/**
* 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.service;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.net.InetAddress;
import java.util.*;
import java.util.concurrent.Callable;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import org.apache.log4j.Logger;
import org.apache.commons.lang.ArrayUtils;
import org.apache.commons.lang.StringUtils;
import com.google.common.collect.AbstractIterator;
import com.google.common.collect.Multimap;
import org.apache.cassandra.concurrent.StageManager;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.db.*;
import org.apache.cassandra.dht.AbstractBounds;
import org.apache.cassandra.dht.IPartitioner;
import org.apache.cassandra.dht.Range;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.locator.AbstractReplicationStrategy;
import org.apache.cassandra.locator.TokenMetadata;
import org.apache.cassandra.net.IAsyncResult;
import org.apache.cassandra.net.Message;
import org.apache.cassandra.net.MessagingService;
import org.apache.cassandra.thrift.ConsistencyLevel;
import org.apache.cassandra.thrift.InvalidRequestException;
import org.apache.cassandra.thrift.UnavailableException;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.LatencyTracker;
import org.apache.cassandra.utils.WrappedRunnable;
public class StorageProxy implements StorageProxyMBean
{
private static final Logger logger = Logger.getLogger(StorageProxy.class);
// mbean stuff
private static final LatencyTracker readStats = new LatencyTracker();
private static final LatencyTracker rangeStats = new LatencyTracker();
private static final LatencyTracker writeStats = new LatencyTracker();
private StorageProxy() {}
static
{
MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
try
{
mbs.registerMBean(new StorageProxy(), new ObjectName("org.apache.cassandra.service:type=StorageProxy"));
}
catch (Exception e)
{
throw new RuntimeException(e);
}
}
private static final Comparator<String> keyComparator = new Comparator<String>()
{
public int compare(String o1, String o2)
{
IPartitioner<?> p = StorageService.getPartitioner();
return p.decorateKey(o1).compareTo(p.decorateKey(o2));
}
};
/**
* Use this method to have these RowMutations applied
* across all replicas. This method will take care
* of the possibility of a replica being down and hint
* the data across to some other replica.
*
* This is the ZERO consistency level. We do not wait for replies.
*
* @param mutations the mutations to be applied across the replicas
*/
public static void mutate(List<RowMutation> mutations)
{
long startTime = System.nanoTime();
try
{
StorageService ss = StorageService.instance;
for (final RowMutation rm: mutations)
{
try
{
String table = rm.getTable();
AbstractReplicationStrategy rs = ss.getReplicationStrategy(table);
List<InetAddress> naturalEndpoints = ss.getNaturalEndpoints(table, rm.key());
Multimap<InetAddress,InetAddress> hintedEndpoints = rs.getHintedEndpoints(table, naturalEndpoints);
Message unhintedMessage = null; // lazy initialize for non-local, unhinted writes
// 3 cases:
// 1. local, unhinted write: run directly on write stage
// 2. non-local, unhinted write: send row mutation message
// 3. hinted write: add hint header, and send message
for (Map.Entry<InetAddress, Collection<InetAddress>> entry : hintedEndpoints.asMap().entrySet())
{
InetAddress destination = entry.getKey();
Collection<InetAddress> targets = entry.getValue();
if (targets.size() == 1 && targets.iterator().next().equals(destination))
{
// unhinted writes
if (destination.equals(FBUtilities.getLocalAddress()))
{
if (logger.isDebugEnabled())
logger.debug("insert writing local key " + rm.key());
Runnable runnable = new WrappedRunnable()
{
public void runMayThrow() throws IOException
{
rm.apply();
}
};
StageManager.getStage(StageManager.MUTATION_STAGE).execute(runnable);
}
else
{
if (unhintedMessage == null)
unhintedMessage = rm.makeRowMutationMessage();
if (logger.isDebugEnabled())
logger.debug("insert writing key " + rm.key() + " to " + unhintedMessage.getMessageId() + "@" + destination);
MessagingService.instance.sendOneWay(unhintedMessage, destination);
}
}
else
{
// hinted
Message hintedMessage = rm.makeRowMutationMessage();
for (InetAddress target : targets)
{
if (!target.equals(destination))
{
addHintHeader(hintedMessage, target);
if (logger.isDebugEnabled())
