Patch for OPENJPA-168

git-svn-id: https://svn.apache.org/repos/asf/incubator/openjpa/trunk@522581 13f79535-47bb-0310-9956-ffa450edef68

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/JDBCStoreManager.java

@@ -43,6 +43,7 @@ import org.apache.openjpa.jdbc.sql.SQLExceptions;
 import org.apache.openjpa.jdbc.sql.SQLFactory;
 import org.apache.openjpa.jdbc.sql.Select;
 import org.apache.openjpa.jdbc.sql.SelectExecutor;
+import org.apache.openjpa.jdbc.sql.SelectImpl;
 import org.apache.openjpa.jdbc.sql.Union;
 import org.apache.openjpa.kernel.FetchConfiguration;
 import org.apache.openjpa.kernel.LockManager;
@@ -368,9 +369,12 @@ public class JDBCStoreManager
         if (!select(sel, mapping, subs, sm, null, fetch,
             JDBCFetchConfiguration.EAGER_JOIN, true, false))
             return null;
-
         sel.wherePrimaryKey(sm.getObjectId(), mapping, this);
-        return sel.execute(this, fetch);
+        //Set the expectedResultCount for the select as 1 as a single
+        //object is being loaded. force = true is an indicator that it is 
+        //internally generated value
+          sel.setExpectedResultCount(1,true);
+       return sel.execute(this, fetch);
     }
 
     /**
@@ -385,7 +389,7 @@ public class JDBCStoreManager
             JDBCFetchConfiguration.EAGER_JOIN);
 
         Union union = _sql.newUnion(mappings.length);
-        union.setSingleResult(true);
+        union.setExpectedResultCount(1,true);
         if (fetch.getSubclassFetchMode(mapping) != fetch.EAGER_JOIN)
             union.abortUnion();
         union.select(new Union.Selector() {

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/kernel/JDBCStoreQuery.java

@@ -312,6 +312,7 @@ public class JDBCStoreQuery
         ClassMapping[] verts;
         boolean unionable = true;
         Select sel;
+        Object optHint = null;
         for (int i = 0; i < mappings.length; i++) {
             // determine vertical mappings to select separately
             verts = getVerticalMappings(mappings[i], subclasses, exps[i],
@@ -322,6 +323,19 @@ public class JDBCStoreQuery
             // create criteria select and clone for each vert mapping
             sel = ((JDBCExpressionFactory) facts[i]).getSelectConstructor().
                 evaluate(ctx, null, null, exps[i], states[i]);
+            //it means it is coming from getSingleResult so set the 
+            //expectedResultCount to 1.force = true indicates that this is 
+            //internally generated value
+            if(this.ctx.isUnique())
+                 sel.setExpectedResultCount(1,true);
+            //it means this is coming from getResultList so set the 
+            //expectedResultCount based on any optimize hint if provided
+            else{
+                   if((optHint = ctx.fetch.getHint
+                        (this.optimizeHint))!= null)
+                         sel.setExpectedResultCount
+                          (((Integer)optHint).intValue(),false);
+               }
             for (int j = 0; j < verts.length; j++) {
                 selMappings.add(verts[j]);
                 if (j == verts.length - 1) {

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/meta/strats/LRSProxyMap.java

@@ -238,7 +238,7 @@ class LRSProxyMap
         final Joins[] resJoins = new Joins[Math.max(1, clss.length)];
         Union union = store.getSQLFactory().newUnion
             (Math.max(1, clss.length));
-        union.setSingleResult(true);
+        union.setExpectedResultCount(1,true);
         if (fetch.getSubclassFetchMode(_strat.getFieldMapping().
             getElementMapping().getTypeMapping())
             != JDBCFetchConfiguration.EAGER_JOIN)

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/meta/strats/RelationFieldStrategy.java

@@ -578,7 +578,7 @@ public class RelationFieldStrategy
         // back to our fk table if not an inverse mapping (in which case we
         // can just make sure the inverse cols == our pk values)
         Union union = store.getSQLFactory().newUnion(rels.length);
-        union.setSingleResult(true);
+        union.setExpectedResultCount(1,true);
         if (fetch.getSubclassFetchMode(field.getTypeMapping())
             != JDBCFetchConfiguration.EAGER_JOIN)
             union.abortUnion();

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/DB2Dictionary.java

@@ -20,6 +20,7 @@ import java.sql.DatabaseMetaData;
 import java.sql.SQLException;
 import java.util.Arrays;
 
