#!/usr/bin/env python3
"""Benchmarks the current working directory against a given baseline.

This script benchmarks both size and speed. Sample output:
"""

import contextlib
import json
import os
import re
import subprocess
import sys
import tempfile

@contextlib.contextmanager
def GitWorktree(commit):
  tmpdir = tempfile.mkdtemp()
  subprocess.run(['git', 'worktree', 'add', '-q', '-d', tmpdir, commit], check=True)
  cwd = os.getcwd()
  os.chdir(tmpdir)
  try:
    yield tmpdir
  finally:
    os.chdir(cwd)
    subprocess.run(['git', 'worktree', 'remove', tmpdir], check=True)

def Run(cmd):
  subprocess.check_call(cmd, shell=True)

def Benchmark(outbase, runs=12):
  tmpfile = "/tmp/bench-output.json"
  Run("rm -rf {}".format(tmpfile))
  Run("bazel test :all")
  Run("bazel build -c opt :benchmark")

  Run("./bazel-bin/benchmark --benchmark_out_format=json --benchmark_out={} --benchmark_repetitions={}".format(tmpfile, runs))

  Run("bazel build -c opt --copt=-g :conformance_upb")
  Run("cp -f bazel-bin/conformance_upb {}.bin".format(outbase))

  with open(tmpfile) as f:
    bench_json = json.load(f)

  # Translate into the format expected by benchstat.
  with open(outbase + ".txt", "w") as f:
    for run in bench_json["benchmarks"]:
      name = re.sub(r'^BM_', 'Benchmark', run["name"])
      if name.endswith("_mean") or name.endswith("_median") or name.endswith("_stddev"):
        continue
      values = (name, run["iterations"], run["cpu_time"])
      print("{} {} {} ns/op".format(*values), file=f)

baseline = "master"

if len(sys.argv) > 1:
  baseline = sys.argv[1]

  # Quickly verify that the baseline exists.
  with GitWorktree(baseline):
    pass

# Benchmark our current directory first, since it's more likely to be broken.
Benchmark("/tmp/new")

# Benchmark the baseline.
with GitWorktree(baseline):
  Benchmark("/tmp/old")

print()
print()

Run("~/go/bin/benchstat /tmp/old.txt /tmp/new.txt")

print()
print()

Run("objcopy --strip-debug /tmp/old.bin /tmp/old.bin.stripped")
Run("objcopy --strip-debug /tmp/new.bin /tmp/new.bin.stripped")
Run("~/code/bloaty/bloaty /tmp/new.bin.stripped -- /tmp/old.bin.stripped --debug-file=/tmp/old.bin --debug-file=/tmp/new.bin -d compileunits,symbols")