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/*
* Copyright 2014-2024 Real Logic Limited.
*
* Licensed 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
*
* https://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 io.aeron.cluster;
import io.aeron.*;
import io.aeron.cluster.client.ClusterException;
import io.aeron.cluster.service.ClusterCounters;
import io.aeron.cluster.service.ClusteredServiceContainer;
import org.agrona.*;
import org.agrona.concurrent.status.AtomicCounter;
import org.agrona.concurrent.status.CountersReader;
import java.io.File;
import java.nio.MappedByteBuffer;
import java.nio.charset.StandardCharsets;
import static io.aeron.CncFileDescriptor.*;
/**
* Toggle control {@link ToggleState}s for a cluster node such as {@link ToggleState#SUSPEND} or
* {@link ToggleState#RESUME}. This can only be applied to the {@link io.aeron.cluster.service.Cluster.Role#LEADER}.
*/
public class ClusterControl
{
/**
* Toggle states for controlling the cluster node once it has entered the active state after initialising.
* The toggle can only we switched into a new state from {@link #NEUTRAL} and will be reset by the
* {@link io.aeron.cluster.ConsensusModule} once the triggered action is complete.
*/
public enum ToggleState
{
/**
* Inactive state, not accepting new actions.
*/
INACTIVE(0),
/**
* Neutral state ready to accept a new action.
*/
NEUTRAL(1),
/**
* Suspend processing of ingress and timers.
*/
SUSPEND(2),
/**
* Resume processing of ingress and timers.
*/
RESUME(3),
/**
* Take a snapshot of cluster state.
*/
SNAPSHOT(4),
/**
* Shut down the cluster in an orderly fashion by taking a snapshot first then terminating.
*/
SHUTDOWN(5),
/**
* Abort processing and terminate the cluster without taking a snapshot.
*/
ABORT(6),
/**
* Trigger a snapshot that will only occur on a cluster standby.
*/
STANDBY_SNAPSHOT(7);
private final int code;
private static final ToggleState[] STATES = values();
ToggleState(final int code)
{
if (code != ordinal())
{
throw new IllegalArgumentException(name() + " - code must equal ordinal value: code=" + code);
}
this.code = code;
}
/**
* Code to be used as the indicator in the control toggle counter.
*
* @return code to be used as the indicator in the control toggle counter.
*/
public final int code()
{
return code;
}
/**
* Toggle the control counter to trigger the requested {@link ToggleState}.
*
* This action is thread safe and will succeed if the toggle is in the {@link ToggleState#NEUTRAL} state,
* or if toggle is {@link ToggleState#SUSPEND} and requested state is {@link ToggleState#RESUME}.
*
* @param controlToggle to change to the trigger state.
* @return true if the counter toggles or false if it is in a state other than {@link ToggleState#NEUTRAL}.
*/
public final boolean toggle(final AtomicCounter controlToggle)
{
if (code() == RESUME.code() && controlToggle.get() == SUSPEND.code())
{
return controlToggle.compareAndSet(SUSPEND.code(), RESUME.code());
}
return controlToggle.compareAndSet(NEUTRAL.code(), code());
}
/**
* Reset the toggle to the {@link #NEUTRAL} state.
*
* @param controlToggle to be reset.
*/
public static void reset(final AtomicCounter controlToggle)
{
controlToggle.set(NEUTRAL.code());
}
/**
* Activate the toggle by setting it to the {@link #NEUTRAL} state.
*
* @param controlToggle to be activated.
*/
public static void activate(final AtomicCounter controlToggle)
{
controlToggle.set(NEUTRAL.code());
}
/**
* Activate the toggle by setting it to the {@link #INACTIVE} state.
*
* @param controlToggle to be deactivated.
*/
public static void deactivate(final AtomicCounter controlToggle)
{
controlToggle.set(INACTIVE.code());
}
/**
* Get the {@link ToggleState} for a given control toggle.
*
* @param controlToggle to get the current state for.
* @return the state for the current control toggle.
* @throws ClusterException if the counter is not one of the valid values.
*/
public static ToggleState get(final AtomicCounter controlToggle)
{
if (controlToggle.isClosed())
{
throw new ClusterException("counter is closed");
}
final long toggleValue = controlToggle.get();
if (toggleValue < 0 || toggleValue > (STATES.length - 1))
{
throw new ClusterException("invalid toggle value: " + toggleValue);
}
return STATES[(int)toggleValue];
}
}
/**
* Counter type id for the control toggle.
*/
public static final int CONTROL_TOGGLE_TYPE_ID = AeronCounters.CLUSTER_CONTROL_TOGGLE_TYPE_ID;
/**
* Map a {@link CountersReader} over the provided {@link File} for the CnC file.
*
* @param cncFile for the counters.
* @return a {@link CountersReader} over the provided CnC file.
*/
public static CountersReader mapCounters(final File cncFile)
{
final MappedByteBuffer cncByteBuffer = IoUtil.mapExistingFile(cncFile, "cnc");
final DirectBuffer cncMetaData = createMetaDataBuffer(cncByteBuffer);
final int cncVersion = cncMetaData.getInt(cncVersionOffset(0));
CncFileDescriptor.checkVersion(cncVersion);
return new CountersReader(
createCountersMetaDataBuffer(cncByteBuffer, cncMetaData),
createCountersValuesBuffer(cncByteBuffer, cncMetaData),
StandardCharsets.US_ASCII);
}
/**
* Find the control toggle counter or return null if not found.
*
* @param counters to search within.
* @param clusterId to which the allocated counter belongs.
* @return the control toggle counter or return null if not found.
*/
public static AtomicCounter findControlToggle(final CountersReader counters, final int clusterId)
{
final int counterId = ClusterCounters.find(counters, CONTROL_TOGGLE_TYPE_ID, clusterId);
if (Aeron.NULL_VALUE != counterId)
{
return new AtomicCounter(counters.valuesBuffer(), counterId, null);
}
return null;
}
/**
* Main method for launching the process.
*
* @param args passed to the process.
*/
public static void main(final String[] args)
{
checkUsage(args);
final ToggleState toggleState = ToggleState.valueOf(args[0].toUpperCase());
final File cncFile = CommonContext.newDefaultCncFile();
System.out.println("Command `n Control file " + cncFile);
final CountersReader countersReader = mapCounters(cncFile);
final int clusterId = ClusteredServiceContainer.Configuration.clusterId();
final AtomicCounter controlToggle = findControlToggle(countersReader, clusterId);
if (null == controlToggle)
{
System.out.println("Failed to find control toggle");
System.exit(0);
}
if (toggleState.toggle(controlToggle))
{
System.out.println(toggleState + " toggled successfully");
}
else
{
System.out.println(toggleState + " did NOT toggle: current state=" + ToggleState.get(controlToggle));
}
}
private static void checkUsage(final String[] args)
{
if (1 != args.length)
{
System.out.format("Usage: [-Daeron.dir= -Daeron.cluster.id=] " +
ClusterControl.class.getName() + " %n");
System.exit(0);
}
}
}