[jboss-cvs] javassist/tutorial ...

[Shigeru Chiba]

  User: chiba   
  Date: 07/06/08 09:32:10

  Modified:    tutorial  tutorial.html
  Log:
  made automatic pruning off by default because I found that pruning does not really save memory (only 20%).  I changed Javassist to compress a class file on memory after toBytecode().
  
  Revision  Changes    Path
  1.32      +33 -25    javassist/tutorial/tutorial.html
  
  (In the diff below, changes in quantity of whitespace are not shown.)
  
  Index: tutorial.html
  ===================================================================
  RCS file: /cvsroot/jboss/javassist/tutorial/tutorial.html,v
  retrieving revision 1.31
  retrieving revision 1.32
  diff -u -b -r1.31 -r1.32
  --- tutorial.html	24 May 2007 07:46:56 -0000	1.31
  +++ tutorial.html	8 Jun 2007 13:32:10 -0000	1.32
  @@ -140,19 +140,37 @@
   to modify a class file that has been already loaded since the JVM does
   not allow reloading a class.
   
  -<p>When Javassist freezes a <code>CtClass</code> object, it also
  -prunes the data structure contained in that object.  To reduce memory
  -consumption, Javassist discards unnecessary attributes
  +<p>A frozen <code>CtClass</code> can be defrost so that
  +modifications of the class definition will be permitted.  For example,
  +
  +<ul><pre>
  +CtClasss cc = ...;
  +    :
  +cc.writeFile();
  +cc.defrost();
  +cc.setSuperclass(...);    // OK since the class is not frozen.
  +</pre></ul>
  +
  +<p>After <code>defrost()</code> is called, the <code>CtClass</code>
  +object can be modified again.
  +
  +<p>If <code>ClassPool.doPruning</code> is set to <code>true</code>,
  +then Javassist prunes the data structure contained
  +in a <code>CtClass</code> object
  +when Javassist freezes that object.
  +To reduce memory
  +consumption, pruning discards unnecessary attributes
   (<code>attribute_info</code> structures) in that object.
   For example, <code>Code_attribute</code> structures (method bodies)
   are discarded.
   Thus, after a
   <code>CtClass</code> object is pruned, the bytecode of a method is not
  -accessible although method names, signatures, and annotations
  -are still accessible.
  +accessible except method names, signatures, and annotations.
  +The pruned <code>CtClass</code> object cannot be defrost again.
  +The default value of <code>ClassPool.doPruning</code> is <code>false</code>.
   
  -<p>To disallow pruning a <code>CtClass</code>, <code>stopPruning()</code>
  -must be called in advance:
  +<p>To disallow pruning a particular <code>CtClass</code>,
  +<code>stopPruning()</code> must be called on that object in advance:
   
   <ul><pre>
   CtClasss cc = ...;
  @@ -162,29 +180,19 @@
   // cc is not pruned.
   </pre></ul>
   
  -<p>If a <code>CtClass</code> is not pruned, it can be defrost so that
  -modifications of the class definition can be permitted.  For example,
  -
  -<ul><pre>
  -CtClasss cc = ...;
  -cc.stopPruning(true);
  -    :
  -cc.writeFile();
  -cc.defrost();
  -cc.setSuperclass(...);    // OK since the class is not frozen.
  -</pre></ul>
  -
  -<p>To disallow pruning for all the <code>CtClass</code>es, set
  -<code>ClassPool.doPruning</code> to <code>false</code>.
  +<p>The <code>CtClass</code> object <code>cc</code> is not pruned.
  +Thus it can be defrost after <code>writeFile()</code> is called.
   
   <ul><b>Note:</b>
  -While debugging, you might want to temporarily stop pruning and write a modified
  -class file to a disk drive.  <code>debugWriteFile()</code> is a convenient method
  -for that purpose.  It stops pruning, write a class file, defrost it, and turn
  -pruning on again (if it was initially on).
  +While debugging, you might want to temporarily stop pruning and freezing
  +and write a modified class file to a disk drive.
  +<code>debugWriteFile()</code> is a convenient method
  +for that purpose.  It stops pruning, writes a class file, defrosts it,
  +and turns pruning on again (if it was initially on).
   </ul>
   
   
  +
   <h4>Class search path</h4>
   
   <p>The default <code>ClassPool</code> returned