logger.debug("insert writing key " + rm.key() + " to " + hintedMessage.getMessageId() + "@" + destination + " for " + target);
}
}
MessagingService.instance.sendOneWay(hintedMessage, destination);
}
}
}
catch (IOException e)
{
throw new RuntimeException("error inserting key " + rm.key(), e);
}
}
}
finally
{
writeStats.addNano(System.nanoTime() - startTime);
}
}
private static void addHintHeader(Message message, InetAddress target)
{
byte[] oldHint = message.getHeader(RowMutation.HINT);
byte[] hint = oldHint == null ? target.getAddress() : ArrayUtils.addAll(oldHint, target.getAddress());
message.setHeader(RowMutation.HINT, hint);
}
public static void mutateBlocking(List<RowMutation> mutations, ConsistencyLevel consistency_level) throws UnavailableException, TimeoutException
{
long startTime = System.nanoTime();
ArrayList<WriteResponseHandler> responseHandlers = new ArrayList<WriteResponseHandler>();
RowMutation mostRecentRowMutation = null;
StorageService ss = StorageService.instance;
try
{
for (RowMutation rm : mutations)
{
mostRecentRowMutation = rm;
String table = rm.getTable();
AbstractReplicationStrategy rs = ss.getReplicationStrategy(table);
List<InetAddress> naturalEndpoints = ss.getNaturalEndpoints(table, rm.key());
Collection<InetAddress> writeEndpoints = rs.getWriteEndpoints(StorageService.getPartitioner().getToken(rm.key()), table, naturalEndpoints);
Multimap<InetAddress, InetAddress> hintedEndpoints = rs.getHintedEndpoints(table, writeEndpoints);
int blockFor = determineBlockFor(writeEndpoints.size(), consistency_level);
// avoid starting a write we know can't achieve the required consistency
assureSufficientLiveNodes(blockFor, writeEndpoints, hintedEndpoints, consistency_level);
// send out the writes, as in mutate() above, but this time with a callback that tracks responses
final WriteResponseHandler responseHandler = ss.getWriteResponseHandler(blockFor, consistency_level, table);
responseHandlers.add(responseHandler);
Message unhintedMessage = null;
for (Map.Entry<InetAddress, Collection<InetAddress>> entry : hintedEndpoints.asMap().entrySet())
{
InetAddress destination = entry.getKey();
Collection<InetAddress> targets = entry.getValue();
if (targets.size() == 1 && targets.iterator().next().equals(destination))
{
// unhinted writes
if (destination.equals(FBUtilities.getLocalAddress()))
{
insertLocalMessage(rm, responseHandler);
}
else
{
// belongs on a different server. send it there.
if (unhintedMessage == null)
{
unhintedMessage = rm.makeRowMutationMessage();
MessagingService.instance.addCallback(responseHandler, unhintedMessage.getMessageId());
}
if (logger.isDebugEnabled())
logger.debug("insert writing key " + rm.key() + " to " + unhintedMessage.getMessageId() + "@" + destination);
MessagingService.instance.sendOneWay(unhintedMessage, destination);
}
}
else
{
// hinted
Message hintedMessage = rm.makeRowMutationMessage();
for (InetAddress target : targets)
{
if (!target.equals(destination))
{
addHintHeader(hintedMessage, target);
if (logger.isDebugEnabled())
logger.debug("insert writing key " + rm.key() + " to " + hintedMessage.getMessageId() + "@" + destination + " for " + target);
}
}
// (non-destination hints are part of the callback and count towards consistency only under CL.ANY)
if (writeEndpoints.contains(destination) || consistency_level == ConsistencyLevel.ANY)
MessagingService.instance.addCallback(responseHandler, hintedMessage.getMessageId());
MessagingService.instance.sendOneWay(hintedMessage, destination);
}
}
}
// wait for writes. throws timeoutexception if necessary
for( WriteResponseHandler responseHandler : responseHandlers )
{
responseHandler.get();
}
}
catch (IOException e)
{
if (mostRecentRowMutation == null)
throw new RuntimeException("no mutations were seen but found an error during write anyway", e);
else
throw new RuntimeException("error writing key " + mostRecentRowMutation.key(), e);
}
finally
{
writeStats.addNano(System.nanoTime() - startTime);
}
}
private static void assureSufficientLiveNodes(int blockFor, Collection<InetAddress> writeEndpoints, Multimap<InetAddress, InetAddress> hintedEndpoints, ConsistencyLevel consistencyLevel)
throws UnavailableException
{
if (consistencyLevel == ConsistencyLevel.ANY)
{
// ensure there are blockFor distinct living nodes (hints are ok).
