/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package edu.uci.ics.crawler4j.frontier;
import org.apache.log4j.Logger;
import com.sleepycat.je.Cursor;
import com.sleepycat.je.DatabaseEntry;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.Environment;
import com.sleepycat.je.OperationStatus;
import com.sleepycat.je.Transaction;
import edu.uci.ics.crawler4j.url.WebURL;
import edu.uci.ics.crawler4j.util.Util;
/**
* This class maintains the list of pages which are
* assigned to crawlers but are not yet processed.
* It is used for resuming a previous crawl.
*
* @author Yasser Ganjisaffar <yganjisa at uci dot edu>
*/
public final class InProcessPagesDB extends WorkQueues {
private static final Logger logger = Logger.getLogger(InProcessPagesDB.class.getName());
public InProcessPagesDB(Environment env) throws DatabaseException {
super(env, "InProcessPagesDB", true);
long docCount = getLength();
if (docCount > 0) {
logger.info("Loaded " + docCount + " URLs that have been in process in the previous crawl.");
}
}
public boolean removeURL(WebURL webUrl) {
synchronized (mutex) {
try {
DatabaseEntry key = new DatabaseEntry(Util.int2ByteArray(webUrl.getDocid()));
Cursor cursor = null;
OperationStatus result = null;
DatabaseEntry value = new DatabaseEntry();
Transaction txn = env.beginTransaction(null, null);
try {
cursor = urlsDB.openCursor(txn, null);
result = cursor.getSearchKey(key, value, null);
if (result == OperationStatus.SUCCESS) {
result = cursor.delete();
if (result == OperationStatus.SUCCESS) {
return true;
}
}
} catch (DatabaseException e) {
if (txn != null) {
txn.abort();
txn = null;
}
throw e;
} finally {
if (cursor != null) {
cursor.close();
}
if (txn != null) {
txn.commit();
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
return false;
}
}