Added ability to enforce max connection lifetime

driver/src/main/java/org/neo4j/driver/internal/DriverFactory.java

@@ -177,7 +177,7 @@ protected ConnectionPool createConnectionPool( AuthToken authToken, SecurityPlan
 
         ConnectionSettings connectionSettings = new ConnectionSettings( authToken, config.connectionTimeoutMillis() );
         PoolSettings poolSettings = new PoolSettings( config.maxIdleConnectionPoolSize(),
-                config.idleTimeBeforeConnectionTest() );
+                config.idleTimeBeforeConnectionTest(), config.maxConnectionLifetime() );
         Connector connector = createConnector( connectionSettings, securityPlan, config.logging() );
 
         return new SocketConnectionPool( poolSettings, connector, createClock(), config.logging() );

driver/src/main/java/org/neo4j/driver/internal/cluster/RoutingPooledConnection.java

@@ -221,6 +221,12 @@ public BoltServerAddress boltServerAddress()
         return delegate.boltServerAddress();
     }
 
+    @Override
+    public long creationTimestamp()
+    {
+        return delegate.creationTimestamp();
+    }
+
     @Override
     public long lastUsedTimestamp()
     {

driver/src/main/java/org/neo4j/driver/internal/net/pooling/BlockingPooledConnectionQueue.java

@@ -107,7 +107,7 @@ public PooledConnection acquire( Supplier<PooledConnection> supplier )
         return connection;
     }
 
-    void disposeBroken( PooledConnection connection )
+    void dispose( PooledConnection connection )
     {
         acquiredConnections.remove( connection );
         disposeSafely( connection );

driver/src/main/java/org/neo4j/driver/internal/net/pooling/PoolSettings.java

@@ -21,17 +21,21 @@
 public class PoolSettings
 {
     public static final int NO_IDLE_CONNECTION_TEST = -1;
+    public static final int INFINITE_CONNECTION_LIFETIME = -1;
 
     public static final int DEFAULT_MAX_IDLE_CONNECTION_POOL_SIZE = 10;
     public static final int DEFAULT_IDLE_TIME_BEFORE_CONNECTION_TEST = NO_IDLE_CONNECTION_TEST;
+    public static final int DEFAULT_MAX_CONNECTION_LIFETIME = INFINITE_CONNECTION_LIFETIME;
 
     private final int maxIdleConnectionPoolSize;
     private final long idleTimeBeforeConnectionTest;
+    private final long maxConnectionLifetime;
 
-    public PoolSettings( int maxIdleConnectionPoolSize, long idleTimeBeforeConnectionTest )
+    public PoolSettings( int maxIdleConnectionPoolSize, long idleTimeBeforeConnectionTest, long maxConnectionLifetime )
     {
         this.maxIdleConnectionPoolSize = maxIdleConnectionPoolSize;
         this.idleTimeBeforeConnectionTest = idleTimeBeforeConnectionTest;
+        this.maxConnectionLifetime = maxConnectionLifetime;
     }
 
     public int maxIdleConnectionPoolSize()
@@ -53,4 +57,19 @@ public boolean idleTimeBeforeConnectionTestConfigured()
     {
         return idleTimeBeforeConnectionTest >= 0;
     }
+
+    public long maxConnectionLifetime()
+    {
+        if ( !maxConnectionLifetimeConfigured() )
+        {
+            throw new IllegalStateException(
+                    "Max connection lifetime is not configured: " + maxConnectionLifetime );
+        }
+        return maxConnectionLifetime;
+    }
+
+    public boolean maxConnectionLifetimeConfigured()
+    {
+        return maxConnectionLifetime > 0;
+    }
 }

driver/src/main/java/org/neo4j/driver/internal/net/pooling/PooledConnectionReleaseConsumer.java

@@ -47,7 +47,7 @@ public void accept( PooledConnection pooledConnection )
         }
         else
         {
-            connections.disposeBroken( pooledConnection );
+            connections.dispose( pooledConnection );
         }
     }
 }

driver/src/main/java/org/neo4j/driver/internal/net/pooling/PooledSocketConnection.java

