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* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.tasks;
import org.elasticsearch.cluster.ClusterChangedEvent;
import org.elasticsearch.cluster.ClusterStateListener;
import org.elasticsearch.cluster.node.DiscoveryNodes;
import org.elasticsearch.common.component.AbstractComponent;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.util.Consumer;
import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
import org.elasticsearch.common.util.concurrent.ConcurrentMapLong;
import org.elasticsearch.transport.TransportRequest;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;
/**
* Task Manager service for keeping track of currently running tasks on the nodes
*/
public class TaskManager extends AbstractComponent implements ClusterStateListener {
private final ConcurrentMapLong<Task> tasks = ConcurrentCollections.newConcurrentMapLongWithAggressiveConcurrency();
private final ConcurrentMapLong<CancellableTaskHolder> cancellableTasks = ConcurrentCollections
.newConcurrentMapLongWithAggressiveConcurrency();
private final AtomicLong taskIdGenerator = new AtomicLong();
private final Map<TaskId, String> banedParents = new ConcurrentHashMap<>();
public TaskManager(Settings settings) {
super(settings);
}
private DiscoveryNodes lastDiscoveryNodes = DiscoveryNodes.EMPTY_NODES;
/**
* Registers a task without parent task
* <p>
* Returns the task manager tracked task or null if the task doesn't support the task manager
*/
public Task register(String type, String action, TransportRequest request) {
Task task = request.createTask(taskIdGenerator.incrementAndGet(), type, action);
if (task != null) {
if (logger.isTraceEnabled()) {
logger.trace("register {} [{}] [{}] [{}]", task.getId(), type, action, task.getDescription());
}
if (task instanceof CancellableTask) {
CancellableTask cancellableTask = (CancellableTask) task;
CancellableTaskHolder holder = new CancellableTaskHolder(cancellableTask);
CancellableTaskHolder oldHolder = cancellableTasks.put(task.getId(), holder);
assert oldHolder == null;
// Check if this task was banned before we start it
if (task.getParentTaskId().isSet() && banedParents.isEmpty() == false) {
String reason = banedParents.get(task.getParentTaskId());
if (reason != null) {
try {
holder.cancel(reason);
throw new IllegalStateException("Task cancelled before it started: " + reason);
} finally {
// let's clean up the registration
unregister(task);
}
}
}
} else {
Task previousTask = tasks.put(task.getId(), task);
assert previousTask == null;
}
}
return task;
}
/**
* Cancels a task
* <p>
* Returns a set of nodes with child tasks where this task should be cancelled if cancellation was successful, null otherwise.
*/
public Set<String> cancel(CancellableTask task, String reason, Consumer<Set<String>> listener) {
CancellableTaskHolder holder = cancellableTasks.get(task.getId());
if (holder != null) {
logger.trace("cancelling task with id {}", task.getId());
return holder.cancel(reason, listener);
}
return null;
}
/**
* Unregister the task
*/
public Task unregister(Task task) {
logger.trace("unregister task for id: {}", task.getId());
if (task instanceof CancellableTask) {
CancellableTaskHolder holder = cancellableTasks.remove(task.getId());
if (holder != null) {
holder.finish();
return holder.getTask();
} else {
return null;
}
} else {
return tasks.remove(task.getId());
}
}
/**
* Returns the list of currently running tasks on the node
*/
public Map<Long, Task> getTasks() {
HashMap<Long, Task> taskHashMap = new HashMap<>(this.tasks);
for (CancellableTaskHolder holder : cancellableTasks.values()) {
taskHashMap.put(holder.getTask().getId(), holder.getTask());
}
return Collections.unmodifiableMap(taskHashMap);
}
/**
* Returns the list of currently running tasks on the node that can be cancelled
*/
public Map<Long, CancellableTask> getCancellableTasks() {
HashMap<Long, CancellableTask> taskHashMap = new HashMap<>();
for (CancellableTaskHolder holder : cancellableTasks.values()) {
taskHashMap.put(holder.getTask().getId(), holder.getTask());
}
return Collections.unmodifiableMap(taskHashMap);
}
/**
* Returns a task with given id, or null if the task is not found.
*/
public Task getTask(long id) {
Task task = tasks.get(id);
if (task != null) {
return task;
} else {
return getCancellableTask(id);
}
}
/**
* Returns a cancellable task with given id, or null if the task is not found.
*/
public CancellableTask getCancellableTask(long id) {
CancellableTaskHolder holder = cancellableTasks.get(id);
if (holder != null) {
return holder.getTask();
} else {
return null;
}
}
/**
* Returns the number of currently banned tasks.
* <p>
* Will be used in task manager stats and for debugging.
*/
public int getBanCount() {
return banedParents.size();
}
/**
* Bans all tasks with the specified parent task from execution, cancels all tasks that are currently executing.
* <p>
* This method is called when a parent task that has children is cancelled.
