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This sub-project aims to provide an agent for the Java Virtual
Machine, which uses the JVM Tool Interface (see [1] and [2]) to print
RTFL messages for Java programs, which must not necessarily be
prepared. This makes using RTFL much less time-consuming and so lowers
the entrance barrier.
The agent consists of the file "librtfl-jvm-ti.so", which is passed to
"java" by the option "-agentlib:rtfl-jvm-ti"; see Makefile.am for
details.
Run "make run-hello" or "run run-test-rtfl-objects-1" to run some
sample programs with the agent.
How it works
------------
Several commands from the object module (like "create") follow the
program structure, and can so easily be printed when the respective
JVM-TI event is processed. Others (like "enter") can be printed by
this approach, but some parameters are missing (aspect and priority)
and so replaced by standard values (empty aspect and priority 0). It
is planned to make these parameters configurable, either by files or
by annotations.
A third group of commands (like "msg") must still be added explicitly
to code. (For "msg", one could think of an integration with existing
logging frameworks.)
Since Java programs often use many third-party code (libraries,
containers, ...), it is crucial for the performance to filter quite
early, and so reduce the total amount of messages. Filtering by
packages seems feasible (like "com.acme" and sub-packages when code of
ACME is debugged). Currently, only "rtfl" and its sub-packages are
considered; this is hard-coded in the function include_class() in
"config.c".
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[1] http://docs.oracle.com/javase/8/docs/technotes/guides/jvmti/index.html
[2] http://www.oracle.com/technetwork/articles/javase/jvmti-136367.html
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