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// Licensed to the Software Freedom Conservancy (SFC) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The SFC 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.openqa.selenium.grid.sessionqueue.local;
import static java.net.HttpURLConnection.HTTP_INTERNAL_ERROR;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static org.openqa.selenium.concurrent.ExecutorServices.shutdownGracefully;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import java.io.Closeable;
import java.io.IOException;
import java.time.Duration;
import java.time.Instant;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.function.Predicate;
import java.util.stream.Collectors;
import org.openqa.selenium.Capabilities;
import org.openqa.selenium.SessionNotCreatedException;
import org.openqa.selenium.concurrent.GuardedRunnable;
import org.openqa.selenium.grid.config.Config;
import org.openqa.selenium.grid.data.CreateSessionResponse;
import org.openqa.selenium.grid.data.RequestId;
import org.openqa.selenium.grid.data.SessionRequest;
import org.openqa.selenium.grid.data.SessionRequestCapability;
import org.openqa.selenium.grid.data.SlotMatcher;
import org.openqa.selenium.grid.data.TraceSessionRequest;
import org.openqa.selenium.grid.distributor.config.DistributorOptions;
import org.openqa.selenium.grid.jmx.JMXHelper;
import org.openqa.selenium.grid.jmx.ManagedAttribute;
import org.openqa.selenium.grid.jmx.ManagedService;
import org.openqa.selenium.grid.log.LoggingOptions;
import org.openqa.selenium.grid.security.Secret;
import org.openqa.selenium.grid.security.SecretOptions;
import org.openqa.selenium.grid.sessionqueue.NewSessionQueue;
import org.openqa.selenium.grid.sessionqueue.config.NewSessionQueueOptions;
import org.openqa.selenium.internal.Either;
import org.openqa.selenium.internal.Require;
import org.openqa.selenium.remote.http.Contents;
import org.openqa.selenium.remote.http.HttpResponse;
import org.openqa.selenium.remote.tracing.Span;
import org.openqa.selenium.remote.tracing.TraceContext;
import org.openqa.selenium.remote.tracing.Tracer;
/**
* An in-memory implementation of the list of new session requests.
*
* The lifecycle of a request can be described as:
*
*
* - User adds an item on to the queue using {@link #addToQueue(SessionRequest)}. This will
* block until the request completes in some way.
*
- If the session request is completed, then {@link #complete(RequestId, Either)} must be
* called. This will ensure that {@link #addToQueue(SessionRequest)} returns.
*
- If the request cannot be handled right now, call {@link #retryAddToQueue(SessionRequest)}
* to return the session request to the front of the queue.
*
*
* There is a background thread that will reap {@link SessionRequest}s that have timed out. This
* means that a request can either complete by a listener calling {@link #complete(RequestId,
* Either)} directly, or by being reaped by the thread.
*/
@ManagedService(
objectName = "org.seleniumhq.grid:type=SessionQueue,name=LocalSessionQueue",
description = "New session queue")
public class LocalNewSessionQueue extends NewSessionQueue implements Closeable {
private static final String NAME = "Local New Session Queue";
private final SlotMatcher slotMatcher;
private final Duration requestTimeout;
private final int batchSize;
private final Map requests;
private final Map contexts;
private final Deque queue;
private final ReadWriteLock lock = new ReentrantReadWriteLock();
private final ScheduledExecutorService service =
Executors.newSingleThreadScheduledExecutor(
r -> {
Thread thread = new Thread(r);
thread.setDaemon(true);
thread.setName(NAME);
return thread;
});
public LocalNewSessionQueue(
Tracer tracer,
SlotMatcher slotMatcher,
Duration requestTimeoutCheck,
Duration requestTimeout,
Secret registrationSecret,
int batchSize) {
super(tracer, registrationSecret);
this.slotMatcher = Require.nonNull("Slot matcher", slotMatcher);
Require.nonNegative("Retry period", requestTimeoutCheck);
this.requestTimeout = Require.positive("Request timeout", requestTimeout);
