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1533bfd63b
yacy_search_server/source/net/yacy/peers/Dispatcher.java
Michael Peter Christen 1533bfd63b refactoring
2012-09-25 21:20:03 +02:00

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// Dispatcher.java
// ------------------------------
// part of YaCy
// (C) 2009 by Michael Peter Christen; mc@yacy.net
// first published on http://yacy.net
// Frankfurt, Germany, 28.01.2009
//
// $LastChangedDate$
// $LastChangedRevision$
// $LastChangedBy$
//
// 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.peers;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import net.yacy.cora.document.ASCII;
import net.yacy.cora.federate.yacy.Distribution;
import net.yacy.cora.order.Base64Order;
import net.yacy.cora.storage.HandleSet;
import net.yacy.cora.util.SpaceExceededException;
import net.yacy.kelondro.data.meta.URIMetadataRow;
import net.yacy.kelondro.data.word.Word;
import net.yacy.kelondro.data.word.WordReference;
import net.yacy.kelondro.index.RowHandleSet;
import net.yacy.kelondro.logging.Log;
import net.yacy.kelondro.rwi.ReferenceContainer;
import net.yacy.kelondro.util.ByteArray;
import net.yacy.kelondro.workflow.WorkflowProcessor;
import net.yacy.search.index.Segment;
public class Dispatcher {
/**
* the dispatcher class accumulates indexContainerCache objects before they are transfered
* to other peers. A dispatcher holds several of such caches to enhance the transmission process.
* Before a RWI is sent, the following process is applied:
* - (1) a number of RWIs are selected and accumulated.
* When they are selected, they are removed from the index
* - (2) the RWI collection is split into a number of partitions according to the vertical DHT.
* - (3) the split RWIs are enqueued as Entry object in the entry 'cloud' of the dispatcher
* - (4) more entries may be enqueued to the dispatcher and entries with the same primary target
* are accumulated.
* - (5) the largest entries are selected from the dispatcher cloud and enqueued to the 'next' array
* which means that they are ready for transmission
* - (6) the dispatcher takes some of the entries in the next queue and initiates
* transmission to other peers concurrently. As much transmissions are initiated concurrently
* as the redundancy factor.
* - (7) a transmission thread executes the entry transmission.
* - (8) the transmission thread initiates another transmission in case that it fails
* - (9) when the wanted number of redundant peers have received the entries,
* they are removed from the next queue
* Concurrency in this process:
* 1-3 follow directly and should be synchronous because of the database operation that are used
* 4 is a repeated action of 1-3 and should be done in a busyThread
* 5&6 is a repeated action as (4), but must be executed multiple times of (4) in a busyThread,
* which idle is shorter than the idle time of (4)
* 7&8 this is done concurrently with other transmission threads for the same entry and other entries
* for example, if the redundancy factor is 3 and 2 entries are in the 'next' queue, then 6
* transmissions are running concurrently
* 9 concurrency ends for the transmission, if the wanted number of redundant peers received the entry,
* or the target queue runs out of entries. If the target queue is empty, the transmission is
* called failed. In case of a fail, the RWI fragment is put back into the backend index structure
*/
// a cloud is a cache for the objects that wait to be transmitted
// the String-key is the primary target as contained in the Entry
private Map<ByteArray, Transmission.Chunk> transmissionCloud;
// the segment backend is used to store the remaining indexContainers in case that the object is closed
private final Segment segment;
// the seed database
private final SeedDB seeds;
// the log
private final Log log;
// transmission process
private WorkflowProcessor<Transmission.Chunk> indexingTransmissionProcessor;
// transmission object
private final Transmission transmission;
public Dispatcher(
final Segment segment,
final SeedDB seeds,
final boolean gzipBody,
final int timeout
) {
this.transmissionCloud = new ConcurrentHashMap<ByteArray, Transmission.Chunk>();
this.segment = segment;
this.seeds = seeds;
this.log = new Log("INDEX-TRANSFER-DISPATCHER");
this.transmission = new Transmission(
this.log,
segment,
seeds,
gzipBody,
timeout);
final int concurrentSender = Math.min(32, Math.max(10, WorkflowProcessor.availableCPU));
this.indexingTransmissionProcessor = new WorkflowProcessor<Transmission.Chunk>(
"transferDocumentIndex",
"This is the RWI transmission process",
new String[]{"RWI/Cache/Collections"},
this, "transferDocumentIndex", concurrentSender * 2, null, concurrentSender);
}
public int cloudSize() {
return (this.transmissionCloud == null) ? 0 : this.transmissionCloud.size();
}
public int transmissionSize() {
return (this.indexingTransmissionProcessor == null) ? 0 : this.indexingTransmissionProcessor.queueSize();
}
/**
* PROCESS(1)
* select a number of index containers from the backend index.
