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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.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.message.ParameterizedMessage;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.ElasticsearchTimeoutException;
import org.elasticsearch.ExceptionsHelper;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.ActionResponse;
import org.elasticsearch.cluster.ClusterChangedEvent;
import org.elasticsearch.cluster.ClusterStateApplier;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.node.DiscoveryNodes;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.unit.ByteSizeValue;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
import org.elasticsearch.common.util.concurrent.ConcurrentMapLong;
import org.elasticsearch.common.util.concurrent.ThreadContext;
import org.elasticsearch.threadpool.ThreadPool;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;
import static org.elasticsearch.common.unit.TimeValue.timeValueMillis;
import static org.elasticsearch.http.HttpTransportSettings.SETTING_HTTP_MAX_HEADER_SIZE;
/**
* Task Manager service for keeping track of currently running tasks on the nodes
*/
public class TaskManager implements ClusterStateApplier {
private static final Logger logger = LogManager.getLogger(TaskManager.class);
private static final TimeValue WAIT_FOR_COMPLETION_POLL = timeValueMillis(100);
/** Rest headers that are copied to the task */
private final List taskHeaders;
private final ThreadPool threadPool;
private final ConcurrentMapLong tasks = ConcurrentCollections.newConcurrentMapLongWithAggressiveConcurrency();
private final ConcurrentMapLong cancellableTasks = ConcurrentCollections
.newConcurrentMapLongWithAggressiveConcurrency();
private final AtomicLong taskIdGenerator = new AtomicLong();
private final Map banedParents = new ConcurrentHashMap<>();
private TaskResultsService taskResultsService;
private DiscoveryNodes lastDiscoveryNodes = DiscoveryNodes.EMPTY_NODES;
private final ByteSizeValue maxHeaderSize;
public TaskManager(Settings settings, ThreadPool threadPool, Set taskHeaders) {
this.threadPool = threadPool;
this.taskHeaders = new ArrayList<>(taskHeaders);
this.maxHeaderSize = SETTING_HTTP_MAX_HEADER_SIZE.get(settings);
}
public void setTaskResultsService(TaskResultsService taskResultsService) {
assert this.taskResultsService == null;
this.taskResultsService = taskResultsService;
}
/**
* Registers a task without parent task
*/
public Task register(String type, String action, TaskAwareRequest request) {
Map headers = new HashMap<>();
long headerSize = 0;
long maxSize = maxHeaderSize.getBytes();
ThreadContext threadContext = threadPool.getThreadContext();
for (String key : taskHeaders) {
String httpHeader = threadContext.getHeader(key);
if (httpHeader != null) {
headerSize += key.length() * 2 + httpHeader.length() * 2;
if (headerSize > maxSize) {
throw new IllegalArgumentException("Request exceeded the maximum size of task headers " + maxHeaderSize);
}
headers.put(key, httpHeader);
}
}
Task task = request.createTask(taskIdGenerator.incrementAndGet(), type, action, request.getParentTask(), headers);
Objects.requireNonNull(task);
assert task.getParentTaskId().equals(request.getParentTask()) : "Request [ " + request + "] didn't preserve it parentTaskId";
if (logger.isTraceEnabled()) {
logger.trace("register {} [{}] [{}] [{}]", task.getId(), type, action, task.getDescription());
}
if (task instanceof CancellableTask) {
registerCancellableTask(task);
} else {
Task previousTask = tasks.put(task.getId(), task);
assert previousTask == null;
}
return task;
}
private void registerCancellableTask(Task task) {
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);
}
}
}
}
/**
* Cancels a task
*
* Returns true if cancellation was started successful, null otherwise.
*
* After starting cancellation on the parent task, the task manager tries to cancel all children tasks
* of the current task. Once cancellation of the children tasks is done, the listener is triggered.