this.requests = new ConcurrentHashMap<>();
this.queue = new ConcurrentLinkedDeque<>();
this.contexts = new ConcurrentHashMap<>();
this.batchSize = Require.positive("Batch size", batchSize);
service.scheduleAtFixedRate(
GuardedRunnable.guard(this::timeoutSessions),
requestTimeoutCheck.toMillis(),
requestTimeoutCheck.toMillis(),
MILLISECONDS);
new JMXHelper().register(this);
}
public static NewSessionQueue create(Config config) {
LoggingOptions loggingOptions = new LoggingOptions(config);
Tracer tracer = loggingOptions.getTracer();
NewSessionQueueOptions newSessionQueueOptions = new NewSessionQueueOptions(config);
SecretOptions secretOptions = new SecretOptions(config);
SlotMatcher slotMatcher = new DistributorOptions(config).getSlotMatcher();
return new LocalNewSessionQueue(
tracer,
slotMatcher,
newSessionQueueOptions.getSessionRequestTimeoutPeriod(),
newSessionQueueOptions.getSessionRequestTimeout(),
secretOptions.getRegistrationSecret(),
newSessionQueueOptions.getBatchSize());
}
private void timeoutSessions() {
Instant now = Instant.now();
Lock readLock = lock.readLock();
readLock.lock();
Set ids;
try {
ids =
requests.entrySet().stream()
.filter(
entry ->
queue.stream()
.anyMatch(
sessionRequest ->
sessionRequest.getRequestId().equals(entry.getKey())))
.filter(entry -> isTimedOut(now, entry.getValue()))
.map(Map.Entry::getKey)
.collect(ImmutableSet.toImmutableSet());
} finally {
readLock.unlock();
}
ids.forEach(this::failDueToTimeout);
}
private boolean isTimedOut(Instant now, Data data) {
return data.endTime.isBefore(now);
}
@Override
public boolean peekEmpty() {
Lock readLock = lock.readLock();
readLock.lock();
try {
return requests.isEmpty() && queue.isEmpty();
} finally {
readLock.unlock();
}
}
@Override
public HttpResponse addToQueue(SessionRequest request) {
Require.nonNull("New session request", request);
Require.nonNull("Request id", request.getRequestId());
TraceContext context = TraceSessionRequest.extract(tracer, request);
try (Span ignored = context.createSpan("sessionqueue.add_to_queue")) {
contexts.put(request.getRequestId(), context);
Data data = injectIntoQueue(request);
if (isTimedOut(Instant.now(), data)) {
failDueToTimeout(request.getRequestId());
}
Either result;
try {
boolean sessionCreated = data.latch.await(requestTimeout.toMillis(), MILLISECONDS);
if (sessionCreated) {
result = data.getResult();
} else {
result = Either.left(new SessionNotCreatedException("New session request timed out"));
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
result =
Either.left(new SessionNotCreatedException("Interrupted when creating the session", e));
} catch (RuntimeException e) {
result =
Either.left(
new SessionNotCreatedException("An error occurred creating the session", e));
}
Lock writeLock = this.lock.writeLock();
writeLock.lock();
try {
requests.remove(request.getRequestId());
queue.remove(request);
} finally {
writeLock.unlock();
}
HttpResponse res = new HttpResponse();
if (result.isRight()) {
res.setContent(Contents.bytes(result.right().getDownstreamEncodedResponse()));
} else {
res.setStatus(HTTP_INTERNAL_ERROR)
.setContent(
Contents.asJson(
ImmutableMap.of(
"value",
ImmutableMap.of(
"error", "session not created",
"message", result.left().getMessage(),
"stacktrace", result.left().getStackTrace()))));
}
return res;
}
}
@VisibleForTesting
Data injectIntoQueue(SessionRequest request) {
Require.nonNull("Session request", request);
Data data = new Data(request.getEnqueued());
Lock writeLock = lock.writeLock();
writeLock.lock();
try {
requests.put(request.getRequestId(), data);
queue.addLast(request);
} finally {
writeLock.unlock();
}
return data;
}
@Override
public boolean retryAddToQueue(SessionRequest request) {
Require.nonNull("New session request", request);
boolean added;
TraceContext context =
contexts.getOrDefault(request.getRequestId(), tracer.getCurrentContext());
try (Span ignored = context.createSpan("sessionqueue.retry")) {
Lock writeLock = lock.writeLock();
writeLock.lock();
try {
if (!requests.containsKey(request.getRequestId())) {
