// IndexCell.java
// (C) 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 1.3.2009 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate: 2011-06-26 23:45:04 +0200 (So, 26. Jun 2011) $
// $LastChangedRevision: 7802 $
// $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.Iterator;
import java.util.Map;
import java.util.TreeMap;
import net.yacy.cora.storage.ComparableARC;
import net.yacy.kelondro.data.meta.URIMetadataRow;
import net.yacy.kelondro.index.HandleSet;
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.order.MergeIterator;
import net.yacy.kelondro.order.Order;
import net.yacy.kelondro.util.EventTracker;
import net.yacy.kelondro.util.MemoryControl;
/*
* an index cell is a part of the horizontal index in the new segment-oriented index
* data structure of YaCy. If there is no filter in front of a cell, it might also be
* the organization for a complete segment index. Each cell consists of a number of BLOB files, that
* must be merged to represent a single index. In fact these index files are only merged on demand
* if there are too many of them. An index merge can be done with a stream read and stream write operation.
* in normal operation, there are only a number of read-only BLOB files and a single RAM cache that is
* kept in the RAM as long as a given limit of entries is reached. Then the cache is flushed and becomes
* another BLOB file in the index array.
*/
public final class IndexCell<ReferenceType extends Reference> extends AbstractBufferedIndex<ReferenceType> implements BufferedIndex<ReferenceType>, Iterable<ReferenceContainer<ReferenceType>> {
private static final long cleanupCycle = 60000;
private static final long dumpCycle = 600000;
// class variables
private final ReferenceContainerArray<ReferenceType> array;
private ReferenceContainerCache<ReferenceType> ram;
private final ComparableARC<byte[], Integer> countCache;
private int maxRamEntries;
private final IODispatcher merger;
private long lastCleanup, lastDump;
private final long targetFileSize, maxFileSize;
private final int writeBufferSize;
private final Map<byte[], HandleSet> removeDelayedURLs; // mapping from word hashes to a list of url hashes
public IndexCell(
final File cellPath,
final String prefix,
final ReferenceFactory<ReferenceType> factory,
final ByteOrder termOrder,
final int termSize,
final int maxRamEntries,
final long targetFileSize,
final long maxFileSize,
final IODispatcher merger,
final int writeBufferSize
) throws IOException {
super(factory);
this.array = new ReferenceContainerArray<ReferenceType>(cellPath, prefix, factory, termOrder, termSize, merger);
this.ram = new ReferenceContainerCache<ReferenceType>(factory, termOrder, termSize);
this.countCache = new ComparableARC<byte[], Integer>(1000, termOrder);
this.maxRamEntries = maxRamEntries;
this.merger = merger;
this.lastCleanup = System.currentTimeMillis();
this.lastDump = System.currentTimeMillis();
this.targetFileSize = targetFileSize;
this.maxFileSize = maxFileSize;
this.writeBufferSize = writeBufferSize;
this.removeDelayedURLs = new TreeMap<byte[], HandleSet>(URIMetadataRow.rowdef.objectOrder);
}
/*
* methods to implement Index
*/
/**
* every index entry is made for a term which has a fixed size
* @return the size of the term
*/
public int termKeyLength() {
return this.ram.termKeyLength();
}
/**
* add entries to the cell: this adds the new entries always to the RAM part, never to BLOBs
* @throws IOException
* @throws RowSpaceExceededException
*/
public void add(final ReferenceContainer<ReferenceType> newEntries) throws IOException, RowSpaceExceededException {
try {
this.ram.add(newEntries);
final long t = System.currentTimeMillis();
if (this.ram.size() % 1000 == 0 || this.lastCleanup + cleanupCycle < t || this.lastDump + dumpCycle < t) {
EventTracker.update(EventTracker.EClass.WORDCACHE, Long.valueOf(this.ram.size()), true);
cleanCache();
}
} catch (final RowSpaceExceededException e) {
EventTracker.update(EventTracker.EClass.WORDCACHE, Long.valueOf(this.ram.size()), true);
cleanCache();
this.ram.add(newEntries);
}
}
public void add(final byte[] termHash, final ReferenceType entry) throws IOException, RowSpaceExceededException {
try {
this.ram.add(termHash, entry);
final long t = System.currentTimeMillis();
if (this.ram.size() % 1000 == 0 || this.lastCleanup + cleanupCycle < t || this.lastDump + dumpCycle < t) {
EventTracker.update(EventTracker.EClass.WORDCACHE, Long.valueOf(this.ram.size()), true);
cleanCache();
}
} catch (final RowSpaceExceededException e) {
EventTracker.update(EventTracker.EClass.WORDCACHE, Long.valueOf(this.ram.size()), true);
cleanCache();
this.ram.add(termHash, entry);
}
}
/**
* checks if there is any container for this termHash, either in RAM or any BLOB
*/
public boolean has(final byte[] termHash) {
if (this.ram.has(termHash)) return true;
return this.array.has(termHash);
}
/**
* count number of references for a given term
* this method may cause strong IO load if called too frequently.
