// ReferenceContainerCache.java
// (C) 2008 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 30.03.2008 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate: 2011-06-24 02:24:00 +0200 (Fr, 24. Jun 2011) $
// $LastChangedRevision: 7797 $
// $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 net.yacy.kelondro.rwi;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import net.yacy.kelondro.blob.HeapWriter;
import net.yacy.kelondro.index.HandleSet;
import net.yacy.kelondro.index.Row;
import net.yacy.kelondro.index.RowSpaceExceededException;
import net.yacy.kelondro.logging.Log;
import net.yacy.kelondro.order.ByteOrder;
import net.yacy.kelondro.order.CloneableIterator;
import net.yacy.kelondro.util.ByteArray;
import net.yacy.kelondro.util.FileUtils;
/**
* A ReferenceContainerCache is the ram cache for word indexes or other entity type indexes
* The <ReferenceType> defines the index reference specification and attributes that can be
* accessed during a search without using the metadata reference that shall be contained within
* the <ReferenceType>. A ReferenceContainerCache has no active backup in a file, it must be flushed to
* a file to save the content of the cache.
*
* @param <ReferenceType>
*/
public final class ReferenceContainerCache<ReferenceType extends Reference> extends AbstractIndex<ReferenceType> implements Index<ReferenceType>, IndexReader<ReferenceType>, Iterable<ReferenceContainer<ReferenceType>> {
private final int termSize;
private final ByteOrder termOrder;
private final ContainerOrder<ReferenceType> containerOrder;
private Map<ByteArray, ReferenceContainer<ReferenceType>> cache;
/**
* open an existing heap file in undefined mode
* after this a initialization should be made to use the heap:
* either a read-only or read/write mode initialization
* @param factory the factory for payload reference objects
* @param termOrder the order on search terms for the cache
* @param termSize the fixed size of search terms
*/
public ReferenceContainerCache(final ReferenceFactory<ReferenceType> factory, final ByteOrder termOrder, final int termSize) {
super(factory);
this.termOrder = termOrder;
this.termSize = termSize;
this.containerOrder = new ContainerOrder<ReferenceType>(this.termOrder);
this.cache = new ConcurrentHashMap<ByteArray, ReferenceContainer<ReferenceType>>();
}
public Row rowdef() {
return this.factory.getRow();
}
/**
* every index entry is made for a term which has a fixed size
* @return the size of the term
*/
public int termKeyLength() {
return this.termSize;
}
public void clear() {
if (this.cache != null) this.cache.clear();
}
public void close() {
this.cache = null;
}
/**
* dump the cache to a file. This method can be used in a destructive way
* which means that memory can be freed during the dump. This may be important
* because the dump is done in such situations when memory gets low. To get more
* memory during the dump helps to solve tight memory situations.
* @param heapFile
* @param writeBuffer
* @param destructive - if true then the cache is cleaned during the dump causing to free memory
*/
public void dump(final File heapFile, final int writeBuffer, final boolean destructive) {
assert this.cache != null;
if (this.cache == null) return;
Log.logInfo("indexContainerRAMHeap", "creating rwi heap dump '" + heapFile.getName() + "', " + this.cache.size() + " rwi's");
if (heapFile.exists()) FileUtils.deletedelete(heapFile);
final File tmpFile = new File(heapFile.getParentFile(), heapFile.getName() + ".prt");
HeapWriter dump;
try {
dump = new HeapWriter(tmpFile, heapFile, this.termSize, this.termOrder, writeBuffer);
} catch (final IOException e1) {
Log.logException(e1);
return;
}
final long startTime = System.currentTimeMillis();
// sort the map
final List<ReferenceContainer<ReferenceType>> cachecopy = sortedClone();
// write wCache
long wordcount = 0, urlcount = 0;
byte[] term = null, lwh;
for (final ReferenceContainer<ReferenceType> container: cachecopy) {
// get entries
lwh = term;
term = container.getTermHash();
// check consistency: entries must be ordered
assert (lwh == null || this.termKeyOrdering().compare(term, lwh) > 0);
// put entries on heap
if (container != null && term.length == this.termSize) {
//System.out.println("Dump: " + wordHash);
try {
dump.add(term, container.exportCollection());
} catch (final IOException e) {
Log.logException(e);
} catch (final RowSpaceExceededException e) {
Log.logException(e);
}
if (destructive) container.clear(); // this memory is not needed any more
urlcount += container.size();
}
wordcount++;
}
try {
dump.close(true);
Log.logInfo("indexContainerRAMHeap", "finished rwi heap dump: " + wordcount + " words, " + urlcount + " word/URL relations in " + (System.currentTimeMillis() - startTime) + " milliseconds");
} catch (final IOException e) {
Log.logSevere("indexContainerRAMHeap", "failed rwi heap dump: " + e.getMessage(), e);
} finally {
dump = null;
}
}
/**
* create a clone of the cache content that is sorted using the this.containerOrder
* @return the sorted ReferenceContainer[]
*/
protected List<ReferenceContainer<ReferenceType>> sortedClone() {
final List<ReferenceContainer<ReferenceType>> cachecopy = new ArrayList<ReferenceContainer<ReferenceType>>(this.cache.size());
synchronized (this.cache) {
for (final Map.Entry<ByteArray, ReferenceContainer<ReferenceType>> entry: this.cache.entrySet()) {
if (entry.getValue() != null && entry.getValue().getTermHash() != null) cachecopy.add(entry.getValue());
}
}
Collections.sort(cachecopy, this.containerOrder);
return cachecopy;
}
public int size() {
return (this.cache == null) ? 0 : this.cache.size();
}
public boolean isEmpty() {
if (this.cache == null) return true;
return this.cache.isEmpty();
}
public int maxReferences() {
// iterate to find the max score
int max = 0;
for (final ReferenceContainer<ReferenceType> container : this.cache.values()) {
if (container.size() > max) max = container.size();
}
return max;
}
/**
* return an iterator object that creates top-level-clones of the indexContainers
* in the cache, so that manipulations of the iterated objects do not change
* objects in the cache.
