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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cassandra.streaming;
import java.io.IOException;
import java.net.InetAddress;
import java.net.Socket;
import java.net.SocketTimeoutException;
import java.util.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicBoolean;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.*;
import org.apache.cassandra.concurrent.DebuggableScheduledThreadPoolExecutor;
import org.apache.cassandra.db.lifecycle.LifecycleTransaction;
import org.apache.cassandra.db.lifecycle.SSTableIntervalTree;
import org.apache.cassandra.db.lifecycle.SSTableSet;
import org.apache.cassandra.db.lifecycle.View;
import org.apache.cassandra.io.sstable.format.SSTableReader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.db.ColumnFamilyStore;
import org.apache.cassandra.db.Keyspace;
import org.apache.cassandra.db.PartitionPosition;
import org.apache.cassandra.dht.Range;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.gms.*;
import org.apache.cassandra.metrics.StreamingMetrics;
import org.apache.cassandra.service.ActiveRepairService;
import org.apache.cassandra.streaming.messages.*;
import org.apache.cassandra.utils.CassandraVersion;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.JVMStabilityInspector;
import org.apache.cassandra.utils.Pair;
import org.apache.cassandra.utils.concurrent.Ref;
import org.apache.cassandra.utils.concurrent.Refs;
/**
* Handles the streaming a one or more section of one of more sstables to and from a specific
* remote node.
*
* Both this node and the remote one will create a similar symmetrical StreamSession. A streaming
* session has the following life-cycle:
*
* 1. Connections Initialization
*
* (a) A node (the initiator in the following) create a new StreamSession, initialize it (init())
* and then start it (start()). Start will create a {@link ConnectionHandler} that will create
* two connections to the remote node (the follower in the following) with whom to stream and send
* a StreamInit message. The first connection will be the incoming connection for the
* initiator, and the second connection will be the outgoing.
* (b) Upon reception of that StreamInit message, the follower creates its own StreamSession,
* initialize it if it still does not exist, and attach connecting socket to its ConnectionHandler
* according to StreamInit message's isForOutgoing flag.
* (d) When the both incoming and outgoing connections are established, StreamSession calls
* StreamSession#onInitializationComplete method to start the streaming prepare phase
* (StreamResultFuture.startStreaming()).
*
* 2. Streaming preparation phase
*
* (a) This phase is started when the initiator onInitializationComplete() method is called. This method sends a
* PrepareMessage that includes what files/sections this node will stream to the follower
* (stored in a StreamTransferTask, each column family has it's own transfer task) and what
* the follower needs to stream back (StreamReceiveTask, same as above). If the initiator has
* nothing to receive from the follower, it goes directly to its Streaming phase. Otherwise,
* it waits for the follower PrepareMessage.
* (b) Upon reception of the PrepareMessage, the follower records which files/sections it will receive
* and send back its own PrepareMessage with a summary of the files/sections that will be sent to
* the initiator (prepare()). After having sent that message, the follower goes to its Streamning
* phase.
* (c) When the initiator receives the follower PrepareMessage, it records which files/sections it will
* receive and then goes to his own Streaming phase.
*
* 3. Streaming phase
*
* (a) The streaming phase is started by each node (the sender in the follower, but note that each side
* of the StreamSession may be sender for some of the files) involved by calling startStreamingFiles().
* This will sequentially send a FileMessage for each file of each SteamTransferTask. Each FileMessage
* consists of a FileMessageHeader that indicates which file is coming and then start streaming the
* content for that file (StreamWriter in FileMessage.serialize()). When a file is fully sent, the
* fileSent() method is called for that file. If all the files for a StreamTransferTask are sent
* (StreamTransferTask.complete()), the task is marked complete (taskCompleted()).
* (b) On the receiving side, a SSTable will be written for the incoming file (StreamReader in
* FileMessage.deserialize()) and once the FileMessage is fully received, the file will be marked as
* complete (received()). When all files for the StreamReceiveTask have been received, the sstables
* are added to the CFS (and 2ndary index are built, StreamReceiveTask.complete()) and the task
* is marked complete (taskCompleted())
* (b) If during the streaming of a particular file an error occurs on the receiving end of a stream
* (FileMessage.deserialize), the node will send a SessionFailedMessage to the sender and close the stream session.
