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/*
* 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.support;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import static java.util.Comparator.comparing;
import org.apache.camel.TimeoutMap;
import org.apache.camel.support.service.ServiceSupport;
import org.apache.camel.util.ObjectHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import static org.apache.camel.TimeoutMap.Listener.Type.Evict;
import static org.apache.camel.TimeoutMap.Listener.Type.Put;
import static org.apache.camel.TimeoutMap.Listener.Type.Remove;
/**
* Default implementation of the {@link TimeoutMap}.
*
* This implementation supports thread safe and non thread safe, in the manner you can enable locking or not.
* By default locking is enabled and thus we are thread safe.
*
* You must provide a {@link java.util.concurrent.ScheduledExecutorService} in the constructor which is used
* to schedule a background task which check for old entries to purge. This implementation will shutdown the scheduler
* if its being stopped.
* You must also invoke {@link #start()} to startup the timeout map, before its ready to be used.
* And you must invoke {@link #stop()} to stop the map when no longer in use.
*/
public class DefaultTimeoutMap extends ServiceSupport implements TimeoutMap {
protected final Logger log = LoggerFactory.getLogger(getClass());
private final ConcurrentMap> map = new ConcurrentHashMap<>();
private final ScheduledExecutorService executor;
private volatile ScheduledFuture future;
private final long purgePollTime;
private final Lock lock;
private final List> listeners = new ArrayList<>(2);
public DefaultTimeoutMap(ScheduledExecutorService executor) {
this(executor, 1000);
}
public DefaultTimeoutMap(ScheduledExecutorService executor, long requestMapPollTimeMillis) {
this(executor, requestMapPollTimeMillis, true);
}
public DefaultTimeoutMap(ScheduledExecutorService executor, long requestMapPollTimeMillis, boolean useLock) {
this(executor, requestMapPollTimeMillis, useLock ? new ReentrantLock() : NoLock.INSTANCE);
}
public DefaultTimeoutMap(ScheduledExecutorService executor, long requestMapPollTimeMillis, Lock lock) {
ObjectHelper.notNull(executor, "ScheduledExecutorService");
this.executor = executor;
this.purgePollTime = requestMapPollTimeMillis;
this.lock = lock;
}
@Override
public V get(K key) {
TimeoutMapEntry entry;
lock.lock();
try {
entry = map.get(key);
if (entry == null) {
return null;
}
updateExpireTime(entry);
} finally {
lock.unlock();
}
return entry.getValue();
}
@Override
public V put(K key, V value, long timeoutMillis) {
TimeoutMapEntry entry = new TimeoutMapEntry<>(key, value, timeoutMillis);
lock.lock();
try {
updateExpireTime(entry);
TimeoutMapEntry result = map.put(key, entry);
return unwrap(result);
} finally {
lock.unlock();
emitEvent(Put, key, value);
}
}
@Override
public V putIfAbsent(K key, V value, long timeoutMillis) {
TimeoutMapEntry entry = new TimeoutMapEntry<>(key, value, timeoutMillis);
TimeoutMapEntry result = null;
lock.lock();
try {
updateExpireTime(entry);
//Just make sure we don't override the old entry
result = map.putIfAbsent(key, entry);
return unwrap(result);
} finally {
lock.unlock();
if (result != entry) {
emitEvent(Put, key, value); // conditional on map being changed
}
}
}
@Override
public V remove(K key) {
V value = null;
lock.lock();
try {
value = unwrap(map.remove(key));
return value;
} finally {
lock.unlock();
if (value != null) {
emitEvent(Remove, key, value); // conditional on map being changed
}
}
}
@Override
public int size() {
return map.size();
}
/**
* The timer task which purges old requests and schedules another poll
*/
private void purgeTask() {
// only purge if allowed
if (!isRunAllowed()) {
log.trace("Purge task not allowed to run");
return;
}
log.trace("Running purge task to see if any entries have been timed out");
try {
purge();
} catch (Throwable t) {
// must catch and log exception otherwise the executor will now schedule next purgeTask
log.warn("Exception occurred during purge task. This exception will be ignored.", t);
}
}
protected void purge() {
log.trace("There are {} in the timeout map", map.size());
if (map.isEmpty()) {
return;
}
long now = currentTime();
List> expired = new ArrayList<>(map.size());
lock.lock();
try {
// need to find the expired entries and add to the expired list
for (Map.Entry> entry : map.entrySet()) {
if (entry.getValue().getExpireTime() < now) {
if (isValidForEviction(entry.getValue())) {
log.debug("Evicting inactive entry ID: {}", entry.getValue());
expired.add(entry.getValue());
}
}
}
// if we found any expired then we need to sort, onEviction and remove
if (!expired.isEmpty()) {
// sort according to the expired time so we got the first expired first
expired.sort(comparing(TimeoutMapEntry::getExpireTime));
// and must remove from list after we have fired the notifications
for (TimeoutMapEntry entry : expired) {
map.remove(entry.getKey());
}
}
} finally {
lock.unlock();
for (TimeoutMapEntry entry : expired) {
emitEvent(Evict, entry.getKey(), entry.getValue());
}
}
}
// Properties
// -------------------------------------------------------------------------
public long getPurgePollTime() {
return purgePollTime;
}
public ScheduledExecutorService getExecutor() {
return executor;
}
// Implementation methods
// -------------------------------------------------------------------------
private static V unwrap(TimeoutMapEntry entry) {
return entry == null ? null : entry.getValue();
}
@Override
public void addListener(Listener listener) {
this.listeners.add(listener);
}
private void emitEvent(Listener.Type type, K key, V value) {
for (Listener listener : listeners) {
try {
listener.timeoutMapEvent(type, key, value);
} catch (Throwable t) {
// Ignore
}
}
}
/**
* lets schedule each time to allow folks to change the time at runtime
*/
protected void schedulePoll() {
future = executor.scheduleWithFixedDelay(this::purgeTask, 0, purgePollTime, TimeUnit.MILLISECONDS);
}
/**
* A hook to allow derivations to avoid evicting the current entry
*/
protected boolean isValidForEviction(TimeoutMapEntry entry) {
return true;
}
protected void updateExpireTime(TimeoutMapEntry entry) {
long now = currentTime();
entry.setExpireTime(entry.getTimeout() + now);
}
protected long currentTime() {
return System.currentTimeMillis();
}
@Override
protected void doStart() throws Exception {
if (executor.isShutdown()) {
throw new IllegalStateException("The ScheduledExecutorService is shutdown");
}
schedulePoll();
}
@Override
protected void doStop() throws Exception {
if (future != null) {
future.cancel(false);
future = null;
}
// clear map if we stop
map.clear();
}
}
