GH-3672: Clean up Jdbc & ZK LockRegistry caches

Fixes #3672

* Clean up `JdbcLockRegistry`, `ZookeeperLockRegistry` cache automatically 
* setCapacity(int capacity) to cacheCapacity(int capacity)
* field rename `capacity`to `cacheCapacity`, add static

Author: Meteorkor

spring-integration-jdbc/src/main/java/org/springframework/integration/jdbc/lock/JdbcLockRegistry.java

@@ -17,10 +17,9 @@
 package org.springframework.integration.jdbc.lock;
 
 import java.time.Duration;
-import java.util.Iterator;
+import java.util.LinkedHashMap;
 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;
@@ -54,19 +53,32 @@
  * @author Stefan Vassilev
  * @author Olivier Hubaut
  * @author Fran Aranda
+ * @author Unseok Kim
  *
  * @since 4.3
  */
 public class JdbcLockRegistry implements ExpirableLockRegistry, RenewableLockRegistry {
 
 	private static final int DEFAULT_IDLE = 100;
 
-	private final Map<String, JdbcLock> locks = new ConcurrentHashMap<>();
+	private static final int DEFAULT_CAPACITY = 100_000;
+
+	private final Map<String, JdbcLock> locks =
+			new LinkedHashMap<String, JdbcLock>(16, 0.75F, true) {
+
+				@Override
+				protected boolean removeEldestEntry(Entry<String, JdbcLock> eldest) {
+					return size() > JdbcLockRegistry.this.cacheCapacity;
+				}
+
+			};
 
 	private final LockRepository client;
 
 	private Duration idleBetweenTries = Duration.ofMillis(DEFAULT_IDLE);
 
+	private int cacheCapacity = DEFAULT_CAPACITY;
+
 	public JdbcLockRegistry(LockRepository client) {
 		this.client = client;
 	}
@@ -82,11 +94,22 @@ public void setIdleBetweenTries(Duration idleBetweenTries) {
 		this.idleBetweenTries = idleBetweenTries;
 	}
 
+	/**
+	 * Set the capacity of cached locks.
+	 * @param cacheCapacity The capacity of cached lock, (default 100_000).
+	 * @since 5.5.6
+	 */
+	public void setCacheCapacity(int cacheCapacity) {
+		this.cacheCapacity = cacheCapacity;
+	}
+
 	@Override
 	public Lock obtain(Object lockKey) {
 		Assert.isInstanceOf(String.class, lockKey);
 		String path = pathFor((String) lockKey);
-		return this.locks.computeIfAbsent(path, (key) -> new JdbcLock(this.client, this.idleBetweenTries, key));
+		synchronized (this.locks) {
+			return this.locks.computeIfAbsent(path, key -> new JdbcLock(this.client, this.idleBetweenTries, key));
+		}
 	}
 
 	private String pathFor(String input) {
@@ -95,22 +118,24 @@ private String pathFor(String input) {
 
 	@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();
-			}
+		synchronized (this.locks) {
+			this.locks.entrySet()
+					.removeIf(entry -> {
+						JdbcLock lock = entry.getValue();
+						return now - lock.getLastUsed() > age && !lock.isAcquiredInThisProcess();
+					});
 		}
 	}
 
 	@Override
 	public void renewLock(Object lockKey) {
 		Assert.isInstanceOf(String.class, lockKey);
 		String path = pathFor((String) lockKey);
-		JdbcLock jdbcLock = this.locks.get(path);
+		JdbcLock jdbcLock;
+		synchronized (this.locks) {
+			jdbcLock = this.locks.get(path);
+		}
 		if (jdbcLock == null) {
 			throw new IllegalStateException("Could not found mutex at " + path);
 		}

spring-integration-jdbc/src/test/java/org/springframework/integration/jdbc/lock/JdbcLockRegistryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2020 the original author or authors.
+ * Copyright 2016-2021 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.
@@ -20,8 +20,12 @@
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 
 import java.util.Map;
+import java.util.Queue;
 import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
+import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.locks.Lock;
@@ -35,6 +39,7 @@
 import org.springframework.core.task.AsyncTaskExecutor;
 import org.springframework.core.task.SimpleAsyncTaskExecutor;
 import org.springframework.integration.test.util.TestUtils;
+import org.springframework.integration.util.UUIDConverter;
 import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
 
