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Subject: svn commit: r1399140 - in
 /db/derby/code/trunk/java/engine/org/apache/derby/impl/sql:
 compile/ActivationClassBuilder.java compile/StatementNode.java
 execute/BaseActivation.java execute/ConstantActionActivation.java
Date: Wed, 17 Oct 2012 07:45:36 -0000
To: derby-commits@db.apache.org
From: kahatlen@apache.org
Message-Id: <20121017074536.9F7E923889BB@eris.apache.org>

Author: kahatlen
Date: Wed Oct 17 07:45:35 2012
New Revision: 1399140

URL: http://svn.apache.org/viewvc?rev=1399140&view=rev
Log:
DERBY-5947: Factor out common code from generated classes

- Move common code from the generated execute() method to a method
  in BaseActivation, and rename the generated execute() method to
  doExecute(), called from BaseActivation.execute().

- Simplify generated code in doExecute(). Specifically, fetch the
  resultSet field only once.

Modified:
    db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/compile/ActivationClassBuilder.java
    db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/compile/StatementNode.java
    db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/execute/BaseActivation.java
    db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/execute/ConstantActionActivation.java

Modified: db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/compile/ActivationClassBuilder.java
URL: http://svn.apache.org/viewvc/db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/compile/ActivationClassBuilder.java?rev=1399140&r1=1399139&r2=1399140&view=diff
==============================================================================
--- db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/compile/ActivationClassBuilder.java (original)
+++ db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/compile/ActivationClassBuilder.java Wed Oct 17 07:45:35 2012
@@ -21,40 +21,14 @@
 
 package org.apache.derby.impl.sql.compile;
 
-import org.apache.derby.iapi.services.compiler.ClassBuilder;
-import org.apache.derby.iapi.services.compiler.MethodBuilder;
-import org.apache.derby.iapi.services.compiler.LocalField;
-import org.apache.derby.iapi.reference.ClassName;
-
-
-import org.apache.derby.iapi.services.sanity.SanityManager;
-
-import org.apache.derby.iapi.sql.compile.CompilerContext;
-import org.apache.derby.iapi.sql.compile.CodeGeneration;
-
-import org.apache.derby.iapi.sql.execute.CursorResultSet;
-
-import org.apache.derby.iapi.sql.ResultSet;
-
-import org.apache.derby.iapi.sql.execute.ExecRow;
-
-import org.apache.derby.iapi.types.DataTypeDescriptor;
-import org.apache.derby.iapi.types.TypeId;
-
+import java.lang.reflect.Modifier;
 import org.apache.derby.iapi.error.StandardException;
-
-import org.apache.derby.iapi.services.loader.GeneratedMethod;
+import org.apache.derby.iapi.reference.ClassName;
 import org.apache.derby.iapi.services.classfile.VMOpcode;
-
-import java.lang.reflect.Modifier;
-
-import java.io.PrintWriter;
-
-import java.io.File;
-import java.io.FileOutputStream;
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.util.Hashtable;
+import org.apache.derby.iapi.services.compiler.LocalField;
+import org.apache.derby.iapi.services.compiler.MethodBuilder;
+import org.apache.derby.iapi.sql.compile.CodeGeneration;
+import org.apache.derby.iapi.sql.compile.CompilerContext;
 
 /**
  * ActivationClassBuilder
@@ -108,8 +82,7 @@ class ActivationClassBuilder	extends	Exp
 	 * <pre>
 	 *    public class #className extends #superClass {
 	 *		// public void reset() { return; }
-	 *		public ResultSet execute() throws StandardException {
-	 *			throwIfClosed("execute");
+	 *		protected ResultSet doExecute() throws StandardException {
 	 *			// statements must be added here
 	 *		}
 	 *		public #className() { super(); }
@@ -192,8 +165,7 @@ class ActivationClassBuilder	extends	Exp
 	/**
 	 * By the time this is done, it has generated the following code
 	 * <pre>
-	 *		public ResultSet execute() throws StandardException {
-	 *			throwIfClosed("execute");
+	 *		protected ResultSet doExecute() throws StandardException {
 	 *			// statements must be added here
 	 *		}
 	 *    }
@@ -222,25 +194,14 @@ class ActivationClassBuilder	extends	Exp
 		// mb.complete(); // there is nothing else.
 
 
-		// This method is an implementation of the interface method
-		// Activation - ResultSet execute()
+		// This method is an implementation of the abstract method
+		// BaseActivation - ResultSet doExecute()
 
 		// create an empty execute method
-		MethodBuilder mb = cb.newMethodBuilder(Modifier.PUBLIC,
-			ClassName.ResultSet, "execute");
+		MethodBuilder mb = cb.newMethodBuilder(Modifier.PROTECTED,
+			ClassName.ResultSet, "doExecute");
 		mb.addThrownException(ClassName.StandardException);
 
-		// put a 'throwIfClosed("execute");' statement into the execute method.
-		mb.pushThis(); // instance
-		mb.push("execute");
-		mb.callMethod(VMOpcode.INVOKEVIRTUAL, ClassName.BaseActivation, "throwIfClosed", "void", 1);
-
-		// call this.startExecution(), so the parent class can know an execution
-		// has begun.
-
-		mb.pushThis(); // instance
-		mb.callMethod(VMOpcode.INVOKEVIRTUAL, ClassName.BaseActivation, "startExecution", "void", 0);
-
 		return	mb;
 	}
 