*/
public boolean cancel(CancellableTask task, String reason, Runnable listener) {
CancellableTaskHolder holder = cancellableTasks.get(task.getId());
if (holder != null) {
logger.trace("cancelling task with id {}", task.getId());
return holder.cancel(reason, listener);
}
return false;
}
/**
* 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());
}
}
/**
* Stores the task failure
*/
public void storeResult(Task task, Exception error, ActionListener listener) {
DiscoveryNode localNode = lastDiscoveryNodes.getLocalNode();
if (localNode == null) {
// too early to store anything, shouldn't really be here - just pass the error along
listener.onFailure(error);
return;
}
final TaskResult taskResult;
try {
taskResult = task.result(localNode, error);
} catch (IOException ex) {
logger.warn(() -> new ParameterizedMessage("couldn't store error {}", ExceptionsHelper.detailedMessage(error)), ex);
listener.onFailure(ex);
return;
}
taskResultsService.storeResult(taskResult, new ActionListener() {
@Override
public void onResponse(Void aVoid) {
listener.onFailure(error);
}
@Override
public void onFailure(Exception e) {
logger.warn(() -> new ParameterizedMessage("couldn't store error {}", ExceptionsHelper.detailedMessage(error)), e);
listener.onFailure(e);
}
});
}
/**
* Stores the task result
*/
public void storeResult(Task task, Response response, ActionListener listener) {
DiscoveryNode localNode = lastDiscoveryNodes.getLocalNode();
if (localNode == null) {
// too early to store anything, shouldn't really be here - just pass the response along
logger.warn("couldn't store response {}, the node didn't join the cluster yet", response);
listener.onResponse(response);
return;
}
final TaskResult taskResult;
try {
taskResult = task.result(localNode, response);
} catch (IOException ex) {
logger.warn(() -> new ParameterizedMessage("couldn't store response {}", response), ex);
listener.onFailure(ex);
return;
}
taskResultsService.storeResult(taskResult, new ActionListener() {
@Override
public void onResponse(Void aVoid) {
listener.onResponse(response);
}
@Override
public void onFailure(Exception e) {
logger.warn(() -> new ParameterizedMessage("couldn't store response {}", response), e);
listener.onFailure(e);
}
});
}
/**
* Returns the list of currently running tasks on the node
*/
public Map getTasks() {
HashMap 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 getCancellableTasks() {
HashMap 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.
*
* 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.
*
* 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 taskEntry : cancellableTasks.entrySet()) {
CancellableTaskHolder holder = taskEntry.getValue();
if (holder.hasParent(parentTaskId)) {
holder.cancel(reason);
}
}
}
/**
* Removes the ban for the specified parent task.
*
* 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 applyClusterState(ClusterChangedEvent event) {
lastDiscoveryNodes = event.state().getNodes();
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 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().getLocalNode());
banIterator.remove();
}
}
}
// Cancel cancellable tasks for the nodes that are gone
for (Map.Entry 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");
}
}
}
}
}
/**
* Blocks the calling thread, waiting for the task to vanish from the TaskManager.
*/
public void waitForTaskCompletion(Task task, long untilInNanos) {
while (System.nanoTime() - untilInNanos < 0) {
if (getTask(task.getId()) == null) {
return;
}
try {
Thread.sleep(WAIT_FOR_COMPLETION_POLL.millis());
} catch (InterruptedException e) {
throw new ElasticsearchException("Interrupted waiting for completion of [{}]", e, task);
}
}
throw new ElasticsearchTimeoutException("Timed out waiting for completion of [{}]", task);
}
private static class CancellableTaskHolder {
private static final String TASK_FINISHED_MARKER = "task finished";
private final CancellableTask task;
private volatile String cancellationReason = null;
private volatile Runnable cancellationListener = null;
CancellableTaskHolder(CancellableTask task) {
this.task = task;
}
/**
* Marks task as cancelled.
*
* Returns true if cancellation was successful, false otherwise.
*/
public boolean cancel(String reason, Runnable listener) {
final boolean cancelled;
synchronized (this) {
assert reason != null;
if (cancellationReason == null) {
cancellationReason = reason;
cancellationListener = listener;
cancelled = true;
} else {
// Already cancelled by somebody else
cancelled = false;
}
}
if (cancelled) {
task.cancel(reason);
}
return cancelled;
}
/**
* Marks task as cancelled.
*
* Returns true if cancellation was successful, false otherwise.
*/
public boolean cancel(String reason) {
return cancel(reason, null);
}
/**
* Marks task as finished.
*/
public void finish() {
Runnable listener = null;
synchronized (this) {
if (cancellationReason != null) {
// The task was cancelled, we need to notify the listener
if (cancellationListener != null) {
listener = cancellationListener;
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.run();
}
}
public boolean hasParent(TaskId parentTaskId) {
return task.getParentTaskId().equals(parentTaskId);
}
public CancellableTask getTask() {
return task;
}
}
}