@@ -43,6 +48,7 @@
  * @author Artem Bilan
  * @author Stefan Vassilev
  * @author Alexandre Strubel
+ * @author Unseok Kim
  *
  * @since 4.3
  */
@@ -312,4 +318,171 @@ public void testLockRenewLockNotOwned() {
 				.isThrownBy(() -> registry.renewLock("foo"));
 	}
 
+	@Test
+	public void concurrentObtainCapacityTest() throws InterruptedException {
+		final int KEY_CNT = 500;
+		final int CAPACITY_CNT = 179;
+		final int THREAD_CNT = 4;
+
+		final CountDownLatch countDownLatch = new CountDownLatch(THREAD_CNT);
+		registry.setCacheCapacity(CAPACITY_CNT);
+		final ExecutorService executorService = Executors.newFixedThreadPool(THREAD_CNT);
+
+		for (int i = 0; i < KEY_CNT; i++) {
+			int finalI = i;
+			executorService.submit(() -> {
+				countDownLatch.countDown();
+				try {
+					countDownLatch.await();
+				}
+				catch (InterruptedException e) {
+					Thread.currentThread().interrupt();
+				}
+				String keyId = "foo:" + finalI;
+				Lock obtain = registry.obtain(keyId);
+				obtain.lock();
+				obtain.unlock();
+			});
+		}
+		executorService.shutdown();
+		executorService.awaitTermination(5, TimeUnit.SECONDS);
+
+		//capacity limit test
+		assertThat(getRegistryLocks(registry)).hasSize(CAPACITY_CNT);
+
+
+		registry.expireUnusedOlderThan(-1000);
+		assertThat(getRegistryLocks(registry)).isEmpty();
+	}
+
+	@Test
+	public void concurrentObtainRemoveOrderTest() throws InterruptedException {
+		final int THREAD_CNT = 2;
+		final int DUMMY_LOCK_CNT = 3;
+
+		final int CAPACITY_CNT = THREAD_CNT;
+
+		final CountDownLatch countDownLatch = new CountDownLatch(THREAD_CNT);
+		registry.setCacheCapacity(CAPACITY_CNT);
+		final ExecutorService executorService = Executors.newFixedThreadPool(THREAD_CNT);
+		final Queue<String> remainLockCheckQueue = new LinkedBlockingQueue<>();
+
+		//Removed due to capcity limit
+		for (int i = 0; i < DUMMY_LOCK_CNT; i++) {
+			Lock obtainLock0 = registry.obtain("foo:" + i);
+			obtainLock0.lock();
+			obtainLock0.unlock();
+		}
+
+		for (int i = DUMMY_LOCK_CNT; i < THREAD_CNT + DUMMY_LOCK_CNT; i++) {
+			int finalI = i;
+			executorService.submit(() -> {
+				countDownLatch.countDown();
+				try {
+					countDownLatch.await();
+				}
+				catch (InterruptedException e) {
+					Thread.currentThread().interrupt();
+				}
+				String keyId = "foo:" + finalI;
+				remainLockCheckQueue.offer(toUUID(keyId));
+				Lock obtain = registry.obtain(keyId);
+				obtain.lock();
+				obtain.unlock();
+			});
+		}
+
+		executorService.shutdown();
+		executorService.awaitTermination(5, TimeUnit.SECONDS);
+
+		assertThat(getRegistryLocks(registry)).containsKeys(
+				remainLockCheckQueue.toArray(new String[remainLockCheckQueue.size()]));
+	}
+
+	@Test
+	public void concurrentObtainAccessRemoveOrderTest() throws InterruptedException {
+		final int THREAD_CNT = 2;
+		final int DUMMY_LOCK_CNT = 3;
+
+		final int CAPACITY_CNT = THREAD_CNT + 1;
+		final String REMAIN_DUMMY_LOCK_KEY = "foo:1";
+
+		final CountDownLatch countDownLatch = new CountDownLatch(THREAD_CNT);
+		registry.setCacheCapacity(CAPACITY_CNT);
+		final ExecutorService executorService = Executors.newFixedThreadPool(THREAD_CNT);
+		final Queue<String> remainLockCheckQueue = new LinkedBlockingQueue<>();
+
+		//Removed due to capcity limit
+		for (int i = 0; i < DUMMY_LOCK_CNT; i++) {
+			Lock obtainLock0 = registry.obtain("foo:" + i);
+			obtainLock0.lock();
+			obtainLock0.unlock();
+		}
+
+		Lock obtainLock0 = registry.obtain(REMAIN_DUMMY_LOCK_KEY);
+		obtainLock0.lock();
+		obtainLock0.unlock();
+		remainLockCheckQueue.offer(toUUID(REMAIN_DUMMY_LOCK_KEY));
+
+		for (int i = DUMMY_LOCK_CNT; i < THREAD_CNT + DUMMY_LOCK_CNT; i++) {
+			int finalI = i;
+			executorService.submit(() -> {
+				countDownLatch.countDown();
+				try {
+					countDownLatch.await();
+				}
+				catch (InterruptedException e) {
+					Thread.currentThread().interrupt();
+				}
+				String keyId = "foo:" + finalI;
+				remainLockCheckQueue.offer(toUUID(keyId));
+				Lock obtain = registry.obtain(keyId);
+				obtain.lock();
+				obtain.unlock();
+			});
+		}
+
+		executorService.shutdown();
+		executorService.awaitTermination(5, TimeUnit.SECONDS);
+
+		assertThat(getRegistryLocks(registry)).containsKeys(
+				remainLockCheckQueue.toArray(new String[remainLockCheckQueue.size()]));
+	}
+
+	@Test
+	public void setCapacityTest() {
+		final int CAPACITY_CNT = 4;
+		registry.setCacheCapacity(CAPACITY_CNT);
+
+		registry.obtain("foo:1");
+		registry.obtain("foo:2");
+		registry.obtain("foo:3");
+
+		//capacity 4->3
+		registry.setCacheCapacity(CAPACITY_CNT - 1);
+
+		registry.obtain("foo:4");
+
+		assertThat(getRegistryLocks(registry)).hasSize(3);
+		assertThat(getRegistryLocks(registry)).containsKeys(toUUID("foo:2"),
+															toUUID("foo:3"),
+															toUUID("foo:4"));
+
+		//capacity 3->4
+		registry.setCacheCapacity(CAPACITY_CNT);
+		registry.obtain("foo:5");
+		assertThat(getRegistryLocks(registry)).hasSize(4);
+		assertThat(getRegistryLocks(registry)).containsKeys(toUUID("foo:3"),
+															toUUID("foo:4"),
+															toUUID("foo:5"));
+	}
+
+	@SuppressWarnings("unchecked")
+	private static Map<String, Lock> getRegistryLocks(JdbcLockRegistry registry) {
+		return TestUtils.getPropertyValue(registry, "locks", Map.class);
+	}
+
+	private static String toUUID(String key) {
+		return UUIDConverter.getUUID(key).toString();
+	}
 }

