|
| 1 | +"""Local baseline comparison between consecutive CodSpeed runs. |
| 2 | +
|
| 3 | +Implements the feature planned in ``plugin.py``:: |
| 4 | +
|
| 5 | + # Storing the results will be later used for features such as |
| 6 | + # local comparison between runs. |
| 7 | +
|
| 8 | +Only walltime runs produce per-benchmark statistics (``mean_ns``). |
| 9 | +Simulation/analysis runs do not include a ``benchmarks`` key in their |
| 10 | +result JSON, so comparisons are silently skipped for those modes. |
| 11 | +""" |
| 12 | + |
| 13 | +from __future__ import annotations |
| 14 | + |
| 15 | +import json |
| 16 | +from dataclasses import dataclass |
| 17 | +from typing import TYPE_CHECKING |
| 18 | + |
| 19 | +if TYPE_CHECKING: |
| 20 | + from pathlib import Path |
| 21 | + from typing import Any |
| 22 | + |
| 23 | +# A benchmark is considered regressed / improved only when the relative |
| 24 | +# change exceeds these thresholds. Below 5 % the measurement noise of a |
| 25 | +# single local run is too high to draw reliable conclusions. |
| 26 | +_REGRESSION_THRESHOLD = 0.05 |
| 27 | +_IMPROVEMENT_THRESHOLD = 0.05 |
| 28 | + |
| 29 | + |
| 30 | +# --------------------------------------------------------------------------- |
| 31 | +# Public data classes |
| 32 | +# --------------------------------------------------------------------------- |
| 33 | + |
| 34 | + |
| 35 | +@dataclass(frozen=True) |
| 36 | +class BenchmarkDiff: |
| 37 | + """Performance delta for a single benchmark between two runs.""" |
| 38 | + |
| 39 | + name: str |
| 40 | + baseline_mean_ns: float |
| 41 | + current_mean_ns: float |
| 42 | + |
| 43 | + @property |
| 44 | + def change_ratio(self) -> float: |
| 45 | + """Signed relative change. |
| 46 | +
|
| 47 | + Positive → slower (regression). |
| 48 | + Negative → faster (improvement). |
| 49 | + """ |
| 50 | + return (self.current_mean_ns - self.baseline_mean_ns) / self.baseline_mean_ns |
| 51 | + |
| 52 | + @property |
| 53 | + def change_pct(self) -> str: |
| 54 | + sign = "+" if self.change_ratio >= 0 else "" |
| 55 | + return f"{sign}{self.change_ratio * 100:.1f}%" |
| 56 | + |
| 57 | + @property |
| 58 | + def is_regression(self) -> bool: |
| 59 | + return self.change_ratio > _REGRESSION_THRESHOLD |
| 60 | + |
| 61 | + @property |
| 62 | + def is_improvement(self) -> bool: |
| 63 | + return self.change_ratio < -_IMPROVEMENT_THRESHOLD |
| 64 | + |
| 65 | + |
| 66 | +@dataclass(frozen=True) |
| 67 | +class ComparisonReport: |
| 68 | + """Full comparison report between a baseline run and the current run.""" |
| 69 | + |
| 70 | + regressions: tuple[BenchmarkDiff, ...] |
| 71 | + improvements: tuple[BenchmarkDiff, ...] |
| 72 | + unchanged: tuple[BenchmarkDiff, ...] |
| 73 | + new_benchmarks: tuple[str, ...] |
| 74 | + removed_benchmarks: tuple[str, ...] |
| 75 | + |
| 76 | + @property |
| 77 | + def has_changes(self) -> bool: |
| 78 | + return bool( |
| 79 | + self.regressions |
| 80 | + or self.improvements |
| 81 | + or self.new_benchmarks |
| 82 | + or self.removed_benchmarks |
| 83 | + ) |
| 84 | + |
| 85 | + @property |
| 86 | + def total_compared(self) -> int: |
| 87 | + return len(self.regressions) + len(self.improvements) + len(self.unchanged) |
| 88 | + |
| 89 | + |
| 90 | +# --------------------------------------------------------------------------- |
