#!/usr/bin/env python3
"""From the raw GC logs of demo-gc-throttling.sh: CPU time the collector got during pauses vs the
pauses' wall time (-Xlog:gc+cpu prints User/Sys/Real per collection, at 10 ms resolution).
A single GC thread that is never descheduled gives a ratio near 1.0; N parallel threads near N.
Well below that means the collector was waiting for CPU - throttled - inside its own pauses.
-> docs/output/gc-cpu-ratio.txt"""
import os, re, sys
out = os.path.join(os.path.dirname(os.path.abspath(__file__)), "..", "docs", "output")
rows = []
for v in "ABCDE":
    path = os.path.join(out, f"gc-throttling-{v}-gclog.txt")
    if not os.path.exists(path):
        continue
    cpu = real = 0.0
    n = 0
    for m in re.finditer(r"User=(\d+\.\d+)s Sys=(\d+\.\d+)s Real=(\d+\.\d+)s", open(path).read()):
        u, s, r = map(float, m.groups())
        cpu += u + s
        real += r
        n += 1
    rows.append((v, n, cpu, real, cpu / real if real else 0))
with open(os.path.join(out, "gc-cpu-ratio.txt"), "w") as f:
    f.write("# CPU the collector received during its pauses, from -Xlog:gc+cpu (sum over every collection)\n\n")
    f.write("%-2s %12s %12s %12s %10s\n" % ("", "collections", "user+sys", "real", "cpu/real"))
    for v, n, cpu, real, ratio in rows:
        f.write("%-2s %12d %11.2fs %11.2fs %10.2f\n" % (v, n, cpu, real, ratio))
print(open(os.path.join(out, "gc-cpu-ratio.txt")).read())