// plasmaCrawlZURL.java
// (C) 2007 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 15.03.2007 on http://www.anomic.de
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate: 2006-04-02 22:40:07 +0200 (So, 02 Apr 2006) $
// $LastChangedRevision: 1986 $
// $LastChangedBy: orbiter $
//
// LICENSE
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package de.anomic.crawler;
import java.io.File;
import java.io.IOException;
import java.util.Date;
import java.util.Iterator;
import java.util.LinkedList;
import de.anomic.kelondro.index.Row;
import de.anomic.kelondro.index.RowSet;
import de.anomic.kelondro.index.ObjectIndex;
import de.anomic.kelondro.order.Base64Order;
import de.anomic.kelondro.table.EcoTable;
import de.anomic.kelondro.table.FlexWidthArray;
import de.anomic.kelondro.util.FileUtils;
import de.anomic.yacy.yacySeedDB;
import de.anomic.yacy.yacyURL;
public class ZURL {
private static final int EcoFSBufferSize = 200;
private static final int maxStackSize = 300;
public final static Row rowdef = new Row(
"String urlhash-" + yacySeedDB.commonHashLength + ", " + // the url's hash
"String executor-" + yacySeedDB.commonHashLength + ", " + // the crawling executor
"Cardinal workdate-8 {b256}, " + // the time when the url was last time tried to load
"Cardinal workcount-4 {b256}, " + // number of load retries
"String anycause-132, " + // string describing load failure
"byte[] entry-" + CrawlEntry.rowdef.objectsize, // extra space
Base64Order.enhancedCoder
);
// the class object
private final ObjectIndex urlIndex;
private final LinkedList<String> stack;
public ZURL(final File cachePath, final String tablename, final boolean startWithEmptyFile) {
// creates a new ZURL in a file
cachePath.mkdirs();
final File f = new File(cachePath, tablename);
if (startWithEmptyFile) {
if (f.exists()) {
if (f.isDirectory()) FlexWidthArray.delete(cachePath, tablename); else FileUtils.deletedelete(f);
}
}
this.urlIndex = new EcoTable(f, rowdef, EcoTable.tailCacheDenyUsage, EcoFSBufferSize, 0);
//urlIndex = new kelondroFlexTable(cachePath, tablename, -1, rowdef, 0, true);
this.stack = new LinkedList<String>();
}
public ZURL() {
// creates a new ZUR in RAM
this.urlIndex = new RowSet(rowdef, 0);
this.stack = new LinkedList<String>();
}
public int size() {
return urlIndex.size() ;
}
public void clear() throws IOException {
if (urlIndex != null) urlIndex.clear();
if (stack != null) stack.clear();
}
public void close() {
try {this.clear();} catch (IOException e) {}
if (urlIndex != null) urlIndex.close();
}
public synchronized Entry newEntry(
final CrawlEntry bentry,
final String executor,
final Date workdate,
final int workcount,
String anycause) {
assert executor != null;
assert executor.length() > 0;
if (anycause == null) anycause = "unknown";
return new Entry(bentry, executor, workdate, workcount, anycause);
}
public boolean remove(final String hash) {
if (hash == null) return false;
//System.out.println("*** DEBUG ZURL " + this.urlIndex.filename() + " remove " + hash);
try {
urlIndex.remove(hash.getBytes());
return true;
} catch (final IOException e) {
return false;
}
}
public synchronized void push(final Entry e) {
stack.add(e.hash());
while (stack.size() > maxStackSize) stack.removeFirst();
}
public Entry top(final int pos) {
String urlhash;
synchronized (stack) {
if (pos >= stack.size()) return null;
urlhash = stack.get(pos);
}
if (urlhash == null) return null;
return getEntry(urlhash);
}
public synchronized Entry getEntry(final String urlhash) {
try {
if (urlIndex == null) return null;
//System.out.println("*** DEBUG ZURL " + this.urlIndex.filename() + " get " + urlhash);
final Row.Entry entry = urlIndex.get(urlhash.getBytes());
if (entry == null) return null;
return new Entry(entry);
} catch (final IOException e) {
e.printStackTrace();
return null;
}
}
public boolean exists(final String urlHash) {
return urlIndex.has(urlHash.getBytes());
}
public void clearStack() {
stack.clear();
}
public int stackSize() {
return stack.size();
}
public class Entry {
CrawlEntry bentry; // the balancer entry
private final String executor; // the crawling executor
private final Date workdate; // the time when the url was last time tried to load
private final int workcount; // number of tryings
private final String anycause; // string describing reason for load fail
private boolean stored;
public Entry(
final CrawlEntry bentry,
final String executor,
final Date workdate,
final int workcount,
final String anycause) {
// create new entry
assert bentry != null;
assert executor != null;
this.bentry = bentry;
this.executor = executor;
this.workdate = (workdate == null) ? new Date() : workdate;
this.workcount = workcount;
this.anycause = (anycause == null) ? "" : anycause;
stored = false;
}
public Entry(final Row.Entry entry) throws IOException {
assert (entry != null);
this.executor = entry.getColString(1, "UTF-8");
this.workdate = new Date(entry.getColLong(2));
this.workcount = (int) entry.getColLong(3);
this.anycause = entry.getColString(4, "UTF-8");
this.bentry = new CrawlEntry(CrawlEntry.rowdef.newEntry(entry.getColBytes(5)));
assert ((new String(entry.getColBytes(0))).equals(bentry.url().hash()));
this.stored = true;
return;
}
public void store() {
// stores the values from the object variables into the database
if (this.stored) return;
if (this.bentry == null) return;
final Row.Entry newrow = rowdef.newEntry();
newrow.setCol(0, this.bentry.url().hash().getBytes());
newrow.setCol(1, this.executor.getBytes());
newrow.setCol(2, this.workdate.getTime());
newrow.setCol(3, this.workcount);
newrow.setCol(4, this.anycause.getBytes());
newrow.setCol(5, this.bentry.toRow().bytes());
try {
//System.out.println("*** DEBUG ZURL " + urlIndex.filename() + " store " + newrow.getColString(0, "UTF-8"));
if (urlIndex != null) urlIndex.put(newrow);
this.stored = true;
} catch (final IOException e) {
System.out.println("INTERNAL ERROR AT plasmaEURL:url2hash:" + e.toString());
}
}
public yacyURL url() {
return this.bentry.url();
}
public String initiator() {
return this.bentry.initiator();
}
public String hash() {
// return a url-hash, based on the md5 algorithm
// the result is a String of 12 bytes within a 72-bit space
// (each byte has an 6-bit range)
// that should be enough for all web pages on the world
return this.bentry.url().hash();
}
public Date workdate() {
return workdate;
}
public String executor() {
// return the creator's hash
return executor;
}
public String anycause() {
return anycause;
}
}
public class kiter implements Iterator<Entry> {
// enumerates entry elements
Iterator<Row.Entry> i;
boolean error = false;
public kiter(final boolean up, final String firstHash) throws IOException {
i = urlIndex.rows(up, (firstHash == null) ? null : firstHash.getBytes());
error = false;
}
public boolean hasNext() {
if (error) return false;
return i.hasNext();
}
public Entry next() throws RuntimeException {
final Row.Entry e = i.next();
if (e == null) return null;
try {
return new Entry(e);
} catch (final IOException ex) {
throw new RuntimeException("error '" + ex.getMessage() + "' for hash " + e.getColString(0, null));
}
}
public void remove() {
i.remove();
}
}
public Iterator<Entry> entries(final boolean up, final String firstHash) throws IOException {
// enumerates entry elements
return new kiter(up, firstHash);
}
}