// HandleSet.java
// (C) 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 10.03.2009 on http://www.anomic.de
//
// $LastChangedDate: 2011-03-08 02:51:51 +0100 (Di, 08. Mär 2011) $
// $LastChangedRevision: 7567 $
// $LastChangedBy: low012 $
//
// 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 net.yacy.kelondro.index;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Iterator;
import net.yacy.kelondro.logging.Log;
import net.yacy.kelondro.order.ByteOrder;
import net.yacy.kelondro.order.CloneableIterator;
import net.yacy.kelondro.util.SetTools;
public final class HandleSet implements Iterable<byte[]>, Cloneable {
private final Row rowdef;
private RowSet index;
public HandleSet(final int keylength, final ByteOrder objectOrder, final int expectedspace) {
this.rowdef = new Row(new Column[]{new Column("key", Column.celltype_binary, Column.encoder_bytes, keylength, "key")}, objectOrder);
try {
this.index = new RowSet(rowdef, expectedspace);
} catch (RowSpaceExceededException e) {
try {
this.index = new RowSet(rowdef, 0);
} catch (RowSpaceExceededException ee) {
Log.logException(ee);
this.index = null;
}
}
}
private HandleSet(Row rowdef, RowSet index) {
this.rowdef = rowdef;
this.index = index;
}
public HandleSet(Row rowdef, byte[] b) throws RowSpaceExceededException {
this.rowdef = rowdef;
this.index = RowSet.importRowSet(b, this.rowdef);
}
@Override
public HandleSet clone() {
return new HandleSet(this.rowdef, this.index.clone());
}
public byte[] export() {
return index.exportCollection();
}
/**
* initialize a HandleSet with the content of a dump
* @param keylength
* @param objectOrder
* @param file
* @throws IOException
* @throws RowSpaceExceededException
*/
public HandleSet(final int keylength, final ByteOrder objectOrder, final File file) throws IOException, RowSpaceExceededException {
this(keylength, objectOrder, (int) (file.length() / (keylength + 8)));
// read the index dump and fill the index
final InputStream is = new BufferedInputStream(new FileInputStream(file), 1024 * 1024);
final byte[] a = new byte[keylength];
int c;
while (true) {
c = is.read(a);
if (c <= 0) break;
this.index.addUnique(this.rowdef.newEntry(a));
}
is.close();
assert this.index.size() == file.length() / keylength;
}
/**
* write a dump of the set to a file. All entries are written in order
* which makes it possible to read them again in a fast way
* @param file
* @return the number of written entries
* @throws IOException
*/
public final int dump(final File file) throws IOException {
// we must use an iterator from the combined index, because we need the entries sorted
// otherwise we could just write the byte[] from the in kelondroRowSet which would make
// everything much faster, but this is not an option here.
final Iterator<Row.Entry> i = this.index.rows(true, null);
OutputStream os;
try {
os = new BufferedOutputStream(new FileOutputStream(file), 1024 * 1024);
} catch (OutOfMemoryError e) {
os = new FileOutputStream(file);
}
int c = 0;
while (i.hasNext()) {
os.write(i.next().bytes());
c++;
}
os.flush();
os.close();
return c;
}
public final synchronized byte[] smallestKey() {
return this.index.smallestKey();
}
public final synchronized byte[] largestKey() {
return this.index.largestKey();
}
public ByteOrder comparator() {
return this.rowdef.objectOrder;
}
public final Row row() {
return index.row();
}
public final void clear() {
this.index.clear();
}
public final synchronized boolean has(final byte[] key) {
assert (key != null);
return index.has(key);
}
public final void putAll(final HandleSet aset) throws RowSpaceExceededException {
for (byte[] b: aset) put(b);
}
/**
* Adds the key to the set
* @param key
* @return true if this set did _not_ already contain the given key.
