Hi everyone,
Love AspectJ. I work on end-to-end tracing using X-Trace, and AspectJ is
an awesome mechanism to do some of the tracing that I'm interested in.
I'm trying to profile file accesses; specifically, calls to
FileInputStream+.read(..) and FileOutputStream+.write(..). However, in
many cases, file streams are wrapped in filter classes, such as Buffered
streams or Data streams. The specific base classes that provide this
mechanism are FilterInputStream and FilterOutputStream. Often, multiple
filter streams are applied recursively to some base stream, for example new
DataOutputStream(new BufferedOutputStream(new
FileOutputStream("myfile.txt")));
Is there a way to define a pointcut that matches any Filter stream, whose
underlying stream is a File stream? The naive solution I have so far is:
Object around(FilterInputStream o): target(o) && call(*
FilterInputStream+.read(..)) {
InputStream base = o;
while (base instanceof FilterInputStream)
base = ((FilterInputStream) base).in;
boolean isFileStream = base instanceof FileInputStream;
if (isFileStream) {
long start = System.nanoTime();
Object ret = proceed(o);
long duration = System.nanoTime() - start;
// do profiling stuff
return ret;
} else {
return proceed(o);
}
}
I'm worried about the overhead of recursively examining the filter streams
to determine whether the base stream is a file stream. I'll also mention
that I don't want to weave rt.jar. It would be great if I could insert
some kind of proxy class when the appropriate Filter instance is created,
then the pointcut can just look for the proxy class.
Cheers,
Jon
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