// Balancer.java
// -----------------------
// part of YaCy
// (C) by Michael Peter Christen; mc@yacy.net
// first published on http://www.anomic.de
// Frankfurt, Germany, 2005
// created: 24.09.2005
//
//$LastChangedDate: 2011-06-13 23:44:03 +0200 (Mo, 13. Jun 2011) $
//$LastChangedRevision: 7778 $
//$LastChangedBy: orbiter $
//
// 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.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ConcurrentMap;
import net.yacy.cora.document.ASCII;
import net.yacy.cora.document.UTF8;
import net.yacy.cora.services.federated.yacy.CacheStrategy;
import net.yacy.kelondro.data.meta.URIMetadataRow;
import net.yacy.kelondro.index.BufferedObjectIndex;
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.Base64Order;
import net.yacy.kelondro.order.CloneableIterator;
import net.yacy.kelondro.table.Table;
import net.yacy.kelondro.util.ByteBuffer;
import net.yacy.kelondro.util.MemoryControl;
import de.anomic.crawler.retrieval.Request;
import de.anomic.http.client.Cache;
public class Balancer {
private static final String indexSuffix = "9.db";
private static final int EcoFSBufferSize = 1000;
private static final int objectIndexBufferSize = 1000;
private static final String localhost = "localhost";
// class variables filled with external values
private final File cacheStacksPath;
private long minimumLocalDelta;
private long minimumGlobalDelta;
private final Set<String> myAgentIDs;
private BufferedObjectIndex urlFileIndex;
// class variables computed during operation
private final ConcurrentMap<String, HandleSet> domainStacks; // a map from host name to lists with url hashs
private final ConcurrentLinkedQueue<byte[]> top; // a list of url-hashes that shall be taken next
private final SortedMap<Long, byte[]> delayed;
private final HandleSet ddc;
private final HandleSet double_push_check; // for debugging
private long lastDomainStackFill;
private int domStackInitSize;
public Balancer(
final File cachePath,
final String stackname,
final long minimumLocalDelta,
final long minimumGlobalDelta,
final Set<String> myAgentIDs,
final boolean useTailCache,
final boolean exceed134217727) {
this.cacheStacksPath = cachePath;
this.domainStacks = new ConcurrentHashMap<String, HandleSet>();
this.top = new ConcurrentLinkedQueue<byte[]>();
this.delayed = new TreeMap<Long, byte[]>();
this.minimumLocalDelta = minimumLocalDelta;
this.minimumGlobalDelta = minimumGlobalDelta;
this.myAgentIDs = myAgentIDs;
this.domStackInitSize = Integer.MAX_VALUE;
this.ddc = new HandleSet(URIMetadataRow.rowdef.primaryKeyLength, URIMetadataRow.rowdef.objectOrder, 0);
this.double_push_check = new HandleSet(URIMetadataRow.rowdef.primaryKeyLength, URIMetadataRow.rowdef.objectOrder, 0);
// create a stack for newly entered entries
if (!(cachePath.exists())) cachePath.mkdir(); // make the path
this.cacheStacksPath.mkdirs();
final File f = new File(this.cacheStacksPath, stackname + indexSuffix);
try {
this.urlFileIndex = new BufferedObjectIndex(new Table(f, Request.rowdef, EcoFSBufferSize, 0, useTailCache, exceed134217727), objectIndexBufferSize);
} catch (final RowSpaceExceededException e) {
try {
this.urlFileIndex = new BufferedObjectIndex(new Table(f, Request.rowdef, 0, 0, false, exceed134217727), objectIndexBufferSize);
} catch (final RowSpaceExceededException e1) {
Log.logException(e1);
}
}
this.lastDomainStackFill = 0;
Log.logInfo("Balancer", "opened balancer file with " + this.urlFileIndex.size() + " entries from " + f.toString());
}
public long getMinimumLocalDelta() {
return this.minimumLocalDelta;
}
public long getMinimumGlobalDelta() {
return this.minimumGlobalDelta;
}
public void setMinimumDelta(final long minimumLocalDelta, final long minimumGlobalDelta) {
this.minimumLocalDelta = minimumLocalDelta;
this.minimumGlobalDelta = minimumGlobalDelta;
}
public synchronized void close() {
if (this.urlFileIndex != null) {
this.urlFileIndex.close();
this.urlFileIndex = null;
}
}
public void clear() {
Log.logInfo("Balancer", "cleaning balancer with " + this.urlFileIndex.size() + " entries from " + this.urlFileIndex.filename());
try {
this.urlFileIndex.clear();
} catch (final IOException e) {
Log.logException(e);
}
this.domainStacks.clear();
this.top.clear();
synchronized (this.delayed) {
this.delayed.clear();
}
}
public Request get(final byte[] urlhash) throws IOException {
assert urlhash != null;
if (this.urlFileIndex == null) return null; // case occurs during shutdown
final Row.Entry entry = this.urlFileIndex.get(urlhash);
if (entry == null) return null;
return new Request(entry);
}
public int removeAllByProfileHandle(final String profileHandle, final long timeout) throws IOException, RowSpaceExceededException {
// removes all entries with a specific profile hash.