if (hintedEndpoints.keySet().size() < blockFor)
throw new UnavailableException();
}
// count destinations that are part of the desired target set
int liveNodes = 0;
for (InetAddress destination : hintedEndpoints.keySet())
{
if (writeEndpoints.contains(destination))
liveNodes++;
}
if (liveNodes < blockFor)
{
throw new UnavailableException();
}
}
private static void insertLocalMessage(final RowMutation rm, final WriteResponseHandler responseHandler)
{
if (logger.isDebugEnabled())
logger.debug("insert writing local key " + rm.key());
Runnable runnable = new WrappedRunnable()
{
public void runMayThrow() throws IOException
{
rm.apply();
responseHandler.localResponse();
}
};
StageManager.getStage(StageManager.MUTATION_STAGE).execute(runnable);
}
private static int determineBlockFor(int expandedTargets, ConsistencyLevel consistency_level)
{
switch (consistency_level)
{
case ONE:
case ANY:
return 1;
case QUORUM:
return (expandedTargets / 2) + 1;
case DCQUORUM:
case DCQUORUMSYNC:
// TODO this is broken
return expandedTargets;
case ALL:
return expandedTargets;
default:
throw new UnsupportedOperationException("invalid consistency level " + consistency_level);
}
}
/**
* Performs the actual reading of a row out of the StorageService, fetching
* a specific set of column names from a given column family.
*/
public static List<Row> readProtocol(List<ReadCommand> commands, ConsistencyLevel consistency_level)
throws IOException, UnavailableException, TimeoutException, InvalidRequestException
{
if (StorageService.instance.isBootstrapMode())
throw new InvalidRequestException("This node cannot accept reads until it has bootstrapped");
long startTime = System.nanoTime();
List<Row> rows;
if (consistency_level == ConsistencyLevel.ONE)
{
rows = weakRead(commands);
}
else
{
assert consistency_level.getValue() >= ConsistencyLevel.QUORUM.getValue();
rows = strongRead(commands, consistency_level);
}
readStats.addNano(System.nanoTime() - startTime);
return rows;
}
private static List<Row> weakRead(List<ReadCommand> commands) throws IOException, UnavailableException, TimeoutException
{
List<Row> rows = new ArrayList<Row>();
// send off all the commands asynchronously
List<Future<Object>> localFutures = null;
List<IAsyncResult> remoteResults = null;
for (ReadCommand command: commands)
{
InetAddress endPoint = StorageService.instance.findSuitableEndPoint(command.table, command.key);
if (endPoint.equals(FBUtilities.getLocalAddress()))
{
if (logger.isDebugEnabled())
logger.debug("weakread reading " + command + " locally");
if (localFutures == null)
localFutures = new ArrayList<Future<Object>>();
Callable<Object> callable = new weakReadLocalCallable(command);
localFutures.add(StageManager.getStage(StageManager.READ_STAGE).submit(callable));
}
else
{
if (remoteResults == null)
remoteResults = new ArrayList<IAsyncResult>();
Message message = command.makeReadMessage();
if (logger.isDebugEnabled())
logger.debug("weakread reading " + command + " from " + message.getMessageId() + "@" + endPoint);
if (DatabaseDescriptor.getConsistencyCheck())
message.setHeader(ReadCommand.DO_REPAIR, ReadCommand.DO_REPAIR.getBytes());
remoteResults.add(MessagingService.instance.sendRR(message, endPoint));
}
}
// wait for results
if (localFutures != null)
{
for (Future<Object> future : localFutures)
{
Row row;
try
{
row = (Row) future.get();
}
catch (Exception e)
{
throw new RuntimeException(e);
}
rows.add(row);
}
}
if (remoteResults != null)
{
for (IAsyncResult iar: remoteResults)
{
byte[] body;
body = iar.get(DatabaseDescriptor.getRpcTimeout(), TimeUnit.MILLISECONDS);
ByteArrayInputStream bufIn = new ByteArrayInputStream(body);
ReadResponse response = ReadResponse.serializer().deserialize(new DataInputStream(bufIn));
if (response.row() != null)
rows.add(response.row());
}
}
return rows;
}
/*
* This function executes the read protocol.
