sim-pez / ptpn_log_verifier

Tool to read a preemptive time petri and verify the feasibility of a real time program execution log

Introduction

Preemptive Time Petri Nets (PTPNs) support modeling and analysis of concurrent timed SW components running under fixed priority preemptive scheduling. This work is based on the Sirio Library[1] and is an extension of Lorenzo Macchiarini[2] work. We try to read a preemptive time petri net (PTPN) and verify the feasibility of a real time program execution log.

For a detailed description of the experiments and results obtained refer to the project presentation (coming soon).

Algorithm

Here is the pseudo-algorithm to check the log feasibility:

1. Read next transition t and time to fire tau from log
2. Check if t is an enabled transition
3. Check if t is a progressing transition
4. Check if tau is in the [min_t , max_t] interval provided from PTPN
5. Check if tau is <= max_t' for each progressing transition t'
6. If all above checks are ok, update the time to fire of enabled transitions and go to 1

Inputs

PTPN

You need to create a PTPN model of your real time program. We reccomend to use Oris tool[3] in order to create Java code from a graphic model

Log

The log file must be a .txt file in this format:

[transition name]
[time to fire]
[transition name]
[time to fire]
...

Example:

t0
900
t1
30
t5
260
...

Note that you need to provide the same transition name of PTPN transitions

Repository structure

The respository extension is structured as follows:

• The src/main/java/org/oristool/logVerifier/LogVerifier.java Class contains the public method isLogFeasible(PetriNet pn, String logName, Marking m) which returns a boolean value indicating the log feasibility.
• src/test/java/org/oristool/logVerifier/LogVerifierTest.java is a JUnit Test where we have used a PTPN and a log to test the LogVerifier Class (please check the Example section).

Example

This is the PTPN model used in JUnit Test

the log.txt file is like this:

t0
910
t1
0
t2
0
t5
70
t3
30
t4
150
...

Output

The output will be:

Checking t0 910
Passed. Updated enabled transitions are: [t0, t1, t5]
Checking t1 0
Passed. Updated enabled transitions are: [t0, t2, t5]
Checking t2 0
Passed. Updated enabled transitions are: [t0, t3, t5]
Checking t5 70
Passed. Updated enabled transitions are: [t0, t3, t5, t6]
...
Log feasible: true

Now let's change the log to something unfeasible. For example, if you chage the first time to fire of t2 to 10 (instead of 0), the output changes to:

Checking t0 910
Passed. Updated enabled transitions are: [t0, t1, t5]
Checking t1 0
Passed. Updated enabled transitions are: [t0, t2, t5]
Checking t2 10
Time to fire of transition t2 non fesible!
Log feasible: false

Bibliography

[1] Sirio Library: https://github.com/oris-tool/sirio.

[2] Lorenzo Macchiarini GitHub profile: https://github.com/loremacchia.

[3] Oris Tool: https://github.com/oris-tool/sirio.

Acknowledgments

Software Engineering for Embedded Systems - Computer Engineering Master Degree @University of Florence.