*/
public void setBan(TaskId parentTaskId, String reason) {
logger.trace("setting ban for the parent task {} {}", parentTaskId, reason);
// Set the ban first, so the newly created tasks cannot be registered
synchronized (banedParents) {
if (lastDiscoveryNodes.nodeExists(parentTaskId.getNodeId())) {
// Only set the ban if the node is the part of the cluster
banedParents.put(parentTaskId, reason);
}
}
// Now go through already running tasks and cancel them
for (Map.Entry<Long, CancellableTaskHolder> taskEntry : cancellableTasks.entrySet()) {
CancellableTaskHolder holder = taskEntry.getValue();
if (holder.hasParent(parentTaskId)) {
holder.cancel(reason);
}
}
}
/**
* Removes the ban for the specified parent task.
* <p>
* This method is called when a previously banned task finally cancelled
*/
public void removeBan(TaskId parentTaskId) {
logger.trace("removing ban for the parent task {}", parentTaskId);
banedParents.remove(parentTaskId);
}
@Override
public void clusterChanged(ClusterChangedEvent event) {
if (event.nodesRemoved()) {
synchronized (banedParents) {
lastDiscoveryNodes = event.state().getNodes();
// Remove all bans that were registered by nodes that are no longer in the cluster state
Iterator<TaskId> banIterator = banedParents.keySet().iterator();
while (banIterator.hasNext()) {
TaskId taskId = banIterator.next();
if (lastDiscoveryNodes.nodeExists(taskId.getNodeId()) == false) {
logger.debug("Removing ban for the parent [{}] on the node [{}], reason: the parent node is gone", taskId,
event.state().getNodes().localNode());
banIterator.remove();
}
}
}
// Cancel cancellable tasks for the nodes that are gone
for (Map.Entry<Long, CancellableTaskHolder> taskEntry : cancellableTasks.entrySet()) {
CancellableTaskHolder holder = taskEntry.getValue();
CancellableTask task = holder.getTask();
TaskId parentTaskId = task.getParentTaskId();
if (parentTaskId.isSet() && lastDiscoveryNodes.nodeExists(parentTaskId.getNodeId()) == false) {
if (task.cancelOnParentLeaving()) {
holder.cancel("Coordinating node [" + parentTaskId.getNodeId() + "] left the cluster");
}
}
}
}
}
public void registerChildTask(Task task, String node) {
if (task == null || task instanceof CancellableTask == false) {
// We don't have a cancellable task - not much we can do here
return;
}
CancellableTaskHolder holder = cancellableTasks.get(task.getId());
if (holder != null) {
holder.registerChildTaskNode(node);
}
}
private static class CancellableTaskHolder {
private static final String TASK_FINISHED_MARKER = "task finished";
private final CancellableTask task;
private final Set<String> nodesWithChildTasks = new HashSet<>();
private volatile String cancellationReason = null;
private volatile Consumer<Set<String>> cancellationListener = null;
public CancellableTaskHolder(CancellableTask task) {
this.task = task;
}
/**
* Marks task as cancelled.
* <p>
* Returns a set of nodes with child tasks where this task should be cancelled if cancellation was successful, null otherwise.
*/
public Set<String> cancel(String reason, Consumer<Set<String>> listener) {
Set<String> nodes;
synchronized (this) {
assert reason != null;
if (cancellationReason == null) {
cancellationReason = reason;
cancellationListener = listener;
nodes = Collections.unmodifiableSet(nodesWithChildTasks);
} else {
// Already cancelled by somebody else
nodes = null;
}
}
if (nodes != null) {
task.cancel(reason);
}
return nodes;
}
/**
* Marks task as cancelled.
* <p>
* Returns a set of nodes with child tasks where this task should be cancelled if cancellation was successful, null otherwise.
*/
public Set<String> cancel(String reason) {
return cancel(reason, null);
}
/**
* Marks task as finished.
*/
public void finish() {
Consumer<Set<String>> listener = null;
Set<String> nodes = null;
synchronized (this) {
if (cancellationReason != null) {
// The task was cancelled, we need to notify the listener
if (cancellationListener != null) {
listener = cancellationListener;
nodes = Collections.unmodifiableSet(nodesWithChildTasks);
cancellationListener = null;
}
} else {
cancellationReason = TASK_FINISHED_MARKER;
}
}
// We need to call the listener outside of the synchronised section to avoid potential bottle necks
// in the listener synchronization
if (listener != null) {
listener.accept(nodes);
}
}
public boolean hasParent(TaskId parentTaskId) {
return task.getParentTaskId().equals(parentTaskId);
}
public CancellableTask getTask() {
return task;
}
public synchronized void registerChildTaskNode(String nodeId) {
if (cancellationReason == null) {
nodesWithChildTasks.add(nodeId);
} else {
throw new IllegalStateException("cannot register child task request, the task is already cancelled");
}
}
}
}