Context

John Doe remarked in #AP1432 that there may be too much code in our application that isn't used at all. Before migrating the application to the new platform, we have to analyze which parts of the system are still in use and which are not.

Idea

To understand how much code isn't used, we recorded the executed code in production with the coverage tool JaCoCo. The measurement took place between 21st Oct 2017 and 27st Oct 2017. The results were exported into a CSV file using the JaCoCo command line tool with the following command:

java -jar jacococli.jar report "C:\Temp\jacoco.exec" --classfiles \
C:\dev\repos\buschmais-spring-petclinic\target\classes --csv jacoco.csv

The CSV file contains all lines of code that were passed through during the measurement's time span. We just take the relevant data and add an additional LINES column to be able to calculate the ratio between covered and missed lines later on.



In [1]:

    
import pandas as pd
coverage = pd.read_csv("datasets/jacoco.csv")
coverage = coverage[['PACKAGE', 'CLASS', 'LINE_COVERED' ,'LINE_MISSED']]
coverage['LINES'] = coverage.LINE_COVERED + coverage.LINE_MISSED
coverage.head(1)









    Out[1]:







  
    
      
      PACKAGE
      CLASS
      LINE_COVERED
      LINE_MISSED
      LINES
    
  
  
    
      0
      org.springframework.samples.petclinic
      PetclinicInitializer
      24
      0
      24

Analysis

It was stated that whole packages wouldn't be needed anymore and that they could be safely removed. Therefore, we sum up the coverage data per class for each package and calculate the coverage ratio for each package.



In [2]:

    
grouped_by_packages = coverage.groupby("PACKAGE").sum()
grouped_by_packages['RATIO'] = grouped_by_packages.LINE_COVERED / grouped_by_packages.LINES
grouped_by_packages = grouped_by_packages.sort_values(by='RATIO')
grouped_by_packages









    Out[2]:







  
    
      
      LINE_COVERED
      LINE_MISSED
      LINES
      RATIO
    
    
      PACKAGE
      
      
      
      
    
  
  
    
      org.springframework.samples.petclinic.repository.jdbc
      0
      150
      150
      0.000000
    
    
      org.springframework.samples.petclinic.util
      13
      17
      30
      0.433333
    
    
      org.springframework.samples.petclinic.web
      75
      40
      115
      0.652174
    
    
      org.springframework.samples.petclinic.model
      75
      33
      108
      0.694444
    
    
      org.springframework.samples.petclinic.repository.jpa
      21
      7
      28
      0.750000
    
    
      org.springframework.samples.petclinic.service
      16
      2
      18
      0.888889
    
    
      org.springframework.samples.petclinic
      24
      0
      24
      1.000000

We plot the data for the coverage ratio to get a brief overview of the result.



In [3]:

    
%matplotlib inline
grouped_by_packages[['RATIO']].plot(kind="barh", figsize=(8,2))









    Out[3]:





<matplotlib.axes._subplots.AxesSubplot at 0x23432088160>

Conclusion

The JDBC package org.springframework.samples.petclinic.repository.jdbc isn't used at all and can be left out safely when migrating to the new platform.

	LINE_COVERED	LINE_MISSED	LINES	RATIO
PACKAGE
org.springframework.samples.petclinic.repository.jdbc	0	150	150	0.000000
org.springframework.samples.petclinic.util	13	17	30	0.433333
org.springframework.samples.petclinic.web	75	40	115	0.652174
org.springframework.samples.petclinic.model	75	33	108	0.694444
org.springframework.samples.petclinic.repository.jpa	21	7	28	0.750000
org.springframework.samples.petclinic.service	16	2	18	0.888889
org.springframework.samples.petclinic	24	0	24	1.000000