* @throws IOException
* @throws RowSpaceExceededException
*/
public final boolean put(final byte[] key) throws RowSpaceExceededException {
assert (key != null);
final Row.Entry newentry = index.row().newEntry(key);
return index.put(newentry);
}
public final void putUnique(final byte[] key) throws RowSpaceExceededException {
assert (key != null);
final Row.Entry newentry = index.row().newEntry(key);
index.addUnique(newentry);
}
public final boolean remove(final byte[] key) {
assert (key != null);
Row.Entry indexentry;
indexentry = index.remove(key);
return indexentry != null;
}
public final synchronized byte[] removeOne() {
Row.Entry indexentry;
indexentry = index.removeOne();
if (indexentry == null) return null;
return indexentry.getPrimaryKeyBytes();
}
/**
* get one entry; objects are taken from the end of the list
* a getOne(0) would return the same object as removeOne() would remove
* @param idx
* @return entry from the end of the list
*/
public final synchronized byte[] getOne(int idx) {
if (idx >= this.size()) return null;
Row.Entry indexentry;
indexentry = index.get(this.size() - 1 - idx, true);
if (indexentry == null) return null;
return indexentry.getPrimaryKeyBytes();
}
public final synchronized boolean isEmpty() {
return index.isEmpty();
}
public final synchronized int size() {
return index.size();
}
public final synchronized CloneableIterator<byte[]> keys(final boolean up, final byte[] firstKey) {
return index.keys(up, firstKey);
}
public final Iterator<byte[]> iterator() {
return keys(true, null);
}
public final synchronized void close() {
index.close();
index = null;
}
@Override
public final String toString() {
return this.index.toString();
}
// set tools
public HandleSet joinConstructive(final HandleSet other) throws RowSpaceExceededException {
return joinConstructive(this, other);
}
// now the same for set-set
public static HandleSet joinConstructive(final HandleSet set1, final HandleSet set2) throws RowSpaceExceededException {
// comparators must be equal
if ((set1 == null) || (set2 == null)) return null;
assert set1.comparator() == set2.comparator();
if (set1.comparator() != set2.comparator()) return null;
if (set1.isEmpty() || set2.isEmpty()) return new HandleSet(set1.rowdef.primaryKeyLength, set1.comparator(), 0);
// decide which method to use
final int high = ((set1.size() > set2.size()) ? set1.size() : set2.size());
final int low = ((set1.size() > set2.size()) ? set2.size() : set1.size());
final int stepsEnum = 10 * (high + low - 1);
final int stepsTest = 12 * SetTools.log2a(high) * low;
// start most efficient method
if (stepsEnum > stepsTest) {
if (set1.size() < set2.size()) return joinConstructiveByTest(set1, set2);
return joinConstructiveByTest(set2, set1);
}
return joinConstructiveByEnumeration(set1, set2);
}
private static HandleSet joinConstructiveByTest(final HandleSet small, final HandleSet large) throws RowSpaceExceededException {
final Iterator<byte[]> mi = small.iterator();
final HandleSet result = new HandleSet(small.rowdef.primaryKeyLength, small.comparator(), 0);
byte[] o;
while (mi.hasNext()) {
o = mi.next();
if (large.has(o)) result.put(o);
}
return result;
}
private static HandleSet joinConstructiveByEnumeration(final HandleSet set1, final HandleSet set2) throws RowSpaceExceededException {
// implement pairwise enumeration
final ByteOrder comp = set1.comparator();
final Iterator<byte[]> mi = set1.iterator();
final Iterator<byte[]> si = set2.iterator();
final HandleSet result = new HandleSet(set1.rowdef.primaryKeyLength, comp, 0);
int c;
if (mi.hasNext() && si.hasNext()) {
byte[] mobj = mi.next();
byte[] sobj = si.next();
while (true) {
c = comp.compare(mobj, sobj);
if (c < 0) {
if (mi.hasNext()) mobj = mi.next(); else break;
} else if (c > 0) {
if (si.hasNext()) sobj = si.next(); else break;
} else {
result.put(mobj);
if (mi.hasNext()) mobj = mi.next(); else break;
if (si.hasNext()) sobj = si.next(); else break;
}
}
}
return result;
}
public void excludeDestructive(final HandleSet other) {
excludeDestructive(this, other);
}
private static void excludeDestructive(final HandleSet set1, final HandleSet set2) {
if (set1 == null) return;
if (set2 == null) return;
assert set1.comparator() == set2.comparator();
if (set1.isEmpty() || set2.isEmpty()) return;
if (set1.size() < set2.size())
excludeDestructiveByTestSmallInLarge(set1, set2);
else
excludeDestructiveByTestLargeInSmall(set1, set2);
}
private static void excludeDestructiveByTestSmallInLarge(final HandleSet small, final HandleSet large) {
final Iterator<byte[]> mi = small.iterator();
while (mi.hasNext()) if (large.has(mi.next())) mi.remove();
}
private static void excludeDestructiveByTestLargeInSmall(final HandleSet large, final HandleSet small) {
final Iterator<byte[]> si = small.iterator();
while (si.hasNext()) large.remove(si.next());
}
}