com.hazelcast.internal.util.ConcurrencyDetection Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2024, Hazelcast, Inc. All Rights Reserved.
*
* Licensed 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 com.hazelcast.internal.util;
import java.util.concurrent.atomic.AtomicLong;
import static java.lang.System.nanoTime;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
/**
* Responsible for tracking if concurrency is detected.
*
* Concurrency is currently triggered at 2 levels:
* - number of concurrent invocations
* - contention on the io system.
*/
public abstract class ConcurrencyDetection {
private final boolean enabled;
private ConcurrencyDetection(boolean enabled) {
this.enabled = enabled;
}
/**
* Checks if any concurrency is detected.
*
* This call is thread-safe.
*
* @return true if detected, false otherwise.
*/
public abstract boolean isDetected();
/**
* Called when concurrency is detected.
*
* This call is thread-safe.
*/
public abstract void onDetected();
/**
* Checks if this ConcurrencyDetection is enabled.
*
* This is useful if you want to fall back to legacy mode.
*
* @return true if enabled, false otherwise.
*/
public boolean enabled() {
return enabled;
}
public static ConcurrencyDetection createEnabled(long durationMs) {
return new EnabledConcurrencyDetection(durationMs);
}
public static ConcurrencyDetection createDisabled() {
return new DisabledConcurrencyDetection();
}
/**
* The DisabledConcurrencyDetection indicates that there is always concurrency,
* even if there is no concurrency. This prevents write through and therefore lets the
* system behave as before to write through was added.
*/
private static final class DisabledConcurrencyDetection extends ConcurrencyDetection {
private DisabledConcurrencyDetection() {
super(false);
}
@Override
public boolean isDetected() {
return true;
}
@Override
public void onDetected() {
//no-op
}
}
private static final class EnabledConcurrencyDetection extends ConcurrencyDetection {
private final long windowNanos;
private final AtomicLong expirationNanosRef = new AtomicLong(System.nanoTime());
private final long halfWindowNanos;
private EnabledConcurrencyDetection(long delayMs) {
super(true);
this.windowNanos = MILLISECONDS.toNanos(delayMs);
this.halfWindowNanos = windowNanos / 2;
}
@Override
public boolean isDetected() {
return nanoTime() - expirationNanosRef.get() < 0;
}
@Override
public void onDetected() {
long nowNanos = nanoTime();
long expirationNanos = expirationNanosRef.get();
if (nowNanos - (expirationNanos - halfWindowNanos) > 0) {
expirationNanosRef.lazySet(nowNanos + windowNanos);
}
}
}
}