spring-integration-redis/src/main/java/org/springframework/integration/redis/util/RedisLockRegistry.java

@@ -99,7 +99,7 @@ public final class RedisLockRegistry implements ExpirableLockRegistry, Disposabl
 
 				@Override
 				protected boolean removeEldestEntry(Entry<String, RedisLock> eldest) {
-					return size() > RedisLockRegistry.this.capacity;
+					return size() > RedisLockRegistry.this.cacheCapacity;
 				}
 
 			};
@@ -114,7 +114,7 @@ protected boolean removeEldestEntry(Entry<String, RedisLock> eldest) {
 
 	private final long expireAfter;
 
-	private int capacity = DEFAULT_CAPACITY;
+	private int cacheCapacity = DEFAULT_CAPACITY;
 
 	/**
 	 * An {@link ExecutorService} to call {@link StringRedisTemplate#delete} in
@@ -168,11 +168,11 @@ public void setExecutor(Executor executor) {
 
 	/**
 	 * Set the capacity of cached locks.
-	 * @param capacity The capacity of cached lock, (default 100_000).
+	 * @param cacheCapacity The capacity of cached lock, (default 100_000).
 	 * @since 5.5.6
 	 */
-	public void setCapacity(int capacity) {
-		this.capacity = capacity;
+	public void setCacheCapacity(int cacheCapacity) {
+		this.cacheCapacity = cacheCapacity;
 	}
 
 	@Override