FileBlobVersion.java

/*
 * Copyright (c) 2011, 3 Round Stones Inc. Some rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * - Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution. 
 * - Neither the name of the openrdf.org nor the names of its contributors may
 *   be used to endorse or promote products derived from this software without
 *   specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 */
package org.openrdf.store.blob.file;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.locks.Lock;

import org.openrdf.store.blob.BlobObject;
import org.openrdf.store.blob.BlobVersion;

/**
 * A blob store transaction that can pool and commit multiple changes at once.
 */
@Deprecated
public class FileBlobVersion implements BlobVersion {
	private final FileBlobStore store;
	private final Map<String, FileBlob> open;
	private boolean prepared;

	protected FileBlobVersion(FileBlobStore store) throws IOException {
		assert store != null;
		this.store = store;
		this.open = new HashMap<String, FileBlob>();
	}

	public synchronized int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + store.hashCode();
		result = prime * result + open.hashCode();
		return result;
	}

	public synchronized boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		FileBlobVersion other = (FileBlobVersion) obj;
		if (!store.equals(other.store))
			return false;
		if (!open.keySet().equals(other.open.keySet()))
			return false;
		return true;
	}

	public boolean erase() throws IOException {
		throw new UnsupportedOperationException(
				"Erasing transactions is not supported by this blob store");
	}

	public synchronized String[] getModifications() throws IOException {
		return open.keySet().toArray(new String[open.size()]);
	}

	public synchronized BlobObject open(String uri) {
		FileBlob blob = open.get(uri);
		if (blob != null)
			return blob;
		open.put(uri, blob = new FileBlob(this, uri));
		return blob;
	}

	public synchronized void prepare() throws IOException {
		if (prepared)
			throw new IllegalStateException("This version is already prepared");
		store.lock();
		prepared = true;
		boolean faild = true;
		try {
			for (FileBlob blob : open.values()) {
				if (blob.hasConflict())
					throw new IOException("Resource has since been modified: "
							+ blob.toUri());
			}
			faild = false;
		} finally {
			if (faild) {
				prepared = false;
				store.unlock();
			}
		}
	}

	public synchronized void commit() throws IOException {
		if (!prepared) {
			prepare();
		}
		Set<String> set = new HashSet<String>(open.size());
		for (Map.Entry<String, FileBlob> e : open.entrySet()) {
			if (e.getValue().sync()) {
				set.add(e.getKey());
			}
		}
		if (!set.isEmpty()) {
			store.changed(set);
		}
		prepared = false;
		store.unlock();
	}

	public synchronized void rollback() {
		try {
			for (FileBlob blob : open.values()) {
				blob.abort();
			}
		} finally {
			if (prepared) {
				prepared = false;
				store.unlock();
			}
		}
	}

	protected File getDirectory() {
		return store.getDirectory();
	}

	protected void watch(String uri, FileListener listener) {
		store.watch(uri, listener);
	}

	protected boolean unwatch(String uri, FileListener listener) {
		return store.unwatch(uri, listener);
	}

	protected Lock readLock() {
		return store.readLock();
	}

}