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From "Conor MacNeill" <co...@cortexebusiness.com.au>
Subject Re: [PATCH] Lazy task class loading
Date Tue, 07 Aug 2001 15:17:11 GMT
Stefan,

You've sent up your test balloon in the middle of the thunderstorm that is
an Ant release. We have done just a cursory look at the outstanding
patches. It is still a long queue. Stefan Bodewig gave this feedback.

* lazy classloading

I'm fine with the changes to project, but not with the changes to
<ant>, as they will lose class loader information for custom taskdefs

Cheers
Conor

----- Original Message -----
From: "Stefan Reich" <doc@drjava.de>
To: <ant-dev@jakarta.apache.org>
Sent: Wednesday, August 08, 2001 12:33 AM
Subject: Re: [PATCH] Lazy task class loading


Hi Ant developers-in-charge,

I sent this to the list two weeks ago and didn't get any reply.

Can you please give me an indication whether this patch is at all useful?
Or if you think it isn't, then tell me why. I would really like to know
that.

I have a couple of ideas for other patches to submit; but I don't want to
go through the hassle to prepare them if there is no interest. So I'm using
this patch as a kind of test balloon ;-)

Best,
-Stefan
  ----- Original Message -----
  From: Stefan Reich
  To: ant-dev@jakarta.apache.org
  Sent: Saturday, July 21, 2001 7:25 PM
  Subject: [PATCH] Lazy task class loading


  Hi,

  currently Ant loads all taskdef classes (as defined in
defaults.properties) on startup. This mechanism has at least 3 drawbacks:

  -It can take up to one second or longer (if you use ant for everyday
development, you will notice the difference)
  -It wastes memory
  -It completely lacks descriptive error messages. For example, if you use
<junit>, but junit.jar isn't in your classpath, you only get a default
message telling you something about optional.jar. I've been puzzled as to
why tasks couldn't be loaded more than once.

  I would like to submit a patch that solves all three problems. I also
took care to ensure that the public interface of
org.apache.tools.ant.Project is backward compatible.

  -Stefan

  Here is the patch against recent CVS (I already added @author tags for
your convenience ;-):

  Index: main/org/apache/tools/ant/Project.java
  ===================================================================
  RCS file:
/home/cvspublic/jakarta-ant/src/main/org/apache/tools/ant/Project.java,v
  retrieving revision 1.64
  diff -u -r1.64 Project.java
  --- main/org/apache/tools/ant/Project.java 2001/07/17 12:12:39 1.64
  +++ main/org/apache/tools/ant/Project.java 2001/07/21 17:03:14
  @@ -68,6 +68,7 @@
    * file paths at runtime as well as defining various project properties.
    *
    * @author duncan@x180.com
  + * @author Stefan Reich <a href="mailto:doc@drjava.de">doc@drjava.de</a>
    */

   public class Project {
  @@ -101,7 +102,8 @@
       private Hashtable references = new Hashtable();
       private String defaultTarget;
       private Hashtable dataClassDefinitions = new Hashtable();
  -    private Hashtable taskClassDefinitions = new Hashtable();
  +    private TaskDefinitionHashtable taskClassDefinitions = new
TaskDefinitionHashtable();
  +
       private Hashtable targets = new Hashtable();
       private Hashtable filters = new Hashtable();
       private File baseDir;
  @@ -114,6 +116,27 @@
       /** The system classloader - may be null */
       private ClassLoader systemLoader = null;

  +    public static class TaskDefinitionHashtable extends Hashtable {
  +      /** lazily call Class.forName */
  +      public Object get(Object key) {
  +        Object value = super.get(key);
  +        if (value instanceof String) {
  +          try {
  +            value = Class.forName((String) value);
  +          } catch (ClassNotFoundException e) {
  +            throw new RuntimeException(e.toString());
  +          } catch (NoClassDefFoundError e) {
  +            throw new RuntimeException(e.toString());
  +          }
  +        }
  +        return value;
  +      }
  +
  +      public String getClassName(Object key) {
  +        return (String) super.get(key);
  +      }
  +    }
  +
       static {

           // Determine the Java version by looking at available classes
  @@ -161,19 +184,23 @@
               props.load(in);
               in.close();

  +            long startTime = System.currentTimeMillis();
               Enumeration enum = props.propertyNames();
               while (enum.hasMoreElements()) {
                   String key = (String) enum.nextElement();
                   String value = props.getProperty(key);
  -                try {
  +                /*try {
                       Class taskClass = Class.forName(value);
                       addTaskDefinition(key, taskClass);
                   } catch (NoClassDefFoundError ncdfe) {
                       // ignore...
                   } catch (ClassNotFoundException cnfe) {
                       // ignore...
  -                }
  +                }*/
  +                addTaskDefinition(key, value);
               }
  +            long endTime = System.currentTimeMillis();
  +            System.out.println("Class loading took
"+(endTime-startTime)+" ms");
           } catch (IOException ioe) {
               throw new BuildException("Can't load default task list");
           }
  @@ -367,13 +394,19 @@
           log("Detected OS: " + System.getProperty("os.name"),
MSG_VERBOSE);
       }

  +    public void addTaskDefinition(String taskName, String taskClass) {
  +        String msg = " +User task: " + taskName + "     " + taskClass;
  +        log(msg, MSG_DEBUG);
  +        taskClassDefinitions.put(taskName, taskClass);
  +    }
  +
       public void addTaskDefinition(String taskName, Class taskClass) {
           String msg = " +User task: " + taskName + "     " +
taskClass.getName();
           log(msg, MSG_DEBUG);
           taskClassDefinitions.put(taskName, taskClass);
       }

  -    public Hashtable getTaskDefinitions() {
  +    public TaskDefinitionHashtable getTaskDefinitions() {
           return taskClassDefinitions;
       }

  @@ -445,7 +478,12 @@
       }

       public Task createTask(String taskType) throws BuildException {
  -        Class c = (Class) taskClassDefinitions.get(taskType);
  +        Class c;
  +        try {
  +          c = (Class) taskClassDefinitions.get(taskType);
  +        } catch (RuntimeException e) {
  +          throw new BuildException(e.getMessage());
  +        }

           if (c == null)
               return null;
  Index: main/org/apache/tools/ant/taskdefs/Ant.java
  ===================================================================
  RCS file:
/home/cvspublic/jakarta-ant/src/main/org/apache/tools/ant/taskdefs/Ant.java
,v
  retrieving revision 1.23
  diff -u -r1.23 Ant.java
  --- main/org/apache/tools/ant/taskdefs/Ant.java 2001/07/06 11:57:29 1.23
  +++ main/org/apache/tools/ant/taskdefs/Ant.java 2001/07/21 17:03:15
  @@ -76,6 +76,7 @@
    *
    *
    * @author costin@dnt.ro
  + * @author Stefan Reich <a href="mailto:doc@drjava.de">doc@drjava.de</a>
    */
   public class Ant extends Task {

  @@ -143,11 +144,11 @@
               }
           }

  -        Hashtable taskdefs = project.getTaskDefinitions();
  +        Project.TaskDefinitionHashtable taskdefs =
project.getTaskDefinitions();
           Enumeration et = taskdefs.keys();
           while (et.hasMoreElements()) {
               String taskName = (String) et.nextElement();
  -            Class taskClass = (Class) taskdefs.get(taskName);
  +            String taskClass = taskdefs.getClassName(taskName);
               p1.addTaskDefinition(taskName, taskClass);
           }





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