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.
hibernate · Jun 8, 2011 · bf066b8 · bf066b8
1 parent 02a866c
commit bf066b8
Showing 1 changed file with 60 additions and 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
@@ -68,49 +68,65 @@ public InFragment setFormula(String alias, String formulaTemplate) {
 	}
 
 	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();
+
 	}
 }