*/
public synchronized CloneableIterator<ReferenceContainer<ReferenceType>> references(final byte[] startWordHash, final boolean rot) {
return new heapCacheIterator(startWordHash, rot);
}
public Iterator<ReferenceContainer<ReferenceType>> iterator() {
return references(null, false);
}
/**
* cache iterator: iterates objects within the heap cache. This can only be used
* for write-enabled heaps, read-only heaps do not have a heap cache
*/
public class heapCacheIterator implements CloneableIterator<ReferenceContainer<ReferenceType>>, Iterable<ReferenceContainer<ReferenceType>> {
// this class exists, because the wCache cannot be iterated with rotation
// and because every indexContainer Object that is iterated must be returned as top-level-clone
// so this class simulates wCache.tailMap(startWordHash).values().iterator()
// plus the mentioned features
private final boolean rot;
private final List<ReferenceContainer<ReferenceType>> cachecopy;
private int p;
private byte[] latestTermHash;
public heapCacheIterator(byte[] startWordHash, final boolean rot) {
this.rot = rot;
if (startWordHash != null && startWordHash.length == 0) startWordHash = null;
this.cachecopy = sortedClone();
assert this.cachecopy != null;
assert ReferenceContainerCache.this.termOrder != null;
this.p = 0;
if (startWordHash != null) {
while ( this.p < this.cachecopy.size() &&
ReferenceContainerCache.this.termOrder.compare(this.cachecopy.get(this.p).getTermHash(), startWordHash) < 0
) this.p++;
}
this.latestTermHash = null;
// The collection's iterator will return the values in the order that their corresponding keys appear in the tree.
}
public heapCacheIterator clone(final Object secondWordHash) {
return new heapCacheIterator((byte[]) secondWordHash, this.rot);
}
public boolean hasNext() {
if (this.rot) return this.cachecopy.size() > 0;
return this.p < this.cachecopy.size();
}
public ReferenceContainer<ReferenceType> next() {
if (this.p < this.cachecopy.size()) {
final ReferenceContainer<ReferenceType> c = this.cachecopy.get(this.p++);
this.latestTermHash = c.getTermHash();
try {
return c.topLevelClone();
} catch (final RowSpaceExceededException e) {
Log.logException(e);
return null;
}
}
// rotation iteration
if (!this.rot) {
return null;
}
if (this.cachecopy.isEmpty()) return null;
this.p = 0;
final ReferenceContainer<ReferenceType> c = this.cachecopy.get(this.p++);
this.latestTermHash = c.getTermHash();
try {
return c.topLevelClone();
} catch (final RowSpaceExceededException e) {
Log.logException(e);
return null;
}
}
public void remove() {
System.arraycopy(this.cachecopy, this.p, this.cachecopy, this.p - 1, this.cachecopy.size() - this.p);
ReferenceContainerCache.this.cache.remove(new ByteArray(this.latestTermHash));
}
public Iterator<ReferenceContainer<ReferenceType>> iterator() {
return this;
}
}
/**
* test if a given key is in the heap
* this works with heaps in write- and read-mode
* @param key
* @return true, if the key is used in the heap; false otherwise
*/
public boolean has(final byte[] key) {
return this.cache.containsKey(new ByteArray(key));
}
/**
* get a indexContainer from a heap
* @param key
* @return the indexContainer if one exist, null otherwise
* @throws
*/
public ReferenceContainer<ReferenceType> get(final byte[] key, final HandleSet urlselection) {
final ReferenceContainer<ReferenceType> c = this.cache.get(new ByteArray(key));
if (urlselection == null) return c;
if (c == null) return null;
// because this is all in RAM, we must clone the entries (flat)
try {
final ReferenceContainer<ReferenceType> c1 = new ReferenceContainer<ReferenceType>(this.factory, c.getTermHash(), c.size());
final Iterator<ReferenceType> e = c.entries();
ReferenceType ee;
while (e.hasNext()) {
ee = e.next();
if (urlselection.has(ee.urlhash())) {
c1.add(ee);
}
}
return c1;
} catch (final RowSpaceExceededException e2) {
Log.logException(e2);
}
return null;
}
/**
* return the size of the container with corresponding key
* @param key
* @return
*/
public int count(final byte[] key) {
final ReferenceContainer<ReferenceType> c = this.cache.get(new ByteArray(key));