* Selected containers are removed from the backend.
* @param hash
* @param limitHash
* @param maxContainerCount
* @param maxtime
* @return
* @throws IOException
*/
private ArrayList<ReferenceContainer<WordReference>> selectContainers(
final byte[] hash,
final byte[] limitHash,
final int maxContainerCount,
final int maxReferenceCount,
final int maxtime) throws IOException {
// prefer file
final ArrayList<ReferenceContainer<WordReference>> containers = selectContainers(hash, limitHash, maxContainerCount, maxReferenceCount, maxtime, false);
// if ram does not provide any result, take from file
//if (containers.isEmpty()) containers = selectContainers(hash, limitHash, maxContainerCount, maxtime, false);
return containers;
}
private ArrayList<ReferenceContainer<WordReference>> selectContainers(
final byte[] hash,
final byte[] limitHash,
final int maxContainerCount,
final int maxReferenceCount,
final int maxtime,
final boolean ram) throws IOException {
final ArrayList<ReferenceContainer<WordReference>> containers = new ArrayList<ReferenceContainer<WordReference>>(maxContainerCount);
final Iterator<ReferenceContainer<WordReference>> indexContainerIterator = this.segment.termIndex().referenceContainerIterator(hash, true, true, ram); // very important that rotation is true here
ReferenceContainer<WordReference> container;
int refcount = 0;
// first select the container
final long timeout = (maxtime < 0) ? Long.MAX_VALUE : System.currentTimeMillis() + maxtime;
while (
(containers.size() < maxContainerCount) &&
(refcount < maxReferenceCount) &&
(indexContainerIterator.hasNext()) &&
(System.currentTimeMillis() < timeout) &&
((container = indexContainerIterator.next()) != null) &&
((containers.isEmpty()) ||
(Base64Order.enhancedCoder.compare(container.getTermHash(), limitHash) < 0))
) {
if (container.isEmpty()) continue;
if (Word.isPrivate(container.getTermHash())) continue; // exclude private containers
refcount += container.size();
containers.add(container);
}
// then remove the container from the backend
final ArrayList<ReferenceContainer<WordReference>> rc;
if (ram) {
// selection was only from ram, so we have to carefully remove only the selected entries
final HandleSet urlHashes = new RowHandleSet(URIMetadataRow.rowdef.primaryKeyLength, URIMetadataRow.rowdef.objectOrder, 0);
Iterator<WordReference> it;
for (final ReferenceContainer<WordReference> c: containers) {
urlHashes.clear();
it = c.entries();
while (it.hasNext()) try { urlHashes.put(it.next().urlhash()); } catch (final SpaceExceededException e) { Log.logException(e); }
if (this.log.isFine()) this.log.logFine("selected " + urlHashes.size() + " urls for word '" + ASCII.String(c.getTermHash()) + "'");
if (!urlHashes.isEmpty()) this.segment.termIndex().remove(c.getTermHash(), urlHashes);
}
rc = containers;
} else {
// selection was from whole index, so we can just delete the whole container
// but to avoid race conditions return the results from the deletes
rc = new ArrayList<ReferenceContainer<WordReference>>(containers.size());
for (final ReferenceContainer<WordReference> c: containers) {
container = this.segment.termIndex().remove(c.getTermHash()); // be aware this might be null!
