refactor(dev): report-backend-memoryのmarkdown生成ロジックを分離

.github/scripts/backend-memory-report.mjs

@@ -0,0 +1,142 @@
+import { readFile, writeFile } from 'node:fs/promises';
+
+const [baseFile, headFile, outputFile] = process.argv.slice(2);
+
+if (baseFile == null || headFile == null || outputFile == null) {
+	console.error('Usage: node .github/scripts/backend-memory-report.mjs <base-memory.json> <head-memory.json> <report.md>');
+	process.exit(1);
+}
+
+const numberFormatter = new Intl.NumberFormat('en-US', {
+	maximumFractionDigits: 2,
+});
+
+const phases = [
+	{
+		key: 'afterGc',
+		title: 'After GC',
+	},
+];
+
+const metrics = [
+	'HeapUsed',
+	'HeapTotal',
+	'External',
+	'Pss',
+	'Private_Dirty',
+];
+
+function formatNumber(value) {
+	return numberFormatter.format(value);
+}
+
+function formatMemory(valueKiB) {
+	return `${formatNumber(valueKiB / 1024)} MB`;
+}
+
+function formatPercent(value) {
+	return `${formatNumber(value)}%`;
+}
+
+function formatMathText(text) {
+	return text
+		.replaceAll('\\', '\\\\')
+		.replaceAll('{', '\\{')
+		.replaceAll('}', '\\}')
+		.replaceAll('%', '\\%');
+}
+
+function formatColoredDiff(text, diff) {
+	const color = diff > 0 ? 'orange' : 'green';
+	return `$\\color{${color}}{\\text{${formatMathText(text)}}}$`;
+}
+
+function formatDiff(baseKiB, headKiB) {
+	const diff = headKiB - baseKiB;
+	if (diff === 0) return formatMemory(0);
+
+	const sign = diff > 0 ? '+' : '-';
+	return formatColoredDiff(`${sign}${formatMemory(Math.abs(diff))}`, diff);
+}
+
+function formatDiffPercent(baseKiB, headKiB) {
+	const diff = headKiB - baseKiB;
+	if (diff === 0) return '0%';
+	if (baseKiB <= 0) return '-';
+
+	const sign = diff > 0 ? '+' : '-';
+	return formatColoredDiff(`${sign}${formatPercent(Math.abs((diff * 100) / baseKiB))}`, diff);
+}
+
+function getMemoryValue(report, phase, metric) {
+	const value = report?.[phase]?.[metric];
+	return Number.isFinite(value) ? value : null;
+}
+
+function renderTable(base, head, phase) {
+	const lines = [
+		'| Metric | Base | Head | Δ | Δ (%) |',
+		'| --- | ---: | ---: | ---: | ---: |',
+	];
+
+	for (const metric of metrics) {
+		const baseValue = getMemoryValue(base, phase, metric);
+		const headValue = getMemoryValue(head, phase, metric);
+		if (baseValue == null || headValue == null) continue;
+
+		lines.push(`| ${metric} | ${formatMemory(baseValue)} | ${formatMemory(headValue)} | ${formatDiff(baseValue, headValue)} | ${formatDiffPercent(baseValue, headValue)} |`);
+	}
+
+	return lines.join('\n');
+}
+
+function getDiffPercent(base, head, phase, metric) {
+	const baseValue = getMemoryValue(base, phase, metric);
+	const headValue = getMemoryValue(head, phase, metric);
+	if (baseValue == null || headValue == null || baseValue <= 0) return null;
+
+	return ((headValue - baseValue) * 100) / baseValue;
+}
+
+function getWarningMetric(base, head) {
+	for (const metric of ['Pss', 'VmRSS']) {
+		if (getMemoryValue(base, 'afterGc', metric) != null && getMemoryValue(head, 'afterGc', metric) != null) {
+			return metric;
+		}
+	}
+	return null;
+}
+
+function workflowFooter() {
+	const repository = process.env.GITHUB_REPOSITORY;
+	const runId = process.env.GITHUB_RUN_ID;
+	if (repository == null || runId == null) {
+		return 'See workflow logs for details.';
+	}
+
+	return `[See workflow logs for details](https://github.com/${repository}/actions/runs/${runId})`;
+}
+
+const base = JSON.parse(await readFile(baseFile, 'utf8'));
+const head = JSON.parse(await readFile(headFile, 'utf8'));
+const lines = [
+	'## Backend Memory Usage Report',
+	'',
+];
+
+for (const phase of phases) {
+	lines.push(`### ${phase.title}`);
+	lines.push(renderTable(base, head, phase.key));
+	lines.push('');
+}
+
+const warningMetric = getWarningMetric(base, head);
+const warningDiffPercent = warningMetric == null ? null : getDiffPercent(base, head, 'afterGc', warningMetric);
+if (warningMetric != null && warningDiffPercent != null && warningDiffPercent > 5) {
+	lines.push(`⚠️ **Warning**: Memory usage (${warningMetric}) has increased by more than 5%. Please verify this is not an unintended change.`);
+	lines.push('');
+}
+
+lines.push(workflowFooter());
+
+await writeFile(outputFile, `${lines.join('\n')}\n`);