Control arguments and return values at runtime #1647
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Test 286 fails with optimizations enabled, because they interfere with the auto-args. Do you suggest a way to deal with this? |
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Signed-off-by: Clément Guidi <cguidi@ciena.com>
Use the =-A/--argument= option from the client to collect new argument values in the trace, or change existing specifications. Example: $ uftrace --agent record my-program $ uftrace -p $(pidof my-program) -A func@arg1 $ uftrace -p $(pidof my-program) -A func@arg2 This will add the values of 'arg1' and then 'arg2' for function 'func' to the trace data. Signed-off-by: Clément Guidi <cguidi@ciena.com>
Use the =-R/--retval= option from the client to collect new return values in the trace, or change existing specifications. Example: $ uftrace --agent record my-program $ uftrace -p $(pidof my-program) -R func@retval This will add the value of the 'func' function's return value to the trace data. Signed-off-by: Clément Guidi <cguidi@ciena.com>
Start collecting all arguments and return values in trace data at runtime. Use automatic spec definitions. Signed-off-by: Clément Guidi <cguidi@ciena.com>
Argument and return value collection require specs to be defined so libmcount knows how to format them. The specs are usually defined at start-up. The definitions will be missing if they are not setup from the start. This commit allows to setup auto-args and prepare debug information at runtime. Signed-off-by: Clément Guidi <cguidi@ciena.com>
The parent uftrace instance is in charge of saving trace data and metadata. But it is now aware of the debug information that the agent saves inside libmcount at runtime. We fetch these data from the target process when libmcount exits. Signed-off-by: Clément Guidi <cguidi@ciena.com>
Test collecting new arguments and return values at runtime. Signed-off-by: Clément Guidi <cguidi@ciena.com>
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I'll stop stop on this feature for now. Changing arg/retval spec at runtime requires a more elaborate data format. I plan to work on session control at runtime, i.e. initiating and finishing recording sessions without terminating the target process (e.g. if the target is a daemon). Then each session can have different arg/retval specs, which solves the problem in this particular use case (multiple sessions). |
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These changes give the user full control over the argument and return value
collection at runtime.
We can use the
-A/--argumentoption from the client to collect new argumentvalues in the trace, or change existing specifications. We can use the
-R/--retvaloption from the client to collect new return values in the trace,or change existing specifications. And we can use the
-a/--auto-argsoptionfrom the client to collect all arguments and return values.
Example:
Based on #1646.