if (container != null && !container.isEmpty()) {
if (this.log.isFine()) this.log.logFine("selected " + container.size() + " urls for word '" + ASCII.String(c.getTermHash()) + "'");
rc.add(container);
}
}
}
// finished. The caller must take care of the containers and must put them back if not needed
return rc;
}
/**
* PROCESS(2)
* split a list of containers into partitions according to the vertical distribution scheme
* @param containers
* @param scheme
* @return
* @throws SpaceExceededException
*/
@SuppressWarnings("unchecked")
private List<ReferenceContainer<WordReference>>[] splitContainers(final List<ReferenceContainer<WordReference>> containers) throws SpaceExceededException {
// init the result vector
final int partitionCount = this.seeds.scheme.verticalPartitions();
final List<ReferenceContainer<WordReference>>[] partitions = new ArrayList[partitionCount];
for (int i = 0; i < partitions.length; i++) partitions[i] = new ArrayList<ReferenceContainer<WordReference>>();
// check all entries and split them to the partitions
final ReferenceContainer<WordReference>[] partitionBuffer = new ReferenceContainer[partitionCount];
WordReference re;
for (final ReferenceContainer<WordReference> container: containers) {
// init the new partitions
for (int j = 0; j < partitionBuffer.length; j++) {
partitionBuffer[j] = new ReferenceContainer<WordReference>(Segment.wordReferenceFactory, container.getTermHash(), container.size() / partitionCount);
}
// split the container
final Iterator<WordReference> i = container.entries();
while (i.hasNext()) {
re = i.next();
if (re == null) continue;
partitionBuffer[this.seeds.scheme.verticalDHTPosition(re.urlhash())].add(re);
}
// add the containers to the result vector
for (int j = 0; j < partitionBuffer.length; j++) {
partitions[j].add(partitionBuffer[j]);
}
}
return partitions;
}
/**
* PROCESS(3) and PROCESS(4)
* put containers into cloud. This needs information about the network,
* because the possible targets are assigned here as well. The indexRepositoryReference
* is the database of references which is needed here because this is the place where
* finally is checked if the reference exists. If the entry does not exist for specific
* entries in the indexContainer, then it is discarded. If it exists, then the entry is
* stored in a cache of the Entry for later transmission to the targets, which means that
* then no additional IO is necessary.
*/
private void enqueueContainersToCloud(final List<ReferenceContainer<WordReference>>[] containers) {
assert (containers.length == this.seeds.scheme.verticalPartitions());
if (this.transmissionCloud == null) return;
ReferenceContainer<WordReference> lastContainer;
byte[] primaryTarget;
ByteArray pTArray;
Transmission.Chunk entry;
for (int vertical = 0; vertical < containers.length; vertical++) {
// the 'new' primary target is the word hash of the last container in the array
lastContainer = containers[vertical].get(containers[vertical].size() - 1);
primaryTarget = Distribution.positionToHash(this.seeds.scheme.verticalDHTPosition(lastContainer.getTermHash(), vertical));
assert primaryTarget[2] != '@';
pTArray = new ByteArray(primaryTarget);
// get or make a entry object
entry = this.transmissionCloud.get(pTArray); // if this is not null, the entry is extended here
final List<Seed> targets = DHTSelection.getAcceptRemoteIndexSeedsList(
this.seeds,
primaryTarget,
this.seeds.redundancy() * 3,
true);
this.log.logInfo("enqueueContainers: selected " + targets.size() + " targets for primary target key " + ASCII.String(primaryTarget) + "/" + vertical + " with " + containers[vertical].size() + " index containers.");
if (entry == null) entry = this.transmission.newChunk(primaryTarget, targets);
/*/ lookup targets
int sc = 1;
for (yacySeed seed : targets) {
if(seed == null) continue;
if(seed == seeds.mySeed()) this.log.logInfo("enqueueContainers: myself-target at position " + sc);
this.log.logInfo("enqueueContainers: primaryTarget distance at position " + sc + ": " + FlatWordPartitionScheme.std.dhtDistance(primaryTarget, null, seed));
this.log.logInfo("enqueueContainers: distance to first container at position " + sc + ": " + FlatWordPartitionScheme.std.dhtDistance(FlatWordPartitionScheme.positionToHash(this.seeds.scheme.dhtPosition(containers[vertical].get(0).getTermHash(), vertical)), null, seed));
sc++;
}*/
// fill the entry with the containers
for (final ReferenceContainer<WordReference> c: containers[vertical]) {
try {
entry.add(c);
} catch (final SpaceExceededException e) {
Log.logException(e);
break;
}
}
// put the entry into the cloud
if (entry.containersSize() > 0) this.transmissionCloud.put(pTArray, entry);
}
}
public boolean selectContainersEnqueueToCloud(
final byte[] hash,