@@ -60,13 +60,16 @@ public class PooledSocketConnection implements PooledConnection
     private boolean unrecoverableErrorsOccurred = false;
     private SessionResourcesHandler resourcesHandler;
     private final Clock clock;
+
+    private final long creationTimestamp;
     private long lastUsedTimestamp;
 
     public PooledSocketConnection( Connection delegate, Consumer<PooledConnection> release, Clock clock )
     {
         this.delegate = delegate;
         this.release = release;
         this.clock = clock;
+        this.creationTimestamp = clock.millis();
         updateLastUsedTimestamp();
     }
 
@@ -280,6 +283,12 @@ public void setResourcesHandler( SessionResourcesHandler resourcesHandler )
         this.resourcesHandler = resourcesHandler;
     }
 
+    @Override
+    public long creationTimestamp()
+    {
+        return creationTimestamp;
+    }
+
     @Override
     public long lastUsedTimestamp()
     {
@@ -315,6 +324,6 @@ private boolean isClientOrTransientError( RuntimeException e )
 
     private void updateLastUsedTimestamp()
     {
-        this.lastUsedTimestamp = clock.millis();
+        lastUsedTimestamp = clock.millis();
     }
 }

driver/src/main/java/org/neo4j/driver/internal/net/pooling/SocketConnectionPool.java

@@ -149,7 +149,7 @@ private PooledConnection acquireConnection( BoltServerAddress address,
             // dispose previous connection that can't be acquired
             if ( connection != null )
             {
-                connectionQueue.disposeBroken( connection );
+                connectionQueue.dispose( connection );
             }
 
             connection = connectionQueue.acquire( connectionSupplier );
@@ -162,18 +162,27 @@ private PooledConnection acquireConnection( BoltServerAddress address,
 
     private boolean canBeAcquired( PooledConnection connection, boolean connectionCreated )
     {
-        if ( poolSettings.idleTimeBeforeConnectionTestConfigured() )
+        if ( connectionCreated )
+        {
+            return true;
+        }
+
+        if ( poolSettings.maxConnectionLifetimeConfigured() )
         {
-            if ( connectionCreated )
+            if ( isTooOld( connection ) )
             {
-                return true;
+                return false;
             }
+        }
 
+        if ( poolSettings.idleTimeBeforeConnectionTestConfigured() )
+        {
             if ( hasBeenIdleForTooLong( connection ) )
             {
                 return connectionValidator.isConnected( connection );
             }
         }
+
         return true;
     }
 
@@ -183,6 +192,12 @@ private boolean hasBeenIdleForTooLong( PooledConnection connection )
         return idleTime > poolSettings.idleTimeBeforeConnectionTest();
     }
 
+    private boolean isTooOld( PooledConnection connection )
+    {
+        long lifetime = clock.millis() - connection.creationTimestamp();
+        return lifetime > poolSettings.maxConnectionLifetime();
+    }
+
     private void assertNotClosed( BoltServerAddress address, BlockingPooledConnectionQueue connections )
     {
         if ( closed.get() )

driver/src/main/java/org/neo4j/driver/internal/spi/PooledConnection.java

@@ -40,6 +40,13 @@ public interface PooledConnection extends Connection
      */
     boolean hasUnrecoverableErrors();
 
+    /**
+     * Timestamp of when this connection was created. This timestamp should never change.
+     *
+     * @return timestamp as returned by {@link Clock#millis()}.
+     */
+    long creationTimestamp();
+
     /**
      * Timestamp of when this connection was used. This timestamp is updated when connection is returned to the pool.
      *

driver/src/main/java/org/neo4j/driver/v1/Config.java

@@ -58,11 +58,8 @@ public class Config
 
     private final int maxIdleConnectionPoolSize;
 
-    /**
-     * Connections that have been idle in the pool longer than this threshold will
-     * be tested for validity before being returned to the user.
-     */
     private final long idleTimeBeforeConnectionTest;
+    private final long maxConnectionLifetime;
 