*/
public int count(final byte[] termHash) {
final Integer cachedCount = this.countCache.get(termHash);
if (cachedCount != null) return cachedCount.intValue();
int countFile = 0;
// read fresh values from file
try {
countFile = this.array.count(termHash);
} catch (final Exception e) {
Log.logException(e);
}
assert countFile >= 0;
// count from container in ram
final ReferenceContainer<ReferenceType> countRam = this.ram.get(termHash, null);
assert countRam == null || countRam.size() >= 0;
int c = countRam == null ? countFile : countFile + countRam.size();
// exclude entries from delayed remove
synchronized (this.removeDelayedURLs) {
final HandleSet s = this.removeDelayedURLs.get(termHash);
if (s != null) c -= s.size();
if (c < 0) c = 0;
}
// put count result into cache
if (MemoryControl.shortStatus()) this.countCache.clear();
this.countCache.insert(termHash, c);
return c;
}
/**
* all containers in the BLOBs and the RAM are merged and returned.
* Please be aware that the returned values may be top-level cloned ReferenceContainers or direct links to containers
* If the containers are modified after they are returned, they MAY alter the stored index.
* @throws IOException
* @return a container with merged ReferenceContainer from RAM and the file array or null if there is no data to be returned
*/
public ReferenceContainer<ReferenceType> get(final byte[] termHash, final HandleSet urlselection) throws IOException {
final ReferenceContainer<ReferenceType> c0 = this.ram.get(termHash, null);
ReferenceContainer<ReferenceType> c1 = null;
try {
c1 = this.array.get(termHash);
} catch (final RowSpaceExceededException e2) {
Log.logException(e2);
}
ReferenceContainer<ReferenceType> result = null;
if (c0 != null && c1 != null) {
try {
result = c1.merge(c0);
} catch (final RowSpaceExceededException e) {
// try to free some ram
try {
result = c1.merge(c0);
} catch (final RowSpaceExceededException e1) {
// go silently over the problem
result = (c1.size() > c0.size()) ? c1: c0;
}
}
} else if (c0 != null) {
result = c0;
} else if (c1 != null) {
result = c1;
}
if (result == null) return null;
// remove the failed urls
synchronized (this.removeDelayedURLs) {
final HandleSet s = this.removeDelayedURLs.get(termHash);
if (s != null) result.removeEntries(s);
}
return result;
}
/**
* deleting a container affects the containers in RAM and all the BLOB files
* the deleted containers are merged and returned as result of the method
* @throws IOException
*/
public ReferenceContainer<ReferenceType> delete(final byte[] termHash) throws IOException {
removeDelayed();
ReferenceContainer<ReferenceType> c1 = null;
try {
c1 = this.array.get(termHash);
} catch (final RowSpaceExceededException e2) {
Log.logException(e2);
}
if (c1 != null) {
this.array.delete(termHash);
}
final ReferenceContainer<ReferenceType> c0 = this.ram.delete(termHash);
cleanCache();
if (c1 == null) return c0;
if (c0 == null) return c1;
try {
return c1.merge(c0);
} catch (final RowSpaceExceededException e) {
// try to free some ram
try {
return c1.merge(c0);
} catch (final RowSpaceExceededException e1) {
// go silently over the problem
return (c1.size() > c0.size()) ? c1: c0;
}
}
}
public void removeDelayed(final byte[] termHash, final HandleSet urlHashes) {
HandleSet r;
synchronized (this.removeDelayedURLs) {
r = this.removeDelayedURLs.get(termHash);
}
if (r == null) {
r = new HandleSet(URIMetadataRow.rowdef.primaryKeyLength, URIMetadataRow.rowdef.objectOrder, 0);
}
try {
r.putAll(urlHashes);
} catch (final RowSpaceExceededException e) {
try {remove(termHash, urlHashes);} catch (final IOException e1) {}
return;
}
synchronized (this.removeDelayedURLs) {
this.removeDelayedURLs.put(termHash, r);
}
}
public void removeDelayed(final byte[] termHash, final byte[] urlHashBytes) {
HandleSet r;
synchronized (this.removeDelayedURLs) {
r = this.removeDelayedURLs.get(termHash);
}
if (r == null) {
r = new HandleSet(URIMetadataRow.rowdef.primaryKeyLength, URIMetadataRow.rowdef.objectOrder, 0);
}
try {
r.put(urlHashBytes);
} catch (final RowSpaceExceededException e) {
try {remove(termHash, urlHashBytes);} catch (final IOException e1) {}
return;
}
synchronized (this.removeDelayedURLs) {
this.removeDelayedURLs.put(termHash, r);
}
}
public void removeDelayed() throws IOException {
final HandleSet words = new HandleSet(URIMetadataRow.rowdef.primaryKeyLength, URIMetadataRow.rowdef.objectOrder, 0); // a set of url hashes where a worker thread tried to work on, but failed.