final byte[] limitHash,
final int maxContainerCount,
final int maxReferenceCount,
final int maxtime) {
if (this.transmissionCloud == null) return false;
List<ReferenceContainer<WordReference>> selectedContainerCache;
try {
selectedContainerCache = selectContainers(hash, limitHash, maxContainerCount, maxReferenceCount, maxtime);
} catch (final IOException e) {
this.log.logSevere("selectContainersEnqueueToCloud: selectedContainer failed", e);
return false;
}
this.log.logInfo("selectContainersEnqueueToCloud: selectedContainerCache was filled with " + selectedContainerCache.size() + " entries");
if (selectedContainerCache == null || selectedContainerCache.isEmpty()) {
this.log.logInfo("selectContainersEnqueueToCloud: selectedContainerCache is empty, cannot do anything here.");
return false;
}
List<ReferenceContainer<WordReference>>[] splitContainerCache;
try {
splitContainerCache = splitContainers(selectedContainerCache);
} catch (final SpaceExceededException e) {
this.log.logSevere("selectContainersEnqueueToCloud: splitContainers failed because of too low RAM", e);
return false;
}
selectedContainerCache = null;
if (splitContainerCache == null) {
this.log.logInfo("selectContainersEnqueueToCloud: splitContainerCache is empty, cannot do anything here.");
return false;
}
this.log.logInfo("splitContainersFromCache: splitContainerCache filled with " + splitContainerCache.length + " partitions, deleting selectedContainerCache");
if (splitContainerCache.length != this.seeds.scheme.verticalPartitions()) {
this.log.logWarning("selectContainersEnqueueToCloud: splitContainerCache has wrong length.");
return false;
}
enqueueContainersToCloud(splitContainerCache);
splitContainerCache = null;
this.log.logInfo("selectContainersEnqueueToCloud: splitContainerCache enqueued to cloud array which has now " + this.transmissionCloud.size() + " entries.");
return true;
}
/**
* PROCESS(5)
* take the largest container from the cloud and put it into the 'next' array,
* where it waits to be processed.
* This method returns true if a container was dequeued, false if not
*/
public boolean dequeueContainer() {
if (this.transmissionCloud == null) return false;
if (this.indexingTransmissionProcessor.queueSize() > this.indexingTransmissionProcessor.concurrency()) return false;
ByteArray maxtarget = null;
int maxsize = -1;
for (final Map.Entry<ByteArray, Transmission.Chunk> chunk: this.transmissionCloud.entrySet()) {
if (chunk.getValue().containersSize() > maxsize) {
maxsize = chunk.getValue().containersSize();
maxtarget = chunk.getKey();
}
}
if (maxsize < 0) return false;
final Transmission.Chunk chunk = this.transmissionCloud.remove(maxtarget);
try {
this.indexingTransmissionProcessor.enQueue(chunk);
} catch (final InterruptedException e) {
Log.logException(e);
}
return true;
}
/**
* transfer job: this method is called using reflection from the switchboard
* the method is called as a Workflow process. That means it is always called whenever
* a job is placed in the workflow queue. This happens in dequeueContainer()
* @param chunk
* @return
*/
public Transmission.Chunk transferDocumentIndex(final Transmission.Chunk chunk) {
// do the transmission
final boolean success = chunk.transmit();
if (success && chunk.isFinished()) {
// finished with this queue!
this.log.logInfo("STORE: Chunk " + ASCII.String(chunk.primaryTarget()) + " has FINISHED all transmissions!");
return chunk;
}
if (!success) this.log.logInfo("STORE: Chunk " + ASCII.String(chunk.primaryTarget()) + " has failed to transmit index; marked peer as busy");
if (chunk.canFinish()) {
try {
if (this.indexingTransmissionProcessor != null) this.indexingTransmissionProcessor.enQueue(chunk);
} catch (final InterruptedException e) {
Log.logException(e);
return null;
}
return chunk;
}
this.log.logInfo("STORE: Chunk " + ASCII.String(chunk.primaryTarget()) + " has not enough targets left. This transmission has failed, putting back index to backend");
chunk.restore();
return null;
}
public void close() {
// removes all entries from the dispatcher and puts them back to a RAMRI
if (this.indexingTransmissionProcessor != null) this.indexingTransmissionProcessor.shutdown();
if (this.transmissionCloud != null) {
outerLoop: for (final Map.Entry<ByteArray, Transmission.Chunk> e : this.transmissionCloud.entrySet()) {
for (final ReferenceContainer<WordReference> i : e.getValue()) try {
this.segment.storeRWI(i);
} catch (final Exception e1) {
Log.logException(e1);
break outerLoop;
}
}
this.transmissionCloud.clear();
}
this.transmissionCloud = null;
if (this.indexingTransmissionProcessor != null) {
this.indexingTransmissionProcessor.clear();
}
this.indexingTransmissionProcessor = null;
}
}
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