| 91 | +# File discovery |
| 92 | +# --------------------------------------------------------------------------- |
| 93 | + |
| 94 | + |
| 95 | +def find_baseline(results_dir: Path, current_path: Path) -> Path | None: |
| 96 | + """Return the most recent ``results_*.json`` that is not *current_path*. |
| 97 | +
|
| 98 | + Files are ranked by modification time (most recent first). The filename |
| 99 | + itself encodes a millisecond timestamp (``results_{ms}.json``) so mtime |
| 100 | + and filename order are equivalent in practice; mtime is simpler to sort. |
| 101 | +
|
| 102 | + Returns ``None`` when the directory contains no prior run. |
| 103 | + """ |
| 104 | + candidates = sorted( |
| 105 | + (p for p in results_dir.glob("results_*.json") if p != current_path), |
| 106 | + key=lambda p: p.stat().st_mtime, |
| 107 | + reverse=True, |
| 108 | + ) |
| 109 | + return candidates[0] if candidates else None |
| 110 | + |
| 111 | + |
| 112 | +# --------------------------------------------------------------------------- |
| 113 | +# Comparison logic |
| 114 | +# --------------------------------------------------------------------------- |
| 115 | + |
| 116 | + |
| 117 | +def _extract_benchmarks(data: dict[str, Any]) -> dict[str, float]: |
| 118 | + """Return ``{uri: mean_ns}`` from a parsed results JSON. |
| 119 | +
|
| 120 | + Benchmarks without a ``stats.mean_ns`` field (e.g. simulation-mode |
| 121 | + stubs) are silently ignored. |
| 122 | + """ |
| 123 | + result: dict[str, float] = {} |
| 124 | + for bench in data.get("benchmarks", []): |
| 125 | + stats = bench.get("stats") or {} |
| 126 | + mean_ns = stats.get("mean_ns") |
| 127 | + if mean_ns is not None: |
| 128 | + result[bench["uri"]] = float(mean_ns) |
| 129 | + return result |
| 130 | + |
| 131 | + |
| 132 | +def compare_results(baseline_path: Path, current_path: Path) -> ComparisonReport: |
| 133 | + """Compare two CodSpeed result files and return a :class:`ComparisonReport`. |
| 134 | +
|
| 135 | + Args: |
| 136 | + baseline_path: Path to the older ``results_*.json`` file. |
| 137 | + current_path: Path to the newly written ``results_*.json`` file. |
| 138 | +
|
| 139 | + Returns: |
| 140 | + A :class:`ComparisonReport` classifying every benchmark as regressed, |
| 141 | + improved, unchanged, new, or removed. |
| 142 | + """ |
| 143 | + baseline = _extract_benchmarks(json.loads(baseline_path.read_text())) |
| 144 | + current = _extract_benchmarks(json.loads(current_path.read_text())) |
| 145 | + |
| 146 | + regressions: list[BenchmarkDiff] = [] |
| 147 | + improvements: list[BenchmarkDiff] = [] |
| 148 | + unchanged: list[BenchmarkDiff] = [] |
| 149 | + new_benchmarks: list[str] = [] |
| 150 | + |
| 151 | + for uri, current_mean in current.items(): |
| 152 | + if uri not in baseline: |
| 153 | + new_benchmarks.append(uri) |
| 154 | + continue |
| 155 | + diff = BenchmarkDiff( |
| 156 | + name=uri, |
| 157 | + baseline_mean_ns=baseline[uri], |
| 158 | + current_mean_ns=current_mean, |
| 159 | + ) |
| 160 | + if diff.is_regression: |
| 161 | + regressions.append(diff) |
| 162 | + elif diff.is_improvement: |
| 163 | + improvements.append(diff) |
| 164 | + else: |
| 165 | + unchanged.append(diff) |
| 166 | + |
| 167 | + removed_benchmarks = [uri for uri in baseline if uri not in current] |
| 168 | + |
| 169 | + return ComparisonReport( |
