| 1 | package bakeoff |
| 2 | |
| 3 | import ( |
| 4 | "crypto/sha256" |
| 5 | "fmt" |
| 6 | "io/fs" |
| 7 | "os" |
| 8 | "os/exec" |
| 9 | "path/filepath" |
| 10 | "sort" |
| 11 | "strings" |
| 12 | "time" |
| 13 | ) |
| 14 | |
| 15 | // Build is the three build times for the shipped arm64 binary, as medians |
| 16 | // in seconds, and its size. |
| 17 | type Build struct { |
| 18 | ColdSeconds, WarmSeconds, EditSeconds float64 |
| 19 | Bytes int64 |
| 20 | Host string |
| 21 | ColdRuns, Runs int // how many cold builds, and warm and edit builds, each median is of |
| 22 | } |
| 23 | |
| 24 | func mk(dir string, targets ...string) error { |
| 25 | cmd := exec.Command("make", targets...) |
| 26 | cmd.Dir = dir |
| 27 | if out, err := cmd.CombinedOutput(); err != nil { |
| 28 | return fmt.Errorf("make %v: %w\n%s", targets, err, out) |
| 29 | } |
| 30 | return nil |
| 31 | } |
| 32 | |
| 33 | func timed(dir string, targets ...string) (float64, error) { |
| 34 | start := time.Now() |
| 35 | err := mk(dir, targets...) |
| 36 | return time.Since(start).Seconds(), err |
| 37 | } |
| 38 | |
| 39 | func median(v []float64) float64 { |
| 40 | sort.Float64s(v) |
| 41 | return v[len(v)/2] |
| 42 | } |
| 43 | |
| 44 | // BuildStats measures cold (clean-deps; COLD=1 for Go, which passes -a) |
| 45 | // builds coldRuns times, and warm (clean) and one-line-change (editBuild) |
| 46 | // builds runs times each. Cold builds under emulation take up to an hour, |
| 47 | // hence the separate count. |
| 48 | func BuildStats(dir string, goCold bool, coldRuns, runs int) (Build, error) { |
| 49 | coldTarget := []string{"build-arm64"} |
| 50 | if goCold { |
| 51 | coldTarget = append(coldTarget, "COLD=1") |
| 52 | } |
| 53 | editFile, err := bumpFile(dir) |
| 54 | if err != nil { |
| 55 | return Build{}, err |
| 56 | } |
| 57 | var cold, warm, edit []float64 |
| 58 | for i := 0; i < coldRuns; i++ { |
| 59 | if err := mk(dir, "clean", "clean-deps"); err != nil { |
| 60 | return Build{}, err |
| 61 | } |
| 62 | s, err := timed(dir, coldTarget...) |
| 63 | if err != nil { |
| 64 | return Build{}, err |
| 65 | } |
| 66 | cold = append(cold, s) |
| 67 | } |
| 68 | for i := 0; i < runs; i++ { |
| 69 | if err := mk(dir, "clean"); err != nil { |
| 70 | return Build{}, err |
| 71 | } |
| 72 | s, err := timed(dir, "build-arm64") |
| 73 | if err != nil { |
| 74 | return Build{}, err |
| 75 | } |
| 76 | warm = append(warm, s) |
| 77 | |
| 78 | s, err = editBuild(dir, editFile, i) |
| 79 | if err != nil { |
| 80 | return Build{}, err |
| 81 | } |
| 82 | edit = append(edit, s) |
| 83 | } |
| 84 | if err := mk(dir, "build-arm64"); err != nil { |
| 85 | return Build{}, err |
| 86 | } |
| 87 | fi, err := os.Stat(filepath.Join(dir, "dist", "app-linux-arm64")) |
| 88 | if err != nil { |
| 89 | return Build{}, err |
| 90 | } |
| 91 | host, _ := os.Hostname() |
| 92 | return Build{ColdSeconds: median(cold), WarmSeconds: median(warm), EditSeconds: median(edit), Bytes: fi.Size(), Host: host, |
| 93 | ColdRuns: coldRuns, Runs: runs}, nil |
| 94 | } |
| 95 | |
| 96 | // bumpFile finds the source file `make bump` edits (the one holding the |
| 97 | // GET / handler, per the brief) by comparing every file before and after, |
| 98 | // then runs `make unbump`. |
| 99 | func bumpFile(dir string) (string, error) { |
| 100 | before, err := snapshot(dir) |
| 101 | if err != nil { |
| 102 | return "", err |
| 103 | } |
| 104 | if err := mk(dir, "bump"); err != nil { |
| 105 | return "", err |
| 106 | } |
| 107 | after, err := snapshot(dir) |
| 108 | if uerr := mk(dir, "unbump"); err == nil { |
| 109 | err = uerr |
| 110 | } |
| 111 | if err != nil { |
| 112 | return "", err |
| 113 | } |
| 114 | for f, h := range after { |
| 115 | if before[f] != h { |
| 116 | return f, nil |
| 117 | } |
| 118 | } |
| 119 | return "", fmt.Errorf("make bump changed no file in %s", dir) |
| 120 | } |
| 121 | |
| 122 | // snapshot hashes every file under dir outside build output and caches. |
| 123 | func snapshot(dir string) (map[string][32]byte, error) { |
| 124 | out := map[string][32]byte{} |
| 125 | err := filepath.WalkDir(dir, func(p string, d fs.DirEntry, err error) error { |
| 126 | if err != nil { |
| 127 | return err |
| 128 | } |
| 129 | if d.IsDir() { |
| 130 | if p != dir && (skipDirs[d.Name()] || strings.HasPrefix(d.Name(), ".")) { |
| 131 | return filepath.SkipDir |
| 132 | } |
| 133 | return nil |
| 134 | } |
| 135 | b, err := os.ReadFile(p) |
| 136 | if err != nil { |
| 137 | return err |
| 138 | } |
| 139 | out[p] = sha256.Sum256(b) |
| 140 | return nil |
| 141 | }) |
| 142 | return out, err |
| 143 | } |
| 144 | |
| 145 | // commentPrefix is the line-comment syntax for a source file. |
| 146 | func commentPrefix(path string) string { |
| 147 | switch strings.ToLower(filepath.Ext(path)) { |
| 148 | case ".hs": |
| 149 | return "-- " |
| 150 | case ".nim", ".rb", ".mojo", ".py": |
| 151 | return "# " |
| 152 | case ".ml", ".mli": |
| 153 | return "(* " |
| 154 | } |
| 155 | return "// " |
| 156 | } |
| 157 | |
| 158 | // editBuild is the one-line change: append a comment line no compiler |
| 159 | // cache has seen to file, time the rebuild, and put the file back. A |
| 160 | // comment changes the source's content (and mtime), so content-addressed |
| 161 | // caches (Go, Zig, Nim, dune) recompile it as surely as mtime-based ones. |
| 162 | func editBuild(dir, file string, run int) (float64, error) { |
| 163 | orig, err := os.ReadFile(file) |
| 164 | if err != nil { |
| 165 | return 0, err |
| 166 | } |
| 167 | defer os.WriteFile(file, orig, 0o644) |
| 168 | line := fmt.Sprintf("%sbakeoff edit %d %d", commentPrefix(file), time.Now().UnixNano(), run) |
| 169 | if strings.HasPrefix(line, "(* ") { |
| 170 | line += " *)" |
| 171 | } |
| 172 | if err := os.WriteFile(file, append(append(orig, '\n'), line+"\n"...), 0o644); err != nil { |
| 173 | return 0, err |
| 174 | } |
| 175 | return timed(dir, "build-arm64") |
| 176 | } |
| 177 | |
amadan