#37 - Add pool size() method as fast simple way to get the current size of the pool (vs getStatus())

Author: rbygrave

src/main/java/io/ebean/datasource/DataSourcePool.java

@@ -13,6 +13,11 @@ public interface DataSourcePool extends DataSource {
    */
   String getName();
 
+  /**
+   * Return the current size of the pool. This includes both busy and idle connections.
+   */
+  int size();
+
   /**
    * Return true if the pool defaults to using autocommit.
    */

src/main/java/io/ebean/datasource/pool/ConnectionPool.java

@@ -26,6 +26,7 @@
 import java.util.Timer;
 import java.util.TimerTask;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
 
 /**
  * A robust DataSource implementation.
@@ -46,6 +47,8 @@ public class ConnectionPool implements DataSourcePool {
    */
   private final String name;
 
+  private final AtomicInteger size = new AtomicInteger(0);
+
   private final DataSourceConfig config;
 
   /**
@@ -351,6 +354,25 @@ public String getName() {
     return name;
   }
 
+  @Override
+  public int size() {
+    return size.get();
+  }
+
+  /**
+   * Increment the current pool size.
+   */
+  public void inc() {
+    size.incrementAndGet();
+  }
+
+  /**
+   * Decrement the current pool size.
+   */
+  public void dec() {
+    size.decrementAndGet();
+  }
+
   /**
    * Return the max size of stack traces used when trying to find connection pool leaks.
    * <p>

src/main/java/io/ebean/datasource/pool/PooledConnection.java

@@ -169,6 +169,7 @@ public PooledConnection(ConnectionPool pool, int uniqueId, Connection connection
     this.maxStackTrace = pool.getMaxStackTraceSize();
     this.creationTime = System.currentTimeMillis();
     this.lastUseTime = creationTime;
+    pool.inc();
   }
 
   /**
@@ -273,6 +274,7 @@ void closeConnectionFully(boolean logErrors) {
     }
     try {
       connection.close();
+      pool.dec();
     } catch (SQLException ex) {
       if (logErrors || logger.isDebugEnabled()) {
         logger.error("Error when fully closing connection [" + getFullDescription() + "]", ex);

src/test/java/io/ebean/datasource/pool/ConnectionPoolOfflineTest.java

@@ -38,17 +38,20 @@ public void testOffline() throws InterruptedException, SQLException {
 
     ConnectionPool pool = new ConnectionPool("testOffline", config);
     assertThat(pool.isOnline()).isFalse();
+    assertThat(pool.size()).isEqualTo(0);
     log.info("pool created ");
     Thread.sleep(3000);
 
     assertEquals(0, pool.getStatus(false).getFree());
     assertEquals(0, pool.getStatus(false).getBusy());
+    assertThat(pool.size()).isEqualTo(0);
 
     pool.online();
     log.info("pool online");
     assertThat(pool.isOnline()).isTrue();
     assertEquals(2, pool.getStatus(false).getFree());
     assertEquals(0, pool.getStatus(false).getBusy());
+    assertThat(pool.size()).isEqualTo(2);
 
     Thread.sleep(3000);
 
@@ -57,6 +60,7 @@ public void testOffline() throws InterruptedException, SQLException {
     assertThat(pool.isOnline()).isFalse();
     assertEquals(0, pool.getStatus(false).getFree());
     assertEquals(0, pool.getStatus(false).getBusy());
+    assertThat(pool.size()).isEqualTo(0);
 
     Thread.sleep(3000);
 
@@ -65,13 +69,15 @@ public void testOffline() throws InterruptedException, SQLException {
     assertThat(pool.isOnline()).isTrue();
     assertEquals(2, pool.getStatus(false).getFree());
     assertEquals(0, pool.getStatus(false).getBusy());
+    assertThat(pool.size()).isEqualTo(2);
     Thread.sleep(3000);
 
     pool.shutdown();
 
     assertThat(pool.isOnline()).isFalse();
     assertEquals(0, pool.getStatus(false).getFree());
     assertEquals(0, pool.getStatus(false).getBusy());
+    assertThat(pool.size()).isEqualTo(0);
   }
 