+import org.apache.openjpa.jdbc.kernel.JDBCFetchConfiguration;
 import org.apache.openjpa.jdbc.schema.Sequence;
 
 /**
@@ -27,7 +28,10 @@ import org.apache.openjpa.jdbc.schema.Sequence;
  */
 public class DB2Dictionary
     extends AbstractDB2Dictionary {
-
+    
+    //variables to support optimize clause
+    public String optimizeClause = "optimize for";
+    public String rowClause = "row";
     public DB2Dictionary() {
         platform = "DB2";
         validationSQL = "SELECT DISTINCT(CURRENT TIMESTAMP) FROM "
@@ -193,4 +197,65 @@ public class DB2Dictionary
             }
     	}
     }
+    //based on the expectedResultCount of the select create the optimize
+    //for clause
+    public String getOptimizeClause(JDBCFetchConfiguration fetch, 
+                                   int expectedResultCount) {
+        Integer rows = null;
+        StringBuffer optimizeString = new StringBuffer();
+        
+        	if(expectedResultCount != 0)
+                optimizeString.append(" ").append(optimizeClause).append(" ")
+                .append(expectedResultCount).append(" ")
+                .append(rowClause).append(" ");
+           return optimizeString.toString();    
+    }
+
+    //override the DBDictionary toSelect to call getOptimizeClause and append 
+    //to the select string
+    public SQLBuffer toSelect(SQLBuffer selects, JDBCFetchConfiguration fetch,
+            SQLBuffer from, SQLBuffer where, SQLBuffer group,
+            SQLBuffer having, SQLBuffer order,
+            boolean distinct, boolean forUpdate, long start, long end,
+            int expectedResultCount) {
+        	
+        	String optimizeString = null;
+        	SQLBuffer selString = toOperation(getSelectOperation(fetch), 
+                                              selects, from, where,
+                                              group, having, order, distinct,
+                                              forUpdate, start, end);
+            //return toOperation(getSelectOperation(fetch), selects, from, where,
+             //group, having, order, distinct, forUpdate, start, end);
+        	
+        	if(fetch != null)
+        	    optimizeString = getOptimizeClause(fetch, expectedResultCount);
+        	if(optimizeString != null && optimizeString.length() > 0)
+        		selString.append(optimizeString);
+        	
+        	return selString;
+        	
+        }
+    //override the DBDictionary toSelect to pass expectedResultcount to the 
+    //other toSelect method
+    public SQLBuffer toSelect(Select sel, boolean forUpdate,
+            JDBCFetchConfiguration fetch) {
+            sel.addJoinClassConditions();
+            
+            boolean update = forUpdate && sel.getFromSelect() == null;
+            SQLBuffer select = getSelects(sel, false, update);
+            SQLBuffer ordering = null;
+            if (!sel.isAggregate() || sel.getGrouping() != null)
+                ordering = sel.getOrdering();
+            SQLBuffer from;
+            if (sel.getFromSelect() != null)
+                from = getFromSelect(sel, forUpdate);
+            else
+                from = getFrom(sel, update);
+            SQLBuffer where = getWhere(sel, update);
+            return toSelect(select, fetch, from, where, sel.getGrouping(),
+                sel.getHaving(), ordering, sel.isDistinct(), forUpdate,
+                sel.getStartIndex(), 
+                sel.getEndIndex(),sel.getExpectedResultCount());
+        }
+
 }

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/LogicalUnion.java

@@ -47,13 +47,18 @@ public class LogicalUnion
 
     private static final Localizer _loc = Localizer.forPackage
         (LogicalUnion.class);
-
+     //expected number of results for this select to be used in 
+    // optimize for clause
+    protected int expectedResultCount = 0;
+    //indicate if this is internally generated result count 
+    //or not
+    protected boolean force = false;
     protected final UnionSelect[] sels;
     protected final DBDictionary dict;
     protected final ClassMapping[] mappings;
     protected final BitSet desc = new BitSet();
     private boolean _distinct = true;
-    private boolean _single = false;
+   
 
     /**
      * Constructor.
@@ -102,15 +107,7 @@ public class LogicalUnion
     public Select[] getSelects() {
         return sels;
     }
-
+   
-    public boolean isSingleResult() {
-        return _single;
-    }
-
-    public void setSingleResult(boolean single) {
-        _single = single;
-    }
-
     public boolean isUnion() {
         return false;
     }
@@ -215,9 +212,12 @@ public class LogicalUnion
             return res;
         }
 
