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The Core Camel Java DSL based router
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF 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.apache.camel.util;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.camel.util.concurrent.ThreadHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Factory to create {@link LRUCache} instances.
*/
public final class LRUCacheFactory {
private static final Logger LOG = LoggerFactory.getLogger(LRUCacheFactory.class);
private static final AtomicBoolean INIT = new AtomicBoolean();
private static final boolean USE_SIMPLE_CACHE;
private LRUCacheFactory() {
}
static {
USE_SIMPLE_CACHE = "true".equalsIgnoreCase(System.getProperty("CamelSimpleLRUCacheFactory", "false"));
if (!USE_SIMPLE_CACHE) {
boolean warmUp = "true".equalsIgnoreCase(System.getProperty("CamelWarmUpLRUCacheFactory", "true"));
if (warmUp) {
// warm-up LRUCache which happens in a background test, which can speedup starting Camel
// as the warm-up can run concurrently with starting up Camel and the runtime container Camel may be running inside
warmUp();
}
}
}
/**
* Warm-up the LRUCache to startup Apache Camel faster.
*/
public static void warmUp() {
// create a dummy map in a separate thread to warm-up the Caffeine cache concurrently
// while Camel is starting up. This allows us to overall startup Camel a bit faster
// as Caffeine takes 150+ millis to initialize.
if (INIT.compareAndSet(false, true)) {
// only need to init Caffeine once in the JVM/classloader
Runnable task = () -> {
StopWatch watch = new StopWatch();
LOG.debug("Warming up LRUCache ...");
newLRUCache(16);
LOG.debug("Warming up LRUCache complete in {} millis", watch.taken());
};
String threadName = ThreadHelper.resolveThreadName(null, "LRUCacheFactory");
Thread thread = new Thread(task, threadName);
thread.start();
}
}
/**
* Constructs an empty LRUCache instance with the
* specified maximumCacheSize, and will stop on eviction.
*
* @param maximumCacheSize the max capacity.
* @throws IllegalArgumentException if the initial capacity is negative
*/
public static Map newLRUCache(int maximumCacheSize) {
LOG.trace("Creating LRUCache with maximumCacheSize: {}", maximumCacheSize);
if (USE_SIMPLE_CACHE) {
return new SimpleLRUCache<>(maximumCacheSize);
}
return new LRUCache<>(maximumCacheSize);
}
/**
* Constructs an empty LRUCache instance with the
* specified initial capacity, maximumCacheSize, and will stop on eviction.
*
* @param initialCapacity the initial capacity.
* @param maximumCacheSize the max capacity.
* @throws IllegalArgumentException if the initial capacity is negative
*/
public static Map newLRUCache(int initialCapacity, int maximumCacheSize) {
LOG.trace("Creating LRUCache with initialCapacity: {}, maximumCacheSize: {}", initialCapacity, maximumCacheSize);
if (USE_SIMPLE_CACHE) {
return new SimpleLRUCache<>(initialCapacity, maximumCacheSize);
}
return new LRUCache<>(initialCapacity, maximumCacheSize);
}
/**
* Constructs an empty LRUCache instance with the
* specified initial capacity, maximumCacheSize,load factor and ordering mode.
*
* @param initialCapacity the initial capacity.
* @param maximumCacheSize the max capacity.
* @param stopOnEviction whether to stop service on eviction.
* @throws IllegalArgumentException if the initial capacity is negative
*/
public static Map newLRUCache(int initialCapacity, int maximumCacheSize, boolean stopOnEviction) {
LOG.trace("Creating LRUCache with initialCapacity: {}, maximumCacheSize: {}, stopOnEviction: {}", initialCapacity, maximumCacheSize, stopOnEviction);
if (USE_SIMPLE_CACHE) {
return new SimpleLRUCache<>(initialCapacity, maximumCacheSize, stopOnEviction);
}
return new LRUCache<>(initialCapacity, maximumCacheSize, stopOnEviction);
}
/**
* Constructs an empty LRUSoftCache instance with the
* specified maximumCacheSize, and will stop on eviction.
*
* @param maximumCacheSize the max capacity.
* @throws IllegalArgumentException if the initial capacity is negative
*/
public static Map newLRUSoftCache(int maximumCacheSize) {
LOG.trace("Creating LRUSoftCache with maximumCacheSize: {}", maximumCacheSize);
if (USE_SIMPLE_CACHE) {
return new SimpleLRUCache<>(maximumCacheSize);
}
return new LRUSoftCache<>(maximumCacheSize);
}
/**
* Constructs an empty LRUWeakCache instance with the
* specified maximumCacheSize, and will stop on eviction.
*
* @param maximumCacheSize the max capacity.
* @throws IllegalArgumentException if the initial capacity is negative
*/
public static Map newLRUWeakCache(int maximumCacheSize) {
LOG.trace("Creating LRUWeakCache with maximumCacheSize: {}", maximumCacheSize);
if (USE_SIMPLE_CACHE) {
return new SimpleLRUCache<>(maximumCacheSize);
}
return new LRUWeakCache<>(maximumCacheSize);
}
private static class SimpleLRUCache extends LinkedHashMap {
static final float DEFAULT_LOAD_FACTOR = 0.75f;
private final int maximumCacheSize;
private final boolean stopOnEviction;
public SimpleLRUCache(int maximumCacheSize) {
this(16, maximumCacheSize, maximumCacheSize > 0);
}
public SimpleLRUCache(int initialCapacity, int maximumCacheSize) {
this(initialCapacity, maximumCacheSize, maximumCacheSize > 0);
}
public SimpleLRUCache(int initialCapacity, int maximumCacheSize, boolean stopOnEviction) {
super(initialCapacity, DEFAULT_LOAD_FACTOR, true);
this.maximumCacheSize = maximumCacheSize;
this.stopOnEviction = stopOnEviction;
}
@Override
protected boolean removeEldestEntry(Map.Entry eldest) {
if (size() >= maximumCacheSize) {
if (stopOnEviction) {
Object value = eldest.getValue();
try {
// stop service as its evicted from cache
ServiceHelper.stopService(value);
} catch (Exception e) {
LOG.warn("Error stopping service: " + value + ". This exception will be ignored.", e);
}
}
return true;
}
return false;
}
}
}