* (c) When all transfer and receive tasks for a session are complete, the move to the Completion phase
* (maybeCompleted()).
*
* 4. Completion phase
*
* (a) When a node has finished all transfer and receive task, it enter the completion phase (maybeCompleted()).
* If it had already received a CompleteMessage from the other side (it is in the WAIT_COMPLETE state), that
* session is done is is closed (closeSession()). Otherwise, the node switch to the WAIT_COMPLETE state and
* send a CompleteMessage to the other side.
*/
public class StreamSession implements IEndpointStateChangeSubscriber
{
/**
* Version where keep-alive support was added
*/
private static final CassandraVersion STREAM_KEEP_ALIVE = new CassandraVersion("3.10");
private static final Logger logger = LoggerFactory.getLogger(StreamSession.class);
private static final DebuggableScheduledThreadPoolExecutor keepAliveExecutor = new DebuggableScheduledThreadPoolExecutor("StreamKeepAliveExecutor");
static {
// Immediately remove keep-alive task when cancelled.
keepAliveExecutor.setRemoveOnCancelPolicy(true);
}
/**
* Streaming endpoint.
*
* Each {@code StreamSession} is identified by this InetAddress which is broadcast address of the node streaming.
*/
public final InetAddress peer;
private final int index;
/** Actual connecting address. Can be the same as {@linkplain #peer}. */
public final InetAddress connecting;
// should not be null when session is started
private StreamResultFuture streamResult;
// stream requests to send to the peer
protected final Set requests = Sets.newConcurrentHashSet();
// streaming tasks are created and managed per ColumnFamily ID
@VisibleForTesting
protected final ConcurrentHashMap transfers = new ConcurrentHashMap<>();
// data receivers, filled after receiving prepare message
private final Map receivers = new ConcurrentHashMap<>();
private final StreamingMetrics metrics;
/* can be null when session is created in remote */
private final StreamConnectionFactory factory;
public final Map>> transferredRangesPerKeyspace = new HashMap<>();
public final ConnectionHandler handler;
private AtomicBoolean isAborted = new AtomicBoolean(false);
private final boolean keepSSTableLevel;
private final boolean isIncremental;
private ScheduledFuture keepAliveFuture = null;
public static enum State
{
INITIALIZED,
PREPARING,
STREAMING,
WAIT_COMPLETE,
COMPLETE,
FAILED,
}
private volatile State state = State.INITIALIZED;
private volatile boolean completeSent = false;
/**
* Create new streaming session with the peer.
*
* @param peer Address of streaming peer
* @param connecting Actual connecting address
* @param factory is used for establishing connection
*/
public StreamSession(InetAddress peer, InetAddress connecting, StreamConnectionFactory factory, int index, boolean keepSSTableLevel, boolean isIncremental)
{
this.peer = peer;
this.connecting = connecting;
this.index = index;
this.factory = factory;
this.handler = new ConnectionHandler(this, isKeepAliveSupported()?
(int)TimeUnit.SECONDS.toMillis(2 * DatabaseDescriptor.getStreamingKeepAlivePeriod()) :
DatabaseDescriptor.getStreamingSocketTimeout());
this.metrics = StreamingMetrics.get(connecting);
this.keepSSTableLevel = keepSSTableLevel;
this.isIncremental = isIncremental;
}
public UUID planId()
{
return streamResult == null ? null : streamResult.planId;
}
public int sessionIndex()
{
return index;
}
public String description()
{
return streamResult == null ? null : streamResult.description;
}
public boolean keepSSTableLevel()
{
return keepSSTableLevel;
}
public boolean isIncremental()
{
return isIncremental;
}
public LifecycleTransaction getTransaction(UUID cfId)
{
assert receivers.containsKey(cfId);
return receivers.get(cfId).getTransaction();
}
private boolean isKeepAliveSupported()
{
CassandraVersion peerVersion = Gossiper.instance.getReleaseVersion(peer);
return STREAM_KEEP_ALIVE.isSupportedBy(peerVersion);
}
/**
* Bind this session to report to specific {@link StreamResultFuture} and
* perform pre-streaming initialization.