// 1. Get the N nodes from storage service where the data needs to be
// replicated
// 2. Construct a message for read\write
* 3. Set one of the messages to get the data and the rest to get the digest
// 4. SendRR ( to all the nodes above )
// 5. Wait for a response from at least X nodes where X <= N and the data node
* 6. If the digest matches return the data.
* 7. else carry out read repair by getting data from all the nodes.
// 5. return success
*/
private static List<Row> strongRead(List<ReadCommand> commands, ConsistencyLevel consistency_level) throws IOException, UnavailableException, TimeoutException
{
List<QuorumResponseHandler<Row>> quorumResponseHandlers = new ArrayList<QuorumResponseHandler<Row>>();
List<InetAddress[]> commandEndPoints = new ArrayList<InetAddress[]>();
List<Row> rows = new ArrayList<Row>();
// send out read requests
for (ReadCommand command: commands)
{
assert !command.isDigestQuery();
ReadCommand readMessageDigestOnly = command.copy();
readMessageDigestOnly.setDigestQuery(true);
Message message = command.makeReadMessage();
Message messageDigestOnly = readMessageDigestOnly.makeReadMessage();
InetAddress dataPoint = StorageService.instance.findSuitableEndPoint(command.table, command.key);
List<InetAddress> endpointList = StorageService.instance.getLiveNaturalEndpoints(command.table, command.key);
final String table = command.table;
int responseCount = determineBlockFor(DatabaseDescriptor.getReplicationFactor(table), consistency_level);
if (endpointList.size() < responseCount)
throw new UnavailableException();
InetAddress[] endPoints = new InetAddress[endpointList.size()];
Message messages[] = new Message[endpointList.size()];
// data-request message is sent to dataPoint, the node that will actually get
// the data for us. The other replicas are only sent a digest query.
int n = 0;
for (InetAddress endpoint : endpointList)
{
Message m = endpoint.equals(dataPoint) ? message : messageDigestOnly;
endPoints[n] = endpoint;
messages[n++] = m;
if (logger.isDebugEnabled())
logger.debug("strongread reading " + (m == message ? "data" : "digest") + " for " + command + " from " + m.getMessageId() + "@" + endpoint);
}
QuorumResponseHandler<Row> quorumResponseHandler = new QuorumResponseHandler<Row>(responseCount, new ReadResponseResolver(command.table, responseCount));
MessagingService.instance.sendRR(messages, endPoints, quorumResponseHandler);
quorumResponseHandlers.add(quorumResponseHandler);
commandEndPoints.add(endPoints);
}
// read results and make a second pass for any digest mismatches
List<QuorumResponseHandler<Row>> repairResponseHandlers = null;
for (int i = 0; i < commands.size(); i++)
{
QuorumResponseHandler<Row> quorumResponseHandler = quorumResponseHandlers.get(i);
Row row;
ReadCommand command = commands.get(i);
try
{
long startTime2 = System.currentTimeMillis();
row = quorumResponseHandler.get();
if (row != null)
rows.add(row);
if (logger.isDebugEnabled())
logger.debug("quorumResponseHandler: " + (System.currentTimeMillis() - startTime2) + " ms.");
}
catch (DigestMismatchException ex)
{
if (DatabaseDescriptor.getConsistencyCheck())
{
if (logger.isDebugEnabled())
logger.debug("Digest mismatch:", ex);
int responseCount = determineBlockFor(DatabaseDescriptor.getReplicationFactor(command.table), consistency_level);
QuorumResponseHandler<Row> qrhRepair = new QuorumResponseHandler<Row>(responseCount, new ReadResponseResolver(command.table, responseCount));
Message messageRepair = command.makeReadMessage();
MessagingService.instance.sendRR(messageRepair, commandEndPoints.get(i), qrhRepair);
if (repairResponseHandlers == null)
repairResponseHandlers = new ArrayList<QuorumResponseHandler<Row>>();
repairResponseHandlers.add(qrhRepair);
}
}
}
// read the results for the digest mismatch retries
if (repairResponseHandlers != null)
{
for (QuorumResponseHandler<Row> handler : repairResponseHandlers)
{
try
{
Row row = handler.get();
if (row != null)
rows.add(row);
}
catch (DigestMismatchException e)
{
throw new AssertionError(e); // full data requested from each node here, no digests should be sent
}
}
}
return rows;
}
/*
* This function executes the read protocol locally. Consistency checks are performed in the background.
