Author: jbalunas(a)redhat.com Date: 2010-12-17 11:26:12 -0500 (Fri, 17 Dec 2010) New Revision: 20659 Modified: branches/enterprise/3.3.1.SP2_RFPL-967/framework/impl/src/main/java/org/ajax4jsf/util/DocumentBuilderPool.java Log: RFPL-967, RF-10035 Updated based on review Modified: branches/enterprise/3.3.1.SP2_RFPL-967/framework/impl/src/main/java/org/ajax4jsf/util/DocumentBuilderPool.java =================================================================== --- branches/enterprise/3.3.1.SP2_RFPL-967/framework/impl/src/main/java/org/ajax4jsf/util/DocumentBuilderPool.java 2010-12-17 16:17:57 UTC (rev 20658) +++ branches/enterprise/3.3.1.SP2_RFPL-967/framework/impl/src/main/java/org/ajax4jsf/util/DocumentBuilderPool.java 2010-12-17 16:26:12 UTC (rev 20659) @@ -36,15 +36,26 @@ * @author balunasj(a)redhat.com * */ -public class DocumentBuilderPool { +public final class DocumentBuilderPool { - // How big the pool is - private static final int POOL_SIZE = 100; - - // status array for pool storage - private static ArrayStack _documentBuilderPool; + /** + * How big the pool is + */ + private static final int DOC_BUILDER_POOL_SIZE = 100; /** + * Creates and holds the pool using the Initialization On Demand Holder idiom. + */ + private static class DocumentBuilderPoolHolder { + static ArrayStack _documentBuilderPool = new ArrayStack(DOC_BUILDER_POOL_SIZE); + } + + /** + * Private constructor + */ + private DocumentBuilderPool (){} + + /** * Get a pooled instance of DocumentBuilder * @return Pooled DocumentBulder * @throws ParserConfigurationException @@ -52,22 +63,11 @@ public static DocumentBuilder getDocumentBuilder() throws ParserConfigurationException{ DocumentBuilder builder = null; - //Check if pool needs to be initialized - if (_documentBuilderPool == null){ - //Sync to avoid conflicts - synchronized (DocumentBuilderPool.class) { - //Second level check - if (_documentBuilderPool == null){ - _documentBuilderPool = new ArrayStack(POOL_SIZE); - } - } - } - try { //freeze the pool - synchronized (_documentBuilderPool) { + synchronized (DocumentBuilderPoolHolder._documentBuilderPool) { //pop the top builder - if empty it will through EmptyStackException - builder = (DocumentBuilder) _documentBuilderPool.pop(); + builder = (DocumentBuilder) DocumentBuilderPoolHolder._documentBuilderPool.pop(); } } catch (EmptyStackException e) { //Stack is empty, create a new builder @@ -84,14 +84,14 @@ public static void returnDocumentBuilder(DocumentBuilder builder) { //validate the builder if (null != builder) { - synchronized (_documentBuilderPool) { + synchronized (DocumentBuilderPoolHolder._documentBuilderPool) { //only add if the pool is full - if (_documentBuilderPool.size() < POOL_SIZE) { + if (DocumentBuilderPoolHolder._documentBuilderPool.size() < DOC_BUILDER_POOL_SIZE) { //reset the builder to initial state builder.reset(); //push the builder back - _documentBuilderPool.push(builder); + DocumentBuilderPoolHolder._documentBuilderPool.push(builder); } } }