Modified: db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/compile/StatementNode.java
URL: http://svn.apache.org/viewvc/db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/compile/StatementNode.java?rev=1399140&r1=1399139&r2=1399140&view=diff
==============================================================================
--- db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/compile/StatementNode.java (original)
+++ db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/compile/StatementNode.java Wed Oct 17 07:45:35 2012
@@ -301,10 +301,10 @@ public abstract class StatementNode exte
 
         /*
          * Generate the code to execute this statement.
-         * Two methods are generated here: execute() and
+         * Two methods are generated here: doExecute() and
          * fillResultSet().
          * <BR>
-         * execute is called for every execution of the
+         * doExecute() is called for every execution of the
          * Activation. Nodes may add code to this using
          * ActivationClassBuilder.getExecuteMethod().
          * This code will be executed every execution.
@@ -315,12 +315,8 @@ public abstract class StatementNode exte
          * <P>
          * The generated code is equivalent to:
          * <code>
-         * public ResultSet execute() {
+         * protected ResultSet doExecute() {
          * 
-         *    // these two added by ActivationClassBuilder
-         *    throwIfClosed("execute");
-         *    startExecution();
-         *    
          *    [per-execution code added by nodes]
          *    
          *    if (resultSet == null)
@@ -346,26 +342,33 @@ public abstract class StatementNode exte
         mbWorker.methodReturn();
         mbWorker.complete();
 
+        // Get the value of the resultSet field.
 		executeMethod.pushThis();
 		executeMethod.getField(ClassName.BaseActivation, "resultSet",
                 ClassName.ResultSet);
-        
+
+        // Keep a copy of the field value on the stack so we don't need
+        // to look it up again if it's non-null.
+        executeMethod.dup();
 		executeMethod.conditionalIfNull();
-        
+
+            // The field was null, so we won't use the value that's on the
+            // stack. Forget about it.
+            executeMethod.pop();
+
             // Generate the result set tree and store the
             // resulting top-level result set into the resultSet
             // field, as well as returning it from the execute method.
-			
+
+            // Push this onto the stack twice, as both callMethod() and
+            // putField() take the instance as first operand.
 			executeMethod.pushThis();
+            executeMethod.dup();
 			executeMethod.callMethod(VMOpcode.INVOKEVIRTUAL, (String) null,
 									 "fillResultSet", ClassName.ResultSet, 0);
-            executeMethod.pushThis();
-            executeMethod.swap();
             executeMethod.putField(ClassName.BaseActivation, "resultSet", ClassName.ResultSet);
             
 		executeMethod.startElseCode(); // this is here as the compiler only supports ? :
-			executeMethod.pushThis();
-			executeMethod.getField(ClassName.BaseActivation, "resultSet", ClassName.ResultSet);
 		executeMethod.completeConditional();
 
    		// wrap up the activation class definition

Modified: db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/execute/BaseActivation.java
URL: http://svn.apache.org/viewvc/db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/execute/BaseActivation.java?rev=1399140&r1=1399139&r2=1399140&view=diff
==============================================================================
--- db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/execute/BaseActivation.java (original)
+++ db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/execute/BaseActivation.java Wed Oct 17 07:45:35 2012
@@ -258,6 +258,27 @@ public abstract class BaseActivation imp
 	// Activation interface
 	//
 
+    public final ResultSet execute() throws StandardException {
+        throwIfClosed("execute");
+
+        // Determine if we should check row counts during this execution.
+        checkRowCounts = shouldWeCheckRowCounts();
+
+        // If we are to check row counts, clear the hash table of row counts
+        // we have checked.
+        if (checkRowCounts) {
+            rowCountsCheckedThisExecution.clear();
+        }
+
+        return doExecute();
+    }
+
+    /**
+     * Abstract method overridden by generated classes, containing the
+     * body of the {@link #execute()} method.
+     */
+    protected abstract ResultSet doExecute() throws StandardException;
+
 	public final ExecPreparedStatement getPreparedStatement() {
 		return preStmt;
 	}
@@ -1046,22 +1067,6 @@ public abstract class BaseActivation imp
 	}
 
 	/**
-	 * The subclass calls this method when it begins an execution.
-	 *
-	 * @exception StandardException		Thrown on error
-	 */
-	public void startExecution() throws StandardException
-	{
-		// determine if we should check row counts during this execution
-        checkRowCounts = shouldWeCheckRowCounts();
-
-		// If we are to check row counts, clear the hash table of row counts
-		// we have checked.
-		if (checkRowCounts)
-			rowCountsCheckedThisExecution.clear();
-	}
-
-	/**
 	 * @see Activation#getHeapConglomerateController
 	 */
 	public ConglomerateController getHeapConglomerateController()

Modified: db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/execute/ConstantActionActivation.java
URL: http://svn.apache.org/viewvc/db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/execute/ConstantActionActivation.java?rev=1399140&r1=1399139&r2=1399140&view=diff
==============================================================================
--- db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/execute/ConstantActionActivation.java (original)
+++ db/derby/code/trunk/java/engine/org/apache/derby/impl/sql/execute/ConstantActionActivation.java Wed Oct 17 07:45:35 2012
@@ -57,14 +57,11 @@ public final class ConstantActionActivat
         return null;
     }
 
-	public ResultSet execute() throws StandardException {
-
-		throwIfClosed("execute");
-		startExecution();
-
+	protected ResultSet doExecute() throws StandardException {
 		if (resultSet == null)
 			resultSet = getResultSetFactory().getDDLResultSet(this);
 		return resultSet;
 	}
+
 	public void postConstructor(){}
 }