*/
public static List<Row> getRangeSlice(RangeSliceCommand command, ConsistencyLevel consistency_level)
throws IOException, UnavailableException, TimeoutException
{
if (logger.isDebugEnabled())
logger.debug(command);
long startTime = System.nanoTime();
final String table = command.keyspace;
int responseCount = determineBlockFor(DatabaseDescriptor.getReplicationFactor(table), consistency_level);
List<AbstractBounds> ranges = getRestrictedRanges(command.range);
// now scan until we have enough results
List<Row> rows = new ArrayList<Row>(command.max_keys);
for (AbstractBounds range : getRangeIterator(ranges, command.range.left))
{
List<InetAddress> liveEndpoints = StorageService.instance.getLiveNaturalEndpoints(command.keyspace, range.right);
if (liveEndpoints.size() < responseCount)
throw new UnavailableException();
DatabaseDescriptor.getEndPointSnitch(command.keyspace).sortByProximity(FBUtilities.getLocalAddress(), liveEndpoints);
List<InetAddress> endpoints = liveEndpoints.subList(0, responseCount);
RangeSliceCommand c2 = new RangeSliceCommand(command.keyspace, command.column_family, command.super_column, command.predicate, range, command.max_keys);
Message message = c2.getMessage();
// collect replies and resolve according to consistency level
RangeSliceResponseResolver resolver = new RangeSliceResponseResolver(command.keyspace, endpoints);
QuorumResponseHandler<List<Row>> handler = new QuorumResponseHandler<List<Row>>(responseCount, resolver);
for (InetAddress endpoint : endpoints)
{
MessagingService.instance.sendRR(message, endpoint, handler);
if (logger.isDebugEnabled())
logger.debug("reading " + c2 + " from " + message.getMessageId() + "@" + endpoint);
}
// TODO read repair on remaining replicas?
// if we're done, great, otherwise, move to the next range
try
{
if (logger.isDebugEnabled())
{
for (Row row : handler.get())
{
logger.debug("range slices read " + row.key);
}
}
rows.addAll(handler.get());
}
catch (DigestMismatchException e)
{
throw new AssertionError(e); // no digests in range slices yet
}
if (rows.size() >= command.max_keys)
break;
}
rangeStats.addNano(System.nanoTime() - startTime);
return rows.size() > command.max_keys ? rows.subList(0, command.max_keys) : rows;
}
/**
* returns an iterator that will return ranges in ring order, starting with the one that contains the start token
*/
private static Iterable<AbstractBounds> getRangeIterator(final List<AbstractBounds> ranges, Token start)
{
// find the one to start with
int i;
for (i = 0; i < ranges.size(); i++)
{
AbstractBounds range = ranges.get(i);
if (range.contains(start) || range.left.equals(start))
break;
}
AbstractBounds range = ranges.get(i);
assert range.contains(start) || range.left.equals(start); // make sure the loop didn't just end b/c ranges were exhausted
// return an iterable that starts w/ the correct range and iterates the rest in ring order
final int begin = i;
return new Iterable<AbstractBounds>()
{
public Iterator<AbstractBounds> iterator()
{
return new AbstractIterator<AbstractBounds>()
{
int n = 0;
protected AbstractBounds computeNext()
{
if (n == ranges.size())
return endOfData();
return ranges.get((begin + n++) % ranges.size());
}
};
}
};
}
/**
* compute all ranges we're going to query, in sorted order, so that we get the correct results back.
* 1) computing range intersections is necessary because nodes can be replica destinations for many ranges,
* so if we do not restrict each scan to the specific range we want we will get duplicate results.
