Benchmark for FreeCAD PR: analytic line/line intersection in WireJoiner.

gistfile1.txt

"""
Benchmark for FreeCAD PR: analytic line/line intersection in WireJoiner.

It builds a sketch of crossing straight lines (N horizontal + N vertical, so
N*N interior crossings) and times a recompute. That recompute runs the shape
build, which is where WireJoiner::splitEdges() does its work, and a grid of
crossing lines is the case that path is most expensive for.

How to run
----------
Linux / macOS:
    freecadcmd gist_bench_wirejoiner.py
  (results print to the console)

Windows:
    FreeCADCmd's stdout is detached, so set an output file and read it:
        set BENCH_OUT=C:\\path\\to\\results.txt
        FreeCADCmd.exe gist_bench_wirejoiner.py
        type C:\\path\\to\\results.txt

How I measured
--------------
Two builds of the same commit, release (-O2), same machine, differing only in
WireJoiner.cpp. Baseline was FreeCAD main; the other build added the change.
Median of 9 runs per size. Note this times a whole recompute, so splitEdges'
own share of the improvement is larger than the recompute-level number.
"""

import os
import sys
import time
import statistics

import FreeCAD as App
import Part
import Sketcher

_out_path = os.environ.get("BENCH_OUT")
_out_file = open(_out_path, "w") if _out_path else None


def emit(line):
    print(line)
    if _out_file:
        _out_file.write(line + "\n")
        _out_file.flush()


def V(x, y):
    return App.Vector(x, y, 0)


def build_grid(n, span=100.0):
    doc = App.newDocument("WJ%d" % n)
    sk = doc.addObject("Sketcher::SketchObject", "S")
    geo = []
    step = span / (n + 1)
    for i in range(1, n + 1):
        geo.append(Part.LineSegment(V(0.0, i * step), V(span, i * step)))
    for i in range(1, n + 1):
        geo.append(Part.LineSegment(V(i * step, 0.0), V(i * step, span)))
    sk.addGeometry(geo, False)
    return doc, sk


def median_ms(fn, reps):
    ts = []
    for _ in range(reps):
        t0 = time.perf_counter()
        fn()
        ts.append((time.perf_counter() - t0) * 1000.0)
    return statistics.median(ts), min(ts), max(ts)


emit("FreeCAD " + " ".join(App.Version()[:4]))
emit("")
emit("%-6s %-10s %-12s %-12s %-12s" % ("N", "edges", "median_ms", "min_ms", "max_ms"))
emit("-" * 56)

for n in [10, 15, 20, 25]:
    doc, sk = build_grid(n)
    doc.recompute()  # warm

    def touch_recompute():
        sk.touch()
        doc.recompute()

    med, lo, hi = median_ms(touch_recompute, 9)
    emit("%-6d %-10d %-12.1f %-12.1f %-12.1f" % (n, 2 * n, med, lo, hi))
    App.closeDocument(doc.Name)

emit("")
emit("DONE")

if _out_file:
    _out_file.close()