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Diffstat (limited to 'docs/faq/faq.xml')
| -rw-r--r-- | docs/faq/faq.xml | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/docs/faq/faq.xml b/docs/faq/faq.xml index 1d0338384..05ddbc903 100644 --- a/docs/faq/faq.xml +++ b/docs/faq/faq.xml @@ -3844,6 +3844,37 @@ aspect A { </para> </answer> </qandaentry> + <qandaentry> + <question id="q:weavingcglib" + xreflabel="Q:I get a VerifyError when running CGLIB generated code that has been woven by AspectJ. Why is this?"> + <para>I get a VerifyError when running CGLIB generated code that has been woven by + AspectJ. Why is this? + </para> + </question> + <answer> + <para>When weaving after advice into any piece of code, the AspectJ strategy is to make all + exit points from that code jump to a single exit point that executes the advice + before returning. There is a verifier rule in the JVM specification that specifies + that all routes to a jump destination must have the same height stack when they get there, + regardless of the route taken to get there through the bytecode. The CGLIB generated code has different + stack heights at the various exit points. This is not a problem with the CGLIB generated code, + it is perfectly valid - it is just unusual and the AspectJ weaving strategy causes the + verify error to trigger when it makes all exits jump to a single destination. + </para> + <para>AspectJ could cope with this and instead implement after advice by calling the + advice and returning at each exit point. However, it is unlikely that the user + actually meant to weave the CGLIB generated code in the first place - and so usually + the right thing to do is to exclude CGLIB generate code from the weaving process by + appropriate use of the exclude element in the aop.xml. A typical clause in the aop.xml might + look as follows: + </para> + <programlisting> +<weaver> + <exclude within="*CGLIB*" /> +</weaver> + </programlisting> + </answer> + </qandaentry> </qandadiv> <qandadiv id="aj11" xreflabel="AspectJ 1.1 and eclipse.org"> |