Skip to main content
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [List Home]
Re: [aspectj-users] Saving information from several pointcuts to an ObjectOutputStream 
Ron is right,
moreover, aspects are singletons by default, and can freely declare any field (like private ObjectOutputStream stream = null) and then create the stream only if it hasn't already been created.
Obviously, care should be taken to avoid threading issues (like more threads creating the stream, writing to it etc..), but this is no way different that how you would do it in plain java : using synchronized if you don't have performance problems, using classes from the concurrent package if you have strict performance requirements.
As in plain java, you'll not have any place to close the stream .. finalizers are not reliable in java and we all have to live with that. For a normal stream on a decent OS, flushing it should anyway be enough. 

Something like this should work :

public aspect TraceToFile {

 private ObjectOutputStream stream = null;

 private ObjectOutputStream setupStream() {
   if (stream != null) return stream;
   stream = new ... // initialize stream
   return stream;
 }

 after() : apointuct() || anoptherpointuct() {
   ObjectOutputStream stream = setupStream();
   stream.write(.... // write here info to the stream
   stream.flush(); // Always flush it, you have no option to close it.
 }

}

Hope this helps clarify,

Simone

Ron DiFrango wrote:

This sounds like a Singleton pattern me.  You could create a different class
that is a Singleton that holds the static reference to the
ObjectOutputStream.  Then just have your pointcut get the object Singleton
instance and have it write the data to the file.


On 2/19/09 6:07 PM, "baumar" <mbjava@xxxxxxxxx> wrote:


Hi,

I'm trying to save information from several pointcut. More precise: I try to
catch method call that eventually will match some conditions, write it to a
class called DetailedSignature implements Serializable and save that
information in one place.

As far as I - as aspectJ-newbie  - understood, I cannot open a file for the
whole life of an aspect, as there is no constructor. Therefore I tried to
use an ObjectOutputStream like this:

pointcut methodWithReturnValue() : (execution(!void
*.*(..))&&(!within(org.test.serversimulation.DetailedSignature))
&&(!within(org.test.serversimulation.SignatureCracker))
&&(!within(junit.*)));

    after() returning(Object o) : methodWithReturnValue() {

try {
File testDataFile = new File("serializedTest.data");
       FileOutputStream fout = new FileOutputStream(testDataFile,
true);
       ObjectOutputStream oos = new ObjectOutputStream(fout);
       oos.writeObject(detailedSignature);
       oos.flush();
       oos.close();
System.out.println("wrote detailedSignature 
"+detailedSignature.toString());
       }
    catch (Exception e) { e.printStackTrace(); }
}

The program runs fine and I actually can see the data I want in the file.
But when I try to read it, I get the exception:

java.io.StreamCorruptedException: invalid type code: AC

Now I searched and found that this always seems to happen when trying to
append to an ObjectOutputStream multiple times
(http://forums.sun.com/thread.jspa?threadID=5177084)

Now I'm a bit at a loss. I was thinking of trying to write kind of
bruteforce the information to a text file and based on that read and
recreate the object manually, but that is certainly not very flexible.

Does anyone know a way how to keep the outputstream open and pass it to
several matches of the pointcut?
Or would you know a more elegant strategy of saving objects from within
several matches of a pointcut?

Thanks for help

Mark




(start of the file with captured method

¬í sr +org.test.serversimulation.DetailedSignature˜Ë±W„çÅ
Z isLiteralValueL allmodifierst Ljava/lang/String;L
callingobjectClassnameq ~ L callingobjectMethodNameq ~ L
callingobjectPackageq ~ L callingobjectPackageAndClassq ~ L
callingobjectParametersq ~ L  modifierst Ljava/util/ArrayList;L
parametersq ~ L returnValueClassq ~ L returnValuePackageq ~ L
returnValuePackageAndClassq ~ L signatureLongStringq ~
... all methods catched appear in the file.
Ron DiFrango Manager and Architect | CapTech Ventures 
(804) 855-9196-6308  |  rdifrango@xxxxxxxxxxxxxxxxxxx

_______________________________________________
aspectj-users mailing list
aspectj-users@xxxxxxxxxxx
https://dev.eclipse.org/mailman/listinfo/aspectj-users



--
Simone Gianni            CEO Semeru s.r.l.           Apache Committer
http://www.simonegianni.it/

Back to the top