return false;
}
if (isTimedOut(Instant.now(), requests.get(request.getRequestId()))) {
// as we try to re-add a session request that has already expired, force session timeout
failDueToTimeout(request.getRequestId());
// return true to avoid handleNewSessionRequest to call 'complete' an other time
return true;
}
if (queue.contains(request)) {
// No need to re-add this
return true;
} else {
added = queue.offerFirst(request);
}
} finally {
writeLock.unlock();
}
return added;
}
}
@Override
public Optional remove(RequestId reqId) {
Require.nonNull("Request ID", reqId);
Lock writeLock = lock.writeLock();
writeLock.lock();
try {
Iterator iterator = queue.iterator();
while (iterator.hasNext()) {
SessionRequest req = iterator.next();
if (reqId.equals(req.getRequestId())) {
iterator.remove();
return Optional.of(req);
}
}
return Optional.empty();
} finally {
writeLock.unlock();
}
}
@Override
public List getNextAvailable(Map stereotypes) {
Require.nonNull("Stereotypes", stereotypes);
Predicate matchesStereotype =
caps ->
stereotypes.entrySet().stream()
.filter(entry -> entry.getValue() > 0)
.anyMatch(
entry -> {
boolean matches = slotMatcher.matches(entry.getKey(), caps);
if (matches) {
Long value = entry.getValue();
entry.setValue(value - 1);
}
return matches;
});
Lock writeLock = lock.writeLock();
writeLock.lock();
try {
List availableRequests =
queue.stream()
.filter(req -> req.getDesiredCapabilities().stream().anyMatch(matchesStereotype))
.limit(batchSize)
.collect(Collectors.toList());
availableRequests.forEach(req -> this.remove(req.getRequestId()));
return availableRequests;
} finally {
writeLock.unlock();
}
}
/** Returns true if the session is still valid (not timed out) */
@Override
public boolean complete(
RequestId reqId, Either result) {
Require.nonNull("New session request", reqId);
Require.nonNull("Result", result);
TraceContext context = contexts.getOrDefault(reqId, tracer.getCurrentContext());
try (Span ignored = context.createSpan("sessionqueue.completed")) {
Lock readLock = lock.readLock();
readLock.lock();
Data data;
boolean isSessionTimedOut = false;
try {
data = requests.get(reqId);
} finally {
readLock.unlock();
}
if (data == null) {
return false;
} else {
isSessionTimedOut = isTimedOut(Instant.now(), data);
}
Lock writeLock = lock.writeLock();
writeLock.lock();
try {
requests.remove(reqId);
queue.removeIf(req -> reqId.equals(req.getRequestId()));
contexts.remove(reqId);
} finally {
writeLock.unlock();
}
data.setResult(result);
return !isSessionTimedOut;
}
}
@Override
public int clearQueue() {
Lock writeLock = lock.writeLock();
writeLock.lock();
try {
int size = queue.size();
queue.clear();
requests.forEach(
(reqId, data) ->
data.setResult(
Either.left(new SessionNotCreatedException("Request queue was cleared"))));
requests.clear();
return size;
} finally {
writeLock.unlock();
}
}
@Override
public List getQueueContents() {
Lock readLock = lock.readLock();
readLock.lock();
try {
return queue.stream()
.map(
req -> new SessionRequestCapability(req.getRequestId(), req.getDesiredCapabilities()))
.collect(Collectors.toList());
} finally {
readLock.unlock();
}
}
@ManagedAttribute(name = "NewSessionQueueSize")
public int getQueueSize() {
return queue.size();
}
@Override
public boolean isReady() {
return true;
}
@Override
public void close() throws IOException {
shutdownGracefully(NAME, service);
}
private void failDueToTimeout(RequestId reqId) {
complete(reqId, Either.left(new SessionNotCreatedException("Timed out creating session")));
}
private class Data {
public final Instant endTime;
private final CountDownLatch latch = new CountDownLatch(1);
private Either result;
private boolean complete;
public Data(Instant enqueued) {
this.endTime = enqueued.plus(requestTimeout);
this.result = Either.left(new SessionNotCreatedException("Session not created"));
}
public synchronized Either getResult() {
return result;
}
public synchronized void setResult(
Either result) {
if (complete) {
return;
}
this.result = result;
complete = true;
latch.countDown();
}
}
}