/*
* Copyright 2016-2017 the original author or authors.
*
* 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 org.springframework.integration.jdbc.lock;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.springframework.dao.CannotAcquireLockException;
import org.springframework.dao.CannotSerializeTransactionException;
import org.springframework.dao.DataAccessResourceFailureException;
import org.springframework.integration.support.locks.DefaultLockRegistry;
import org.springframework.integration.support.locks.ExpirableLockRegistry;
import org.springframework.integration.support.locks.LockRegistry;
import org.springframework.integration.util.UUIDConverter;
import org.springframework.transaction.TransactionTimedOutException;
import org.springframework.util.Assert;
/**
*
* A {@link LockRegistry} using a shared database to co-ordinate the locks. Provides the
* same semantics as the {@link DefaultLockRegistry}, but the locks taken will be global,
* as long as the underlying database supports the "serializable" isolation level in its
* transactions.
*
* @author Dave Syer
* @author Artem Bilan
* @author Vedran Pavic
*
* @since 4.3
*/
public class JdbcLockRegistry implements ExpirableLockRegistry {
private final Map<String, JdbcLock> locks = new ConcurrentHashMap<>();
private final LockRepository client;
public JdbcLockRegistry(LockRepository client) {
this.client = client;
}
@Override
public Lock obtain(Object lockKey) {
Assert.isInstanceOf(String.class, lockKey);
String path = pathFor((String) lockKey);
return this.locks.computeIfAbsent(path, p -> new JdbcLock(this.client, p));
}
private String pathFor(String input) {
return input == null ? null : UUIDConverter.getUUID(input).toString();
}
@Override
public void expireUnusedOlderThan(long age) {
Iterator<Entry<String, JdbcLock>> iterator = this.locks.entrySet().iterator();
long now = System.currentTimeMillis();
while (iterator.hasNext()) {
Entry<String, JdbcLock> entry = iterator.next();
JdbcLock lock = entry.getValue();
if (now - lock.getLastUsed() > age && !lock.isAcquiredInThisProcess()) {
iterator.remove();
}
}
}
private static final class JdbcLock implements Lock {
private final LockRepository mutex;
private final String path;
private volatile long lastUsed = System.currentTimeMillis();
private final ReentrantLock delegate = new ReentrantLock();
JdbcLock(LockRepository client, String path) {
this.mutex = client;
this.path = path;
}
public long getLastUsed() {
return this.lastUsed;
}
@Override
public void lock() {
this.delegate.lock();
while (true) {
try {
while (!doLock()) {
Thread.sleep(100); //NOSONAR
}
break;
}
catch (CannotSerializeTransactionException e) {
// try again
}
catch (TransactionTimedOutException e) {
// try again
}
catch (InterruptedException e) {
/*
* This method must be uninterruptible so catch and ignore
* interrupts and only break out of the while loop when
* we get the lock.
*/
}
catch (Exception e) {
this.delegate.unlock();
rethrowAsLockException(e);
}
}
}
private void rethrowAsLockException(Exception e) {
throw new CannotAcquireLockException("Failed to lock mutex at " + this.path, e);
}
@Override
public void lockInterruptibly() throws InterruptedException {
this.delegate.lockInterruptibly();
while (true) {
try {
while (!doLock()) {
Thread.sleep(100); //NOSONAR
if (Thread.currentThread().isInterrupted()) {
throw new InterruptedException();
}
}
break;
}
catch (CannotSerializeTransactionException e) {
// try again
}
catch (TransactionTimedOutException e) {
// try again
}
catch (InterruptedException ie) {
this.delegate.unlock();
Thread.currentThread().interrupt();
throw ie;
}
catch (Exception e) {
this.delegate.unlock();
rethrowAsLockException(e);
}
}
}
@Override
public boolean tryLock() {
try {
return tryLock(0, TimeUnit.MICROSECONDS);
}
catch (InterruptedException e) {
Thread.currentThread().interrupt();
return false;
}
}
@Override
public boolean tryLock(long time, TimeUnit unit) throws InterruptedException {
long now = System.currentTimeMillis();
if (!this.delegate.tryLock(time, unit)) {
return false;
}
long expire = now + TimeUnit.MILLISECONDS.convert(time, unit);
boolean acquired;
while (true) {
try {
while (!(acquired = doLock()) && System.currentTimeMillis() < expire) { //NOSONAR
Thread.sleep(100); //NOSONAR
}
if (!acquired) {
this.delegate.unlock();
}
return acquired;
}
catch (CannotSerializeTransactionException e) {
// try again
}
catch (TransactionTimedOutException e) {
// try again
}
catch (Exception e) {
this.delegate.unlock();
rethrowAsLockException(e);
}
}
}
private boolean doLock() {
boolean acquired = this.mutex.acquire(this.path);
if (acquired) {
this.lastUsed = System.currentTimeMillis();
}
return acquired;
}
@Override
public void unlock() {
if (!this.delegate.isHeldByCurrentThread()) {
throw new IllegalMonitorStateException("You do not own mutex at " + this.path);
}
if (this.delegate.getHoldCount() > 1) {
this.delegate.unlock();
return;
}
try {
this.mutex.delete(this.path);
}
catch (Exception e) {
throw new DataAccessResourceFailureException("Failed to release mutex at " + this.path, e);
}
finally {
this.delegate.unlock();
}
}
@Override
public Condition newCondition() {
throw new UnsupportedOperationException("Conditions are not supported");
}
public boolean isAcquiredInThisProcess() {
return this.mutex.isAcquired(this.path);
}
}
}