[aspectj-dev] Bug#36430: Xreweavable now checked in.

[Andrew Clement <CLEMAS@xxxxxxxxxx>]

Hi,

Xreweavable support is now checked
in to CVS. 

To summarise the feature:  if
you supply -Xreweavable when invoking ajc
then although the class files produced
will be woven, they can be rewoven
on a later invocation of ajc.  Reweavable
class files are larger than their
non reweavable variants.  The
rules are:

- -Xreweavable puts the weaver in reweavable
mode.  A weaver in reweavable mode
  produces reweavable class files.
- A weaver *NOT* in reweavable mode
can understand reweavable classes and use
  them, but when they are written
out again by that weaver, the reweavable 
  information will be not be included.
- If you attempt to reweave a class,
any aspects that previously touched that 
  class through advice or intertype
declarations need to be accessible by the 
  weaver, otherwise the reweave
is unpredictable.
- If the size of the reweavable classes
proves to be a problem for you, you can 
  specify -Xreweavable:compress
which attempts (at the cost of performance) to 
  compress the reweavable information
stored in the reweavable classes.

Finally, see below for a typical interaction
sequence when using -Xreweavable
from the command line.

Andy.
--
Andy Clement
AspectJ/AJDT Development

================================================
Interacting with XReweavable on the
tjp demo:


# Compile the code normally
C:\aspectj1.1\doc\examples\tjp>ajc
-d output *.java

# How big are the classes?
C:\aspectj1.1\doc\examples\tjp>dir
*.class /s

 Directory of C:\aspectj1.1\doc\examples\tjp\output\tjp
24/02/2004  09:25    
        5,759 Demo.class
24/02/2004  09:25    
        4,618 GetInfo.class
         
    
C:\aspectj1.1\doc\examples\tjp>cd
output

# Try a binary weave using those files,
it fails
C:\aspectj1.1\doc\examples\tjp\output>ajc
-inpath .
C:\aspectj1.1\doc\examples\tjp\GetInfo.java:0
class 'tjp.GetInfo' is already 
woven and has not been built with -Xreweavable
C:\aspectj1.1\doc\examples\tjp\output\tjp\Demo.java:0
class 'tjp.Demo' is 
already woven and has not been built
with -Xreweavable

2 errors

C:\aspectj1.1\doc\examples\tjp\output>cd
..

# Build reweavable classes
C:\aspectj1.1\doc\examples\tjp>ajc
-d output *.java -Xreweavable

# How big are they now?
C:\aspectj1.1\doc\examples\tjp>dir
*.class /s

 Directory of C:\aspectj1.1\doc\examples\tjp\output\tjp
24/02/2004  09:25    
        7,169 Demo.class
24/02/2004  09:25    
        9,024 GetInfo.class


# Build reweavable classes optimized
with compressed internal data
C:\aspectj1.1\doc\examples\tjp>ajc
-d output *.java -Xreweavable:compress


# How big are they now?
C:\aspectj1.1\doc\examples\tjp>dir
*.class /s

 Directory of C:\aspectj1.1\doc\examples\tjp\output\tjp
24/02/2004  09:26    
        6,529 Demo.class
24/02/2004  09:26    
        6,726 GetInfo.class


C:\aspectj1.1\doc\examples\tjp>cd
output


# Try a binary weave - with verbose
output - it succeeds
C:\aspectj1.1\doc\examples\tjp\output>ajc
-verbose -inpath .
zipfile classpath entry does not exist:

  C:\Program Files\Java\j2re1.4.2_01\lib\i18n.jar
zipfile classpath entry does not exist:

  C:\Program Files\Java\j2re1.4.2_01\lib\charsets.jar
directory classpath entry does not
exist: 
  C:\Program Files\Java\j2re1.4.2_01\classes
weaving
might need to weave [UnwovenClassFile(
   C:\aspectj1.1\doc\examples\tjp\output\tjp\Demo.class,
tjp.Demo),
 UnwovenClassFile(
   C:\aspectj1.1\doc\examples\tjp\output\tjp\GetInfo.class,
tjp.GetInfo)](world=true)
processing reweavable type tjp.Demo:
tjp\Demo.java
successfully verified type tjp.GetInfo
exists.  Originates from 
  C:\aspectj1.1\doc\examples\tjp\GetInfo.java
processing reweavable type tjp.GetInfo:
C:\aspectj1.1\doc\examples\tjp\GetInfo.java


# Run the code
C:\aspectj1.1\doc\examples\tjp\output>java
tjp.Demo
Intercepted message: foo
in class: tjp.Demo
Arguments:
  0. i : int = 1
  1. o : java.lang.Object = tjp.Demo@6eb38a
Running original method:

Demo.foo(1, tjp.Demo@6eb38a)

  result: null
Intercepted message: bar
in class: tjp.Demo
Arguments:
  0. j : java.lang.Integer = 3
Running original method:

Demo.bar(3)

  result: Demo.bar(3)
Demo.bar(3)



# How big now?  The reweavable
info was removed on last
# call to ajc as -Xreweavable wasn't
supplied.
C:\aspectj1.1\doc\examples\tjp\output>dir
*.class /s

 Directory of C:\aspectj1.1\doc\examples\tjp\output\tjp
24/02/2004  09:26    
        5,759 Demo.class
24/02/2004  09:26    
        4,618 GetInfo.class



# Finally, lets do try an illegal reweave
operation - lets delete
# GetInfo.class which is required for
reweaving of Demo.class
# to be valid

C:\aspectj1.1\doc\examples\tjp>ajc
-d output -Xreweavable *.java

C:\aspectj1.1\doc\examples\tjp>cd
output

C:\aspectj1.1\doc\examples\tjp\output>erase
tjp\GetInfo.class

C:\aspectj1.1\doc\examples\tjp\output>ajc
-inpath .
C:\aspectj1.1\doc\examples\tjp\output\tjp\Demo.java:0
type tjp.GetInfo is needed
 by reweavable type tjp.Demo

1 error

C:\aspectj1.1\doc\examples\tjp\output>