// this may last some time
// returns number of deletions
// first find a list of url hashes that shall be deleted
final HandleSet urlHashes = Base64Order.enhancedCoder.getHandleSet(this.urlFileIndex.row().primaryKeyLength, 100);
final long terminate = (timeout > 0) ? System.currentTimeMillis() + timeout : Long.MAX_VALUE;
synchronized (this) {
final Iterator<Row.Entry> i = this.urlFileIndex.rows();
Row.Entry rowEntry;
Request crawlEntry;
while (i.hasNext() && (System.currentTimeMillis() < terminate)) {
rowEntry = i.next();
crawlEntry = new Request(rowEntry);
if (crawlEntry.profileHandle().equals(profileHandle)) {
urlHashes.put(crawlEntry.url().hash());
}
}
}
// then delete all these urls from the queues and the file index
return remove(urlHashes);
}
/**
* this method is only here, because so many import/export methods need it
and it was implemented in the previous architecture
however, usage is not recommended
* @param urlHashes, a list of hashes that shall be removed
* @return number of entries that had been removed
* @throws IOException
*/
public synchronized int remove(final HandleSet urlHashes) throws IOException {
final int s = this.urlFileIndex.size();
int removedCounter = 0;
for (final byte[] urlhash: urlHashes) {
final Row.Entry entry = this.urlFileIndex.remove(urlhash);
if (entry != null) removedCounter++;
// remove from double-check caches
this.ddc.remove(urlhash);
this.double_push_check.remove(urlhash);
}
if (removedCounter == 0) return 0;
assert this.urlFileIndex.size() + removedCounter == s : "urlFileIndex.size() = " + this.urlFileIndex.size() + ", s = " + s;
// iterate through the top list
final Iterator<byte[]> j = this.top.iterator();
byte[] urlhash;
while (j.hasNext()) {
urlhash = j.next();
if (urlHashes.has(urlhash)) j.remove();
}
// remove from delayed
synchronized (this.delayed) {
final Iterator<Map.Entry<Long, byte[]>> k = this.delayed.entrySet().iterator();
while (k.hasNext()) {
if (urlHashes.has(k.next().getValue())) k.remove();
}
}
// iterate through the domain stacks
final Iterator<Map.Entry<String, HandleSet>> q = this.domainStacks.entrySet().iterator();
HandleSet stack;
while (q.hasNext()) {
stack = q.next().getValue();
for (final byte[] handle: urlHashes) stack.remove(handle);
if (stack.isEmpty()) q.remove();
}
return removedCounter;
}
public boolean has(final byte[] urlhashb) {
return this.urlFileIndex.has(urlhashb) || this.ddc.has(urlhashb);
}
public boolean notEmpty() {
// alternative method to the property size() > 0
// this is better because it may avoid synchronized access to domain stack summarization
return domainStacksNotEmpty();
}
public int size() {
return this.urlFileIndex.size();
}
public boolean isEmpty() {
return this.urlFileIndex.isEmpty();
}
private boolean domainStacksNotEmpty() {
if (this.domainStacks == null) return false;
synchronized (this.domainStacks) {
for (final HandleSet l: this.domainStacks.values()) {
if (!l.isEmpty()) return true;
}
}
return false;
}
/**
* push a crawl request on the balancer stack
* @param entry
* @return null if this was successful or a String explaining what went wrong in case of an error
* @throws IOException
* @throws RowSpaceExceededException
*/
public String push(final Request entry) throws IOException, RowSpaceExceededException {
assert entry != null;
final byte[] hash = entry.url().hash();
synchronized (this) {
// double-check
if (this.double_push_check.has(hash)) return "double occurrence in double_push_check";
if (this.ddc.has(hash)) return "double occurrence in ddc";
if (this.urlFileIndex.has(hash)) return "double occurrence in urlFileIndex";
if (this.double_push_check.size() > 10000 || MemoryControl.shortStatus()) this.double_push_check.clear();
this.double_push_check.put(hash);
// add to index
final int s = this.urlFileIndex.size();
this.urlFileIndex.put(entry.toRow());
assert s < this.urlFileIndex.size() : "hash = " + ASCII.String(hash) + ", s = " + s + ", size = " + this.urlFileIndex.size();
assert this.urlFileIndex.has(hash) : "hash = " + ASCII.String(hash);