-        if (_single) {
+        if (this.getExpectedResultCount()== 1) {
             AbstractResult res;
             for (int i = 0; i < sels.length; i++) {
+                //for each select set the expected result count to 1
+                //and force true indicating that this internally generated value
+                 sels[i].sel.setExpectedResultCount(1,true);
                 res = (AbstractResult) sels[i].execute(store, fetch,
                     lockLevel);
                 res.setBaseMapping(mappings[i]);
@@ -305,7 +305,12 @@ public class LogicalUnion
         protected final int pos;
         protected int orders = 0;
         protected List orderIdxs = null;
-
+        //  expected number of results for this select to be used in 
+        // optimize for clause
+        protected int expectedResultCount = 0;
+        //force indicates it is internally generated result count or not
+        protected boolean force = false;
+       
         public UnionSelect(SelectImpl sel, int pos) {
             this.sel = sel;
             this.pos = pos;
@@ -838,6 +843,18 @@ public class LogicalUnion
         public String toString() {
             return sel.toString();
         }
+
+		public int getExpectedResultCount() {
+			return expectedResultCount;
+		}
+
+		public void setExpectedResultCount(int expectedResultCount, boolean force) {
+			this.expectedResultCount = expectedResultCount;
+            this.force = force;
+		}
+         public boolean isExpRsltCntForced() {
+                return force;
+            }
     }
 
     /**
@@ -918,4 +935,16 @@ public class LogicalUnion
             return a1.length - a2.length;
         }
     }
+
+    public int getExpectedResultCount() {
+        return expectedResultCount;
+    }
+
+    public void setExpectedResultCount(int expectedResultCount,boolean force) {
+        this.expectedResultCount = expectedResultCount;
+        this.force = force;
+    }
+    public boolean isExpRsltCntForced() {
+        return force;
+    }
 }

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/SelectExecutor.java

@@ -119,4 +119,23 @@ public interface SelectExecutor {
     public Result execute(JDBCStore store, JDBCFetchConfiguration fetch,
         int lockLevel)
         throws SQLException;
+    
+    /**
+     * Return the expected result count for the query
+     */
+    public int getExpectedResultCount() ;
+
+    /**
+     * Set the expected result count for the query
+     * force indicates whether the count is internally generated
+     * or given by the user as optimize hint
+     */
+    
+    public void setExpectedResultCount(int expectedResultCount,boolean force) ;
+    
+    /**
+     * Indicates whether the expectedResultCount is internally generated
+     */
+     
+     public boolean isExpRsltCntForced();
 }

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/SelectImpl.java

@@ -153,7 +153,14 @@ public class SelectImpl
     // from select if this select selects from a tmp table created by another
     private SelectImpl _from = null;
     private SelectImpl _outer = null;
-
+    
+    //expected number of results for this select to be used in 
+    // optimize for clause
+    private int expectedResultCount = 0;
+    //true if the expectedResultCount is internally set false if
+    //it is set by the user
+    private boolean force = false;
+     
     /**
      * Helper method to return the proper table alias for the given alias index.
      */
@@ -304,6 +311,20 @@ public class SelectImpl
         JDBCFetchConfiguration fetch, int lockLevel)
         throws SQLException {
         boolean forUpdate = false;
+        
+        //expectedResultCount = 1 and force means that it is internally generated value 
+        //for getSingleResult,single valued relationship.We need to check if 
+        //there are any eager joins in the select if there are then the 
+        //optimize for 1 row clause is not generated else we do. if 
+        //!force then it is set by the user through hint and we 
+        //do not check the eager joins
+        if(this.expectedResultCount == 1 && force ){
+            if(this.hasEagerJoin(true))
+                this.setExpectedResultCount(0,false);
+            else
+               this.setExpectedResultCount(1,false); 
+           }
+      
         if (!isAggregate() && _grouping == null) {
             JDBCLockManager lm = store.getLockManager();
             if (lm != null)
@@ -2799,6 +2820,19 @@ public class SelectImpl
             _idents = null;
         }
     }
+
+	public int getExpectedResultCount() {
+		return expectedResultCount;
+	}
+
+	public void setExpectedResultCount(int expectedResultCount, boolean force) {
+		this.expectedResultCount = expectedResultCount;
+        this.force = force;
+	}
+
+    public boolean isExpRsltCntForced() {
+        return force;
+    }
 }
 
 /**

openjpa-jdbc/src/main/java/org/apache/openjpa/jdbc/sql/Union.java

@@ -33,20 +33,6 @@ public interface Union
      */
     public String getOrdering();
 
