org.opensearch.grok.MatcherWatchdog Maven / Gradle / Ivy
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* SPDX-License-Identifier: Apache-2.0
*
* The OpenSearch Contributors require contributions made to
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* compatible open source license.
*/
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* the Apache License, Version 2.0 (the "License"); you may
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*
* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing,
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/*
* Modifications Copyright OpenSearch Contributors. See
* GitHub history for details.
*/
package org.opensearch.grok;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.BiConsumer;
import java.util.function.LongSupplier;
import org.joni.Matcher;
/**
* Protects against long running operations that happen between the register and unregister invocations.
* Threads that invoke {@link #register(Matcher)}, but take too long to invoke the {@link #unregister(Matcher)} method
* will be interrupted.
*
* This is needed for Joni's {@link org.joni.Matcher#search(int, int, int)} method, because
* it can end up spinning endlessly if the regular expression is too complex. Joni has checks
* that for every 30k iterations it checks if the current thread is interrupted and if so
* returns {@link org.joni.Matcher#INTERRUPTED}.
*/
public interface MatcherWatchdog {
/**
* Registers the current matcher and interrupts the this matcher
* if the takes too long for this thread to invoke {@link #unregister(Matcher)}.
*
* @param matcher The matcher to register
*/
void register(Matcher matcher);
/**
* @return The maximum allowed time in milliseconds for a thread to invoke {@link #unregister(Matcher)}
* after {@link #register(Matcher)} has been invoked before this ThreadWatchDog starts to interrupting that thread.
*/
long maxExecutionTimeInMillis();
/**
* Unregisters the current matcher and prevents it from being interrupted.
*
* @param matcher The matcher to unregister
*/
void unregister(Matcher matcher);
/**
* Returns an implementation that checks for each fixed interval if there are threads that have invoked {@link #register(Matcher)}
* and not {@link #unregister(Matcher)} and have been in this state for longer than the specified max execution interval and
* then interrupts these threads.
*
* @param interval The fixed interval to check if there are threads to interrupt
* @param maxExecutionTime The time a thread has the execute an operation.
* @param relativeTimeSupplier A supplier that returns relative time
* @param scheduler A scheduler that is able to execute a command for each fixed interval
*/
static MatcherWatchdog newInstance(
long interval,
long maxExecutionTime,
LongSupplier relativeTimeSupplier,
BiConsumer scheduler
) {
return new Default(interval, maxExecutionTime, relativeTimeSupplier, scheduler);
}
/**
* @return A noop implementation that does not interrupt threads and is useful for testing and pre-defined grok expressions.
*/
static MatcherWatchdog noop() {
return Noop.INSTANCE;
}
class Noop implements MatcherWatchdog {
private static final Noop INSTANCE = new Noop();
private Noop() {}
@Override
public void register(Matcher matcher) {}
@Override
public long maxExecutionTimeInMillis() {
return Long.MAX_VALUE;
}
@Override
public void unregister(Matcher matcher) {}
}
class Default implements MatcherWatchdog {
private final long interval;
private final long maxExecutionTime;
private final LongSupplier relativeTimeSupplier;
private final BiConsumer scheduler;
private final AtomicInteger registered = new AtomicInteger(0);
private final AtomicBoolean running = new AtomicBoolean(false);
final ConcurrentHashMap registry = new ConcurrentHashMap<>();
private Default(long interval, long maxExecutionTime, LongSupplier relativeTimeSupplier, BiConsumer scheduler) {
this.interval = interval;
this.maxExecutionTime = maxExecutionTime;
this.relativeTimeSupplier = relativeTimeSupplier;
this.scheduler = scheduler;
}
public void register(Matcher matcher) {
registered.getAndIncrement();
Long previousValue = registry.put(matcher, relativeTimeSupplier.getAsLong());
if (running.compareAndSet(false, true)) {
scheduler.accept(interval, this::interruptLongRunningExecutions);
}
assert previousValue == null;
}
@Override
public long maxExecutionTimeInMillis() {
return maxExecutionTime;
}
public void unregister(Matcher matcher) {
Long previousValue = registry.remove(matcher);
registered.decrementAndGet();
assert previousValue != null;
}
private void interruptLongRunningExecutions() {
final long currentRelativeTime = relativeTimeSupplier.getAsLong();
for (Map.Entry entry : registry.entrySet()) {
if ((currentRelativeTime - entry.getValue()) > maxExecutionTime) {
entry.getKey().interrupt();
// not removing the entry here, this happens in the unregister() method.
}
}
if (registered.get() > 0) {
scheduler.accept(interval, this::interruptLongRunningExecutions);
} else {
running.set(false);
}
}
}
}