Add poolMaxIdleTime configuration option to TCP appenders

README.md

@@ -126,7 +126,9 @@ Find more advanced examples in the [examples directory](examples).
 * **poolSize**: Number of concurrent tcp connections (minimum 1). Default: 2.
 * **poolMaxWaitTime**: Maximum amount of time (in milliseconds) to wait for a connection to become
   available from the pool. A value of -1 disables the timeout. Default: 5,000 milliseconds.
-
+* **poolMaxIdleTime**: Maximum amount of time (in seconds) that a pooled connection can be idle
+  before it is considered 'stale' and will not be reused. A value of -1 disables the max idle time
+  feature. Default: -1 (disabled).
 
 `de.siegmar.logbackgelf.GelfTcpTlsAppender`
 

examples/advanced_tcp.xml

@@ -9,6 +9,7 @@
         <retryDelay>3000</retryDelay>
         <poolSize>2</poolSize>
         <poolMaxWaitTime>5000</poolMaxWaitTime>
+        <poolMaxIdleTime>10</poolMaxIdleTime>
         <encoder class="de.siegmar.logbackgelf.GelfEncoder">
             <originHost>localhost</originHost>
             <includeRawMessage>false</includeRawMessage>

src/main/java/de/siegmar/logbackgelf/GelfTcpAppender.java

@@ -31,6 +31,7 @@ public class GelfTcpAppender extends AbstractGelfAppender {
     private static final int DEFAULT_RETRY_DELAY = 3_000;
     private static final int DEFAULT_POOL_SIZE = 2;
     private static final int DEFAULT_POOL_MAX_WAIT_TIME = 5_000;
+    private static final int DEFAULT_POOL_MAX_IDLE_TIME = -1;
 
     /**
      * Maximum time (in milliseconds) to wait for establishing a connection. A value of 0 disables
@@ -66,6 +67,13 @@ public class GelfTcpAppender extends AbstractGelfAppender {
      */
     private int poolMaxWaitTime = DEFAULT_POOL_MAX_WAIT_TIME;
 
+    /**
+     * Maximum amount of time (in seconds) that a pooled connection can be idle before it is
+     * considered 'stale' and will not be reused. A value of -1 disables the max idle time feature.
+     * Default: -1 (disabled).
+     */
+    private int poolMaxIdleTime = DEFAULT_POOL_MAX_IDLE_TIME;
+
     private SimpleObjectPool<TcpConnection> connectionPool;
 
     public int getConnectTimeout() {
@@ -121,7 +129,7 @@ protected void startAppender() {
 
         connectionPool = new SimpleObjectPool<>(() -> new TcpConnection(initSocketFactory(),
             addressResolver, getGraylogPort(), connectTimeout),
-            poolSize, poolMaxWaitTime, reconnectInterval);
+            poolSize, poolMaxWaitTime, reconnectInterval, poolMaxIdleTime);
     }
 
     protected SocketFactory initSocketFactory() {

src/main/java/de/siegmar/logbackgelf/pool/AbstractPooledObject.java

@@ -22,11 +22,20 @@
 public abstract class AbstractPooledObject {
 
     private final long createdAt = System.currentTimeMillis();
+    private long lastBorrowed = createdAt;
 
     final long lifeTime() {
         return System.currentTimeMillis() - createdAt;
     }
 
+    final long lastBorrowed() {
+        return lastBorrowed;
+    }
+
+    final void borrow() {
+        this.lastBorrowed = System.currentTimeMillis();
+    }
+
     protected void close() {
     }
 

src/main/java/de/siegmar/logbackgelf/pool/SimpleObjectPool.java

@@ -35,10 +35,11 @@ public class SimpleObjectPool<T extends AbstractPooledObject> {
     private final PooledObjectFactory<T> objectFactory;
     private final int maxWaitTime;
     private final int maxLifeTime;
+    private final int maxIdleTime;
 
     public SimpleObjectPool(final PooledObjectFactory<T> objectFactory,
                             final int poolSize, final int maxWaitTime,
-                            final int maxLifeTime) {
+                            final int maxLifeTime, final int maxIdleTime) {
 
         if (poolSize < 1) {
             throw new IllegalArgumentException("poolSize must be > 0");
@@ -47,6 +48,7 @@ public SimpleObjectPool(final PooledObjectFactory<T> objectFactory,
         this.objectFactory = objectFactory;
         this.maxWaitTime = maxWaitTime;
         this.maxLifeTime = maxLifeTime < 0 ? maxLifeTime : maxLifeTime * MILLIS_PER_SECOND;
+        this.maxIdleTime = maxIdleTime < 0 ? maxIdleTime : maxIdleTime * MILLIS_PER_SECOND;
 
         for (int i = 0; i < poolSize; i++) {
             final T pooledObject = this.objectFactory.newInstance();
@@ -87,11 +89,19 @@ public T borrowObject() throws InterruptedException {
             }
         }
 
-        return needToEvict(pooledObject) ? recycle(pooledObject) : pooledObject;
+        final T result = needToEvict(pooledObject) ? recycle(pooledObject) : pooledObject;
+        result.borrow();
+        return result;
     }
 
     private boolean needToEvict(final T pooledObject) {
-        return maxLifeTime < 0 || pooledObject.lifeTime() > maxLifeTime;
+        if (maxLifeTime > 0 && pooledObject.lifeTime() > maxLifeTime) {
+            return true;
+        } else if (maxIdleTime >= 0 && (System.currentTimeMillis() - pooledObject.lastBorrowed()) > maxIdleTime) {
+            return true;
+        } else {
+            return false;
+        }
     }
 
     private T recycle(final T oldInstance) {

src/test/java/de/siegmar/logbackgelf/pool/SimpleObjectPoolTest.java

@@ -40,7 +40,7 @@ public MyPooledObject newInstance() {
     @Test
     public void simple() throws InterruptedException {
         final SimpleObjectPool<MyPooledObject> pool =
-            new SimpleObjectPool<>(factory, 2, 100, 100);
+            new SimpleObjectPool<>(factory, 2, 100, 100, 100);
 
         for (int i = 0; i < 10; i++) {
             final MyPooledObject o1 = pool.borrowObject();
@@ -56,7 +56,7 @@ public void simple() throws InterruptedException {
     @Test
     public void invalidate() throws InterruptedException {
         final SimpleObjectPool<MyPooledObject> pool =
-            new SimpleObjectPool<>(factory, 2, 100, 100);
+            new SimpleObjectPool<>(factory, 2, 100, 100, 100);
 
         final MyPooledObject o1 = pool.borrowObject();
         assertEquals(1, o1.getId());
@@ -71,6 +71,28 @@ public void invalidate() throws InterruptedException {
         pool.returnObject(o3);
     }
 
+    @Test
+    public void maxLastBorrowed() throws InterruptedException {
+        final SimpleObjectPool<MyPooledObject> pool =
+                new SimpleObjectPool<>(factory, 1, 100, 100, 0);
+
+        final MyPooledObject o1 = pool.borrowObject();
+        assertEquals(1, o1.getId());
+        pool.returnObject(o1);
+
+        Thread.sleep(2);
+
+        final MyPooledObject o2 = pool.borrowObject();
+        assertEquals(2, o2.getId());
+        pool.returnObject(o2);
+
+        Thread.sleep(2);
+
+        final MyPooledObject o3 = pool.borrowObject();
+        assertEquals(3, o3.getId());
+        pool.returnObject(o3);
+    }
+
     private static final class MyPooledObject extends AbstractPooledObject {
 
         private final int id;