*
* @param streamResult result to report to
*/
public void init(StreamResultFuture streamResult)
{
this.streamResult = streamResult;
StreamHook.instance.reportStreamFuture(this, streamResult);
if (isKeepAliveSupported())
scheduleKeepAliveTask();
else
logger.debug("Peer {} does not support keep-alive.", peer);
}
public void start()
{
if (requests.isEmpty() && transfers.isEmpty())
{
logger.info("[Stream #{}] Session does not have any tasks.", planId());
closeSession(State.COMPLETE);
return;
}
try
{
logger.info("[Stream #{}] Starting streaming to {}{}", planId(),
peer,
peer.equals(connecting) ? "" : " through " + connecting);
handler.initiate();
onInitializationComplete();
}
catch (Exception e)
{
JVMStabilityInspector.inspectThrowable(e);
onError(e);
}
}
public Socket createConnection() throws IOException
{
assert factory != null;
return factory.createConnection(connecting);
}
/**
* Request data fetch task to this session.
*
* @param keyspace Requesting keyspace
* @param ranges Ranges to retrieve data
* @param columnFamilies ColumnFamily names. Can be empty if requesting all CF under the keyspace.
*/
public void addStreamRequest(String keyspace, Collection> ranges, Collection columnFamilies, long repairedAt)
{
requests.add(new StreamRequest(keyspace, ranges, columnFamilies, repairedAt));
}
/**
* Set up transfer for specific keyspace/ranges/CFs
*
* Used in repair - a streamed sstable in repair will be marked with the given repairedAt time
*
* @param keyspace Transfer keyspace
* @param ranges Transfer ranges
* @param columnFamilies Transfer ColumnFamilies
* @param flushTables flush tables?
* @param repairedAt the time the repair started.
*/
public synchronized void addTransferRanges(String keyspace, Collection> ranges, Collection columnFamilies, boolean flushTables, long repairedAt)
{
failIfFinished();
Collection stores = getColumnFamilyStores(keyspace, columnFamilies);
if (flushTables)
flushSSTables(stores);
List> normalizedRanges = Range.normalize(ranges);
List sections = getSSTableSectionsForRanges(normalizedRanges, stores, repairedAt, isIncremental);
try
{
addTransferFiles(sections);
Set> toBeUpdated = transferredRangesPerKeyspace.get(keyspace);
if (toBeUpdated == null)
{
toBeUpdated = new HashSet<>();
}
toBeUpdated.addAll(ranges);
transferredRangesPerKeyspace.put(keyspace, toBeUpdated);
}
finally
{
for (SSTableStreamingSections release : sections)
release.ref.release();
}
}
private void failIfFinished()
{
if (state() == State.COMPLETE || state() == State.FAILED)
throw new RuntimeException(String.format("Stream %s is finished with state %s", planId(), state().name()));
}
private Collection getColumnFamilyStores(String keyspace, Collection columnFamilies)
{
Collection stores = new HashSet<>();
// if columnfamilies are not specified, we add all cf under the keyspace
if (columnFamilies.isEmpty())
{
stores.addAll(Keyspace.open(keyspace).getColumnFamilyStores());
}
else
{
for (String cf : columnFamilies)
stores.add(Keyspace.open(keyspace).getColumnFamilyStore(cf));
}
return stores;
}
@VisibleForTesting
public static List getSSTableSectionsForRanges(Collection> ranges, Collection stores, long overriddenRepairedAt, final boolean isIncremental)
{
Refs refs = new Refs<>();
try
{
for (ColumnFamilyStore cfStore : stores)
{
final List> keyRanges = new ArrayList<>(ranges.size());
for (Range range : ranges)
keyRanges.add(Range.makeRowRange(range));
refs.addAll(cfStore.selectAndReference(view -> {
Set sstables = Sets.newHashSet();
SSTableIntervalTree intervalTree = SSTableIntervalTree.build(view.select(SSTableSet.CANONICAL));
for (Range keyRange : keyRanges)
{
// keyRange excludes its start, while sstableInBounds is inclusive (of both start and end).
// This is fine however, because keyRange has been created from a token range through Range.makeRowRange (see above).