// add the hash to a queue
pushHashToDomainStacks(entry.url().getHost(), entry.url().hash());
return null;
}
}
private void pushHashToDomainStacks(String host, final byte[] urlhash) throws RowSpaceExceededException {
// extend domain stack
if (host == null) host = localhost;
HandleSet domainList = this.domainStacks.get(host);
if (domainList == null) {
// create new list
domainList = new HandleSet(12, Base64Order.enhancedCoder, 1);
domainList.put(urlhash);
this.domainStacks.put(host, domainList);
} else {
// extend existent domain list
domainList.put(urlhash);
}
}
private void removeHashFromDomainStacks(String host, final byte[] urlhash) {
// reduce domain stack
if (host == null) host = localhost;
final HandleSet domainList = this.domainStacks.get(host);
if (domainList == null) {
this.domainStacks.remove(host);
return;
}
domainList.remove(urlhash);
if (domainList.isEmpty()) this.domainStacks.remove(host);
}
private byte[] nextFromDelayed() {
if (this.delayed.isEmpty()) return null;
final Long first = this.delayed.firstKey();
if (first.longValue() < System.currentTimeMillis()) {
return this.delayed.remove(first);
}
return null;
}
private byte[] anyFromDelayed() {
if (this.delayed.isEmpty()) return null;
final Long first = this.delayed.firstKey();
return this.delayed.remove(first);
}
/**
* get the next entry in this crawl queue in such a way that the domain access time delta is maximized
* and always above the given minimum delay time. An additional delay time is computed using the robots.txt
* crawl-delay time which is always respected. In case the minimum time cannot ensured, this method pauses
* the necessary time until the url is released and returned as CrawlEntry object. In case that a profile
* for the computed Entry does not exist, null is returned
* @param delay true if the requester demands forced delays using explicit thread sleep
* @param profile
* @return a url in a CrawlEntry object
* @throws IOException
* @throws RowSpaceExceededException
*/
public Request pop(final boolean delay, final CrawlSwitchboard cs) throws IOException {
// returns a crawl entry from the stack and ensures minimum delta times
try {
filltop(delay, -600000, false);
filltop(delay, -60000, false);
filltop(delay, -10000, false);
filltop(delay, -6000, false);
filltop(delay, -4000, false);
filltop(delay, -3000, false);
filltop(delay, -2000, false);
filltop(delay, -1000, false);
filltop(delay, -500, false);
filltop(delay, 0, true);
filltop(delay, 500, true);
filltop(delay, 1000, true);
filltop(delay, 2000, true);
filltop(delay, 3000, true);
filltop(delay, 4000, true);
filltop(delay, 6000, true);
filltop(delay, Long.MAX_VALUE, true);
} catch (final RowSpaceExceededException e) {}
long sleeptime = 0;
Request crawlEntry = null;
synchronized (this) {
byte[] failhash = null;
while (!this.urlFileIndex.isEmpty()) {
// first simply take one of the entries in the top list, that should be one without any delay
byte[] nexthash = nextFromDelayed();
//System.out.println("*** nextFromDelayed=" + nexthash);
if (nexthash == null && !this.top.isEmpty()) {
nexthash = this.top.remove();
//System.out.println("*** top.remove()=" + nexthash);
}
if (nexthash == null) {
nexthash = anyFromDelayed();
}
// check minimumDelta and if necessary force a sleep
//final int s = urlFileIndex.size();
Row.Entry rowEntry = (nexthash == null) ? null : this.urlFileIndex.remove(nexthash);
if (rowEntry == null) {
//System.out.println("*** rowEntry=null, nexthash=" + UTF8.String(nexthash));
rowEntry = this.urlFileIndex.removeOne();
if (rowEntry == null) {
nexthash = null;
} else {
nexthash = rowEntry.getPrimaryKeyBytes();
//System.out.println("*** rowEntry.getPrimaryKeyBytes()=" + UTF8.String(nexthash));
}
}
if (rowEntry == null) {
Log.logWarning("Balancer", "removeOne() failed - size = " + size());
return null;
}
//assert urlFileIndex.size() + 1 == s : "urlFileIndex.size() = " + urlFileIndex.size() + ", s = " + s + ", result = " + result;
crawlEntry = new Request(rowEntry);
