support/scripts: add size-stats-compare script

From: Thomas De Schampheleire <[email protected]>

Leverage the CSV files produces by size-stats (make graph-size) to allow for a comparison of rootfs size between two different buildroot compilations.

The script takes the file-size CSV files of two compilations as input, and produces a textual report of the differences per package. Using the -d/--detail flag, the report will show the file size changes instead of package size changes.
The -t/--threshold option allows to ignore file size differences smaller or equal than the given threshold (in bytes).

Example output is:

Size difference per package (bytes), threshold = 0
--------------------------------------------------------------------------------

       -8192         busybox
      228572   added dmalloc
      301584   added jq
--------------------------------------------------------------------------------
      521964         TOTAL

or with detailed view:

Size difference per file (bytes), threshold = 0
--------------------------------------------------------------------------------
-8192 bin/busybox
18152 added usr/bin/jq
39252 added usr/bin/dmalloc
46968 added usr/lib/libdmalloc.so
47288 added usr/lib/libdmallocxx.so
47316 added usr/lib/libdmallocth.so
47748 added usr/lib/libdmallocthcxx.so
283432 added usr/lib/libjq.so.1.0.4
--------------------------------------------------------------------------------

      521964         TOTAL

---
v3:
- rename this/other to old/new and swap input arguments to match 'diff'-like expectations (ThomasP)
- change visual representation
v2:
Addressing Arnout's comments:
- improve help text
- remove references to commits-to-be-backported
- fix references to 'package' while really file or package could be meant
- verify header of CSV file is as expected
- don't print output header for sections that are empty
- use <= instead of < for threshold
- use argparse.Filetype for file path verification
- use positional args for input files
- improve string wrapping
- add reference to script in manual
- ensure Python 3 compatibility
Other changes:
- also print out total size difference
- add docstrings to methods
- add TODO with possible improvements

 docs/manual/common-usage.txt       |  10 +++
 support/scripts/size-stats-compare | 127 +++++++++++++++++++++++++++++++++++++
 2 files changed, 137 insertions(+)
 create mode 100755 support/scripts/size-stats-compare

index 8d0ba63..18677b8 100644
@@ -317,6 +317,16 @@ The collected filesystem size data is only meaningful after a complete
 clean rebuild. Be sure to run +make clean all+ before using +make
 graph-size+.
 
+To compare the root filesystem size of two different Buildroot compilations,
+for example after adjusting the configuration or when switching to another
+Buildroot release, use the +size-stats-compare+ script. It takes two
++file-size-stats.csv+ files (produced by +make graph-size+) as input.
+Refer to the help text of this script for more details:
+
+----------------
+support/scripts/size-stats-compare -h
+----------------
+
 include::eclipse-integration.txt[]
 
 include::advanced.txt[]

2.4.10

Dear Thomas De Schampheleire,

Applied, thanks.

Thomas

Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com