// And that later method uses the Token.maxKeyBound() method to creates the range, which return a "fake" key that
// sort after all keys having the token. That "fake" key cannot however be equal to any real key, so that even
// including keyRange.left will still exclude any key having the token of the original token range, and so we're
// still actually selecting what we wanted.
for (SSTableReader sstable : View.sstablesInBounds(keyRange.left, keyRange.right, intervalTree))
{
if (!isIncremental || !sstable.isRepaired())
sstables.add(sstable);
}
}
if (logger.isDebugEnabled())
logger.debug("ViewFilter for {}/{} sstables", sstables.size(), Iterables.size(view.select(SSTableSet.CANONICAL)));
return sstables;
}).refs);
}
List sections = new ArrayList<>(refs.size());
for (SSTableReader sstable : refs)
{
long repairedAt = overriddenRepairedAt;
if (overriddenRepairedAt == ActiveRepairService.UNREPAIRED_SSTABLE)
repairedAt = sstable.getSSTableMetadata().repairedAt;
sections.add(new SSTableStreamingSections(refs.get(sstable),
sstable.getPositionsForRanges(ranges),
sstable.estimatedKeysForRanges(ranges),
repairedAt));
}
return sections;
}
catch (Throwable t)
{
refs.release();
throw t;
}
}
public synchronized void addTransferFiles(Collection sstableDetails)
{
failIfFinished();
Iterator iter = sstableDetails.iterator();
while (iter.hasNext())
{
SSTableStreamingSections details = iter.next();
if (details.sections.isEmpty())
{
// A reference was acquired on the sstable and we won't stream it
details.ref.release();
iter.remove();
continue;
}
UUID cfId = details.ref.get().metadata.cfId;
StreamTransferTask task = transfers.get(cfId);
if (task == null)
{
//guarantee atomicity
StreamTransferTask newTask = new StreamTransferTask(this, cfId);
task = transfers.putIfAbsent(cfId, newTask);
if (task == null)
task = newTask;
}
task.addTransferFile(details.ref, details.estimatedKeys, details.sections, details.repairedAt);
iter.remove();
}
}
public static class SSTableStreamingSections
{
public final Ref ref;
public final List> sections;
public final long estimatedKeys;
public final long repairedAt;
public SSTableStreamingSections(Ref ref, List> sections, long estimatedKeys, long repairedAt)
{
this.ref = ref;
this.sections = sections;
this.estimatedKeys = estimatedKeys;
this.repairedAt = repairedAt;
}
}
private synchronized void closeSession(State finalState)
{
if (isAborted.compareAndSet(false, true))
{
state(finalState);
if (finalState == State.FAILED)
{
for (StreamTask task : Iterables.concat(receivers.values(), transfers.values()))
task.abort();
}
if (keepAliveFuture != null)
{
logger.debug("[Stream #{}] Finishing keep-alive task.", planId());
keepAliveFuture.cancel(false);
keepAliveFuture = null;
}
// Note that we shouldn't block on this close because this method is called on the handler
// incoming thread (so we would deadlock).
handler.close();
streamResult.handleSessionComplete(this);
}
}
/**
* Set current state to {@code newState}.
*
* @param newState new state to set
*/
public void state(State newState)
{
state = newState;
}
/**
* @return current state
*/
public State state()
{
return state;
}
/**
* Return if this session completed successfully.
*
* @return true if session completed successfully.
*/
public boolean isSuccess()
{
return state == State.COMPLETE;
}
public void messageReceived(StreamMessage message)
{
switch (message.type)
{
case PREPARE:
PrepareMessage msg = (PrepareMessage) message;
prepare(msg.requests, msg.summaries);
break;
case FILE:
receive((IncomingFileMessage) message);
break;
case RECEIVED:
ReceivedMessage received = (ReceivedMessage) message;
received(received.cfId, received.sequenceNumber);
break;
case COMPLETE:
complete();
break;
case SESSION_FAILED:
sessionFailed();
break;
}
}
/**
* Call back when connection initialization is complete to start the prepare phase.
*/
public void onInitializationComplete()
{
// send prepare message
state(State.PREPARING);
PrepareMessage prepare = new PrepareMessage();
prepare.requests.addAll(requests);
for (StreamTransferTask task : transfers.values())
prepare.summaries.add(task.getSummary());
handler.sendMessage(prepare);
// if we don't need to prepare for receiving stream, start sending files immediately
if (requests.isEmpty())
startStreamingFiles();
}
/**l
* Call back for handling exception during streaming.