* 2) sorting the intersection ranges is necessary because wraparound node ranges can be discontiguous.
* Consider a 2-node ring, (D, T] and (T, D]. A query for [A, Z] will intersect the 2nd node twice,
* at [A, D] and (T, Z]. We need to scan the (D, T] range in between those, or we will skip those
* results entirely if the limit is low enough.
* 3) we unwrap the intersection ranges because otherwise we get results in the wrong order.
* Consider a 2-node ring, (D, T] and (T, D]. A query for [D, Z] will get results in the wrong
* order if we use (T, D] directly -- we need to start with that range, because our query starts with
* D, but we don't want any other results from it until after the (D, T] range. Unwrapping so that
* the ranges we consider are (D, T], (T, MIN], (MIN, D] fixes this.
*/
private static List<AbstractBounds> getRestrictedRanges(final AbstractBounds queryRange)
{
TokenMetadata tokenMetadata = StorageService.instance.getTokenMetadata();
if (logger.isDebugEnabled())
logger.debug("computing restricted ranges for query " + queryRange);
List<AbstractBounds> ranges = new ArrayList<AbstractBounds>();
// for each node, compute its intersection with the query range, and add its unwrapped components to our list
for (Token nodeToken : tokenMetadata.sortedTokens())
{
Range nodeRange = new Range(tokenMetadata.getPredecessor(nodeToken), nodeToken);
for (AbstractBounds range : queryRange.restrictTo(nodeRange))
{
for (AbstractBounds unwrapped : range.unwrap())
{
if (logger.isDebugEnabled())
logger.debug("Adding to restricted ranges " + unwrapped + " for " + nodeRange);
ranges.add(unwrapped);
}
}
}
// re-sort ranges in ring order, post-unwrapping
Comparator<AbstractBounds> comparator = new Comparator<AbstractBounds>()
{
// no restricted ranges will overlap so we don't need to worry about inclusive vs exclusive left,
// just sort by raw token position.
public int compare(AbstractBounds o1, AbstractBounds o2)
{
// sort in order that the original query range would see them.
int queryOrder1 = queryRange.left.compareTo(o1.left);
int queryOrder2 = queryRange.left.compareTo(o2.left);
if (queryOrder1 < queryOrder2)
return -1; // o1 comes after query start, o2 wraps to after
if (queryOrder1 > queryOrder2)
return 1; // o2 comes after query start, o1 wraps to after
return o1.left.compareTo(o2.left); // o1 and o2 are on the same side of query start
}
};
Collections.sort(ranges, comparator);
if (logger.isDebugEnabled())
logger.debug("Sorted ranges are [" + StringUtils.join(ranges, ", ") + "]");
return ranges;
}
public long getReadOperations()
{
return readStats.getOpCount();
}
public long getTotalReadLatencyMicros()
{
return readStats.getTotalLatencyMicros();
}
public double getRecentReadLatencyMicros()
{
return readStats.getRecentLatencyMicros();
}
public long getRangeOperations()
{
return rangeStats.getOpCount();
}
public long getTotalRangeLatencyMicros()
{
return rangeStats.getTotalLatencyMicros();
}
public double getRecentRangeLatencyMicros()
{
return rangeStats.getRecentLatencyMicros();
}
public long getWriteOperations()
{
return writeStats.getOpCount();
}
public long getTotalWriteLatencyMicros()
{
return writeStats.getTotalLatencyMicros();
}
public double getRecentWriteLatencyMicros()
{
return writeStats.getRecentLatencyMicros();
}
static class weakReadLocalCallable implements Callable<Object>
{
private ReadCommand command;
weakReadLocalCallable(ReadCommand command)
{
this.command = command;
}
public Object call() throws IOException
{
if (logger.isDebugEnabled())
logger.debug("weakreadlocal reading " + command);
Table table = Table.open(command.table);
Row row = command.getRow(table);
// Do the consistency checks in the background
if (DatabaseDescriptor.getConsistencyCheck())
{
List<InetAddress> endpoints = StorageService.instance.getLiveNaturalEndpoints(command.table, command.key);
if (endpoints.size() > 1)
StorageService.instance.doConsistencyCheck(row, endpoints, command);
}
return row;
}
}
}