Optimized find strategy

Author: rPraml

ebean-datasource/src/main/java/io/ebean/datasource/pool/ConnectionBuffer.java

@@ -119,7 +119,8 @@
 final class ConnectionBuffer {
 
   // special key to return the oldest connection from freeList.
-  static final Object GET_OLDEST = new Object();
+  static final Object GET_LAST = new Object();
+  static final Object GET_FIRST = new Object();
 
   private final ConnectionList[] affinityLists;
   private final ConnectionList freeList = new ConnectionList();
@@ -218,17 +219,23 @@ boolean removeBusy(PooledConnection c) {
    */
   PooledConnection removeFree(Object affinityId) {
     PooledConnection pc;
-    if (affinityId == GET_OLDEST) {
-      pc = freeList.peekLast();
-    } else if (affinityLists == null) {
+    if (affinityLists == null) {
+      // affinity disabled. Always use first in list
       pc = freeList.peekFirst();
     } else if (affinityId == null) {
+      // null affinity passed
       pc = affinityLists[hashSize].peekFirst();
-    } else { // we have an affinity id.
+    } else if (affinityId == GET_FIRST) {
+      // explicitly first one was requested (for heartbeat)
+      pc = freeList.peekFirst();
+    } else if (affinityId == GET_LAST) {
+      // explicitly last one was requested (for changing affinityId)
+      pc = freeList.peekLast();
+    } else {
+      // we have an affinity id request
       pc = affinityLists[affinityId.hashCode() % hashSize].find(affinityId);
       if (pc == null) {
-        // no pc with this affinity-id in the pool.
-        // query "null"-affinityList
+        // no pc with this affinity-id in the pool. Query "null"-affinityList
         pc = affinityLists[hashSize].peekFirst();
       }
     }

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

@@ -382,7 +382,7 @@ private void testConnection() {
     PooledConnection conn = null;
     try {
       // Get a connection from the pool and test it
-      conn = getPooledConnection(affinityProvider.get());
+      conn = getPooledConnection(ConnectionBuffer.GET_FIRST);
       heartbeatPoolExhaustedCount = 0;
       if (testConnection(conn)) {
         notifyDataSourceIsUp();
@@ -648,7 +648,6 @@ public DataSourceConnection getConnection(Object affinityId) throws SQLException
    */
   private PooledConnection getPooledConnection(Object affinitiyId) throws SQLException {
     PooledConnection c = queue.obtainConnection(affinitiyId);
-    c.setAffinityId(affinitiyId);
     if (captureStackTrace) {
       c.setStackTrace(Thread.currentThread().getStackTrace());
     }

ebean-datasource/src/main/java/io/ebean/datasource/pool/PooledConnectionQueue.java

@@ -190,6 +190,9 @@ PooledConnection obtainConnection(Object affinitiyId) throws SQLException {
     try {
       PooledConnection pc = _obtainConnection(affinitiyId);
       pc.resetForUse();
+      if (affinitiyId != ConnectionBuffer.GET_FIRST && affinitiyId != ConnectionBuffer.GET_LAST) {
+        pc.setAffinityId(affinitiyId);
+      }
       return pc;
 
     } catch (InterruptedException e) {
@@ -227,11 +230,6 @@ private PooledConnection _obtainConnection(Object affinitiyId) throws Interrupte
           return connection;
         }
         connection = createConnection();
-        if (connection == null && buffer.isAffinitySupported()) {
-          // we could not find connection with required affinity and
-          // buffer is full. So try to get oldest connection from buffer
-          connection = extractFromFreeList(ConnectionBuffer.GET_OLDEST);
-        }
         if (connection != null) {
           return connection;
         }
@@ -254,7 +252,7 @@ private PooledConnection _obtainConnection(Object affinitiyId) throws Interrupte
   }
 
   private PooledConnection createConnection() throws SQLException {
-    if (buffer.busySize() < maxSize) {
+    if (totalConnections() < maxSize) {
       // grow the connection pool
       PooledConnection c = pool.createConnectionForQueue(connectionId++);
       int busySize = registerBusyConnection(c);
@@ -279,6 +277,13 @@ private PooledConnection _obtainConnectionWaitLoop(Object affinitiyId) throws SQ
         if (conn != null) {
           return conn;
         }
+        // we could not create new connection, so we take the last one and change the affinity id
+        if (buffer.isAffinitySupported()) {
+          conn = extractFromFreeList(ConnectionBuffer.GET_LAST);
+        }
+        if (conn != null) {
+          return conn;
+        }
         String msg = "Unsuccessfully waited [" + waitTimeoutMillis + "] millis for a connection to be returned."
           + " No connections are free. You need to Increase the max connections of [" + maxSize + "]"
           + " or look for a connection pool leak using datasource.xxx.capturestacktrace=true";
@@ -292,9 +297,7 @@ private PooledConnection _obtainConnectionWaitLoop(Object affinitiyId) throws SQ
       try {
         nanos = notEmpty.awaitNanos(nanos);
         PooledConnection c = extractFromFreeList(affinitiyId);
-        if (c == null && buffer.isAffinitySupported()) {
-          c = extractFromFreeList(ConnectionBuffer.GET_OLDEST);
-        }
+
         if (c != null) {
           // successfully waited
           return c;

ebean-datasource/src/test/java/io/ebean/datasource/pool/ConnectionBufferTest.java

@@ -187,7 +187,7 @@ public void test_Affinity() {
   private static PooledConnection getConnection(ConnectionBuffer b, Object affinity) {
     PooledConnection c1 = b.removeFree(affinity);
     if (c1 == null) {
-      c1 = b.removeFree(ConnectionBuffer.GET_OLDEST);
+      c1 = b.removeFree(ConnectionBuffer.GET_LAST);
     }
     c1.setAffinityId(affinity);
     b.addBusy(c1);