-    /**
-     * Whether this union will return at most a single result. Setting this
-     * flag makes it more efficient to execute logical unions that are actually
-     * made up from multiple selects executed in batch.
-     */
-    public boolean isSingleResult();
-
-    /**
-     * Whether this union will return at most a single result. Setting this
-     * flag makes it more efficient to execute logical unions that are actually
-     * made up from multiple selects executed in batch.
-     */
-    public void setSingleResult(boolean single);
-
     /**
      * Whether this is a true UNION, rather than a logical combination of
      * independent selects.

openjpa-kernel/src/main/java/org/apache/openjpa/kernel/AbstractStoreQuery.java

@@ -33,6 +33,7 @@ public abstract class AbstractStoreQuery
     implements StoreQuery {
 
     protected QueryContext ctx = null;
+    public static final String optimizeHint ="openjpa.hint.OptimizeResultCount";
 
     public QueryContext getContext() {
         return ctx;

openjpa-kernel/src/main/java/org/apache/openjpa/kernel/QueryImpl.java

@@ -1289,7 +1289,11 @@ public class QueryImpl
                 // Collections.singletonList is JDK 1.3, so...
                 return Arrays.asList(new Object[]{ single });
             }
-
+             
+            if(single == null)
+                throw new InvalidStateException(_loc.get("is-null",
+                        _class, _query));
+            
             // return single result
             return single;
         } finally {

openjpa-kernel/src/main/resources/org/apache/openjpa/kernel/localizer.properties

@@ -259,6 +259,9 @@ executing-query-with-params: Executing query: [{0}] with parameters: {1}
 not-unique: The query on candidate type "{0}" with filter "{1}" was \
 	configured to have a unique result, but more than one instance matched \
 	the query.
+is-null: The query on candidate type "{0}" with filter "{1}" was \
+	configured to have a unique result, but no instance matched \
+	the query.
 serialized: Queries that have been serialized do not support this operation.
 read-only: Attempt to modify a read-only query object.
 no-class: A candidate Class must be specified before executing a query.

openjpa-persistence/src/main/java/org/apache/openjpa/persistence/QueryImpl.java

@@ -279,24 +279,15 @@ public class QueryImpl
      */
     public Object getSingleResult() {
         _em.assertNotCloseInvoked();
+        //Indicate that this query returns single result.Later copied into
+        //select.expectedResultCount
+        _query.setUnique(true);
+        try{
         Object ob = execute();
-        if (!(ob instanceof List))
+           return ob;
-            return ob;
 
-        List res = (List) ob;
-        try {
-            // don't use size() b/c can be inefficient under some LRS settings
-            Iterator itr = res.iterator();
-            if (!itr.hasNext())
-                throw new NoResultException(_loc.get("no-results",
-                    _query.getQueryString()).getMessage(), null, null, false);
-            Object ret = itr.next();
-            if (itr.hasNext())
-                throw new NonUniqueResultException(_loc.get("mult-results",
-                    _query.getQueryString()).getMessage(), null, null, false);
-            return ret;
         } finally {
-            OpenJPAPersistence.close(res);
+            _query.setUnique(false);
         }
     }
 
@@ -375,13 +366,29 @@ public class QueryImpl
             } else if (k.startsWith("FetchPlan.")) {
                 k = k.substring("FetchPlan.".length());
                 Filters.hintToSetter(getFetchPlan(), k, value);
-            } else if (k.startsWith("hint."))
+            } else if (k.startsWith("hint.")){
+            	if("hint.OptimizeResultCount".equals(k)){
+            		if((!(value instanceof String)&&!(value instanceof Integer))
+                       ||  (value instanceof String &&(Integer.parseInt
+                       ((String)value)< 0))||((value instanceof Integer)
+                        && (((Integer)value).intValue()<0)) )
+            			    throw new ArgumentException(_loc.get
+                                      ("bad-hint-value", key),
+                                      null, null, false);
+                    if(value instanceof String)
+                        value = new Integer((String)value);
+         	}
                 _query.getFetchConfiguration().setHint(key, value);
+            }
             else
                 throw new ArgumentException(_loc.get("bad-query-hint", key),
                     null, null, false);
             return this;
-        } catch (Exception e) {
+        }catch(NumberFormatException e1){
+              throw new ArgumentException(_loc.get("bad-hint-value", key),
+                null, null, false); 
+        }
+         catch (Exception e) {
             throw PersistenceExceptions.toPersistenceException(e);
         }
     }