*
* @param e thrown exception
*/
public void onError(Throwable e)
{
logError(e);
// send session failure message
if (handler.isOutgoingConnected())
handler.sendMessage(new SessionFailedMessage());
// fail session
closeSession(State.FAILED);
}
private void logError(Throwable e)
{
if (e instanceof SocketTimeoutException)
{
if (isKeepAliveSupported())
logger.error("[Stream #{}] Did not receive response from peer {}{} for {} secs. Is peer down? " +
"If not, maybe try increasing streaming_keep_alive_period_in_secs.", planId(),
peer.getHostAddress(),
peer.equals(connecting) ? "" : " through " + connecting.getHostAddress(),
2 * DatabaseDescriptor.getStreamingKeepAlivePeriod(),
e);
else
logger.error("[Stream #{}] Streaming socket timed out. This means the session peer stopped responding or " +
"is still processing received data. If there is no sign of failure in the other end or a very " +
"dense table is being transferred you may want to increase streaming_socket_timeout_in_ms " +
"property. Current value is {}ms.", planId(), DatabaseDescriptor.getStreamingSocketTimeout(), e);
}
else
{
logger.error("[Stream #{}] Streaming error occurred on session with peer {}{}", planId(),
peer.getHostAddress(),
peer.equals(connecting) ? "" : " through " + connecting.getHostAddress(),
e);
}
}
/**
* Prepare this session for sending/receiving files.
*/
public void prepare(Collection requests, Collection summaries)
{
// prepare tasks
state(State.PREPARING);
for (StreamRequest request : requests)
addTransferRanges(request.keyspace, request.ranges, request.columnFamilies, true, request.repairedAt); // always flush on stream request
for (StreamSummary summary : summaries)
prepareReceiving(summary);
// send back prepare message if prepare message contains stream request
if (!requests.isEmpty())
{
PrepareMessage prepare = new PrepareMessage();
for (StreamTransferTask task : transfers.values())
prepare.summaries.add(task.getSummary());
handler.sendMessage(prepare);
}
// if there are files to stream
if (!maybeCompleted())
startStreamingFiles();
}
/**
* Call back after sending FileMessageHeader.
*
* @param header sent header
*/
public void fileSent(FileMessageHeader header)
{
long headerSize = header.size();
StreamingMetrics.totalOutgoingBytes.inc(headerSize);
metrics.outgoingBytes.inc(headerSize);
// schedule timeout for receiving ACK
StreamTransferTask task = transfers.get(header.cfId);
if (task != null)
{
task.scheduleTimeout(header.sequenceNumber, 12, TimeUnit.HOURS);
}
}
/**
* Call back after receiving FileMessageHeader.
*
* @param message received file
*/
public void receive(IncomingFileMessage message)
{
long headerSize = message.header.size();
StreamingMetrics.totalIncomingBytes.inc(headerSize);
metrics.incomingBytes.inc(headerSize);
// send back file received message
handler.sendMessage(new ReceivedMessage(message.header.cfId, message.header.sequenceNumber));
receivers.get(message.header.cfId).received(message.sstable);
}
public void progress(String filename, ProgressInfo.Direction direction, long bytes, long total)
{
ProgressInfo progress = new ProgressInfo(peer, index, filename, direction, bytes, total);
streamResult.handleProgress(progress);
}
public void received(UUID cfId, int sequenceNumber)
{
transfers.get(cfId).complete(sequenceNumber);
}
/**
* Check if session is completed on receiving {@code StreamMessage.Type.COMPLETE} message.
*/
public synchronized void complete()
{
if (state == State.WAIT_COMPLETE)
{
if (!completeSent)
{
handler.sendMessage(new CompleteMessage());
completeSent = true;
}
closeSession(State.COMPLETE);
}
else
{
state(State.WAIT_COMPLETE);
handler.closeIncoming();
}
}
private synchronized void scheduleKeepAliveTask()
{
if (keepAliveFuture == null)
{
int keepAlivePeriod = DatabaseDescriptor.getStreamingKeepAlivePeriod();
logger.debug("[Stream #{}] Scheduling keep-alive task with {}s period.", planId(), keepAlivePeriod);
keepAliveFuture = keepAliveExecutor.scheduleAtFixedRate(new KeepAliveTask(), 0, keepAlivePeriod, TimeUnit.SECONDS);
}
}
/**
* Call back on receiving {@code StreamMessage.Type.SESSION_FAILED} message.