     /** Indicator for encrypted traffic */
     private final boolean encrypted;
@@ -83,6 +80,7 @@ private Config( ConfigBuilder builder)
         this.logLeakedSessions = builder.logLeakedSessions;
 
         this.idleTimeBeforeConnectionTest = builder.idleTimeBeforeConnectionTest;
+        this.maxConnectionLifetime = builder.maxConnectionLifetime;
         this.maxIdleConnectionPoolSize = builder.maxIdleConnectionPoolSize;
 
         this.encrypted = builder.encrypted;
@@ -143,6 +141,16 @@ public long idleTimeBeforeConnectionTest()
         return idleTimeBeforeConnectionTest;
     }
 
+    /**
+     * Pooled connections older than this threshold will be closed and removed from the pool.
+     *
+     * @return maximum lifetime in milliseconds
+     */
+    public long maxConnectionLifetime()
+    {
+        return maxConnectionLifetime;
+    }
+
     /**
      * @return the configured connection timeout value in milliseconds.
      */
@@ -223,6 +231,7 @@ public static class ConfigBuilder
         private boolean logLeakedSessions;
         private int maxIdleConnectionPoolSize = PoolSettings.DEFAULT_MAX_IDLE_CONNECTION_POOL_SIZE;
         private long idleTimeBeforeConnectionTest = PoolSettings.DEFAULT_IDLE_TIME_BEFORE_CONNECTION_TEST;
+        private long maxConnectionLifetime = PoolSettings.DEFAULT_MAX_CONNECTION_LIFETIME;
         private boolean encrypted = true;
         private TrustStrategy trustStrategy = trustAllCertificates();
         private LoadBalancingStrategy loadBalancingStrategy = LoadBalancingStrategy.LEAST_CONNECTED;
@@ -348,7 +357,7 @@ public ConfigBuilder withSessionLivenessCheckTimeout( long timeout )
          * Value {@code 0} means connections will always be tested for
          * validity and negative values mean connections will never be tested.
          *
-         * @param value the minimum idle time in milliseconds
+         * @param value the minimum idle time
          * @param unit the unit in which the duration is given
          * @return this builder
          */
@@ -358,6 +367,32 @@ public ConfigBuilder withConnectionLivenessCheckTimeout( long value, TimeUnit un
             return this;
         }
 
+        /**
+         * Pooled connections older than this threshold will be closed and removed from the pool. Such discarding
+         * happens during connection acquisition so that new session is never backed by an old connection.
+         * <p>
+         * Setting this option to a low value will cause a high connection churn and might result in a performance hit.
+         * <p>
+         * It is recommended to set maximum lifetime to a slightly smaller value than the one configured in network
+         * equipment (load balancer, proxy, firewall, etc. can also limit maximum connection lifetime).
+         * <p>
+         * Setting can also be used in combination with {@link #withConnectionLivenessCheckTimeout(long, TimeUnit)}. In
+         * this case, it is recommended to set liveness check to a value smaller than network equipment has and maximum
+         * lifetime to a reasonably large value to "renew" connections once in a while.
+         * <p>
+         * No maximum lifetime limit is imposed by default. Zero and negative values result in lifetime not being
+         * checked.
+         *
+         * @param value the maximum connection lifetime
+         * @param unit the unit in which the duration is given
+         * @return this builder
+         */
+        public ConfigBuilder withMaxConnectionLifetime( long value, TimeUnit unit )
+        {
+            this.maxConnectionLifetime = unit.toMillis( value );
+            return this;
+        }
+
         /**
          * Configure the {@link EncryptionLevel} to use, use this to control wether the driver uses TLS encryption or not.
          * @param level the TLS level to use

driver/src/test/java/org/neo4j/driver/internal/cluster/RoutingPooledConnectionErrorHandlingTest.java

