an I/O error occurred
	 */
	public void setContents(InputStream stream, IProgressMonitor monitor) throws TeamException {
		// Use a lock to only allow one write at a time
		beginOperation();
		try {
			internalSetContents(stream, monitor);
		} finally {
			endOperation();
		}
	}

	private void endOperation() {
		lock.release();
	}

	private void beginOperation() {
		lock.acquire();
	}

	private void internalSetContents(InputStream stream, IProgressMonitor monitor) throws TeamException {
		// if the state is DISPOSED then there is a problem
		if (state == DISPOSED) {
			throw new TeamException(NLS.bind(Messages.RemoteContentsCacheEntry_3, new String[] { cache.getName(), id }));
		}
		// Otherwise, the state is UNINITIALIZED or READY so we can proceed
		registerHit();
		File ioFile = getFile();
		try {

			// Open the cache file for writing
			OutputStream out;
			try {
				if (state == UNINITIALIZED) {
					out = new BufferedOutputStream(new FileOutputStream(ioFile));
				} else {
					// If the entry is READY, the contents must have been read in another thread.
					// We still need to red the contents but they can be ignored since presumably they are the same
					out = new ByteArrayOutputStream();
				}
			} catch (FileNotFoundException e) {
				throw new TeamException(NLS.bind(Messages.RemoteContentsCache_fileError, new String[] { ioFile.getAbsolutePath() }), e);
			}

			// Transfer the contents
			try {
				try {
					byte[] buffer = new byte[1024];
					int read;
					while ((read = stream.read(buffer)) >= 0) {
						Policy.checkCanceled(monitor);
						out.write(buffer, 0, read);
					}
				} finally {
					out.close();
				}
			} catch (IOException e) {
				// Make sure we don't leave the cache file around as it may not have the right contents
				cache.purgeFromCache(this);
				throw e;
			}

			// Mark the cache entry as ready
			state = READY;
		} catch (IOException e) {
			throw new TeamException(NLS.bind(Messages.RemoteContentsCache_fileError, new String[] { ioFile.getAbsolutePath() }), e);
		} finally {
			try {
				stream.close();
			} catch (IOException e1) {
				// Ignore close errors
			}
		}

	}

	/*
	 * @see org.eclipse.team.core.sync.ICacheEntry#getState()
	 */
	public int getState() {
		return state;
	}

	/*
	 * @see org.eclipse.team.core.sync.ICacheEntry#getSize()
	 */
	public long getSize() {
		if (state != READY) return 0;
		File ioFile = getFile();
		if (ioFile.exists()) {
			return ioFile.length();
		}
		return 0;
	}

	/*
	 * @see org.eclipse.team.core.sync.ICacheEntry#getLastAccessTimeStamp()
	 */
	public long getLastAccessTimeStamp() {
		return lastAccess;
	}

	
Registers a hit on this cache entry. This updates the last access timestamp.
This method is intended to only be invoked from inside this class or the cache itself.
Other clients should not use it.
/**
	 * Registers a hit on this cache entry. This updates the last access timestamp.
	 * This method is intended to only be invoked from inside this class or the cache itself.
	 * Other clients should not use it.
	 */
	protected void registerHit() {
		lastAccess = new Date().getTime();
	}

	public void dispose() {
		// Use a lock to avoid changing state while another thread may be writing
		beginOperation();
		try {
			state = DISPOSED;
			cache.purgeFromCache(this);
		} finally {
			endOperation();
		}
	}


	public String getId() {
		return id;
	}

	public CachedResourceVariant getResourceVariant() {
		return resourceVariant;
	}

	public void setResourceVariant(CachedResourceVariant resourceVariant) {
		this.resourceVariant = resourceVariant;
	}
}