INT-3722: Additional Fix: TCP OG with Caching CF

JIRA: https://jira.spring.io/browse/INT-3722

While the initial fix solved the reported problem, it caused a memory leak when
the gateway completed its work before the reader thread "closed" the connection,
releasing it to the pool. This left the connection in the deferred close state.

Handle the condition where the gateway signals it has completed its work
before the connection is released to the pool.

spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/connection/CachingClientConnectionFactory.java

@@ -16,7 +16,9 @@
 
 package org.springframework.integration.ip.tcp.connection;
 
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Executor;
 
@@ -48,6 +50,8 @@ public class CachingClientConnectionFactory extends AbstractClientConnectionFact
 	private final Map<String, CachedConnection> deferredClosures =
 			new ConcurrentHashMap<String, CachedConnection>();
 
+	private final Set<String> okToRelease = new HashSet<String>();
+
 	private volatile boolean deferClose;
 
 	/**
@@ -149,9 +153,14 @@ public void enableCloseDeferral(boolean defer) {
 
 	@Override
 	public void closeDeferred(String connectionId) {
-		CachedConnection deferred = this.deferredClosures.remove(connectionId);
-		if (deferred != null) {
-			deferred.doClose();
+		synchronized(this.okToRelease) {
+			CachedConnection deferred = this.deferredClosures.remove(connectionId);
+			if (deferred != null) {
+				deferred.doClose();
+			}
+			else {
+				this.okToRelease.add(connectionId);
+			}
 		}
 	}
 
@@ -165,12 +174,14 @@ public CachedConnection(TcpConnectionSupport connection) {
 		}
 
 		@Override
-		public synchronized void close() {
-			if (deferClose && !this.released) {
-				deferredClosures.put(getConnectionId(), this);
-			}
-			else {
-				doClose();
+		public void close() {
+			synchronized(okToRelease) {
+				if (deferClose && !this.released && !okToRelease.remove(getConnectionId())) {
+					deferredClosures.put(getConnectionId(), this);
+				}
+				else {
+					doClose();
+				}
 			}
 		}
 

spring-integration-ip/src/test/java/org/springframework/integration/ip/tcp/connection/CachingClientConnectionFactoryTests.java

@@ -457,6 +457,7 @@ public void integrationTest() throws Exception {
 	}
 
 	@Test
+//	@Repeat(1000) // INT-3722
 	public void gatewayIntegrationTest() throws Exception {
 		final List<String> connectionIds = new ArrayList<String>();
 		final AtomicBoolean okToRun = new AtomicBoolean(true);