synchronized (this.removeDelayedURLs) {
for (final byte[] b: this.removeDelayedURLs.keySet()) try {words.put(b);} catch (final RowSpaceExceededException e) {}
}
synchronized (this.removeDelayedURLs) {
for (final byte[] b: words) {
final HandleSet urls = this.removeDelayedURLs.remove(b);
if (urls != null) remove(b, urls);
}
}
this.countCache.clear();
}
/**
* remove url references from a selected word hash. this deletes also in the BLOB
* files, which means that there exists new gap entries after the deletion
* The gaps are never merged in place, but can be eliminated when BLOBs are merged into
* new BLOBs. This returns the sum of all url references that have been removed
* @throws IOException
*/
public int remove(final byte[] termHash, final HandleSet urlHashes) throws IOException {
this.countCache.remove(termHash);
final int removed = this.ram.remove(termHash, urlHashes);
int reduced;
//final long am = this.array.mem();
try {
reduced = this.array.reduce(termHash, new RemoveReducer<ReferenceType>(urlHashes));
} catch (final RowSpaceExceededException e) {
reduced = 0;
Log.logWarning("IndexCell", "not possible to remove urlHashes from a RWI because of too low memory. Remove was not applied. Please increase RAM assignment");
}
//assert this.array.mem() <= am : "am = " + am + ", array.mem() = " + this.array.mem();
return removed + (reduced / this.array.rowdef().objectsize);
}
public boolean remove(final byte[] termHash, final byte[] urlHashBytes) throws IOException {
this.countCache.remove(termHash);
final boolean removed = this.ram.remove(termHash, urlHashBytes);
int reduced;
//final long am = this.array.mem();
try {
reduced = this.array.reduce(termHash, new RemoveReducer<ReferenceType>(urlHashBytes));
} catch (final RowSpaceExceededException e) {
reduced = 0;
Log.logWarning("IndexCell", "not possible to remove urlHashes from a RWI because of too low memory. Remove was not applied. Please increase RAM assignment");
}
//assert this.array.mem() <= am : "am = " + am + ", array.mem() = " + this.array.mem();
return removed || (reduced > 0);
}
private static class RemoveReducer<ReferenceType extends Reference> implements ReferenceContainerArray.ContainerReducer<ReferenceType> {
HandleSet urlHashes;
public RemoveReducer(final HandleSet urlHashes) {
this.urlHashes = urlHashes;
}
public RemoveReducer(final byte[] urlHashBytes) {
this.urlHashes = new HandleSet(URIMetadataRow.rowdef.primaryKeyLength, URIMetadataRow.rowdef.objectOrder, 0);
try {
this.urlHashes.put(urlHashBytes);
} catch (final RowSpaceExceededException e) {
Log.logException(e);
}
}
public ReferenceContainer<ReferenceType> reduce(final ReferenceContainer<ReferenceType> container) {
container.sort();
container.removeEntries(this.urlHashes);
return container;
}
}
public Iterator<ReferenceContainer<ReferenceType>> iterator() {
return references(null, false);
}
public CloneableIterator<ReferenceContainer<ReferenceType>> references(final byte[] starttermHash, final boolean rot) {
final Order<ReferenceContainer<ReferenceType>> containerOrder = new ReferenceContainerOrder<ReferenceType>(this.factory, this.ram.rowdef().getOrdering().clone());
containerOrder.rotate(new ReferenceContainer<ReferenceType>(this.factory, starttermHash));
return new MergeIterator<ReferenceContainer<ReferenceType>>(
this.ram.references(starttermHash, rot),
new MergeIterator<ReferenceContainer<ReferenceType>>(
this.ram.references(starttermHash, false),
this.array.wordContainerIterator(starttermHash, false),
containerOrder,
ReferenceContainer.containerMergeMethod,
true),
containerOrder,
ReferenceContainer.containerMergeMethod,
true);
}
public CloneableIterator<ReferenceContainer<ReferenceType>> references(final byte[] startTermHash, final boolean rot, final boolean ram) {
final Order<ReferenceContainer<ReferenceType>> containerOrder = new ReferenceContainerOrder<ReferenceType>(this.factory, this.ram.rowdef().getOrdering().clone());
containerOrder.rotate(new ReferenceContainer<ReferenceType>(this.factory, startTermHash));
if (ram) {
return this.ram.references(startTermHash, rot);
}
return new MergeIterator<ReferenceContainer<ReferenceType>>(
this.ram.references(startTermHash, false),
this.array.wordContainerIterator(startTermHash, false),