   @Test
@@ -119,17 +125,20 @@ public void offline_whenBusy_allowed() throws SQLException, InterruptedException
     Thread.sleep(200);
     System.out.println("-- taking pool offline (with a busy connection)");
     assertEquals(1, pool.getStatus(false).getBusy());
+    assertThat(pool.size()).isEqualTo(2);
 
     pool.offline();
     assertEquals(0, pool.getStatus(false).getFree());
     assertEquals(1, pool.getStatus(false).getBusy()); // still 1 busy connection
+    assertThat(pool.size()).isEqualTo(1);
 
     // a bit of time to let busy connection finish and close
     Thread.sleep(4000);
 
     // all done now
     assertEquals(0, pool.getStatus(false).getFree());
     assertEquals(0, pool.getStatus(false).getBusy());
+    assertThat(pool.size()).isEqualTo(0);
   }
 
   @Test

src/test/java/io/ebean/datasource/pool/ConnectionPoolTest.java

@@ -44,22 +44,27 @@ public void getConnection_expect_poolGrowsAboveMin() throws SQLException {
 
     assertThat(pool.getStatus(false).getBusy()).isEqualTo(2);
     assertThat(pool.getStatus(false).getFree()).isEqualTo(0);
+    assertThat(pool.size()).isEqualTo(2);
 
     Connection con3 = pool.getConnection();
     assertThat(pool.getStatus(false).getBusy()).isEqualTo(3);
     assertThat(pool.getStatus(false).getFree()).isEqualTo(0);
+    assertThat(pool.size()).isEqualTo(3);
 
     con2.close();
     assertThat(pool.getStatus(false).getBusy()).isEqualTo(2);
     assertThat(pool.getStatus(false).getFree()).isEqualTo(1);
+    assertThat(pool.size()).isEqualTo(3);
 
     con3.close();
     assertThat(pool.getStatus(false).getBusy()).isEqualTo(1);
     assertThat(pool.getStatus(false).getFree()).isEqualTo(2);
+    assertThat(pool.size()).isEqualTo(3);
 
     con1.close();
     assertThat(pool.getStatus(false).getBusy()).isEqualTo(0);
     assertThat(pool.getStatus(false).getFree()).isEqualTo(3);
+    assertThat(pool.size()).isEqualTo(3);
   }
 
   @Test

src/test/java/io/ebean/datasource/pool/ConnectionPoolTrimIdleTest.java

@@ -32,22 +32,25 @@ private ConnectionPool createPool() {
   public void test() throws SQLException, InterruptedException {
 
     ConnectionPool pool = createPool();
+    assertThat(pool.size()).isEqualTo(1);
     try {
       Connection con1 = pool.getConnection();
       Connection con2 = pool.getConnection();
       Connection con3 = pool.getConnection();
       Connection con4 = pool.getConnection();
+      assertThat(pool.size()).isEqualTo(4);
 
       con1.close();
       con2.close();
       con3.close();
       con4.close();
-
+      assertThat(pool.size()).isEqualTo(4);
       assertThat(pool.getStatus(false).getFree()).isEqualTo(4);
 
       Thread.sleep(5000);
 
       assertThat(pool.getStatus(false).getFree()).isEqualTo(1);
+      assertThat(pool.size()).isEqualTo(1);
 
     } finally {
       pool.shutdown();
@@ -70,6 +73,7 @@ public void test_withDecreasingActivity_expect_trimToActivityLevel() throws SQLE
 
       // start at 10 connections
       assertThat(pool.getStatus(false).getFree()).isEqualTo(10);
+      assertThat(pool.size()).isEqualTo(10);
 
       // keep 4 connections busy
       Timer timer0 = createTimer(pool, 4);
@@ -88,6 +92,7 @@ public void test_withDecreasingActivity_expect_trimToActivityLevel() throws SQLE
       // Go Idle
       Thread.sleep(5000);
       assertThat(pool.getStatus(false).getFree()).isEqualTo(1);
+      assertThat(pool.size()).isEqualTo(1);
 
     } finally {
       pool.shutdown();
@@ -100,7 +105,7 @@ private Timer createTimer(ConnectionPool pool, int count) {
     return timer;
   }
 
-  class Task extends TimerTask {
+  static class Task extends TimerTask {
 
     final ConnectionPool pool;