*/
public synchronized void sessionFailed()
{
logger.error("[Stream #{}] Remote peer {} failed stream session.", planId(), peer.getHostAddress());
closeSession(State.FAILED);
}
/**
* @return Current snapshot of this session info.
*/
public SessionInfo getSessionInfo()
{
List receivingSummaries = Lists.newArrayList();
for (StreamTask receiver : receivers.values())
receivingSummaries.add(receiver.getSummary());
List transferSummaries = Lists.newArrayList();
for (StreamTask transfer : transfers.values())
transferSummaries.add(transfer.getSummary());
return new SessionInfo(peer, index, connecting, receivingSummaries, transferSummaries, state);
}
public synchronized void taskCompleted(StreamReceiveTask completedTask)
{
receivers.remove(completedTask.cfId);
maybeCompleted();
}
public synchronized void taskCompleted(StreamTransferTask completedTask)
{
transfers.remove(completedTask.cfId);
maybeCompleted();
}
public void onJoin(InetAddress endpoint, EndpointState epState) {}
public void beforeChange(InetAddress endpoint, EndpointState currentState, ApplicationState newStateKey, VersionedValue newValue) {}
public void onChange(InetAddress endpoint, ApplicationState state, VersionedValue value) {}
public void onAlive(InetAddress endpoint, EndpointState state) {}
public void onDead(InetAddress endpoint, EndpointState state) {}
public void onRemove(InetAddress endpoint)
{
logger.error("[Stream #{}] Session failed because remote peer {} has left.", planId(), peer.getHostAddress());
closeSession(State.FAILED);
}
public void onRestart(InetAddress endpoint, EndpointState epState)
{
logger.error("[Stream #{}] Session failed because remote peer {} was restarted.", planId(), peer.getHostAddress());
closeSession(State.FAILED);
}
private boolean maybeCompleted()
{
boolean completed = receivers.isEmpty() && transfers.isEmpty();
if (completed)
{
if (state == State.WAIT_COMPLETE)
{
if (!completeSent)
{
handler.sendMessage(new CompleteMessage());
completeSent = true;
}
closeSession(State.COMPLETE);
}
else
{
// notify peer that this session is completed
handler.sendMessage(new CompleteMessage());
completeSent = true;
state(State.WAIT_COMPLETE);
handler.closeOutgoing();
}
}
return completed;
}
/**
* Flushes matching column families from the given keyspace, or all columnFamilies
* if the cf list is empty.
*/
private void flushSSTables(Iterable stores)
{
List> flushes = new ArrayList<>();
for (ColumnFamilyStore cfs : stores)
flushes.add(cfs.forceFlush());
FBUtilities.waitOnFutures(flushes);
}
private synchronized void prepareReceiving(StreamSummary summary)
{
failIfFinished();
if (summary.files > 0)
receivers.put(summary.cfId, new StreamReceiveTask(this, summary.cfId, summary.files, summary.totalSize));
}
private void startStreamingFiles()
{
streamResult.handleSessionPrepared(this);
state(State.STREAMING);
for (StreamTransferTask task : transfers.values())
{
Collection messages = task.getFileMessages();
if (messages.size() > 0)
handler.sendMessages(messages);
else
taskCompleted(task); // there is no file to send
}
}
class KeepAliveTask implements Runnable
{
private KeepAliveMessage last = null;
public void run()
{
//to avoid jamming the message queue, we only send if the last one was sent
if (last == null || last.wasSent())
{
logger.trace("[Stream #{}] Sending keep-alive to {}.", planId(), peer);
last = new KeepAliveMessage();
try
{
handler.sendMessage(last);
}
catch (RuntimeException e) //connection handler is closed
{
logger.debug("[Stream #{}] Could not send keep-alive message (perhaps stream session is finished?).", planId(), e);
}
}
else
{
logger.trace("[Stream #{}] Skip sending keep-alive to {} (previous was not yet sent).", planId(), peer);
}
}
}
}