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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.tracing;
import java.net.InetAddress;
import java.nio.ByteBuffer;
import java.util.Collections;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import com.google.common.base.Stopwatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.helpers.MessageFormatter;
import org.apache.cassandra.concurrent.Stage;
import org.apache.cassandra.concurrent.StageManager;
import org.apache.cassandra.db.ConsistencyLevel;
import org.apache.cassandra.db.Mutation;
import org.apache.cassandra.exceptions.OverloadedException;
import org.apache.cassandra.service.StorageProxy;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.JVMStabilityInspector;
import org.apache.cassandra.utils.WrappedRunnable;
import org.apache.cassandra.utils.progress.ProgressEvent;
import org.apache.cassandra.utils.progress.ProgressEventNotifier;
import org.apache.cassandra.utils.progress.ProgressListener;
/**
* ThreadLocal state for a tracing session. The presence of an instance of this class as a ThreadLocal denotes that an
* operation is being traced.
*/
public class TraceState implements ProgressEventNotifier
{
private static final Logger logger = LoggerFactory.getLogger(TraceState.class);
private static final int WAIT_FOR_PENDING_EVENTS_TIMEOUT_SECS =
Integer.valueOf(System.getProperty("cassandra.wait_for_tracing_events_timeout_secs", "0"));
public final UUID sessionId;
public final InetAddress coordinator;
public final Stopwatch watch;
public final ByteBuffer sessionIdBytes;
public final Tracing.TraceType traceType;
public final int ttl;
private boolean notify;
private final List listeners = new CopyOnWriteArrayList<>();
private String tag;
public enum Status
{
IDLE,
ACTIVE,
STOPPED
}
private volatile Status status;
// Multiple requests can use the same TraceState at a time, so we need to reference count.
// See CASSANDRA-7626 for more details.
private final AtomicInteger references = new AtomicInteger(1);
public TraceState(InetAddress coordinator, UUID sessionId, Tracing.TraceType traceType)
{
assert coordinator != null;
assert sessionId != null;
this.coordinator = coordinator;
this.sessionId = sessionId;
sessionIdBytes = ByteBufferUtil.bytes(sessionId);
this.traceType = traceType;
this.ttl = traceType.getTTL();
watch = Stopwatch.createStarted();
this.status = Status.IDLE;
}
/**
* Activate notification with provided {@code tag} name.
*
* @param tag Tag name to add when emitting notification
*/
public void enableActivityNotification(String tag)
{
assert traceType == Tracing.TraceType.REPAIR;
notify = true;
this.tag = tag;
}
@Override
public void addProgressListener(ProgressListener listener)
{
assert traceType == Tracing.TraceType.REPAIR;
listeners.add(listener);
}
@Override
public void removeProgressListener(ProgressListener listener)
{
assert traceType == Tracing.TraceType.REPAIR;
listeners.remove(listener);
}
public int elapsed()
{
long elapsed = watch.elapsed(TimeUnit.MICROSECONDS);
return elapsed < Integer.MAX_VALUE ? (int) elapsed : Integer.MAX_VALUE;
}
public synchronized void stop()
{
waitForPendingEvents();
status = Status.STOPPED;
notifyAll();
}
/*
* Returns immediately if there has been trace activity since the last
* call, otherwise waits until there is trace activity, or until the
* timeout expires.
* @param timeout timeout in milliseconds
* @return activity status
*/
public synchronized Status waitActivity(long timeout)
{
if (status == Status.IDLE)
{
try
{
wait(timeout);
}
catch (InterruptedException e)
{
throw new RuntimeException();
}
}
if (status == Status.ACTIVE)
{
status = Status.IDLE;
return Status.ACTIVE;
}
return status;
}
private synchronized void notifyActivity()
{
status = Status.ACTIVE;
notifyAll();
}
public void trace(String format, Object arg)
{
trace(MessageFormatter.format(format, arg).getMessage());
}
public void trace(String format, Object arg1, Object arg2)
{
trace(MessageFormatter.format(format, arg1, arg2).getMessage());
}
public void trace(String format, Object[] args)
{
trace(MessageFormatter.arrayFormat(format, args).getMessage());
}
public void trace(String message)
{
if (notify)
notifyActivity();
final String threadName = Thread.currentThread().getName();
final int elapsed = elapsed();
executeMutation(TraceKeyspace.makeEventMutation(sessionIdBytes, message, elapsed, threadName, ttl));
if (logger.isTraceEnabled())
logger.trace("Adding <{}> to trace events", message);
for (ProgressListener listener : listeners)
{
listener.progress(tag, ProgressEvent.createNotification(message));
}
}
static void executeMutation(final Mutation mutation)
{
StageManager.getStage(Stage.TRACING).execute(new WrappedRunnable()
{
protected void runMayThrow() throws Exception
{
mutateWithCatch(mutation);
}
});
}
/**
* Called from {@link org.apache.cassandra.net.OutboundTcpConnection} for non-local traces (traces
* that are not initiated by local node == coordinator).
*/
public static void mutateWithTracing(final ByteBuffer sessionId, final String message, final int elapsed, final int ttl)
{
final String threadName = Thread.currentThread().getName();
StageManager.getStage(Stage.TRACING).execute(new WrappedRunnable()
{
public void runMayThrow()
{
mutateWithCatch(TraceKeyspace.makeEventMutation(sessionId, message, elapsed, threadName, ttl));
}
});
}
static void mutateWithCatch(Mutation mutation)
{
try
{
StorageProxy.mutate(Collections.singletonList(mutation), ConsistencyLevel.ANY);
}
catch (OverloadedException e)
{
Tracing.logger.warn("Too many nodes are overloaded to save trace events");
}
}
/**
* Post a no-op event to the TRACING stage, so that we can be sure that any previous mutations
* have at least been applied to one replica. This works because the tracking executor only
* has one thread in its pool, see {@link StageManager#tracingExecutor()}.
*/
protected void waitForPendingEvents()
{
if (WAIT_FOR_PENDING_EVENTS_TIMEOUT_SECS <= 0)
return;
try
{
if (logger.isTraceEnabled())
logger.trace("Waiting for up to {} seconds for trace events to complete",
+WAIT_FOR_PENDING_EVENTS_TIMEOUT_SECS);
StageManager.getStage(Stage.TRACING).submit(StageManager.NO_OP_TASK)
.get(WAIT_FOR_PENDING_EVENTS_TIMEOUT_SECS, TimeUnit.SECONDS);
}
catch (Throwable t)
{
JVMStabilityInspector.inspectThrowable(t);
logger.debug("Failed to wait for tracing events to complete: {}", t);
}
}
public boolean acquireReference()
{
while (true)
{
int n = references.get();
if (n <= 0)
return false;
if (references.compareAndSet(n, n + 1))
return true;
}
}
public int releaseReference()
{
waitForPendingEvents();
return references.decrementAndGet();
}
}
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