io.druid.indexing.overlord.CriticalAction Maven / Gradle / Ivy
/*
* Licensed to Metamarkets Group Inc. (Metamarkets) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. Metamarkets 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 io.druid.indexing.overlord;
import com.google.common.base.Preconditions;
import io.druid.indexing.common.TaskLockType;
import io.druid.indexing.common.task.Task;
import org.joda.time.Interval;
/**
* This class represents a critical action must be done while the task's lock is guaranteed to not be revoked in the
* middle of the action.
*
* Implementations must not change the lock state by calling {@link TaskLockbox#lock(TaskLockType, Task, Interval)},
* {@link TaskLockbox#lock(TaskLockType, Task, Interval, long)}, {@link TaskLockbox#tryLock(TaskLockType, Task, Interval)},
* or {@link TaskLockbox#unlock(Task, Interval)}.
*
* Also, implementations should be finished as soon as possible because all methods in {@link TaskLockbox} are blocked
* until this action is finished.
*
* @see TaskLockbox#doInCriticalSection
*/
public class CriticalAction
{
private final Action actionOnValidLocks;
private final Action actionOnInvalidLocks;
private CriticalAction(Action actionOnValidLocks, Action actionOnInvalidLocks)
{
this.actionOnValidLocks = Preconditions.checkNotNull(actionOnValidLocks, "actionOnValidLocks");
this.actionOnInvalidLocks = Preconditions.checkNotNull(actionOnInvalidLocks, "actionOnInvalidLocks");
}
T perform(boolean isTaskLocksValid) throws Exception
{
return isTaskLocksValid ? actionOnValidLocks.perform() : actionOnInvalidLocks.perform();
}
public static Builder builder()
{
return new Builder<>();
}
public static class Builder
{
private Action actionOnInvalidLocks;
private Action actionOnValidLocks;
public Builder onValidLocks(Action action)
{
this.actionOnValidLocks = action;
return this;
}
public Builder onInvalidLocks(Action action)
{
this.actionOnInvalidLocks = action;
return this;
}
public CriticalAction build()
{
return new CriticalAction<>(actionOnValidLocks, actionOnInvalidLocks);
}
}
public interface Action
{
T perform() throws Exception;
}
}