containerOrder,
ReferenceContainer.containerMergeMethod,
true);
}
/**
* clear the RAM and BLOB part, deletes everything in the cell
* @throws IOException
*/
public synchronized void clear() throws IOException {
this.countCache.clear();
this.removeDelayedURLs.clear();
this.ram.clear();
this.array.clear();
}
/**
* when a cell is closed, the current RAM is dumped to a file which will be opened as
* BLOB file the next time a cell is opened. A name for the dump is automatically generated
* and is composed of the current date and the cell salt
*/
public synchronized void close() {
this.countCache.clear();
try {removeDelayed();} catch (final IOException e) {}
if (!this.ram.isEmpty()) this.ram.dump(this.array.newContainerBLOBFile(), (int) Math.min(MemoryControl.available() / 3, this.writeBufferSize), true);
// close all
this.ram.close();
this.array.close();
}
public int size() {
throw new UnsupportedOperationException("an accumulated size of index entries would not reflect the real number of words, which cannot be computed easily");
}
public int[] sizes() {
final int[] as = this.array.sizes();
final int[] asr = new int[as.length + 1];
System.arraycopy(as, 0, asr, 0, as.length);
asr[as.length] = this.ram.size();
return asr;
}
public int sizesMax() {
int m = 0;
final int[] s = sizes();
for (final int element : s)
if (element > m) m = element;
return m;
}
public int minMem() {
return 10 * 1024 * 1024;
}
public ByteOrder termKeyOrdering() {
return this.array.ordering();
}
/*
* cache control methods
*/
private void cleanCache() {
// dump the cache if necessary
final long t = System.currentTimeMillis();
if ((this.ram.size() >= this.maxRamEntries ||
(this.ram.size() > 3000 && !MemoryControl.request(80L * 1024L * 1024L, false)) ||
(this.ram.size() > 0 && this.lastDump + dumpCycle < t))) {
synchronized (this.merger) {
if (this.ram.size() >= this.maxRamEntries ||
(this.ram.size() > 3000 && !MemoryControl.request(80L * 1024L * 1024L, false)) ||
(this.ram.size() > 0 && this.lastDump + dumpCycle < t)) try {
this.lastDump = System.currentTimeMillis();
// removed delayed
try {removeDelayed();} catch (final IOException e) {}
// dump the ram
final File dumpFile = this.array.newContainerBLOBFile();
// a critical point: when the ram is handed to the dump job,
// don't write into it any more. Use a fresh one instead
ReferenceContainerCache<ReferenceType> ramdump;
final ByteOrder termOrder = this.ram.termKeyOrdering();
final int termSize = this.ram.termKeyLength();
synchronized (this) {
ramdump = this.ram;
// get a fresh ram cache
this.ram = new ReferenceContainerCache<ReferenceType>(this.factory, termOrder, termSize);
}
// dump the buffer
this.merger.dump(ramdump, dumpFile, this.array);
this.lastDump = System.currentTimeMillis();
} catch (final Exception e) {
// catch all exceptions
Log.logException(e);
}
}
}
// clean-up the cache
if ((this.array.entries() > 50 ||
this.lastCleanup + cleanupCycle < t)) {
synchronized (this.array) {
if (this.array.entries() > 50 || (this.lastCleanup + cleanupCycle < System.currentTimeMillis())) try {
this.lastCleanup = System.currentTimeMillis(); // set time to prevent that this is called to soon again
this.array.shrink(this.targetFileSize, this.maxFileSize);
this.lastCleanup = System.currentTimeMillis(); // set again to mark end of procedure
} catch (final Exception e) {
// catch all exceptions
Log.logException(e);
}
}
}
}
public File newContainerBLOBFile() {
// for migration of cache files
return this.array.newContainerBLOBFile();
}
public void mountBLOBFile(final File blobFile) throws IOException {
// for migration of cache files
this.array.mountBLOBFile(blobFile);
}
public long getBufferMaxAge() {
return System.currentTimeMillis();
}
public int getBufferMaxReferences() {
return this.ram.maxReferences();
}
public long getBufferMinAge() {
return System.currentTimeMillis();
}
public int getBufferSize() {
return this.ram.size();
}
public long getBufferSizeBytes() {
return 10000 * this.ram.size(); // guessed; we don't know that exactly because there is no statistics here (expensive, not necessary)
}
public void setBufferMaxWordCount(final int maxWords) {
this.maxRamEntries = maxWords;
this.cleanCache();
}
}