//Log.logInfo("Balancer", "fetched next url: " + crawlEntry.url().toNormalform(true, false));
// at this point we must check if the crawlEntry has relevance because the crawl profile still exists
// if not: return null. A calling method must handle the null value and try again
final CrawlProfile profileEntry = cs.getActive(UTF8.getBytes(crawlEntry.profileHandle()));
if (profileEntry == null) {
Log.logWarning("Balancer", "no profile entry for handle " + crawlEntry.profileHandle());
return null;
}
// depending on the caching policy we need sleep time to avoid DoS-like situations
sleeptime = (
profileEntry.cacheStrategy() == CacheStrategy.CACHEONLY ||
(profileEntry.cacheStrategy() == CacheStrategy.IFEXIST && Cache.has(crawlEntry.url()))
) ? 0 : Latency.waitingRemaining(crawlEntry.url(), this.myAgentIDs, this.minimumLocalDelta, this.minimumGlobalDelta); // this uses the robots.txt database and may cause a loading of robots.txt from the server
assert Base64Order.enhancedCoder.equal(nexthash, rowEntry.getPrimaryKeyBytes()) : "result = " + ASCII.String(nexthash) + ", rowEntry.getPrimaryKeyBytes() = " + ASCII.String(rowEntry.getPrimaryKeyBytes());
assert Base64Order.enhancedCoder.equal(nexthash, crawlEntry.url().hash()) : "result = " + ASCII.String(nexthash) + ", crawlEntry.url().hash() = " + ASCII.String(crawlEntry.url().hash());
if (failhash != null && Base64Order.enhancedCoder.equal(failhash, nexthash)) break; // prevent endless loops
if (delay && sleeptime > 0 && this.domStackInitSize > 1) {
//System.out.println("*** putback: nexthash=" + nexthash + ", failhash="+failhash);
// put that thing back to omit a delay here
if (!ByteBuffer.contains(this.delayed.values(), nexthash)) {
//System.out.println("*** delayed +=" + nexthash);
this.delayed.put(Long.valueOf(System.currentTimeMillis() + sleeptime + 1), nexthash);
}
try {
this.urlFileIndex.put(rowEntry);
String host = crawlEntry.url().getHost();
if (host == null) host = localhost;
this.domainStacks.remove(host);
failhash = nexthash;
} catch (final RowSpaceExceededException e) {
Log.logException(e);
}
continue;
}
break;
}
if (crawlEntry != null) {
if (this.ddc.size() > 10000 || MemoryControl.shortStatus()) this.ddc.clear();
try { this.ddc.put(crawlEntry.url().hash()); } catch (final RowSpaceExceededException e) {}
}
}
if (crawlEntry == null) return null;
if (delay && sleeptime > 0) {
// force a busy waiting here
// in best case, this should never happen if the balancer works propertly
// this is only to protection against the worst case, where the crawler could
// behave in a DoS-manner
Log.logInfo("BALANCER", "forcing crawl-delay of " + sleeptime + " milliseconds for " + crawlEntry.url().getHost() + ": " + Latency.waitingRemainingExplain(crawlEntry.url(), this.myAgentIDs, this.minimumLocalDelta, this.minimumGlobalDelta) + ", top.size() = " + this.top.size() + ", delayed.size() = " + this.delayed.size() + ", domainStacks.size() = " + this.domainStacks.size() + ", domainStacksInitSize = " + this.domStackInitSize);
long loops = sleeptime / 1000;
long rest = sleeptime % 1000;
if (loops < 3) {
rest = rest + 1000 * loops;
loops = 0;
}
if (rest > 0) {try {this.wait(rest); } catch (final InterruptedException e) {}}
for (int i = 0; i < loops; i++) {
Log.logInfo("BALANCER", "waiting for " + crawlEntry.url().getHost() + ": " + (loops - i) + " seconds remaining...");
try {this.wait(1000); } catch (final InterruptedException e) {}
}
}
this.ddc.remove(crawlEntry.url().hash());
Latency.update(crawlEntry.url());
return crawlEntry;
}
private void filltop(final boolean delay, final long maximumwaiting, final boolean acceptonebest) throws RowSpaceExceededException {
if (!this.top.isEmpty()) return;
//System.out.println("*** DEBUG started filltop delay=" + ((delay) ? "true":"false") + ", maximumwaiting=" + maximumwaiting + ", acceptonebest=" + ((acceptonebest) ? "true":"false"));
// check if we need to get entries from the file index
try {
fillDomainStacks();
} catch (final IOException e) {
Log.logException(e);
}