if (c == null) return 0;
return c.size();
}
/**
* delete a indexContainer from the heap cache. This can only be used for write-enabled heaps
* @param wordHash
* @return the indexContainer if the cache contained the container, null otherwise
*/
public ReferenceContainer<ReferenceType> delete(final byte[] termHash) {
// returns the index that had been deleted
assert this.cache != null;
if (this.cache == null) return null;
return this.cache.remove(new ByteArray(termHash));
}
public void removeDelayed(final byte[] termHash, final byte[] urlHashBytes) {
remove(termHash, urlHashBytes);
}
public boolean remove(final byte[] termHash, final byte[] urlHashBytes) {
assert this.cache != null;
if (this.cache == null) return false;
final ByteArray tha = new ByteArray(termHash);
synchronized (this.cache) {
final ReferenceContainer<ReferenceType> c = this.cache.get(tha);
if (c != null && c.delete(urlHashBytes)) {
// removal successful
if (c.isEmpty()) {
delete(termHash);
} else {
this.cache.put(tha, c);
}
return true;
}
}
return false;
}
public void removeDelayed(final byte[] termHash, final HandleSet urlHashes) {
remove(termHash, urlHashes);
}
public int remove(final byte[] termHash, final HandleSet urlHashes) {
assert this.cache != null;
if (this.cache == null) return 0;
if (urlHashes.isEmpty()) return 0;
final ByteArray tha = new ByteArray(termHash);
int count;
synchronized (this.cache) {
final ReferenceContainer<ReferenceType> c = this.cache.get(tha);
if ((c != null) && ((count = c.removeEntries(urlHashes)) > 0)) {
// removal successful
if (c.isEmpty()) {
delete(termHash);
} else {
this.cache.put(tha, c);
}
return count;
}
}
return 0;
}
public void removeDelayed() {}
public void add(final ReferenceContainer<ReferenceType> container) throws RowSpaceExceededException {
// this puts the entries into the cache
if (this.cache == null || container == null || container.isEmpty()) return;
// put new words into cache
final ByteArray tha = new ByteArray(container.getTermHash());
int added = 0;
synchronized (this.cache) {
ReferenceContainer<ReferenceType> entries = this.cache.get(tha); // null pointer exception? wordhash != null! must be cache==null
if (entries == null) {
entries = container.topLevelClone();
added = entries.size();
} else {
added = entries.putAllRecent(container);
}
if (added > 0) {
this.cache.put(tha, entries);
}
entries = null;
return;
}
}
public void add(final byte[] termHash, final ReferenceType newEntry) throws RowSpaceExceededException {
assert this.cache != null;
if (this.cache == null) return;
final ByteArray tha = new ByteArray(termHash);
// first access the cache without synchronization
ReferenceContainer<ReferenceType> container = this.cache.remove(tha);
if (container == null) container = new ReferenceContainer<ReferenceType>(this.factory, termHash, 1);
container.put(newEntry);
// synchronization: check if the entry is still empty and set new value
synchronized (this.cache) {
final ReferenceContainer<ReferenceType> containerNew = this.cache.put(tha, container);
if (containerNew == null) return;
if (container == containerNew) {
// The containers are the same, so nothing needs to be done
return;
}
// Now merge the smaller container into the lager.
// The other way around can become very slow
if (container.size() >= containerNew.size()) {
container.putAllRecent(containerNew);
this.cache.put(tha, container);
} else {
containerNew.putAllRecent(container);
this.cache.put(tha, containerNew);
}
}
}
public int minMem() {
return 0;
}
public ByteOrder termKeyOrdering() {
return this.termOrder;
}
public static class ContainerOrder<ReferenceType extends Reference> implements Comparator<ReferenceContainer<ReferenceType>> {
private final ByteOrder o;
public ContainerOrder(final ByteOrder order) {
this.o = order;
}
public int compare(final ReferenceContainer<ReferenceType> arg0, final ReferenceContainer<ReferenceType> arg1) {
if (arg0 == arg1) return 0;
if (arg0 == null) return -1;
if (arg1 == null) return 1;
return this.o.compare(arg0.getTermHash(), arg1.getTermHash());
}
}
}