From bf066b812138801635e52e2af86871e9f7151af3 Mon Sep 17 00:00:00 2001
From: "andy.miller" <andy.miller@jboss.com>
Date: Fri, 27 May 2011 14:12:57 -0600
Subject: [PATCH] HHH-6258:  Performance enhancement to toFragmentString method
 to only append to the StringBuffer, and not do inserts into the beginning,
 which causes additional buffer allocations and copies that are unnecessary. 
 Also, changed the StringBuffer to a StringBuilder.

---
 .../java/org/hibernate/sql/InFragment.java    | 104 ++++++++++--------
 1 file changed, 60 insertions(+), 44 deletions(-)

diff --git a/hibernate-core/src/main/java/org/hibernate/sql/InFragment.java b/hibernate-core/src/main/java/org/hibernate/sql/InFragment.java
index 8c6e107c53..56c2ad99b3 100644
--- a/hibernate-core/src/main/java/org/hibernate/sql/InFragment.java
+++ b/hibernate-core/src/main/java/org/hibernate/sql/InFragment.java
@@ -68,49 +68,65 @@ public class InFragment {
 	}
 
 	public String toFragmentString() {
-		if ( values.size()==0 ) return "1=2";
-		StringBuffer buf = new StringBuffer( values.size() * 5 );
-		buf.append(columnName);
-		//following doesn't handle (null, not null) but unnecessary
-		//since this would mean all rows
-		if ( values.size()>1 ) {
-			boolean allowNull = false;
-			buf.append(" in (");
-			Iterator iter = values.iterator();
-			while ( iter.hasNext() ) {
-				Object value = iter.next();
-				if ( NULL.equals(value) ) {
-					allowNull = true;
-				}
-				else if ( NOT_NULL.equals(value) ) {
-					throw new IllegalArgumentException("not null makes no sense for in expression");
-				}
-				else {
-					buf.append(value);
-					buf.append(", ");
-				}
-			}
-			buf.setLength( buf.length()-2 );
-			buf.append(')');
-			if (allowNull) {
-				buf.insert(0, " is null or ")
-					.insert(0, columnName)
-					.insert(0, '(')
-					.append(')');
-			}
-		}
-		else {
-			Object value = values.iterator().next();
-			if ( NULL.equals(value) ) {
-				buf.append(" is null");
-			}
-			else if ( NOT_NULL.equals(value) ) {
-				buf.append(" is not null");
-			}
-			else {
-				buf.append("=").append(value);
-			}
-		}
-		return buf.toString();
+
+                if (values.size() == 0) {
+                   return "1=2";
+                }
+
+                StringBuilder buf = new StringBuilder(values.size() * 5);
+
+                if (values.size() == 1) {
+                   Object value = values.get(0);
+                   buf.append(columnName);
+
+                   if (NULL.equals(value)) {
+                      buf.append(" is null");
+                   } else {
+                      if (NOT_NULL.equals(value)) {
+                         buf.append(" is not null");
+                      } else {
+                         buf.append('=').append(value);
+                      }
+                   }
+                   return buf.toString();
+                }
+                   
+                boolean allowNull = false;
+
+                for (Object value : values) {
+                   if (NULL.equals(value)) {
+                      allowNull = true;
+                   } else {
+                      if (NOT_NULL.equals(value)) {
+                         throw new IllegalArgumentException("not null makes no sense for in expression");
+                      }
+                   }
+                }
+
+                if (allowNull) {
+                   buf.append('(').append(columnName).append(" is null or ").append(columnName).append(" in (");
+                } else {
+                   buf.append(columnName).append(" in (");
+                }
+
+                for (Object value : values) {
+                   if (NULL.equals(value)) {
+                      ;
+                   } else {
+                      buf.append(value);
+                      buf.append(", ");
+                   }
+                }
+
+                buf.setLength(buf.length() - 2);
+
+                if (allowNull) {
+                   buf.append("))");
+                } else {
+                   buf.append(')');
+                }
+
+                return buf.toString();
+
 	}
 }