// iterate over the domain stacks
final Iterator<Map.Entry<String, HandleSet>> i = this.domainStacks.entrySet().iterator();
Map.Entry<String, HandleSet> entry;
long smallestWaiting = Long.MAX_VALUE;
byte[] besturlhash = null;
String besthost = null;
while (i.hasNext()) {
entry = i.next();
// clean up empty entries
if (entry.getValue().isEmpty()) {
i.remove();
continue;
}
final byte[] n = entry.getValue().removeOne();
if (n == null) continue;
if (delay) {
final long w = Latency.waitingRemainingGuessed(entry.getKey(), this.minimumLocalDelta, this.minimumGlobalDelta);
if (w > maximumwaiting) {
if (w < smallestWaiting) {
smallestWaiting = w;
besturlhash = n;
besthost = entry.getKey();
}
entry.getValue().put(n); // put entry back
continue;
}
}
this.top.add(n);
if (entry.getValue().isEmpty()) i.remove();
}
// if we could not find any entry, then take the best we have seen so far
if (acceptonebest && !this.top.isEmpty() && besturlhash != null) {
removeHashFromDomainStacks(besthost, besturlhash);
this.top.add(besturlhash);
}
}
private void fillDomainStacks() throws IOException {
if (!this.domainStacks.isEmpty() && System.currentTimeMillis() - this.lastDomainStackFill < 120000L) return;
this.domainStacks.clear();
this.top.clear();
this.lastDomainStackFill = System.currentTimeMillis();
final HandleSet handles = this.urlFileIndex.keysFromBuffer(objectIndexBufferSize / 2);
final CloneableIterator<byte[]> i = handles.keys(true, null);
byte[] handle;
String host;
Request request;
while (i.hasNext()) {
handle = i.next();
final Row.Entry entry = this.urlFileIndex.get(handle);
if (entry == null) continue;
request = new Request(entry);
host = request.url().getHost();
try {
pushHashToDomainStacks(host, handle);
} catch (final RowSpaceExceededException e) {
break;
}
}
Log.logInfo("BALANCER", "re-fill of domain stacks; fileIndex.size() = " + this.urlFileIndex.size() + ", domainStacks.size = " + this.domainStacks.size() + ", collection time = " + (System.currentTimeMillis() - this.lastDomainStackFill) + " ms");
this.domStackInitSize = this.domainStacks.size();
}
public List<Request> top(int count) {
final List<Request> cel = new ArrayList<Request>();
if (count == 0) return cel;
byte[][] ta = new byte[Math.min(count, this.top.size())][];
ta = this.top.toArray(ta);
for (final byte[] n: ta) {
if (n == null) break;
try {
final Row.Entry rowEntry = this.urlFileIndex.get(n);
if (rowEntry == null) continue;
final Request crawlEntry = new Request(rowEntry);
cel.add(crawlEntry);
count--;
if (count <= 0) break;
} catch (final IOException e) {}
}
int depth = 0;
loop: while (count > 0) {
// iterate over the domain stacks
final int celsize = cel.size();
ll: for (final HandleSet list: this.domainStacks.values()) {
if (list.size() <= depth) continue ll;
final byte[] n = list.getOne(depth);
if (n == null) continue ll;
try {
final Row.Entry rowEntry = this.urlFileIndex.get(n);
if (rowEntry == null) continue;
final Request crawlEntry = new Request(rowEntry);
cel.add(crawlEntry);
count--;
if (count <= 0) break loop;
} catch (final IOException e) {}
}
if (cel.size() == celsize) break loop;
depth++;
}
if (cel.size() < count) try {
final List<Row.Entry> list = this.urlFileIndex.top(count - cel.size());
for (final Row.Entry entry: list) cel.add(new Request(entry));
} catch (final IOException e) { }
return cel;
}
public Iterator<Request> iterator() throws IOException {
return new EntryIterator();
}
private class EntryIterator implements Iterator<Request> {
private Iterator<Row.Entry> rowIterator;
public EntryIterator() throws IOException {
this.rowIterator = Balancer.this.urlFileIndex.rows();
}
public boolean hasNext() {
return (this.rowIterator == null) ? false : this.rowIterator.hasNext();
}
public Request next() {
final Row.Entry entry = this.rowIterator.next();
try {
return (entry == null) ? null : new Request(entry);
} catch (final IOException e) {
Log.logException(e);
this.rowIterator = null;
return null;
}
}
public void remove() {
if (this.rowIterator != null) this.rowIterator.remove();
}
}
}