| 170 | + # Sort regressions worst-first, improvements best-first. |
| 171 | + regressions=tuple( |
| 172 | + sorted(regressions, key=lambda d: d.change_ratio, reverse=True) |
| 173 | + ), |
| 174 | + improvements=tuple(sorted(improvements, key=lambda d: d.change_ratio)), |
| 175 | + unchanged=tuple(unchanged), |
| 176 | + new_benchmarks=tuple(new_benchmarks), |
| 177 | + removed_benchmarks=tuple(removed_benchmarks), |
| 178 | + ) |
| 179 | + |
| 180 | + |
| 181 | +# --------------------------------------------------------------------------- |
| 182 | +# Terminal output |
| 183 | +# --------------------------------------------------------------------------- |
| 184 | + |
| 185 | + |
| 186 | +def _format_ns(ns: float) -> str: |
| 187 | + """Format a nanosecond duration as a human-readable string.""" |
| 188 | + if ns >= 1_000_000_000: |
| 189 | + return f"{ns / 1_000_000_000:.2f}s" |
| 190 | + if ns >= 1_000_000: |
| 191 | + return f"{ns / 1_000_000:.2f}ms" |
| 192 | + if ns >= 1_000: |
| 193 | + return f"{ns / 1_000:.2f}µs" |
| 194 | + return f"{ns:.0f}ns" |
| 195 | + |
| 196 | + |
| 197 | +def _short_name(uri: str) -> str: |
| 198 | + """Return the test function name part of a benchmark URI.""" |
| 199 | + return uri.split("::")[-1] if "::" in uri else uri |
| 200 | + |
| 201 | + |
| 202 | +def print_comparison_report(report: ComparisonReport, baseline_path: Path) -> None: |
| 203 | + """Print a human-readable comparison report to stdout. |
| 204 | +
|
| 205 | + Produces no output when no benchmarks were compared (e.g. simulation |
| 206 | + mode) to avoid polluting CI logs with empty sections. |
| 207 | + """ |
| 208 | + if report.total_compared == 0 and not report.new_benchmarks: |
| 209 | + return |
| 210 | + |
| 211 | + print(f"\n CodSpeed local comparison (vs {baseline_path.name})") |
| 212 | + print(" " + "─" * 62) |
| 213 | + |
| 214 | + if report.regressions: |
| 215 | + print(f"\n ✗ Regressions ({len(report.regressions)})") |
| 216 | + for diff in report.regressions: |
| 217 | + print( |
| 218 | + f" {_short_name(diff.name):<42}" |
| 219 | + f" {_format_ns(diff.baseline_mean_ns):>8}" |
| 220 | + f" → {_format_ns(diff.current_mean_ns):>8}" |
| 221 | + f" {diff.change_pct}" |
| 222 | + ) |
| 223 | + |
| 224 | + if report.improvements: |
| 225 | + print(f"\n ✓ Improvements ({len(report.improvements)})") |
| 226 | + for diff in report.improvements: |
| 227 | + print( |
| 228 | + f" {_short_name(diff.name):<42}" |
| 229 | + f" {_format_ns(diff.baseline_mean_ns):>8}" |
| 230 | + f" → {_format_ns(diff.current_mean_ns):>8}" |
| 231 | + f" {diff.change_pct}" |
| 232 | + ) |
| 233 | + |
| 234 | + if report.new_benchmarks: |
| 235 | + print(f"\n + New ({len(report.new_benchmarks)})") |
| 236 | + for uri in report.new_benchmarks: |
| 237 | + print(f" {_short_name(uri)}") |
| 238 | + |
| 239 | + if report.removed_benchmarks: |
| 240 | + print(f"\n - Removed ({len(report.removed_benchmarks)})") |
| 241 | + for uri in report.removed_benchmarks: |
| 242 | + print(f" {_short_name(uri)}") |
| 243 | + |
| 244 | + print( |
| 245 | + f"\n {report.total_compared} compared" |
| 246 | + f" · {len(report.regressions)} regression(s)" |
| 247 | + f" · {len(report.improvements)} improvement(s)" |
| 248 | + ) |
| 249 | + print() |
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