@@ -59,6 +59,7 @@
 import static org.mockito.Mockito.when;
 import static org.neo4j.driver.internal.logging.DevNullLogging.DEV_NULL_LOGGING;
 import static org.neo4j.driver.internal.net.pooling.PoolSettings.DEFAULT_MAX_IDLE_CONNECTION_POOL_SIZE;
+import static org.neo4j.driver.internal.net.pooling.PoolSettings.INFINITE_CONNECTION_LIFETIME;
 import static org.neo4j.driver.internal.net.pooling.PoolSettings.NO_IDLE_CONNECTION_TEST;
 import static org.neo4j.driver.internal.spi.Collector.NO_OP;
 import static org.neo4j.driver.internal.util.Matchers.containsReader;
@@ -351,7 +352,8 @@ private static RoutingTable newRoutingTable( ClusterComposition clusterCompositi
     private static ConnectionPool newConnectionPool( Connector connector, BoltServerAddress... addresses )
     {
         int maxIdleConnections = DEFAULT_MAX_IDLE_CONNECTION_POOL_SIZE;
-        PoolSettings settings = new PoolSettings( maxIdleConnections, NO_IDLE_CONNECTION_TEST );
+        PoolSettings settings = new PoolSettings( maxIdleConnections, NO_IDLE_CONNECTION_TEST,
+                INFINITE_CONNECTION_LIFETIME );
         SocketConnectionPool pool = new SocketConnectionPool( settings, connector, Clock.SYSTEM, DEV_NULL_LOGGING );
 
         // force pool to create and memorize some connections

driver/src/test/java/org/neo4j/driver/internal/cluster/RoutingPooledConnectionTest.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2002-2017 "Neo Technology,"
+ * Network Engine for Objects in Lund AB [http://neotechnology.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * 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.neo4j.driver.internal.cluster;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.runners.MockitoJUnitRunner;
+
+import org.neo4j.driver.internal.spi.PooledConnection;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.when;
+
+@RunWith( MockitoJUnitRunner.class )
+public class RoutingPooledConnectionTest
+{
+    @Mock
+    private PooledConnection pooledConnection;
+    @InjectMocks
+    private RoutingPooledConnection routingPooledConnection;
+
+    @Test
+    public void shouldExposeCreationTimestamp()
+    {
+        when( pooledConnection.creationTimestamp() ).thenReturn( 42L );
+
+        long timestamp = routingPooledConnection.creationTimestamp();
+
+        assertEquals( 42L, timestamp );
+    }
+
+    @Test
+    public void shouldExposeLastUsedTimestamp()
+    {
+        when( pooledConnection.lastUsedTimestamp() ).thenReturn( 42L );
+
+        long timestamp = routingPooledConnection.lastUsedTimestamp();
+
+        assertEquals( 42L, timestamp );
+    }
+}

driver/src/test/java/org/neo4j/driver/internal/net/pooling/BlockingPooledConnectionQueueTest.java

@@ -287,15 +287,33 @@ public void shouldReportActiveConnections()
 
     @Test
     @SuppressWarnings( "unchecked" )
-    public void shouldDisposeBrokenConnections()
+    public void shouldDisposeConnections()
     {
         BlockingPooledConnectionQueue queue = newConnectionQueue( 5 );
 
         queue.offer( mock( PooledConnection.class ) );
         PooledConnection connection = queue.acquire( mock( Supplier.class ) );
         assertEquals( 1, queue.activeConnections() );
 
-        queue.disposeBroken( connection );
+        queue.dispose( connection );
+        assertEquals( 0, queue.activeConnections() );
+        verify( connection ).dispose();
+    }
+
+    @Test
+    @SuppressWarnings( "unchecked" )
+    public void shouldDisposeConnectionsThatThrowOnDisposal()
+    {
+        BlockingPooledConnectionQueue queue = newConnectionQueue( 5 );
+
+        PooledConnection pooledConnection = mock( PooledConnection.class );
+        doThrow( new RuntimeException() ).when( pooledConnection ).dispose();
+
+        queue.offer( pooledConnection );
+        PooledConnection connection = queue.acquire( mock( Supplier.class ) );
+        assertEquals( 1, queue.activeConnections() );
+
+        queue.dispose( connection );
         assertEquals( 0, queue.activeConnections() );
         verify( connection ).dispose();
     }